I had great time attending the 2011 edition of the America Association for Cancer research satellite meeting “Molecular Targets and Cancer Therapeutics 2011″ held in San-Francisco. I am very pleased with the overall quality of the meeting and the data presented. It was a fantastic opportunity to expand my background, present our research and connect with various individuals for future collaborative work. Several companies have shown great interest in our work especially regarding our current studies on histone methyl transferase and their specific and selective inhibitors. The poster I presented can be downloaded here (PDF). Below, is the abstract submitted to the meeting.

Background: The nuclear receptor binding SET domain (NSD) protein is a family of three histone-lysine N-methyltransferase (HMTase), NSD1, NSD2/MMSET/WHSC1, and NSD3/WHSC1L1 that are critical in maintaining the chromatin integrity. NSD1 methylates H3K36 and H4K20 and is associated with acute myeloid leukemia, multiple myeloma, and lung cancer. The NSD1-NUP98 translocation plays a significant role in childhood acute myeloid leukemia with NUP98-NSD1 being an active H3K36 methylase. NSD1 is amplified in multiple myeloma, lung cancer, neuroblastomas and glioblastomas. NSD2 methylates H3K36 and is linked to prostate cancer and multiple myeloma. Over expression of NSD2 in myeloma cells leads to aberrantly high levels of H3K36 di-methylation, accompanied by a decrease in H3K27 methylation. NSD2 is found over expressed in fifteen different cancers and is associated with tumor aggressiveness or prognosis in most types of cancers. NSD3 methylates H3K36 and is associated with both lung and breast cancers along with the acute myeloid leukemia. The amplification of either NSD1 or NSD2 triggers the cellular transformation. NSD3 is found amplified in breast cancer cell lines and primary breast carcinomas. Reducing NSDs activity through specific and selective lysine-HMTase inhibitors appears promising to help suppressing cancer growth.

Little is known about the NSD pathways and our understanding of the histone Lysine-HMTase mechanism is partial. The SET domain of NSD1 has specific mechanisms to recognize histone marks unlike other HMTase. The precise catalytic activities of the NSDs are obscure and discrepancies exist hindering progress in understanding their exact biological functions and pathways in cancer pathogenesis. In this study, we explored the in vitro catalytic activities on histone substrates to understand the substrate recognition and to pave the way for the design of selective and specific NSD inhibitors usable in cancer therapies.

Methods: We used both biochemical and computational methods to understand the substrates recognition by the NSDs and to investigate the structural mechanisms happening in the SET domain during the binding of histone tails.

Results: A key regulatory and a recognition mechanism is driven by the flexibility of a loop at the interface of the SET and postSET region who rotates ~45° and translated 7Å opening the SET domain for the binding of the peptide ligand. This regulatory loop acts as a seat belt for the ligand and contributes to the discrimination and the substrate specificity. In vitro, The SET domain of the NSDs favor H3 recognition and are able to methylate a range of substrate. To reconcile with the in vivo activities previously reported on H3K36 and H4K20, we propose a cross-talk mechanism controlling the substrate recognition.

My lab is having a terrific summer so far. I’m not saying that to make a statement or massage my ego but I am happy to see progress. My two Dutch students (Daan and Lennart) made significant contributions to the projects. With Masayo in maternity leave, I was anxious about slowdowns in the lab. Lennart took some of Masayo duties in managing the day to day lab-life. I must say Lennart is doing a great job. As for myself, I’m stuck in front of my computers writing papers and grant proposals. However, I’m always pleased to discuss results, propose futur experiments, and explain projects anytime with my lab members. My office door is always open, and I like to keep it that way.

A photo of Lennart’s crystal photos of PRMT5, a 72Kda human argine-methyltransferase. This is one of the hits we obtained and we are currently optimizing the crystallization conditions.

The last 4 months have been really exciting. The work in the lab has been terrific. Thanks to Masayo’s skills, the projects have been really taking off. We have been doing a bunch of cloning and building numerous constructs of various histone methyltransferase (HMTase). In addition, we started working on some putative regulatory partners. One of our goals is to find highly selective and specific HMTase inhibitors, especially for the NSD family. To do so, we are heavily using virtual ligand screening methods and come-up with a short list of molecules to try in the lab. The latest incarnation of AutoDock, AutoDock Vina, have been very useful and efficient to us. Here an animation of the best candidate we found so far, out of over 10,000 molecules of potential interest.

NSD1 SET domain virtual ligand screening

After weeks of ordering lab stuffs, chemicals and equipments, the research projects are taking off. Good data starts accumulating. I’m very pleased with that. Thanks to a grant from the national research foundation of Korea, Masayo joined the lab along with a lab assistant and an undergraduate student. I’m thrilled to see the lab alive and moving forward through our projects. Check-out our lab website: http://webbuild.knu.ac.kr/~diluccio/