Biology subjects

Provencher, D.

Publications and source records attributed to Provencher, D..

5 recordsLinked to original sources

bioRxiv2025

Identification of a new inhibitor of Ran GTPase with therapeutic value in epithelial ovarian cancer

Compiled research studies suggest that the small GTPase Ran is critical in cancer initiation and progression. Compounds that block Ran activity would be valuable for cancer treatment. Yet, to date, there is no inhibitor proven to be efficient and specific to Ran. Here, by learning lessons from the discovery of KRAS G12C inhibitors, we generated a structural model of the switch II pocket of GDP-bound Ran to identify potential inhibitors of Ran by virtual screening. After in vitro verification, compound M26 was detected. Subsequent hit optimization lead us to identify compound M36 as an inhibitor of Ran with a promising therapeutic value. Binding of M36 to Ran was confirmed by cellular thermal shift assay. The specificity of M36 towards Ran was demonstrated by the evaluation of the active GTP-bound forms of a range of GTPases including Ran, RhoA, Cdc42 and Rac1; and by the expression of a dominant active mutant of Ran. Remarkably, similar to depletion of Ran by siRNA, M36 exhibits a specific toxicity in aneuploid ovarian cancer cells and represses DNA repair systems. In accordance with this, we demonstrated a synergistic relationship between M36 and the FDA approved PARP inhibitor Olaparib. In vivo, M36 presents acceptable pharmacokinetic properties and, more importantly, inhibits the tumor growth of an aggressive epithelial ovarian cancer xenograft model. Clinically relevant, M36 was able to induce cell death in ex vivo EOC patient derived micro-dissected tumor. Overall, our study is the first to provide a small-molecule compound inhibitor of Ran with a promising therapeutic potential.

cancer biology↗

bioRxiv2023

53BP1 mediates sensitivity to chemotherapy and is associated with poor clinical outcomes in high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) remains the most lethal gynecological malignancy in North American women. At a cellular level, the current first-line chemotherapies cause DNA-damage and activate the DNA damage response signalling cascade. Here we explore the role of 53BP1, a central mediator of the DNA damage response, in HGSOC chemotherapy outcomes. Tissue 53BP1 protein levels were quantified in two independent HGSOC cohorts, the COEUR validation cohort (n = 173) and CHUM cohort (n = 56). Univariate and multivariate analyses showed that high nuclear 53BP1 levels in ovarian cancer cells were strongly associated with poor disease-specific survival in both cohorts. High 53BP1 was associated with poor progression-free survival (PFS) in the COEUR cohort, and trended towards poor PFS in the CHUM cohort. These findings were validated by whole-tumour TP53BP1 mRNA of the TCGA Firehose Legacy cohort (n = 591) in which high TP53BP1 mRNA levels were associated with poor overall survival on multivariate analysis. In HGSOC cell lines, 53BP1 levels were positively correlated with resistance to carboplatin using colony formation assay, and depletion of 53BP1 sensitized resistant cell lines to genotoxic therapies. These results suggest that 53BP1 is associated with poor prognosis in HGSOC and may mediate this relationship by modulating cellular sensitivity to chemotherapy. Statement of translational relevanceCurrent first-line chemotherapies in ovarian cancer cause DNA damage and activate the DNA damage response, culminating in the taking of cell fate decisions. 53BP1 is a central mediator in this signalling cascade, where it is involved at multiple levels: signal amplification, recruitment of effectors, DNA repair pathway choice, and cell cycle regulation. However, its role in ovarian cancer treatment outcomes remains unknown. In this study, we found that 53BP1 correlated with poor clinical outcomes in three ovarian cancer patient cohorts and mediated carboplatin sensitivity in ovarian cancer cells. These results reveal 53BP1 and the DNA damage response as important actors in ovarian cancer treatment response. Though further studies are necessary to gain a more complete understanding of their involvement in clinical outcomes, they appear as promising candidates for potential therapeutic targeting in ovarian cancer.

