Vaginal Squamous Cell Carcinoma Develops in Mice with Conditional Arid1a Loss and Gain of Oncogenic Kras Driven by Progesterone Receptor Cre

ARID1A: Multiple functions in human pregnancy

AT-rich interacting domain containing respectively protein 1 A (ARID1A), a key member of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complex, has been shown to play an important role in various physiological processes and diseases including female reproductive tumors, such as ovarian cancer and breast cancer. In addition to the studies regarding ARID1A expression and function in cancer, recent findings elucidate its important role in maintaining normal tissue homeostasis and cell differentiation by controlling chromatin remodeling and transcription factors recruitment. In the context of human pregnancy, ARID1A has been implicated in several pregnancy-related complications, including gestational diabetes, preeclampsia, and intrauterine growth restriction. This review examines the current research on the role of ARID1A in pregnancy, highlighting its potential as a biomarker and therapeutic target for these complications. Understanding the involvement of ARID1A in placental function and pregnancy-related disorders may provide valuable insights for the development of novel diagnostic and therapeutic strategies.

Targeting KRAS in gynecological malignancies

Cervical, endometrial, and ovarian cancers stand prominently as the leading gynecological malignancies of the female reproductive system. The conventional therapeutic modalities for gynecological malignancies have predominantly encompassed surgery, chemotherapy, and radiotherapy. However, efficacy of these approaches remains limited in cases of relapse or drug resistance. KRAS is one of the most frequently mutated oncogenes in human cancers. The KRAS gene encodes a small guanosine triphosphatase protein that acts as a molecular switch for crucial intracellular signaling pathways. KRAS mutations are deeply involved in the occurrence and development of gynecological malignancies. The present review aims to expound upon the role of oncogenic KRAS as a biomarker, elucidating various therapeutic approaches under investigation targeting the KRAS pathway in gynecological tumors.

ARID1A in Gynecologic Precancers and Cancers

The highest frequency of genetic alterations in the tumor suppressor ARID1A occurs in malignancies of the female reproductive tract. The prevalence of ARID1A alterations in gynecologic precancers and cancers is summarized from the literature, and the putative mechanisms of tumor suppressive action examined both in benign/precursor lesions including endometriosis and atypical hyperplasia and in malignancies of the ovary, uterus, cervix and vagina. ARID1A alterations in gynecologic cancers are usually loss-of-function mutations, resulting in diminished or absent protein expression. ARID1A deficiency results in pleiotropic downstream effects related not only to its role in transcriptional regulation as a SWI/SNF complex subunit, but also related to the functions of ARID1A in DNA replication and repair, immune modulation, cell cycle progression, endoplasmic reticulum (ER) stress and oxidative stress. The most promising actionable signaling pathway interactions and therapeutic vulnerabilities of ARID1A mutated cancers are presented with a critical review of the currently available experimental and clinical evidence. The role of ARID1A in response to chemotherapeutic agents, radiation therapy and immunotherapy is also addressed. In summary, the multi-faceted role of ARID1A mutation in precancer and cancer is examined through a clinical lens focused on development of novel preventive and therapeutic interventions for gynecological cancers.

Co-existing TP53 and ARID1A mutations promote aggressive endometrial tumorigenesis

TP53 and ARID1A are frequently mutated across cancer but rarely in the same primary tumor. Endometrial cancer has the highest TP53-ARID1A mutual exclusivity rate. However, the functional relationship between TP53 and ARID1A mutations in the endometrium has not been elucidated. We used genetically engineered mice and in vivo genomic approaches to discern both unique and overlapping roles of TP53 and ARID1A in the endometrium. TP53 loss with oncogenic PIK3CA^H1047R in the endometrial epithelium results in features of endometrial hyperplasia, adenocarcinoma, and intraepithelial carcinoma. Mutant endometrial epithelial cells were transcriptome profiled and compared to control cells and ARID1A/PIK3CA mutant endometrium. In the context of either TP53 or ARID1A loss, PIK3CA mutant endometrium exhibited inflammatory pathway activation, but other gene expression programs differed based on TP53 or ARID1A status, such as epithelial-to-mesenchymal transition. Gene expression patterns observed in the genetic mouse models are reflective of human tumors with each respective genetic alteration. Consistent with TP53-ARID1A mutual exclusivity, the p53 pathway is activated following ARID1A loss in the endometrial epithelium, where ARID1A normally directly represses p53 pathway genes in vivo, including the stress-inducible transcription factor, ATF3. However, co-existing TP53-ARID1A mutations led to invasive adenocarcinoma associated with mutant ARID1A-driven ATF3 induction, reduced apoptosis, TP63+ squamous differentiation and invasion. These data suggest TP53 and ARID1A mutations drive shared and distinct tumorigenic programs in the endometrium and promote invasive endometrial cancer when existing simultaneously. Hence, TP53 and ARID1A mutations may co-occur in a subset of aggressive or metastatic endometrial cancers, with ARID1A loss promoting squamous differentiation and the acquisition of invasive properties.

Endometrial cancer is the most commonly diagnosed gynecologic malignancy in the United States, with annual incidence continuing to rise. Although the majority of endometrial cancer patients have an excellent overall prognosis if the disease is confined to the endometrium, myometrial invasion and metastasis to other sites correlate with poor survival. Here, we used genetically engineered mice, in vivo genomics, and public cancer patient data to understand the relationship between TP53 and ARID1A, two of the most commonly mutated genes in endometrial cancer, in the context of mutant PIK3CA. Mutations in TP53 and ARID1A change different aspects of endometrial cell health but also share some similarities. ARID1A mutations specifically promote cancer cells to invade nearby tissue, a hallmark of metastasis, associated with squamous differentiation. Mice with co-existing TP53 and ARID1A mutations developed more invasive disease. Our studies suggest that co-existing TP53 and ARID1A tumor mutations may promote invasion and metastasis.

Sex-dependent development of Kras-induced anal squamous cell carcinoma in mice

Anal squamous cell carcinoma (SCC) will be diagnosed in an estimated 9,080 adults in the United States this year, and rates have been rising over the last several decades. Most people that develop anal SCC have associated human papillomavirus (HPV) infection (~85-95%), with approximately 5-15% of anal SCC cases occurring in HPV-negative patients from unknown etiology. This study identified and characterized the Kras-driven, female sex hormone-dependent development of anal squamous cell carcinoma (SCC) in the LSL-KrasG12D; Pdx1-Cre (KC) mouse model that is not dependent on papillomavirus infection. One hundred percent of female KC mice develop anal SCC, while no male KC mice develop tumors. Both male and female KC anal tissue express Pdx1 and Cre-recombinase mRNA, and the activated mutant KrasG12D gene. Although the driver gene mutation KrasG12D is present in anus of both sexes, only female KC mice develop Kras-mutant induced anal SCC. To understand the sex-dependent differences, KC male mice were castrated and KC female mice were ovariectomized. Castrated KC males displayed an unchanged phenotype with no anal tumor formation. In contrast, ovariectomized KC females demonstrated a marked reduction in anal SCC development, with only 15% developing anal SCC. Finally, exogenous administration of estrogen rescued the tumor development in ovariectomized KC female mice and induced tumor development in castrated KC males. These results confirm that the anal SCC is estrogen mediated. The delineation of the role of female sex hormones in mediating mutant Kras to drive anal SCC pathogenesis highlights a subtype of anal SCC that is independent of papillomavirus infection. These findings may have clinical applicability for the papillomavirus-negative subset of anal SCC patients that typically respond poorly to standard of care chemoradiation.