Inhibition of PI3K-AKT-mTOR pathway sensitizes endometrial cancer cell lines to PARP inhibitors.

BACKGROUND: Phosphatase and Tensin homolog (PTEN) is a tumor suppressor gene. Loss of its function is the most frequent genetic alteration in endometrioid endometrial cancers (70-80%) and high grade tumors (90%). We assessed the sensitivity of endometrial cancer cell lines to PARP inhibitors (olaparib and BMN-673) and a PI3K inhibitor (BKM-120), alone or in combination, in the context of their PTEN mutation status. We also highlighted a direct pathway linking PTEN to DNA repair. METHODS: Using endometrial cancer cellular models with known PTEN status, we evaluated their homologous recombination (HR) functionality by RAD51 foci formation assay. The 50% Inhibitory concentration (IC50) of PI3K and PARP inhibitors in these cells was assessed, and western blotting was performed to determine the expression of proteins involved in the PI3K/mTOR pathway. Moreover, we explored the interaction between RAD51 and PI3K/mTOR by immunofluorescence. Next, the combination effect of PI3K and PARP inhibitors on cell proliferation was evaluated by a clonogenic assay. RESULTS: Cells with mutated PTEN showed over-activation of the PI3K/mTOR pathway. These cells were more sensitive to PARP inhibition compared to PTEN wild-type cells. In addition, PI3K inhibitor treatment reduced RAD51 foci formation in PTEN mutated cells, and sensitized these cells to PARP inhibitor. CONCLUSION: Targeting both PARP and PI3K might lead to improved personalized therapeutic approaches in endometrial cancer patients with PTEN mutations. Understanding the complex interaction of PTEN mutations with DNA repair in endometrial cancer will help to better select patients that are likely to respond to some of the new and costly targeted therapies.

Metformin Increases E-cadherin in Tumors of Diabetic Patients With Endometrial Cancer and Suppresses Epithelial-Mesenchymal Transition in Endometrial Cancer Cell Lines.

PURPOSE: Epithelial-mesenchymal transition (EMT) is a critical process for cancer metastasis and recurrence. Metformin, an effective oral antidiabetic drug, has been associated with decreased cancer risk and mortality. In this pilot study, we started to evaluate the effect of metformin on EMT in vivo and in vitro in endometrial cancer (EC). METHODS: Endometrial cancer cell lines and freshly isolated EC tumor specimens were used to assess EMT after metformin treatment. Cell lines were subjected to wound healing and AlamarBlue assays to determine cell migration and cell proliferation; messenger RNA levels were measured by real-time reverse transcriptase (RT) quantitative polymerase chain reaction (PCR), and protein levels were measured by Western blots to detect EMT marker expression. RESULTS: Protein expression and messenger RNA of E-cadherin was found to be increased (P = 0.02 and 0.04, respectively) in 30 EC tumor specimens of diabetic patients treated with metformin compared with 20 EC tumor specimens of diabetic patients treated with other antidiabetic agents. In vitro, metformin reduced cell migration at 5 mM for 48 hours, as determined by the wound healing assay in EC cell lines (Ishikawa, 45% reduction; HEC50, 40% reduction), whereas more than 90% of the cells remained viable on the AlamarBlue assay. Metformin reduced EMT in the cell lines and regulated the expression of the EMT-related epithelial markers, E-cadherin and Pan-keratin; the mesenchymal markers, N-cadherin, fibronectin, and vimentin; and the EMT drivers, Twist-1, snail-1, and ZEB-1. CONCLUSIONS: Tumors of patients on metformin have increased E-cadherin expression, and metformin decreases EMT in EC cell lines in vitro, suggesting clinical biological relevance of metformin in women with EC.

Suppression of Homologous Recombination by insulin-like growth factor-1 inhibition sensitizes cancer cells to PARP inhibitors.

