CHARACTERIZATION OF IMMORTALIZED HUMAN PROSTATE EPITHELIAL CELLS

Abstract

Prostate cancer (PCa) accounts for an estimated 20% of new cancer cases and 10% of deaths in just US males in 2020. Despite this prevalence, the molecular basis of its development and initiation remains unclear. To help identify the molecular basis of PCa progression, it is important to generate a collection of human prostate epithelial cells (hPrEC) that remain karyotypically normal and represent the epithelial cell types present in the human prostate. hPrEC can only go through a limited number of passages before they become senescent. Immortalization prevents senescence and enables continuous cell division. Our lab previously immortalized hPrEC cells by the expression of human telomerase (hTERT) with concomitant CRISPR inactivation of the CDKN2A locus, which directs the expression of both p16INK4A and p14ARF genes.Characterization of the two clonal cell lines that were generated showed that they maintained normal cell growth characteristics with intact p53 and pRb pathways, near normal karyotypes and have characteristics of basal cell origin. Subsequently, our lab sought to determine if expression of hTERT with knockout of just p16INK4A alone was also sufficient for immortalization, using CRISPR technology to inactivate exon 1α of the CDKN2A locus along with ectopic expression of the hTERT transgene. Knockout of p16INK4A but not p14ARF along with exogenous expression of hTERT resulted in the generation of a new immortal clone. Using these immortalized clones, along with primary hPrEC from ATCC our goal is to further characterize these cells to aid in future attempts aimed at immortalizing normal PrEC from multiple individuals and for the efficient establishment of a primary prostate cancer cell line. Our first approach included immunophenotyping our generated immortal hPrEC clones and ATCC hPrEC’s to identify the cell populations defining each of our clones and the different cell populations present in the primary hPrEC. We also characterized the expression of cells using 3D cell culture to determine their morphology and the expression of relevant markers. Finally, we identified the differentially expressed genes by RNA-seq in our immortalized hPrEC clones and ATCC hPrEC to determine their closest lineage identity as well as find suitable markers to use for future studies. These cell lines will also serve as a model to study transformation of PrEC in culture and xenograft tumorigenesis in mice.