cancer biology↗

bioRxiv2023

A senescence-like state is beneficial for ovarian cancer treatment

High-grade serous ovarian carcinoma (HGSOC) commonly responds to initial therapy, but this response is rarely durable. Understanding cell fate decisions taken by HGSOC cells in response to treatment could guide new therapeutic opportunities. Here we find that tissue-derived primary HGSOC epithelial cultures reflecting the original disease primarily undergo therapy-induced senescence in response to DNA damage and first-line carboplatin/paclitaxel chemotherapy. Unlike previous observations using cell lines, primary HGSOC cell TIS displays a stable senescence proliferation arrest and p16INK4A expression, and is accompanied by persistent DNA damage, an inflammatory secretome, and senolytic sensitivity, suggesting new avenues for selective pharmacological manipulation of these cells. Whether cell senescence induced by cancer therapy is beneficial or detrimental to clinical outcomes remains unknown. Single cell comparison of pre- and post-chemotherapy patient HGSOC tissue samples revealed changes in physio-pathological senescence biomarkers supporting a post-treatment senescence-like state. Importantly, patients with stronger senescence signatures post-chemotherapy displayed better 5-year survival suggesting that senescence accounts, at least in part, for beneficial cellular responses to treatment. Given that ovarian cancer epithelial cells almost universally retain the capacity to undergo senescence and that senescence appears beneficial in this context, HGSOC senescence-centric therapeutic avenues should be further explored. Author SummaryWhether cancer therapy-induced cell fate decisions like senescence are good or bad for patient treatment outcome is unknown. We find that ovarian cancer cells almost universally retain senescence competence and that senescence in treated cancer tissues correlate with good clinical outcomes. This reveals that senescence is a relevant drug target in ovarian cancer.

cancer biology↗

bioRxiv2019

Gravity-based microfiltration reveals unexpected prevalence of circulating tumor cell clusters in ovarian cancer

Circulating tumor cells (CTCs) are rare (few cells per milliliter of blood) and mostly isolated as single cell CTCs (scCTCs). CTC clusters (cCTCs), even rarer, are of growing interest, notably because of their higher metastatic potential, but very difficult to isolate. Here, we introduce gravity-based microfiltration (G{micro}F) for facile isolation of cCTCs while minimizing unwanted cluster disaggregation, with [~]85% capture efficiency. G{micro}F from orthotopic ovarian cancer mouse models, from 17 epithelial ovarian cancer (EOC) with either localized or metastatic disease, and from 13 metastatic colorectal cancer liver metastasis (CRCLM) patients uncovered cCTCs in every case, with between 2-100+ cells. cCTCs represented between 5-30% of all CTC capture events, and 10-80% of CTCs were clustered; remarkably, in 10 patients, most CTCs were circulating not as scCTCs, but as cCTCs. G{micro}F uncovered the unexpected prevalence and frequency of cCTCs including sometimes very large ones in EOC patients, and motivates additional studies to uncover their properties and role in disease progression.

bioengineering↗

bioRxiv2018

Cellular senescence is a central response to cytotoxic chemotherapy in high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) commonly responds to initial therapy, but this response is rarely durable. Understanding cell fate decisions taken by HGSOC cells in response to treatment could guide new therapeutic opportunities. Here we find that primary HGSOC cultures undergo therapy-induced senescence (TIS) in response to DNA damage induced by chemotherapy. HGSOC-TIS displays most senescence hallmarks including persistent DNA damage, senescence-associated inflammatory secretome, and selective sensitivity to senolytic Bcl-2 family inhibitors, suggesting avenues for preferential synergistic clearance of these cells. Comparison of pre- and post-chemotherapy HGSOC patient tissue samples revealed changes in senescence biomarkers suggestive of post-treatment \"in patient\" TIS, and a stronger TIS response in post-chemotherapy tissues correlated with better 5-year survival rates for patients. Together, these data suggest that the induction of cellular senescence in HGSOC cells accounts at least in part for beneficial cellular responses to treatment in patients providing a new therapeutic target.\n\nOne Sentence SummaryCellular senescence is a central beneficial response to chemotherapy in high-grade serous ovarian cancer both in vitro and in patient.

cancer biology↗