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Newsroom: Time Spent with Media in China Grows amid COVID-19 Pandemic

Our Estimate for Time Spent with TV in 2020 Is Revised Upward by 5 Minutes April 24, 2020 (New York, NY) – Over the course of just a few months, […]




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Inhibition of the erythropoietin-producing receptor EPHB4 antagonizes androgen receptor overexpression and reduces enzalutamide resistance [Molecular Bases of Disease]

Prostate cancer (PCa) cells heavily rely on an active androgen receptor (AR) pathway for their survival. Enzalutamide (MDV3100) is a second-generation antiandrogenic drug that was approved by the Food and Drug Administration in 2012 to treat patients with castration-resistant prostate cancer (CRPC). However, emergence of resistance against this drug is inevitable, and it has been a major challenge to develop interventions that help manage enzalutamide-resistant CRPC. Erythropoietin-producing human hepatocellular (Eph) receptors are targeted by ephrin protein ligands and have a broad range of functions. Increasing evidence indicates that this signaling pathway plays an important role in tumorigenesis. Overexpression of EPH receptor B4 (EPHB4) has been observed in multiple types of cancer, being closely associated with proliferation, invasion, and metastasis of tumors. Here, using RNA-Seq analyses of clinical and preclinical samples, along with several biochemical and molecular methods, we report that enzalutamide-resistant PCa requires an active EPHB4 pathway that supports drug resistance of this tumor type. Using a small kinase inhibitor and RNAi-based gene silencing to disrupt EPHB4 activity, we found that these disruptions re-sensitize enzalutamide-resistant PCa to the drug both in vitro and in vivo. Mechanistically, we found that EPHB4 stimulates the AR by inducing proto-oncogene c-Myc (c-Myc) expression. Taken together, these results provide critical insight into the mechanism of enzalutamide resistance in PCa, potentially offering a therapeutic avenue for enhancing the efficacy of enzalutamide to better manage this common malignancy.




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Iraq's Reconstruction: In Conversation with Governor of Anbar Ali Farhan Hamid

Invitation Only Research Event

18 December 2019 - 9:00am to 10:30am

Chatham House | 10 St James's Square | London | SW1Y 4LE

Event participants

Ali Farhan Hamid, Governor of Anbar Province
Chair: Dr Renad Mansour, Senior Research Fellow, Middle East and North Africa Programme, Chatham House

In the aftermath of the liberation from ISIS, the government of Iraq was left to count the cost of three years of brutal conflict, only the most recent phase in the ongoing cycle of conflict and stabilization that has plagued Iraq for 16 years. While reconstruction has been a focus of both the Iraqi government and international policymakers since 2003, billions of dollars in pledged funds have continually failed to reach the places they are most needed. 

At this roundtable, Ali Farhan Hamid will discuss the efforts of his provincial government to rebuild the cities and towns worst-hit by the conflict. He will provide insights into the practical and structural impediments to reconstruction efforts in both Anbar and neighbouring provinces such as Ninewah where the worst damage was sustained under ISIS but where little in the way of reconstruction has been achieved thereby leaving the door open to the potential resurgence of conflict.

The roundtable is part of the Chatham House Iraq Initiative.

Event attributes

Chatham House Rule

Reni Zhelyazkova

Programme Coordinator, Middle East and North Africa Programme
+44 (0)20 7314 3624




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How the Soleimani Assassination Will Reverberate Throughout the Middle East

6 January 2020

Dr Sanam Vakil

Deputy Director and Senior Research Fellow, Middle East and North Africa Programme

Dr Renad Mansour

Senior Research Fellow, Middle East and North Africa Programme; Project Director, Iraq Initiative

Dr Lina Khatib

Director, Middle East and North Africa Programme
Regional experts examine how Iran benefits from the fallout of the killing, the implications for politics in Iraq and how Tehran might respond with its proxies in the region.

2020-01-06-Soleimani.jpg

Protesters hold up an image of Qassem Soleimani during a demonstration in Tehran on 3 January. Photo: Getty Images.

An unexpected bounty for Iran

Sanam Vakil

The assassination of Qassem Soleimani has been an unexpected bounty for the Islamic Republic at a time when Iran was balancing multiple economic, domestic and regional pressures stemming from the Trump administration’s maximum pressure campaign.

Coming on the heels of anti-Iranian demonstrations in Iraq and Lebanon, and following Iran’s own November 2019 protests that resulted in a brutal government crackdown against its own people, the Soleimani killing has helped the Iranian government shift the narrative away from its perceived regional and domestic weaknesses to one of strength.  

