Abstract A025: TSHZ2 is a regulator of the intermediate subtype of pancreatic adenocarcinoma

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is characterized by extensive tumor cell heterogeneity and transcriptional plasticity. Basal and Classical subtypes have represented the main cellular states in PDAC for years, but recently an intermediate cell-state has become more recognized. The transcriptional regulators of the intermediate cell-state remain poorly defined. A recent single-cell study in metastatic PDAC, defined the intermediate cell-state and identified TSHZ2 as one of the top differentially expressed genes associated with this transcriptional program. TSHZ2 is zinc finger/homeobox transcription factor with an emerging role in biology of epithelial tumors, but its function in PDAC has not been determined. We hypothesize that TSHZ2 regulates the transcriptional program defining the intermediate cell-state. To test this, we have evaluated the endogenous expression of TSHZ2 in several PDAC cell lines, and generated doxycycline inducible knock-down cell models for TSHZ2. In the UM32 cell line, TSHZ2 knock-down simultaneously decreased TFF1 and KRT5 expression, at RNA and protein levels. Because TFF1 and KRT5 represent markers associated with the classical and basal expression programs respectively, this data suggests TSHZ2 coordinately regulates the expression cellular state markers. We also generated TSHZ2 doxycycline-inducible knockdown in multiple PDAC cell lines, which showed appropriate doxycycline reporter activity. To test the role of TSHZ2 in vivo, we generated a tamoxifen inducible pancreas-specific Tszh2 knockout mouse model and crossed it with KC (Kras-driven) models of pancreatic neoplasia and cancer. Preliminary analysis suggests that Tshz2 loss plays an important role in pancreatic tumor formation. Together, our findings support TSHZ2 as candidate regulator of the intermediate cell-state programs and suggest that may also contribute to the pancreatic tumor development.