PARP inhibition sensitizes endometrial cancer cells to paclitaxel-induced apoptosis

Small molecule targeted therapies for endometrial cancer: progress, challenges, and opportunities

Endometrial cancer (EC) is a common malignancy among women worldwide, and its recurrence makes it a common cause of cancer-related death. Surgery and external radiation, chemotherapy, or a combination of strategies are the cornerstone of therapy for EC patients. However, adjuvant treatment strategies face certain drawbacks, such as resistance to chemotherapeutic drugs; therefore, it is imperative to explore innovative therapeutic strategies to improve the prognosis of EC. With the development of pathology and pathophysiology, several biological targets associated with EC have been identified, including PI3K/Akt/mTOR, PARP, GSK-3β, STAT-3, and VEGF. In this review, we summarize the progress of small molecule targeted therapies in terms of both basic research and clinical trials and provide cases of small molecules combined with fluorescence properties in the clinical applications of integrated diagnosis and treatment. We hope that this review will facilitate the further understanding of the regulatory mechanism governing the dysregulation of oncogenic signaling in EC and provide insights into the possible future directions of targeted therapeutic regimens for EC treatment by developing new agents with fluorescence properties for the clinical applications of integrated diagnosis and treatment.

Molecular characterization as new driver in prognostic signatures and therapeutic strategies for endometrial cancer

Endometrial cancer (EC) incidence and mortality rates have been increasing, particularly among young females. Although more than 90% of ECs are sporadic, 5-10% are hereditary, a majority of which occurs within Hereditary Non-Polyposis Colorectal Cancer syndrome (HNPCC) or Lynch syndrome. The traditional histopathological classification differentiates EC between two main groups: type I (or endometrioid) and type II (including all other histopathological subtypes). However, this classification lacks reproducibility and does not account for the emerging molecular heterogeneity. In 2013, The Cancer Genome Atlas (TCGA) project proposed EC molecular classification defining four groups with different prognostic and predictive values and the current international guidelines are progressively establishing EC risk stratification and treatment based on both histopathological and molecular criteria. Our manuscript aims to summarize the current state of EC molecular characterizations, including germline alterations at the basis of hereditary EC predisposition, to discuss their clinical utility as prognostic and predictive markers.

Flavone-based dual PARP-Tubulin inhibitor manifesting efficacy against endometrial cancer

Structural tailoring of the flavone framework (position 7) via organopalladium-catalyzed C-C bond formation was attempted in this study. The impact of substituents with varied electronic effects (phenyl ring, position 2 of the benzopyran scaffold) on the antitumor properties was also assessed. Resultantly, the efforts yielded a furyl arm bearing benzopyran possessing a 4-fluoro phenyl ring (position 2) (14) that manifested a magnificent antitumor profile against the Ishikawa cell lines mediated through dual inhibition of PARP and tubulin [(IC50 (PARP1) = 74 nM, IC50 (PARP2) = 109 nM) and tubulin (IC50 = 1.4 µM)]. Further investigations confirmed the ability of 14 to induce apoptosis as well as autophagy and cause cell cycle arrest at the G2/M phase. Overall, the outcome of the study culminated in a tractable dual PARP-tubulin inhibitor endowed with an impressive activity profile against endometrial cancer.

Precision Medicine for BRCA/PALB2-Mutated Pancreatic Cancer and Emerging Strategies to Improve Therapeutic Responses to PARP Inhibition

Simple Summary

For the small subset of pancreatic ductal adenocarcinoma (PDAC) patients with loss-of-function mutations to BRCA1/2 or PALB2, both first-line and maintenance therapy differs significantly. These mutations confer a loss of double-strand break DNA homologous recombination (HR), substantially altering drug sensitivities. In this review, we discuss the current treatment guidelines for PDAC tumors deficient in HR, as well as newly emerging strategies to improve drug responses in this population. We also highlight additional patient populations in which these strategies may also be effective, and novel strategies aiming to confer similar drug sensitivity to tumors proficient in HR repair.

Abstract

Pancreatic cancer is projected to become the second leading cause of cancer-related death by 2030. As patients typically present with advanced disease and show poor responses to broad-spectrum chemotherapy, overall survival remains a dismal 10%. This underscores an urgent clinical need to identify new therapeutic approaches for PDAC patients. Precision medicine is now the standard of care for several difficult-to-treat cancer histologies. Such approaches involve the identification of a clinically actionable molecular feature, which is matched to an appropriate targeted therapy. Selective poly (ADP-ribose) polymerase (PARP) inhibitors such as Niraparib, Olaparib, Talazoparib, Rucaparib, and Veliparib are now approved for several cancers with loss of high-fidelity double-strand break homologous recombination (HR), namely those with deleterious mutations to BRCA1/2, PALB2, and other functionally related genes. Recent evidence suggests that the presence of such mutations in pancreatic ductal adenocarcinoma (PDAC), the most common and lethal pancreatic cancer histotype, significantly alters drug responses both with respect to first-line chemotherapy and maintenance therapy. In this review, we discuss the current treatment paradigm for PDAC tumors with confirmed deficits in double-strand break HR, as well as emerging strategies to both improve responses to PARP inhibition in HR-deficient PDAC and confer sensitivity to tumors proficient in HR repair.