The massive funeral scenes in multiple Iranian cities displaying unending waves of mourners chanting against the United States has provided the Islamic Republic with a unique opportunity to showcase its mobilizing potential. This potential is not limited to Iran but also extends to Iraq and Lebanon, where Tehran’s transnational summoning power has also been visible. The Iraqi parliamentary vote to end the American military presence is one early negative consequence. While the region awaits Iran’s response, further anti-American rallying cries will continue to reverberate.  

Domestically, Soleimani’s death and President Donald Trump’s continued provocations on Twitter, including threats to attack 52 Iranian cultural sites, are being used as a nationalist rallying cry. This sentiment should not be seen solely as Islamic or ideological, but rather an opportunity for the state to pivot to an Iranian-based nationalism that is more inclusive and empowering for much of the country’s disgruntled youth.

Iran’s notoriously divided political factions have also unified in the face of this crisis. With parliamentary elections looming in February and turnout previously expected to be low, the political establishment is likely to use this crisis to mobilize voters in favour of conservative candidates.  

How Tehran chooses to respond to Qassem Soleimani’s death will very much determine its ability to continue to control the narrative and manage its swell of domestic and regional support. For these benefits to continue to manifest, it is important for Tehran to balance the mix of public sympathy and international anxiety and not overplay its hand in its quest for revenge.

A reset for Iraqi politics

Renad Mansour

The US strike which killed Qassem Soleimani and Abu Mehdi al-Muhandis has grave implications for Iraq. The act jeopardizes Iraq’s recently stabilized security situation, and threatens to reshape the country’s political environment, moving backwards to the days of anti-Americanism and sect-based mobilization. If Baghdad loses relations with the US and other diplomatic representations, it risks turning into a pariah state. 

Over the past few years, and notably since October 2019, young Iraqis have taken to the streets demanding reform and the downfall of the political establishment, and its main external backer Iran. The political establishment, including political parties and militias close to Tehran, failed to appease or suppress these protests. Now, these political elites are using the deaths of Muhandis and Soleimani to (re)gain popularity from their own population, by drawing on the old tool of anti-Americanism. 

Following the attacks, Shia populist cleric Muqtada al-Sadr – who until recently had called for an end to Iranian and pro-Iranian militia influence in Iraq – has called to revamp the Mehdi Army that he led until 2008 and is calling for ‘Islamic resistance’ to the US. In seeking to regain control of his former movement, he is coming closer to former Shia foes.

For years, pro-Iranian groups attempted to push the US out of Iraq. Their calls often fell on deaf ears, as public opinion in Iraq did not consider the US as a threat and some even supported the US and international effort against ISIS. Following the attacks, however, anti-American voices have gained more ammunition.

A complete American withdrawal would not only have direct security implications but force other countries and organizations, from European states to NATO, to reconsider their positions and role.

Limited options for ‘revenge’ in the Levant

Lina Khatib

Iran’s use of Lebanon and Syria as spaces for revenge against the US is unlikely.

On Sunday, Hezbollah leader Hassan Nasrallah vowed revenge for Soleimani’s death by singling out American soldiers as a target. However, Hezbollah’s options are limited. Lebanon is in the middle of wide-ranging protests against the country’s ruling political class, of which Nasrallah is a key figure.

Unlike in 2006, when Hezbollah’s military actions against Israel rallied the public around it, today there is no public appetite for dragging Lebanon into a war. Were Hezbollah to instigate one, it would incur public anger, if only for the economic repercussions that would exacerbate an already severe financial crisis in Lebanon. Lebanon also does not have any US military bases that could be a target for Hezbollah.

In theory, Hezbollah or other Iranian-backed groups could attack American bases in Syria. But these bases are staffed by multinational forces from the international anti-ISIS coalition. Attacking them would therefore put Iran in confrontation with other countries besides the US, which is not in Iran’s interest.

Attacking US soldiers in northeast Syria would also go against Kurdish interests because it would weaken the anti-ISIS coalition front of which Kurdish forces are part. It would, furthermore, anger Arab tribes in the area, opening up possibilities for ISIS to take advantage of public dissent to stage a comeback. Iran would then find itself fighting on several fronts at once, which it does not have the capacity to handle. 

More likely, Iran’s allies and proxies in the Levant are going to engage in strong rhetoric without taking hasty actions. When a key Hezbollah leader, Imad Mughniyeh, was assassinated in Damascus on 2008, there were strong words and public vows to seek revenge for his killing, but ultimately there was no response.    




