CCNE1 Is a Putative Therapeutic Target for ARID1A-Mutated Ovarian Clear Cell Carcinoma

ARID1A restrains EMT and stemness of ovarian cancer cells through the Hippo pathway

Genes encoding subunits of SWI/SNF (BAF) chromatin‑remodeling complexes are recurrently mutated in a broad array of tumor types, and among the subunits, ARID1A is the most frequent target with mutations. In the present study, it was reported that ARID1A inhibits the epithelial‑mesenchymal transition (EMT) and stemness of ovarian cancer cells, accompanied by reduced cell viability, migration and colony formation, suggesting that ARID1A acts as a tumor suppressor in ovarian cancer. Mechanistically, ARID1A exerts its inhibitory effects on ovarian cancer cells by activating the Hippo signaling pathway. Conversely, the overexpression of a gain‑of‑function transcriptional co‑activator with PDZ‑binding motif (TAZ) mutant (TAZ‑Ser89) effectively reverses the effects induced by ARID1A. In addition, activation of Hippo signaling apparently upregulates ARID1A protein expression, whereas ectopic expression of TAZ‑Ser89 results in the markedly decreased ARID1A levels, indicating a feedback of ARID1A‑TAZ in regulating ovarian cancer cell EMT and stemness. Thus, the present study uncovered the role of ARID1A through the Hippo/TAZ pathway in modulating EMT and stemness of ovarian cancer cells, and providing with evidence that TAZ inhibitors could effectively prevent initiation and metastasis of ovarian cancer cases where ARID1A is lost or mutated.

Review the progression of ovarian clear cell carcinoma from the perspective of genomics and epigenomics

Ovarian clear cell carcinoma (OCCC) is a rare subtype of epithelial ovarian cancer with unique molecular characteristics, specific biological and clinical behavior, poor prognosis and high resistance to chemotherapy. Pushed by the development of genome-wide technologies, our knowledge about the molecular features of OCCC has been considerably advanced. Numerous studies are emerging as groundbreaking, and many of them are promising treatment strategies. In this article, we reviewed studies about the genomics and epigenetics of OCCC, including gene mutation, copy number variations, DNA methylation and histone modifications.

A practical spatial analysis method for elucidating the biological mechanisms of cancers with abdominal dissemination in vivo

Elucidation of spatial interactions between cancer and host cells is important for the development of new therapies against disseminated cancers. The aim of this study is to establish easy and useful method for elucidating spatial interactions. In this study, we developed a practical spatial analysis method using a gel-based embedding system and applied it to a murine model of cancer dissemination. After euthanization, every abdominal organ enclosed in the peritoneum was extracted en bloc. We injected agarose gel into the peritoneal cavities to preserve the spatial locations of the organs, including their metastatic niches, and then produced specimens when the gel had solidified. Preservation of the original spatial localization was confirmed by correlating magnetic resonance imaging results with the sectioned specimens. We examined the effects of spatial localization on cancer hypoxia using immunohistochemical hypoxia markers. Finally, we identified the mRNA expression of the specimens and demonstrated the applicability of spatial genetic analysis. In conclusion, we established a practical method for the in vivo investigation of spatial location-specific biological mechanisms in disseminated cancers. Our method can elucidate dissemination mechanisms, find therapeutic targets, and evaluate cancer therapeutic effects.

SWI/SNF complex gene variations are associated with a higher tumor mutational burden and a better response to immune checkpoint inhibitor treatment: a pan-cancer analysis of next-generation sequencing data corresponding to 4591 cases

Background

Genes related to the SWItch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex are frequently mutated across cancers. SWI/SNF-mutant tumors are vulnerable to synthetic lethal inhibitors. However, the landscape of SWI/SNF mutations and their associations with tumor mutational burden (TMB), microsatellite instability (MSI) status, and response to immune checkpoint inhibitors (ICIs) have not been elucidated in large real-world Chinese patient cohorts.

Methods

The mutational rates and variation types of six SWI/SNF complex genes (ARID1A, ARID1B, ARID2, SMARCA4, SMARCB1, and PBRM1) were analyzed retrospectively by integrating next-generation sequencing data of 4591 cases covering 18 cancer types. Thereafter, characteristics of SWI/SNF mutations were depicted and the TMB and MSI status and therapeutic effects of ICIs in the SWI/SNF-mutant and SWI/SNF-non-mutant groups were compared.