Research progress of PARP inhibitor monotherapy and combination therapy for endometrial cancer

Endometrial cancer is one of the three most common malignant tumors in the female reproductive system. Advanced and recurrent endometrial cancers have poor prognoses and lack effective treatments. Poly(ADP-ribose) polymerase (PARP) inhibitors have been applied to many different types of tumors, and they can selectively kill tumor cells that are defective in homologous recombination repair. Endometrial cancer is characterized by mutations in homologous recombination repair genes; accordingly, PARP inhibitors have achieved positive results in off-label treatments of endometrial cancer cases. Clinical trials of PARP inhibitors as monotherapies and within combination therapies for endometrial cancer are ongoing. For this review, we searched PubMed with "endometrial cancer" and "PARP inhibitor" as keywords, and we used "olaparib", "rucaparib", "niraparib" and "talazoparib" as search terms in clinicaltrials.gov for ongoing trials. The literature search ended in October 2020, and only English-language publications were selected. Multiple studies confirm that PARP inhibitors play an important role in killing tumor cells with defects in homologous recombination repair. Its combination with immune checkpoint inhibitors, PI3K/AKT/mTOR pathway inhibitors, cell cycle checkpoint inhibitors, and other drugs can improve the treatment of endometrial cancer.

Adjuvant effects of chemotherapeutics and Metformin on MFE-319 endometrial carcinoma cell line

We aimed to investigate the cytotoxicity of Metformin, Cisplatin, and Paclitaxel on MFE-319 endometrial carcinoma cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and immunocytochemistry assays. Half maximal inhibitory concentration (IC₅₀) doses of three drugs alone and in the dual combinations were applied to the cells. Immunocytochemical method was performed for the cell survival and for phosphatidylinositol 3-kinase (PI3K), phosphorylated extracellular regulated kinases (pErk)-1/2, Akt-1, phosphorylated Akt (pAkt)-1/2/3 cell growth markers and angiogenic vascular endothelial growth factor (VEGF). Immunoreactivities were evaluated using H-score and analyzed using the one-way analysis of variance (ANOVA) test for statistics. It was found that these drugs caused a decrease in the immunoreactivities of these markers. Particularly, dual combination of Paclitaxel and Cisplatin decreased the immunoreactivities of PI3K, pErk-1/2, Akt-1, and pAkt-1/2/3. Cisplatin and Paclitaxel were more effective than Metformin; on the other hand, Metformin has been shown to enhance the efficacy of these two drugs. In vitro or in vivo further studies are needed to investigate the efficacy of these three drugs via PI3K/Akt signal pathway.

Frequency and prognostic value of mutations associated with the homologous recombination DNA repair pathway in a large pan cancer cohort

PARP inhibitors have shown remarkable efficacy in the clinical management of several BRCA-mutated tumors. This approach is based on the long-standing hypothesis that PARP inhibition will impair the repair of single stranded breaks, causing synthetic lethality in tumors with loss of high-fidelity double-strand break homologous recombination. While this is now well accepted and has been the basis of several successful clinical trials, emerging evidence strongly suggests that mutation to several additional genes involved in homologous recombination may also have predictive value for PARP inhibitors. While this notion is supported by early clinical evidence, the mutation frequencies of these and other functionally related genes are largely unknown, particularly in cancers not classically associated with homologous recombination deficiency. We therefore evaluated the mutation status of 22 genes associated with the homologous recombination DNA repair pathway or PARP inhibitor sensitivity, first in a pan-cancer cohort of 55,586 patients, followed by a more focused analysis in The Cancer Genome Atlas cohort of 12,153 patients. In both groups we observed high rates of mutations in a variety of HR-associated genes largely unexplored in the setting of PARP inhibition, many of which were associated also with poor clinical outcomes. We then extended our study to determine which mutations have a known oncogenic role, as well as similar to known oncogenic mutations that may have a similar phenotype. Finally, we explored the individual cancer histologies in which these genomic alterations are most frequent. We concluded that the rates of deleterious mutations affecting genes associated with the homologous recombination pathway may be underrepresented in a wide range of human cancers, and several of these genes warrant further and more focused investigation, particularly in the setting of PARP inhibition and HR deficiency.