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The Middle East and North Africa Region in 2020

Invitation Only Research Event

15 January 2020 - 8:15am to 9:30am

Chatham House | 10 St James's Square | London | SW1Y 4LE

Event participants

Chair: Dr Lina Khatib, Director, Middle East and North Africa Programme, Chatham House

2019 was a turbulent year for the Middle East and North Africa. The region was swept by a wave of anti-government protests with popular unrest erupting across Algeria, Egypt, Lebanon, Iraq and Iran. Tensions in the Gulf escalated following clashes between Iran, Saudi Arabia and the United States. Nearly a decade after the Arab Spring, civil wars in Libya, Syria and Yemen continue to rage with little hope for political solutions to the crises.

At this breakfast briefing, Chatham House's Middle East and North Africa Programme researchers will discuss possible scenarios for the region in the year ahead. The experts will explore key trends relevant to the business community and will share insights from recent research trips and discussions with key stakeholders in the MENA region. 

Please note that participation in this event is only open to supporters of the Chatham House Middle East and North Africa Programme and selected guests.

Event attributes

Chatham House Rule

Reni Zhelyazkova

Programme Coordinator, Middle East and North Africa Programme
+44 (0)20 7314 3624




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Dr Lina Khatib to head Middle East and North Africa Programme

3 May 2016

Chatham House is pleased to announce that Dr Lina Khatib has joined the institute as head of the Middle East and North Africa Programme.

Dr Lina Khatib takes up her role at Chatham House as of 3 May 2016. She joins Chatham House from her position as a senior research associate with the Arab Reform Initiative. Previously, she was director of the Carnegie Middle East Center in Beirut and, prior to that, the co-founding head of the Program on Arab Reform and Democracy at Stanford University’s Center on Democracy, Development, and the Rule of Law.

Dr Robin Niblett, director of Chatham House, said: ‘I take great pleasure in welcoming Dr Lina Khatib to Chatham House. Dr Khatib joins our team at a critical time of prolonged turmoil and upheaval in the Middle East and North Africa. Her significant international experience of analysing developments in the region will be a great asset to Chatham House as it assesses the core political, economic, societal and security issues affecting peace and prosperity across this region. I would also like to thank Dr Neil Quilliam for his strong leadership of the Middle East and North Africa Programme since 2014.’

Dr Lina Khatib, said: ‘At a time when countries in the Middle East and North Africa face critical challenges, from continuing conflicts in Syria, Libya, and elsewhere, to increasing socio-economic pressures, it is essential for policy decisions to be informed by rigorous and forward-thinking research and debate. I look forward to working with the team at Chatham House to assist decision-makers and the public in understanding the complexities of an important region at this turbulent moment and seeking creative ways of alleviating its challenges.’ 

Dr Neil Quilliam, who has been acting head of the programme since December 2015, will continue with his role as senior research fellow and Syria project director. 

Editor's notes

Dr Khatib holds a BA from the American University of Beirut and an MA and PhD from the University of Leicester. Her research spans the international relations of the Middle East, Islamist groups, political transitions and foreign policy, with a focus on the regional and international political and security dimensions of the Syrian conflict.

Dr Khatib has published seven books, including Image Politics in the Middle East: The Role of the Visual in Political Struggle (I. B. Tauris, 2013), Taking to the Streets: The Transformation of Arab Activism (co-edited with Ellen Lust, Johns Hopkins University Press, 2014), and The Hizbullah Phenomenon: Politics and Communication (co-authored with Dina Matar and Atef Alshaer, Hurst/Oxford University Press, 2014). She has also published widely on public diplomacy, political communication, and political participation in the Middle East.

Since 2008, Dr Khatib has been a founding co-editor of the Middle East Journal of Culture and Communication and a research associate at the University of London’s School of Oriental and African Studies. From 2010 to 2012, she was a non-resident research fellow at the University of Southern California’s Center on Public Diplomacy. She lectured at Royal Holloway, University of London from 2003 to 2010.

Prior to joining the academic field, Dr Khatib worked in broadcast journalism in Lebanon.




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Transatlantic Strategy Group on the Future of US Global Leadership: Transatlantic Security Policy Towards a Changing Middle East

Invitation Only Research Event

6 February 2015 - 8:45am to 4:30pm

Residence of the British Ambassador to France, Paris

With the Middle East in chaos and the future of many states increasingly uncertain, there is a large amount of attention as to how policy-makers in Europe and the US should respond. In particular, many in Europe are unsure of long-term US policy in light of competing American priorities, budgetary constraints and a public adverse to committing further resources abroad. In this context, it is important that European and American policy-makers understand each other’s positions.