Results

SWI/SNF mutations were observed in 21.8% of tumors. Endometrial (54.1%), gallbladder and biliary tract (43.4%), and gastric (33.9%) cancers exhibited remarkably higher SWI/SNF mutational rates than other malignancies. Further, ARID1A was the most frequently mutated SWI/SNF gene, and ARID1A D1850fs was identified as relatively crucial. The TMB value, TMB-high (TMB-H), and MSI-high (MSI-H) proportions corresponding to SWI/SNF-mutant cancers were significantly higher than those corresponding to SWI/SNF-non-mutant cancers (25.8 vs. 5.6 mutations/Mb, 44.3% vs. 10.3%, and 16.0% vs. 0.9%, respectively; all p  < 0.0001). Furthermore, these indices were even higher for tumors with co-mutations of SWI/SNF genes and MLL2/3. Regarding immunotherapeutic effects, patients with SWI/SNF variations showed significantly longer progression-free survival (PFS) rates than their SWI/SNF-non-mutant counterparts (hazard ratio [HR], 0.56 [95% confidence interval {CI} 0.44–0.72]; p < 0.0001), and PBRM1 mutations were associated with relatively better ICI treatment outcomes than the other SWI/SNF gene mutations (HR, 0.21 [95% CI 0.12–0.37]; p = 0.0007). Additionally, patients in the SWI/SNF-mutant + TMB-H (HR, 0.48 [95% CI 0.37–0.54]; p  < 0.0001) cohorts had longer PFS rates than those in the SWI/SNF-non-mutant + TMB-low cohort.

Conclusions

SWI/SNF complex genes are frequently mutated and are closely associated with TMB-H status, MSI-H status, and superior ICI treatment response in several cancers, such as colorectal cancer, gastric cancer, and non-small cell lung cancer. These findings emphasize the necessity and importance of molecular-level detection and interpretation of SWI/SNF complex mutations.

ARID1A serves as a receivable biomarker for the resistance to EGFR-TKIs in non-small cell lung cancer

ARID1A is a key component of the SWI/SNF chromatin remodeling complexes which is important for the maintaining of biological processes of cells. Recent studies had uncovered the potential role of ARID1A alterations or expression loss in the therapeutic sensitivity of cancers, but the studies in this field requires to be further summarized and discussed. Therefore, we proposed a series of mechanisms related to the resistance to EGFR-TKIs induced by ARID1A alterations or expression loss and the potential therapeutic strategies to overcome the resistance based on published studies. It suggested that ARID1A alterations or expression loss might be the regulators in PI3K/Akt, JAK/STAT and NF-κB signaling pathways which are strongly associated with the resistance to EGFR-TKIs in NSCLC patients harboring sensitive EGFR mutations. Besides, ARID1A alterations or expression loss could lead to the resistance to EGFR-TKIs via a variety of processes during the tumorigenesis and development of cancers, including epithelial to mesenchymal transition, angiogenesis and the inhibition of apoptosis. Based on the potential mechanisms related to ARID1A, we summarized that the small molecular inhibitors targeting ARID1A or PI3K/Akt pathway, the anti-angiogenic therapy and immune checkpoint inhibitors could be used for the supplementary treatment for EGFR-TKIs among NSCLC patients harboring the concomitant alterations of sensitive EGFR mutations and ARID1A.

Development of New Cancer Treatment by Identifying and Focusing the Genetic Mutations or Altered Expression in Gynecologic Cancers

With the advent of next-generation sequencing (NGS), The Cancer Genome Atlas (TCGA) research network has given gynecologic cancers molecular classifications, which impacts clinical practice more and more. New cancer treatments that identify and target pathogenic abnormalities of genes have been in rapid development. The most prominent progress in gynecologic cancers is the clinical efficacy of poly(ADP-ribose) polymerase (PARP) inhibitors, which have shown breakthrough benefits in reducing hazard ratios (HRs) (HRs between 0.2 and 0.4) of progression or death from BRCA1/2 mutated ovarian cancer. Immune checkpoint inhibition is also promising in cancers that harbor mismatch repair deficiency (dMMR)/microsatellite instability (MSI). In this review, we focus on the druggable genetic alterations in gynecologic cancers by summarizing literature findings and completed and ongoing clinical trials.