PARP Inhibitors in Endometrial Cancer: Current Status and Perspectives

Advanced, recurrent and metastatic endometrial cancer (EC) has a dismal prognosis due to poor response rates to conventional treatments. In the era of precision medicine, the improved understanding of cancer genetics and molecular biology has led to the development of targeted therapies, such as poly (ADP-ribose) polymerase (PARP) inhibitors. This class of drugs that inhibit PARP enzymes has been investigated in many different types of tumors and its use in the treatment of gynecological malignancies has rapidly increased over the past few years. Data from several clinical trials showed that PARP inhibitors have a beneficial role in cancers with a defect in the homologous DNA recombination system, regardless of the BRCA mutational status. Since EC frequently shows mutations in PTEN and TP53 genes, indirectly involved in the homologous DNA recombination pathway, several in vivo and in vitro studies investigated the efficacy of PARP inhibitors in EC, showing promising results. This review will discuss the use of PARP inhibitors in endometrial cancer, summarizing data from preclinical studies and providing an overview of the ongoing trials, with a special focus on the development of combined treatment strategies with PARP inhibitors and immune checkpoint inhibitors.

PARP-1 inhibitor modulate β-catenin signaling to enhance cisplatin sensitivity in cancer cervix

Cisplatin is a keystone for treatment of both recurring and locally advanced cervical cancer. However toxic side effects and acquired resistance limits its efficacy. Enhanced DNA repair is one of the mechanisms through which cancer cells acquire cisplatin resistance. Inhibitors of PARP, which is a DNA damage repair enzyme, have been approved for use in BRCA mutated cancers like breast and ovary cancer. However little is known about the therapeutic efficacy of PARP inhibitors in cervical cancer, either as a single agent or in combination with cisplatin. We hypothesized that PARP-1 inhibition might improve the sensitivity of cervical cancer cells to cisplatin by diminishing DNA repair. To ascertain this, we determined effect of PARP-1 inhibition on cisplatin cytotoxicity in HeLa and SiHa cell lines. Combination of cisplatin with PJ34, a phenanthridinone-derived PARP-1 inhibitor, augmented cisplatin toxicity in vitro by decreasing cell proliferation, enhancing cell cycle block and cell death, and decreasing invasion and metastasis, when compared with either of the single agent alone. We further show that PARP-1 inhibition inhibited β-catenin signaling and its downstream components such as c-Myc, cyclin D1 and MMPs indicating a possible link between single strand base damage repair and WNT signaling. In conclusion, PARP-1 inhibition might augment cisplatin cytotoxicity in cervical cancer cells by modulating β-catenin signaling pathway. Combining PARP-1 inhibitors with cisplatin might be a promising approach to overcome cisplatin resistance and to achieve a better therapeutic effect.

Upregulation of miR-183-5p is responsible for the promotion of apoptosis and inhibition of the epithelial-mesenchymal transition, proliferation, invasion and migration of human endometrial cancer cells by downregulating Ezrin

Endometrial cancer is a life‑threatening malignancy that affects women all over the world, and it has an increasing incidence. MicroRNAs (miRNAs/miRs) have been reported to be involved in cellular activities in endometrial cancer. The present study aimed to examine the effects of miR‑183‑5p on the epithelial‑mesenchymal transition (EMT), proliferation, invasion, migration and apoptosis of human endometrial cancer cells by targeting Ezrin. Primary endometrial cancer tissues and adjacent normal tissues were obtained for the investigation. The protein expression of Ezrin in tissues was detected by immunohistochemistry. The expression level of miR‑183‑5p and the mRNA and protein expression levels of Ezrin and EMT‑associated genes were determined by reverse transcription‑quantitative polymerase chain reaction and western blot analyses. Endometrial cancer cells were treated with miR‑183‑5p inhibitors, small interfering RNA targeting Ezrin or miR‑183‑5p inhibitors. Cell proliferation, cell cycle, apoptosis, migration and invasion were then evaluated using an MTT assay, flow cytometry, scratch test and Transwell assay, respectively. Compared with normal adjacent tissues, the expression of miR‑183‑5p was decreased in endometrial cancer tissues, and the expression of Ezrin was significantly increased in endometrial cancer tissues. The protein expression of Ezrin was correlated with the severity and poor prognosis of endometrial cancer. Notably, the target prediction program and the luciferase reporter gene assay confirmed that miR‑183‑5p targeted and negatively regulated the expression of Ezrin. In vivo experiments revealed that the increased expression of miR‑183‑5p and decreased expression of Ezrin inhibited EMT, cell proliferation, migration and invasion, but promoted cell apoptosis in Ishikawa cells. These results suggested that the upregulated expression of miR‑183‑5p promoted apoptosis and suppressed the EMT, proliferation, invasion and migration of human endometrial cancer cells by downregulating Ezrin.