At this all-day event, a group of experts will discuss how US policy towards the Middle East is changing, what this means for Europe and, subsequently, how Europe should respond. 

Attendance at this event is by invitation only.

The workshop is held as part of the Transatlantic Strategy Group on the Future of US Global Leadership run jointly with the German Marshall Fund of the United States. Over the course of a year, this group will discuss how US policy is changing on key issues and the implications for Europe. This project is supported by the Fritz Thyssen Foundation, with support for this event provided by the Delegation of Strategic Affairs of the French Ministry of Defence and the British Embassy in Paris.

Event attributes

External event

Department/project




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Webinar: International Humanitarian Law Amid Coronavirus

Members Event Webinar

15 May 2020 - 1:00pm to 2:00pm
Add to Calendar

Emanuela-Chiara Gillard, Associate Fellow, International Law Programme, Chatham House

Chair: Chanu Peiris, Programme Manager, International Law Programme, Chatham House

Further speakers to be announced.

In April 2020, UN Secretary General Antonio Guterres called for a global ceasefire in order for communities and states to focus efforts on responding to the coronavirus outbreak. The consequences of armed conflict – including displacement, detention, lack of access to health services and disrupted social infrastructures – mean that those in conflict-ridden areas are amongst the most vulnerable to the virus. Observing international humanitarian law (IHL) could be one way of safeguarding against, at least, the provision of vital medical supplies and personnel for vulnerable groups. Against the backdrop of a growing health and economic emergency that is otherwise dominating government agendas, how do we emphasise the importance of humanitarian action and guarantee - or improve - compliance?

The panellists will discuss the remit and limitations of international humanitarian law and how the pandemic might complicate compliance. What is the framework for humanitarian action under international humanitarian law? What are the challenges to delivering relief? And how has COVID-19 impacted humanitarian action in conflict-ridden areas?

This event is for Chatham House members only. Not a member? Find out more.




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Inside Syria: Life Amidst Revolution and War

Members Event

28 January 2016 - 1:00pm to 2:00pm

Chatham House, London

Event participants

Mina Al-Oraibi, Journalist on Middle East affairs
Robin Yassin-Kassab, Author, Burning Country: Syrians in Revolution and War
Chair: Dr Neil Quilliam, Acting Head, Middle East and North Africa Programme, Chatham House

In 2011, many Syrians took to the streets of Damascus to demand the overthrow of the government of Bashar al-Assad. Today, much of Syria has become a warzone and many worry that the country is on the brink of collapse.

Drawing on first-hand testimonies from opposition fighters, exiles and human rights activists, the panel will explore the complicated reality of life in present-day Syria. Looking at the militarization of the uprising, the rise of the Islamists and sectarian warfare, and the role of Syria’s government in the conflict, the speakers will discuss the issues from the grassroots to the geopolitical, including the role of the international community in bringing to an end the bloodshed.

This event is now full and registration has closed. An audio recording will be made available shortly after the event has taken place.

Members Events Team




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US 2020: America’s National Security Strategy and Middle East Policy

Invitation Only Research Event

10 February 2020 - 10:30am to 11:30am

Chatham House | 10 St James's Square | London | SW1Y 4LE

Event participants

Dr Kori Schake, Resident Scholar and Director of Foreign and Defense Policy Studies, American Enterprise Institute 
Chair: Dr Leslie Vinjamuri, Director, US and Americas Programme

In the run-up to the 2016 US presidential election, then-candidate Donald Trump made a series of campaign promises concerning US foreign policy towards the Middle East. Since assuming office, President Trump has withdrawn the US from the Joint Comprehensive Plan of Action, withdrawn troops from Syria, relocated the US embassy in Israel to Jerusalem and orchestrated the strike against ISIS leader Abu Bakr al-Baghdadi.

Against a backdrop of Trump's inclination towards withdrawing from the region, countries across the Middle East are being rocked by protests, Turkey’s purchase of Russia’s S-400 missile has threatened to undermine cohesion within NATO and the much hoped for ceasefire in Libya between UN-backed government leader, Fayez al-Sarraj, and opposition leader, Khalifa Haftar, failed to materialize.

In light of the upcoming US elections in November 2020, the future of US national security policy promises to be a prominent issue for the next administration. In this vein, the US and Americas Programme at Chatham House plans a yearlong focus on the pivotal US 2020 elections.

