Mismatch repair deficiency is associated with specific morphologic features and frequent loss of ARID1A expression in ovarian clear cell carcinoma

ARID1A deficiency associated with MMR deficiency and a high abundance of tumor-infiltrating lymphocytes predicts a good prognosis of endometrial carcinoma

BACKGROUND

ARID1A alterations have been detected in 40% of endometrial carcinomas (ECs) and are associated with loss of its expression. The role of ARID1A in tumorigenesis and development is complex, and the prognostic role in EC remains controversial. Hence, it is of great significance to confirm the role of ARID1A in EC.

METHODS

A total of 549 EC patients (cohort A) from TCGA were evaluated to explore the prognostic role of ARID1A. NGS was performed for 13 EC patients (cohort B), and expression of ARID1A, CD3, CD8 and mismatch repair (MMR) proteins in 52 patients (cohort C) from our center was determined by immunohistochemistry (IHC). The Kaplan-Meier method was used to perform survival analyses.

RESULTS

ARID1A alterations were detected in 32% of EC patients and correlated with good disease-free survival (DFS, P = 0.004) and overall survival (OS, P = 0.0353). ARID1A alterations were found to co-occur with MMR-related gene mutations and correlated with higher PD-L1 expression. Patients concomitantly harboring ARID1A alterations and MMR-related gene mutations had the best prognosis (DFS: P = 0.0488; OS: P = 0.0024). A cohort from our center showed that ARID1A deficiency was an independent prognostic factor and predicted longer recurrence-free survival (P = 0.0476). ARID1A loss was associated with a tendency toward MSI-H (P = 0.0060). ARID1A alterations and expression loss were associated with a higher abundance of CD3+ (P = 0.0406) and CD8+ (P = 0.0387) T cells.

CONCLUSION

ARID1A alterations and expression loss are tightly associated with MMR deficiency and a high abundance of tumor-infiltrating lymphocytes, which might contribute to the good prognosis of EC.

Mismatch-repair deficiency, microsatellite instability, and lynch syndrome in ovarian cancer: A systematic review and meta-analysis

OBJECTIVE

Investigating for mismatch repair protein deficiency (MMRd), microsatellite instability (MSI), and Lynch syndrome (LS) is widely accepted in endometrial cancer, but knowledge is limited on its value in epithelial ovarian cancer (EOC). The primary objective was to evaluate the prevalence of mismatch repair protein deficiency (MMRd), microsatellite instability (MSI)-high, and Lynch syndrome (LS) in epithelial ovarian cancer (EOC), as well as the diagnostic accuracy of LS screening tests. The secondary objective was to determine the prevalence of MMRd, MSI-high, and LS in synchronous ovarian endometrial cancer and in histological subtypes.

METHODS

We systematically searched the MEDLINE, Epub Ahead of Print, MEDLINE In-Process and Other Non-Indexed Citations, Cochrane Central Register of Controlled Trials, and Embase databases. We included studies analysing MMR, MSI, and/or LS by sequencing.

RESULTS

A total of 55 studies were included. The prevalence of MMRd, MSI-high, and LS in EOC was 6% (95% confidence interval (CI) 5-8%), 13% (95% CI 12-15%), and 2% (95% CI 1-3%) respectively. Hypermethylation was present in 76% of patients with MLH1 deficiency (95% CI 64-84%). The MMRd prevalence was highest in endometrioid (12%) followed by non-serous non-mucinous (9%) and lowest in serous (1%) histological subtypes. MSI-high prevalence was highest in endometrioid (12%) and non-serous non-mucinous (12%) and lowest in serous (9%) histological subtypes. Synchronous and endometrioid EOC had the highest prevalence of LS pathogenic variants at 7% and 3% respectively, with serous having lowest prevalence (1%). Synchronous ovarian and endometrial cancers had highest rates of MMRd (28%) and MSI-high (28%). Sensitivity was highest for IHC (91.1%) and IHC with MSI (92.8%), while specificity was highest for IHC with methylation (92.3%).