BACKGROUND: Impairment of homologous recombination (HR) is found in close to 50 % of ovarian and breast cancer. Tumors with BRCA1 mutations show increased expression of the Insulin-like growth factor type 1 receptor (IGF-1R). We previously have shown that inhibition of IGF-1R results in growth inhibition and apoptosis of ovarian tumor cells. In the current study, we aimed to investigate the correlation between HR and sensitivity to IGF-1R inhibition. Further, we hypothesized that IGF-1R inhibition might sensitize HR proficient cancers to Poly ADP ribose polymerase (PARP) inhibitors. METHODS: Using ovarian and breast cancer cellular models with known BRCA1 status, we evaluated their HR functionality by RAD51 foci formation assay. The 50 % lethal concentration (LC50) of Insulin-like growth factor type 1 receptor kinase inhibitor (IGF-1Rki) in these cells was assessed, and western immunoblotting was performed to determine the expression of proteins involved in the IGF-1R pathway. Moreover, IGF-1R inhibitors were added on HR proficient cell lines to assess mRNA and protein expression of RAD51 by qPCR and western blot. Also, we explored the interaction between RAD51 and Insulin receptor substance 1 (IRS-1) by immunoprecipitation. Next, combination effect of IGF-1R and PARP inhibitors was evaluated by clonogenic assay. RESULTS: Cells with mutated/methylated BRCA1 showed an impaired HR function, and had an overactivation of the IGF-1R pathway. These cells were more sensitive to IGF-1R inhibition compared to HR proficient cells. In addition, the IGF-IR inhibitor reduced RAD51 expression at mRNA and protein levels in HR proficient cells, and sensitized these cells to PARP inhibitor. CONCLUSION: Targeting IGF-1R might lead to improved personalized therapeutic approaches in cancer patients with HR deficiency. Targeting both PARP and IGF-1R might increase the clinical efficacy in HR deficient patients and increase the population of patients who may benefit from PARP inhibitors.

Rising trends in iatrogenic urogenital fistula: A new challenge.

OBJECTIVE: To analyze trends in iatrogenic urogenital fistula among patients admitted for fistula repair at the Pakistan Institute of Medical Sciences, Islamabad. METHODS: In this longitudinal study, all patients who presented for fistula repair between 2006 and 2018 were included in the study. Patient data were collected on age, parity, and type and etiology of fistula, which was classified as ischemic or iatrogenic. RESULTS: Of 634 fistula patients, 371 (58.5%) had iatrogenic fistula, while 263 (41.5%) patients developed ischemic fistula due to obstructed labor. Mean age of patients was 31.6 years. Yearly trends showed an increase in iatrogenic fistula from 43.2% in 2006-2008 to 71.4% in 2017-2018. The major etiological contributor to iatrogenic fistula was hysterectomy (52.5%), followed by cesarean hysterectomy (26.4%), and cesarean delivery (19.9%). CONCLUSION: A rising trend in iatrogenic fistula was observed. This emphasizes the need for optimization of surgical approaches and surgical skills. Moreover, gynecologic surgeries should be restricted to authorized gynecologic surgeons.

Biguanides in combination with olaparib limits tumorigenesis of drug-resistant ovarian cancer cells through inhibition of Snail.

Ovarian cancer is the most lethal gynecological malignancy. Currently, new chemotherapeutic strategies are required to improve patient outcome and survival. Biguanides, classic anti-diabetic drugs, have gained importance for theiri antitumor potency demonstrated by various studies. Olaparib is a PARP inhibitor approved for maintenance therapy following platinum-based chemotherapy. Furthermore, Snai1, a transcription factor that works as a master regulator of the epithelial/mesenchymal transition process (EMT) is involved in ovarian cancer resistance and progression. Here we aimed to demonstrate the possible cross talk between biguanides and Snail in response to olaparib combination therapy. In this study, we have shown that while in A2780CR cells biguanides reduced cell survival (single treatments ~20%; combined treatment ~44%) and cell migration (single treatments ~45%; biguanide-olaparib ~80%) significantly, A2780PAR exhibited superior efficacy with single (~60%) and combined treatments (~80%). Moreover, our results indicate that knock-down of Snail further enhances the attenuation of migration, inhibits EMT related-proteins (~90%) and induces a synergistic effect in biguanide-olaparib treatment. Altogether, this work suggests a novel treatment strategy against drug-resistant or recurrent ovarian cancer.