At this event, Dr Kori Schake, director of foreign and defense policy studies at the American Enterprise Institute will discuss the future of US foreign policy towards the Middle East. How have domestic and party politics in the US – and the unfolding presidential campaign – shaped recent policy decisions by the Trump administration? Should we expect policy objectives in the Middle East to remain consistent or shift under a second Trump term? And what direction could US foreign policy towards the region take under a Democratic administration?

Attendance at this event is by invitation only. 

Event attributes

Chatham House Rule

Department/project

US and Americas Programme




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Webinar: International Humanitarian Law Amid Coronavirus

Members Event Webinar

15 May 2020 - 1:00pm to 2:00pm
Add to Calendar

Emanuela-Chiara Gillard, Associate Fellow, International Law Programme, Chatham House

Chair: Chanu Peiris, Programme Manager, International Law Programme, Chatham House

Further speakers to be announced.

In April 2020, UN Secretary General Antonio Guterres called for a global ceasefire in order for communities and states to focus efforts on responding to the coronavirus outbreak. The consequences of armed conflict – including displacement, detention, lack of access to health services and disrupted social infrastructures – mean that those in conflict-ridden areas are amongst the most vulnerable to the virus. Observing international humanitarian law (IHL) could be one way of safeguarding against, at least, the provision of vital medical supplies and personnel for vulnerable groups. Against the backdrop of a growing health and economic emergency that is otherwise dominating government agendas, how do we emphasise the importance of humanitarian action and guarantee - or improve - compliance?

The panellists will discuss the remit and limitations of international humanitarian law and how the pandemic might complicate compliance. What is the framework for humanitarian action under international humanitarian law? What are the challenges to delivering relief? And how has COVID-19 impacted humanitarian action in conflict-ridden areas?

This event is for Chatham House members only. Not a member? Find out more.




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The Politics of Personality in the Middle East




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Voices of Jordan: The Kingdom in the Centre of the Middle East




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Assessing the Midterm Elections and the Impact on the Trump Presidency




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Undercurrents: Episode 21 - EU-US Relations after the Midterms, and Tackling the Illegal Wildlife Trade in Africa




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Citizenship and Discontent in the Middle East




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Conflict Economies in the Middle East and North Africa





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CBD Press Release: AEON Environmental Foundation Established 'The Midori Prize for Biodiversity'.




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CBD Communiqué: Winners of the MIDORI Prize for Biodiversity announced at the United Nations.




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CBD Communiqué: Implementing the Nagoya Biodiversity Compact in North Africa and the Middle East.




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CBD Communiqué: The MIDORI Prize for Biodiversity at the service of the United Nations Decade on Biodiversity




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CBD Press Release: Capacity-building workshop for North Africa and the Middle East on mainstreaming the economics of ecosystems and biodiversity (TEEB) into national planning and decision-making




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CBD News: Statement by Mr. Braulio Ferreira de Souza Dias, CBD Executive Secretary, on the occasion of the Wider Caribbean and Western Mid-Atlantic Regional Workshop to Facilitate the Description of Ecologically or Biologically Significant Marine Areas,




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CBD Press Release: Nominations open for the 2012 Midori Prize for Biodiversity




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CBD Press Release: Tokyo/Montreal 20 September 2012 - The winners of the MIDORI Prize for Biodiversity have been announced today in Tokyo.




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CBD News: Statement by Mr. Braulio Ferreira de Souza Dias, CBD Executive Secretary, on the occasion of the Regional Capacity-Building Workshop on the Nagoya Protocol on Acess and Benefit-Sharing for Middle East Region and Djibouti, Libya, Mauritania, Amma




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CBD News: Statement by Mr. Braulio F. de Souza Dias, CBD Executive Secretary, at the Opening of the Regional Workshop for Middle East and North Africa on the Preparation of the Fifth National Report, Doha, Qatar, 14-17 December 2013




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CBD News: Nominations are now invited for The MIDORI Prize for Biodiversity 2014, a biennial international prize co-organized by the AEON Environmental Foundation and the Secretariat of the Convention on Biological Diversity (CBD). The Prize honours indiv




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CBD News: Bringing international recognition and a substantial monetary prize to three outstanding individuals, nominations are now invited for The MIDORI Prize for Biodiversity 2014. The call for nominations remains open from 1 March to 31 May 2014.




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CBD News: The Midori Prize for Biodiversity, established by the AEON environmental Foundation, was awarded today to three individuals who have made outstanding contributions to the conservation and sustainable use of biodiversity at all levels.




