Elucidating the role of metabolic changes in modulating cell fate following treatment with anti-mitotic drugs

Anti-mitotic drugs are the most-commonly utilised class of chemotherapeutic agents that are administered as first-line therapy; however, their clinical success has been impeded by chemoresistance and disease relapse. Better understanding of the cellular pathways underlying this escape from antimitotic drug-induced cell death, known as mitotic slippage, is crucial for development of combinatorial therapies that can enhance existing treatment regimen in patients. Mitotic slippage describes a phenomenon where cells escape mitotic arrest and cell death following treatment with anti-mitotic drugs, and "slip" into interphase without proper chromosome segregation and cytokinesis. One of the cell fates following mitotic slippage is a cell cycle-enforced G1 arrest where cells eventually enter senescence. However, the consequences of mitotic-slippage induced senescence is unclear for anti-mitotic drug therapy. This thesis seeks to address this conundrum. In my study, my observations revealed that multinucleated post-slippage cells undergo senescence and elicit paracrine pro-tumourigenic effects, both in vitro and in vivo. The SASP factors secreted by post-slippage senescence cells promote migration, invasiveness and angiogenesis. My investigation into potential senescence effectors revealed two major metabolic pathways, autophagy and lipid metabolism, that could abrogate the tumour-promoting effects of antimitotic therapies; either by eliminating pro-tumourigenic senescent cells or by suppressing the secretion of the associated pro-tumorigenic factors. Understanding cell fate post-slippage provides opportunities for the development of novel therapeutic strategies to circumvent antimitotic drug resistance and enhance the treatment efficacy for cancer patients.Doctor of Philosoph

Dropping in on lipid droplets: insights into cellular stress and cancer

10.1042/BSR20180764BIOSCIENCE REPORTS38

TACI constrains TH17 pathogenicity and protects against gut inflammation

TACI (transmembrane activator and calcium modulator and cyclophilin ligand interactor) plays critical roles in B cells by promoting immunoglobulin class switching and plasma cell survival. However, its expression and function in T cells remain controversial. We show here that TACI expression can be strongly induced in murine CD4+ T cells in vitro by cytokines responsible for TH17 but not TH1 or TH2 differentiation. Frequencies and numbers of TH17 cells were elevated in TACI−/− compared with wild-type mice as well as among TACI−/− versus wild-type CD4+ T cells in mixed bone marrow chimeras, arguing for a T cell-intrinsic effect in the contribution of TACI deficiency to TH17 cell accumulation. TACI−/− mice were more susceptible to severe colitis induced by dextran sodium sulfate or adoptive T cell transfer, suggesting that TACI negatively regulates TH17 function and limits intestinal inflammation in a cell-autonomous manner. Finally, transcriptomic and biochemical analyses revealed that TACI−/− CD4+ T cells exhibited enhanced activation of TH17-promoting transcription factors NFAT, IRF4, c-MAF, and JUNB. Taken together, these findings reveal an important role of TACI in constraining TH17 pathogenicity and protecting against gut disease.Agency for Science, Technology and Research (A*STAR)Published versionWe thank staff of the Biological Resource Centre (BRC) for care and maintenance of mice and members of the laboratory for insightful discussions. The Advanced Molecular Pathology Laboratory (AMPL) of the Institute of Molecular and Cell Biology assisted in the preparation and histological staining of colon samples. This research was supported by Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore (A∗STAR)