CONCLUSION

MMRd and germline LS testing should be considered for non-serous non-mucinous EOC, particularly for endometrioid.

PRECIS

The rates of mismatch repair deficiency, microsatellite instability high, and mismatch repair germline mutations are highest in endometrioid subtype and non-serous non-mucinous ovarian cancer. The rates are lowest in serous histologic subtype.

Complete response to pembrolizumab in a patient with dermatomyositis and MMR deficient ovarian cancer: A case report

•Immune checkpoint inhibitors can be safely administered to patients with dermatomyositis.•Immunosuppressants did not impact the efficacy of treatment with an immune check point inhibitor.•Patients with autoimmune disorders who require immune check point inhibitors should be monitored by a rheumatologist.

Mutational signatures are markers of drug sensitivity of cancer cells

Genomic analyses have revealed mutational footprints associated with DNA maintenance gone awry, or with mutagen exposures. Because cancer therapeutics often target DNA synthesis or repair, we asked if mutational signatures make useful markers of drug sensitivity. We detect mutational signatures in cancer cell line exomes (where matched healthy tissues are not available) by adjusting for the confounding germline mutation spectra across ancestries. We identify robust associations between various mutational signatures and drug activity across cancer cell lines; these are as numerous as associations with established genetic markers such as driver gene alterations. Signatures of prior exposures to DNA damaging agents - including chemotherapy - tend to associate with drug resistance, while signatures of deficiencies in DNA repair tend to predict sensitivity towards particular therapeutics. Replication analyses across independent drug and CRISPR genetic screening data sets reveal hundreds of robust associations, which are provided as a resource for drug repurposing guided by mutational signature markers.

Clinical impact of genetic alterations of CTNNB1 in patients with grade 3 endometrial endometrioid carcinoma

To identify prognostic factors in patients with grade 3 (high‐grade) endometrial endometrioid carcinoma, we evaluated the spectrum of genomic alterations and examined whether previously reported molecular subtypes of endometrial carcinoma were adapted to clinical outcome prediction. Seventy‐five Japanese patients with grade 3 endometrial endometrioid carcinoma, who underwent a potentially curative resection procedure between 1997 and 2018 at the National Cancer Center Hospital, were included. We classified the patients into four risk groups of the disease based on the Proactive Molecular Risk Classifier for Endometrial Cancer. Genomic alterations in PTEN, ARID1A, TP53, and PIK3CA were detected in more than 30% of the patients. Overall survival and recurrence‐free survival of patients with genomic alterations in CTNNB1 were poorer than those of patients with wild‐type CTNNB1 (p = 0.006 and p = 0.004, respectively). Compared with that of alterations prevalent in Caucasians, the frequency of genomic alterations in POLE and TP53 was higher in our study than in The Cancer Genome Atlas dataset (p = 0.01 and p = 0.01, respectively). The tendency for recurrence‐free survival in the POLE exonuclease domain mutation group was better than that in the TP53 mutation and mismatch repair‐deficient groups (p = 0.08 and p = 0.07, respectively), consistent with the Proactive Molecular Risk Classifier for Endometrial Cancer risk classifier definition. The CTNNB1 mutation is a potential novel biomarker for the prognosis of patients with grade 3 endometrial endometrioid carcinoma, and prognosis classification using Proactive Molecular Risk Classifier for Endometrial Cancer may help screen Japanese patients with the disease.