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CBD News: The fourth addition of Global Biodiversity Outlook is now available in Japanese, courtesy of the Nature Conservation Bureau of Japan's Ministry of the Environment. This brings to eight the number of languages in which the mid-term assessment




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CBD News: With the aim to encourage positive action for biodiversity and inspire others by showcasing the notable work of those it honours, nominations are now invited for the MIDORI Prize for Biodiversity 2016. The call for nominations remains open from




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CBD News: The winners of the MIDORI Prize for Biodiversity 2016 have today been announced.




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CBD News: Nominations are now invited for the MIDORI Prize for Biodiversity 2018. The call for nominations remains open until 15 June 2018.




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CBD News: The winners of the MIDORI Prize for Biodiversity 2018 were announced today. The MIDORI Prize is a prestigious biennial international prize organized by the AEON Environmental Foundation and the Secretariat of the Convention on Biological Diversi




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CBD News: The two-year wait is over! Amidst the beating sun of Sharm-el-Sheikh comes a project from the cold, dark winter of Northern Europe.




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CBD News: Nominations are now invited for The MIDORI Prize for Biodiversity 2020. The call for nominations remains open until 30 March 2020.




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CBD Notification SCBD/IMS/JMF/NP/CR/IH/88710 (2020-027): Final Call for Nominations for the MIDORI Prize for Biodiversity 2020




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CapitalRise reassesses its mission amidst Brexit and regulation change

The proptech startup wanted to democratise investment in prime real estate projects through crowdfunding, but government regulations have limited its reach to high net worth individuals




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HKTDC helps SMEs amid unprecedented challenges

With the novel coronavirus expected to further impact Hong Kong’s already slowing economy, the Hong Kong Trade Development Council (HKTDC) is working hand in hand with local small and medium-sized enterprises (SMEs) to brave the...




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Exporter confidence hits record low amid COVID-19 outbreak

The confidence level of Hong Kong’s exporters has fallen to its lowest-ever level in the face of a triple challenge – the COVID-19 outbreak, softening global demand and lingering trade tension between the United States and Mainland...




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Inhibition of the erythropoietin-producing receptor EPHB4 antagonizes androgen receptor overexpression and reduces enzalutamide resistance [Molecular Bases of Disease]

Prostate cancer (PCa) cells heavily rely on an active androgen receptor (AR) pathway for their survival. Enzalutamide (MDV3100) is a second-generation antiandrogenic drug that was approved by the Food and Drug Administration in 2012 to treat patients with castration-resistant prostate cancer (CRPC). However, emergence of resistance against this drug is inevitable, and it has been a major challenge to develop interventions that help manage enzalutamide-resistant CRPC. Erythropoietin-producing human hepatocellular (Eph) receptors are targeted by ephrin protein ligands and have a broad range of functions. Increasing evidence indicates that this signaling pathway plays an important role in tumorigenesis. Overexpression of EPH receptor B4 (EPHB4) has been observed in multiple types of cancer, being closely associated with proliferation, invasion, and metastasis of tumors. Here, using RNA-Seq analyses of clinical and preclinical samples, along with several biochemical and molecular methods, we report that enzalutamide-resistant PCa requires an active EPHB4 pathway that supports drug resistance of this tumor type. Using a small kinase inhibitor and RNAi-based gene silencing to disrupt EPHB4 activity, we found that these disruptions re-sensitize enzalutamide-resistant PCa to the drug both in vitro and in vivo. Mechanistically, we found that EPHB4 stimulates the AR by inducing proto-oncogene c-Myc (c-Myc) expression. Taken together, these results provide critical insight into the mechanism of enzalutamide resistance in PCa, potentially offering a therapeutic avenue for enhancing the efficacy of enzalutamide to better manage this common malignancy.




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Determination of globotriaosylceramide analogs in the organs of a mouse model of Fabry disease [Lipids]

