Evidence of sex differences in cancer-related cardiac complications in mouse models of pancreatic and liver cancer.

Abnormal heart rate variability (HRV) is commonly observed in cancer patients who have undergone targeted therapy and/or surgery, yet the effects of cancer itself on cardiac function remain underexplored. Specifically, there is limited knowledge about sex-specific manifestations of HRV in cancer patients. Transgenic mouse models are widely used to study different types of cancer. Here, we aimed to investigate the sex-specific effects of cancer on cardiac function using transgenic mouse models of pancreatic and liver cancers. This study used male and female transgenic mice with cancer and wild-type controls. Cardiac function was assessed by recording electrocardiograms in conscious mice. RR intervals were detected to determine HRV using time and frequency domain analyses. Histological analysis with Masson's trichrome staining was performed to determine structural changes. In females, increased HRV was observed in both pancreatic and liver cancer-bearing mice. In contrast, in males, increased HRV was observed only in the liver cancer group. Male pancreatic cancer mice demonstrated autonomic balance shift showing an increase in parasympathetic to sympathetic tone. The heart rate (HR) was higher in control and liver cancer male mice groups than in females. Histological analysis did not show significant sex differences but suggested a higher degree of remodeling in liver cancer mice than in control, specifically in the right atrium and left ventricle. This study revealed sex differences in cancer's HR modulation. Specifically, female cancer mice had lower median HR and higher HRV. These findings indicate that sex must be considered when using HRV as a cancer biomarker.

BAP1 is a haploinsufficient tumor suppressor linking chronic pancreatitis to pancreatic cancer in mice.

Chronic pancreatitis represents a risk factor for the development of pancreatic cancer. We find that heterozygous loss of histone H2A lysine 119 deubiquitinase BAP1 (BRCA1 Associated Protein-1) associates with a history of chronic pancreatitis and occurs in 25% of pancreatic ductal adenocarcinomas and 40% of acinar cell carcinomas. Deletion or heterozygous loss of Bap1 in murine pancreata causes genomic instability, tissue damage, and pancreatitis with full penetrance. Concomitant expression of KrasG12D leads to predominantly intraductal papillary mucinous neoplasms and mucinous cystic neoplasms, while pancreatic intraepithelial neoplasias are rarely detected. These lesions progress to metastatic pancreatic cancer with high frequency. Lesions with histological features mimicking Acinar Cell Carcinomas are also observed in some tumors. Heterozygous mice also develop pancreatic cancer suggesting a haploinsufficient tumor suppressor role for BAP1. Mechanistically, BAP1 regulates genomic stability, in a catalytic independent manner, and its loss confers sensitivity to irradiation and platinum-based chemotherapy in pancreatic cancer.

Loss of KDM6A Activates Super-Enhancers to Induce Gender-Specific Squamous-like Pancreatic Cancer and Confers Sensitivity to BET Inhibitors.

KDM6A, an X chromosome-encoded histone demethylase and member of the COMPASS-like complex, is frequently mutated in a broad spectrum of malignancies and contributes to oncogenesis with poorly characterized mechanisms. We found that KDM6A loss induced squamous-like, metastatic pancreatic cancer selectively in females through deregulation of the COMPASS-like complex and aberrant activation of super-enhancers regulating ΔNp63, MYC, and RUNX3 oncogenes. This subtype of tumor developed in males had concomitant loss of UTY and KDM6A, suggesting overlapping roles, and points to largely demethylase independent tumor suppressor functions. We also demonstrate that KDM6A-deficient pancreatic cancer is selectively sensitive to BET inhibitors, which reversed squamous differentiation and restrained tumor growth in vivo, highlighting a therapeutic niche for patient tailored therapies.