ARID1A knockdown enhances carcinogenesis features and aggressiveness of Caco-2 colon cancer cells: An in vitro cellular mechanism study

Loss of ARID1A, a tumor suppressor gene, is associated with the higher grade of colorectal cancer (CRC). However, molecular and cellular mechanisms underlying the progression and aggressiveness of CRC induced by the loss of ARID1A remain poorly understood. Herein, we evaluated cellular mechanisms underlying the effects of ARID1A knockdown on the carcinogenesis features and aggressiveness of CRC cells. A human CRC cell line (Caco-2) was transfected with small interfering RNA (siRNA) specific to ARID1A (siARID1A) or scrambled (non-specific) siRNA (siControl). Cell death, proliferation, senescence, chemoresistance and invasion were then evaluated. In addition, formation of polyploid giant cancer cells (PGCCs), self-aggregation (multicellular spheroid) and secretion of an angiogenic factor, vascular endothelial growth factor (VEGF), were examined. The results showed that ARID1A knockdown led to significant decreases in cell death and senescence. On the other hand, ARID1A knockdown enhanced cell proliferation, chemoresistance and invasion. The siARID1A-transfected cells also had greater number of PGCCs and larger spheroid size and secreted greater level of VEGF compared with the siControl-transfected cells. These data, at least in part, explain the cellular mechanisms of ARID1A deficiency in carcinogenesis and aggressiveness features of CRC.

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.

ARID1A mutation/ARID1A loss is associated with a high immunogenic profile in clear cell ovarian cancer

OBJECTIVES

ARID1A mutation is frequently found in clear cell ovarian cancer (CCC) and endometrioid ovarian cancer (EC). Anti-PD-1 monotherapy has been found to have limited efficacy in epithelial ovarian cancer; however, anti-PD-1 therapy showed significant clinical benefit in some CCC. We sought to define the relationship of ARID1A mutation/ARID1A expression to the immunogenic profile of different histologic subtypes of ovarian cancer.

METHODS

We performed next-generation sequencing of 160 cancer-related genes. Also, we analyzed the immunohistochemical status of ARID1A, PD-L1, and CD8 with survival in different histologic subtypes of ovarian cancer in a total of 103 cases.

RESULTS

ARID1A mutation was found in 0% of the high-grade serous ovarian cancer (HGSC) (n = 36), 41.5% of the CCC (n = 41), 45.0% of the EC (n = 20), and 33.3% of the mucinous ovarian cancer (MC) (n = 6) cases. ARID1A loss was found in 19.4% of the HGSC, 75.6% of the CCC, 60.0% of the EC and 0% of the MC cases. ARID1A mutation was found to be associated with high PD-L1 (p < 0.001) or CD8 levels (p < 0.001) in CCC but not in other histologic subtypes. Meanwhile, ARID1A loss was associated with high PD-L1 or CD8 levels in CCC (p < 0.001) and HGSC (p < 0.001) but not in EC and MC. In addition, ARID1A mutation was associated with high tumor mutation burden in CCC (p = 0.006).

CONCLUSIONS

ARID1A mutation/ARID1A expression is associated with immune microenvironmental factors in CCC but not in EC. ARID1A status can be a biomarker for selecting candidates for immune checkpoint blockade in CCC.

The Role of ARID1A in Tumors: Tumor Initiation or Tumor Suppression?

Genes encoding subunits of SWItch/Sucrose Non-Fermenting (SWI/SNF) chromatin remodeling complexes are collectively mutated in 20% of all human cancers, among which the AT-rich interacting domain-containing protein 1A (ARID1A, also known as BAF250a, B120, C1orf4, Osa1) that encodes protein ARID1A is the most frequently mutated, and mutations in ARID1A have been found in various types of cancer. ARID1A is thought to play a significant role both in tumor initiation and in tumor suppression, which is highly dependent upon context. Recent molecular mechanistic research has revealed that ARID1A participates in tumor progression through its effects on control of cell cycle, modulation of cellular functions such as EMT, and regulation of various signaling pathways. In this review, we synthesize a mechanistic understanding of the role of ARID1A in human tumor initiation as well as in tumor suppression and further discuss the implications of these new discoveries for potential cancer intervention. We also highlight the mechanisms by which mutations affecting the subunits in SWI/SNF complexes promote cancer.