Fabry disease is a heritable lipid disorder caused by the low activity of α-galactosidase A and characterized by the systemic accumulation of globotriaosylceramide (Gb3). Recent studies have reported a structural heterogeneity of Gb3 in Fabry disease, including Gb3 isoforms with different fatty acids and Gb3 analogs with modifications on the sphingosine moiety. However, Gb3 assays are often performed only on the selected Gb3 isoforms. To precisely determine the total Gb3 concentration, here we established two methods for determining both Gb3 isoforms and analogs. One was the deacylation method, involving Gb3 treatment with sphingolipid ceramide N-deacylase, followed by an assay of the deacylated products, globotriaosylsphingosine (lyso-Gb3) and its analogs, by ultra-performance LC coupled to tandem MS (UPLC-MS/MS). The other method was a direct assay established in the present study for 37 Gb3 isoforms and analogs/isoforms by UPLC-MS/MS. Gb3s from the organs of symptomatic animals of a Fabry disease mouse model were mainly Gb3 isoforms and two Gb3 analogs, such as Gb3(+18) containing the lyso-Gb3(+18) moiety and Gb3(−2) containing the lyso-Gb3(−2) moiety. The total concentrations and Gb3 analog distributions determined by the two methods were comparable. Gb3(+18) levels were high in the kidneys (24% of total Gb3) and the liver (13%), and we observed Gb3(−2) in the heart (10%) and the kidneys (5%). These results indicate organ-specific expression of Gb3 analogs, insights that may lead to a deeper understanding of the pathophysiology of Fabry disease.




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Determination of globotriaosylceramide analogs in the organs of a mouse model of Fabry disease [Lipids]

Fabry disease is a heritable lipid disorder caused by the low activity of α-galactosidase A and characterized by the systemic accumulation of globotriaosylceramide (Gb3). Recent studies have reported a structural heterogeneity of Gb3 in Fabry disease, including Gb3 isoforms with different fatty acids and Gb3 analogs with modifications on the sphingosine moiety. However, Gb3 assays are often performed only on the selected Gb3 isoforms. To precisely determine the total Gb3 concentration, here we established two methods for determining both Gb3 isoforms and analogs. One was the deacylation method, involving Gb3 treatment with sphingolipid ceramide N-deacylase, followed by an assay of the deacylated products, globotriaosylsphingosine (lyso-Gb3) and its analogs, by ultra-performance LC coupled to tandem MS (UPLC-MS/MS). The other method was a direct assay established in the present study for 37 Gb3 isoforms and analogs/isoforms by UPLC-MS/MS. Gb3s from the organs of symptomatic animals of a Fabry disease mouse model were mainly Gb3 isoforms and two Gb3 analogs, such as Gb3(+18) containing the lyso-Gb3(+18) moiety and Gb3(−2) containing the lyso-Gb3(−2) moiety. The total concentrations and Gb3 analog distributions determined by the two methods were comparable. Gb3(+18) levels were high in the kidneys (24% of total Gb3) and the liver (13%), and we observed Gb3(−2) in the heart (10%) and the kidneys (5%). These results indicate organ-specific expression of Gb3 analogs, insights that may lead to a deeper understanding of the pathophysiology of Fabry disease.




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Combined Visual and Semi-quantitative Evaluation Improves Outcome Prediction by Early Mid-treatment 18F-fluoro-deoxi-glucose Positron Emission Tomography in Diffuse Large B-cell Lymphoma.

The purpose of this study was to assess the predictive and prognostic value of interim FDG PET (iPET) in evaluating early response to immuno-chemotherapy after two cycles (PET-2) in diffuse large B-cell lymphoma (DLBCL) by applying two different methods of interpretation: the Deauville visual five-point scale (5-PS) and a change in standardised uptake value by semi-quantitative evaluation. Methods: 145 patients with newly diagnosed DLBCL underwent pre-treatment PET (PET-0) and PET-2 assessment. PET-2 was classified according to both the visual 5-PS and percentage SUV changes (SUV). Receiver operating characteristic (ROC) analysis was performed to compare the accuracy of the two methods for predicting progression-free survival (PFS). Survival estimates, based on each method separately and combined, were calculated for iPET-positive (iPET+) and iPET-negative (iPET–) groups and compared. Results: Both with visual and SUV-based evaluations significant differences were found between the PFS of iPET– and iPET+ patient groups (p<0.001). Visually the best negative (NPV) and positive predictive value (PPV) occurred when iPET was defined as positive if Deauville score 4-5 (89% and 59%, respectively). Using the 66% SUV cut-off value, reported previously, NPV and PPV were 80 and 76%, respectively. SUV at 48.9% cut-off point, reported for the first time here, produced 100% specificity along with the highest sensitivity (24%). Visual and semi-quantitative SUV<48.9% assessment of each PET-2 gave the same PET-2 classification (positive or negative) in 70% (102/145) of all patients. This combined classification delivered NPV and PPV of 89% and 100% respectively, and all iPET+ patients failed to achieve or remain in remission. Conclusion: In this large consistently treated and assessed series of DLBCL, iPET had good prognostic value interpreted either visually or semi-quantitatively. We determined that the most effective SUV cut-off was at 48.9%, and that when combined with visual 5-PS assessment, a positive PET-2 was highly predictive of treatment failure.




