Selim Misirlioglu

PARP Inhibitors Differentially Regulate Immune Responses in Distinct Genetic Backgrounds of High-Grade Serous Tubo-Ovarian Carcinoma

Abstract Immune checkpoint inhibitors (ICI) have revolutionized treatment for several tumor indications without demonstrated benefit for patients with ovarian cancer. To improve the therapeutic ratio of ICIs in patients with ovarian cancer, several different clinical trials are testing combinations with poly(ADP-ribose) polymerase (PARP) inhibitors. Comparing the immunomodulatory effects of clinically advanced PARP inhibitors (PARPi) may help to identify the best partner to combine with ICIs. We examined the treatment effect of talazoparib (a PARP trapper) and veliparib (a solely PARP enzymatic inhibitor) in homologous recombination deficient (HRD) and homologous recombination proficient high-grade serous tubo-ovarian carcinoma (HGSC) cell lines on immune-related gene expression. We discovered and validated that CXCL8, IL-6, and TNF gene expression were upregulated after talazoparib treatment in both OVCAR3 (HRD) and CAOV3 homologous recombination proficient HGSC cell lines. In contrast, veliparib treatment slightly elevated similar genes exclusively in an HRD HGSC cell line model. We expanded these studies to include olaparib, a PARP trapper less potent than talazoparib, and found effects specific to COV361 (BRCA1 mutant) and OVCAR8 (BRCA1 methylated) HGSC cells but not all HRD HGSC cell lines. Our studies also identified differences among PARP trappers versus veliparib on augmenting CXCL10 expression. Finally, we show that talazoparib modulates the CXCL10 response in cGAS-defective cell lines, independent of the cGAS-STING pathway. These mechanistic studies advance our understanding of how different PARPis affect the immune system in various genetic backgrounds. Significance: This work highlights how different PARPis, especially talazoparib, modulate immune-related gene expression in ovarian cancer cells, independent of the cGAS-STING pathway. These findings may improve our understanding of how different PARPis affect the immune system in various genetic backgrounds.

Mini-plus percutaneous setting in total laparoscopic hysterectomy

We aimed to analyze the preliminary experience of a mini-plus percutaneous instrument (MpPc) setting in total laparoscopic hysterectomy (TLH). Forty-three women who underwent a mini-plus percutaneous total laparoscopic hysterectomy at a tertiary-care university-based teaching hospital and academic affiliated private hospital between May 2017 and 2018 were included. MpPc-TLH was performed through one optical trans-umbilical 5-mm trocar, one 5-mm ancillary port on the right side, either one 2.4-mm percutaneous endoscopic instrument or 3-mm mini-laparoscopic port on the right upper quadrant and if required one 3-mm ancillary port on the left lower quadrant. A total of 43 patients were included, with a median age of 48 years (range, 38-71 years). Indication for surgery included uterine myomas ( The preliminary data suggest that MpPc approach is a feasible and safe surgical modality for total laparoscopic hysterectomy.

SMARCA4 Loss Increases RNA Polymerase II Pausing and Elevates R-Loops to Inhibit BRCA1-Mediated Repair in Ovarian Cancer

Abstract Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare, aggressive cancer affecting young women driven by inactivating mutations in SMARCA4, a key SWI/SNF chromatin remodeling gene. To uncover its druggable vulnerabilities, we performed a compound screen and found that SCCOHT cells and tumors were sensitive to PARP inhibitors. Paradoxically, SCCOHT displayed BRCA-deficient traits despite retaining wild-type BRCA1 expression. Elevated R-loop in SCCOHT sequestered BRCA1, limiting its availability for DNA damage repair. Proximity-dependent biotin identification revealed that wild-type SMARCA4, but not its pathogenic variants, promoted RNA polymerase II (Pol II) elongation by mediating the assembly of the polymerase-associated factor 1 complex. Thus, SMARCA4 loss increased Pol II pausing, resulting in elevated R-loops and BRCA1 redistribution. The suppression of BRCA1 activity sensitized SMARCA4-deficient SCCOHT cells and tumors to PARP inhibitors, which was further enhanced by the addition of a CDK9 inhibitor targeting Pol II elongation. Cotargeting PARP/CDK9 also elicited synergistic effects against other undifferentiated ovarian cancer cells with SMARCA4 loss. These findings link SMARCA4 loss to perturbed Pol II elongation and compromised DNA repair by BRCA1, providing a therapeutic opportunity to target SCCOHT and other SWI/SNF-deficient ovarian cancers. Significance: Pol II stalling induced by SMARCA4 loss leads to R-loop accumulation that sequesters BRCA1 to transcription complexes, underlying the sensitivity of SMARCA4-deficient ovarian cancers to inhibitors targeting PARPs and Pol II elongation.