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Imaging P-glycoprotein Induction at the Blood-Brain Barrier of a Beta-Amyloidosis Mouse Model with 11C-Metoclopramide PET

P-glycoprotein (ABCB1) plays an important role at the blood-brain barrier (BBB) in promoting the clearance of neurotoxic beta-amyloid (Aß) peptides from the brain into the blood. ABCB1 expression and activity were found to be decreased in the brains of Alzheimer disease (AD) patients. Treatment with drugs which induce cerebral ABCB1 activity may be a promising approach to delay the build-up of Aß deposits in the brain by enhancing the clearance of Aß peptides from the brain. The aim of this study was to investigate whether PET with the weak ABCB1 substrate radiotracer 11C-metoclopramide can measure ABCB1 induction at the BBB in a beta-amyloidosis mouse model (APP/PS1-21 mice) and in wild-type mice. Methods: Groups of wild-type and APP/PS1-21 mice aged 50 or 170 days underwent 11C-metoclopramide baseline PET scans or scans after intraperitoneal treatment with the rodent pregnane X receptor (PXR) activator 5-pregnen-3β-ol-20-one-16α-carbonitrile (PCN, 25 mg/kg) or its vehicle over 7 days. At the end of the PET scans, brains were harvested for immunohistochemical analysis of ABCB1 and Aß levels. In separate groups of mice, radiolabeled metabolites of 11C-metoclopramide were determined in plasma and brain at 15 min after radiotracer injection. As an outcome parameter of cerebral ABCB1 activity, the elimination slope of radioactivity washout from the brain (kE,brain) was calculated. Results: PCN treatment resulted in an increased clearance of radioactivity from the brain as reflected by significant increases in kE,brain (from +26% to +54% relative to baseline). Immunohistochemical analysis confirmed ABCB1 induction in the brains of PCN-treated APP/PS1-21 mice with a concomitant decrease in Aß levels. There was a significant positive correlation between kE,brain values and ABCB1 levels in the brain. In wild-type mice, a significant age-related decrease in kE,brain values was found. Metabolite analysis showed that the majority of radioactivity in the brain was composed of unmetabolized 11C-metoclopramide in all animal groups. Conclusion: 11C-metoclopramide can measure ABCB1 induction in the mouse brain without the need to consider an arterial input function and may find potential application in AD patients to non-invasively evaluate strategies to enhance the clearance properties of the BBB.




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Skin barrier lipid enzyme activity in Netherton patients is associated with protease activity and ceramide abnormalities

Jeroen van Smeden
Apr 7, 2020; 0:jlr.RA120000639v1-jlr.RA120000639
Research Articles




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Comparative profiling and comprehensive quantification of stratum corneum ceramides in humans and mice by LC-MS/MS

Momoko Kawana
Apr 7, 2020; 0:jlr.RA120000671v1-jlr.RA120000671
Research Articles




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Comparative profiling and comprehensive quantification of stratum corneum ceramides in humans and mice by LC-MS/MS [Research Articles]

Ceramides are the predominant lipids in the stratum corneum (SC) and are crucial components for normal skin barrier function. Although the composition of various ceramide classes in the human SC has been reported, that in mice is still unknown, despite mice being widely used as animal models of skin barrier function. Here, we performed LC–MS/MS analyses using recently available ceramide class standards to measure 25 classes of free ceramides and 5 classes of protein-bound ceramides from the human and mouse SC. Phytosphingosine-type ceramides (P-ceramides) and 6-hydroxy sphingosine-type ceramides (H-ceramides), which both contain an additional hydroxyl group, were abundant in human SC (35% and 45% of total ceramides, respectively). In contrast, in mice, P-ceramides and H-ceramides were present at ~1% and undetectable levels, respectively, and sphingosine-type ceramides accounted for ~90%. In humans, ceramides containing α-hydroxy FA were abundant, whereas ceramides containing β-hydroxy FA (B-ceramides) or -hydroxy FA were abundant in mice. The hydroxylated β-carbon in B-ceramides was in the (R)-configuration. Genetic knockout of β-hydroxy acyl-CoA dehydratases in HAP1 cells increased B-ceramide levels, suggesting that β-hydroxy acyl-CoA, an FA-elongation cycle intermediate in the endoplasmic reticulum, is a substrate for B-ceramide synthesis. We anticipate that our methods and findings will help to elucidate the role of each ceramide class in skin barrier formation and in the pathogenesis of skin disorders.