A novel function of colony-stimulating factor 1 receptor in hTERT immortalization of human epithelial cells

Abstract

The receptor for macrophage colony-stimulating factor 1 receptor (CSF1R) is a product of the proto-oncogene c-fms and a member of the class III transmembrane tyrosine kinase receptor family. Earlier, we described increased mRNA expression of CSF1R in human telomerase reverse transcriptase (hTERT) immortalized human ovarian surface epithelial (IOSE) cell lines derived from a single donor. Here, we further describe that CSF1R is upregulated at both the mRNA and protein level in hTERT immortalized human normal OSE cells from two different donors and in hTERT immortalized human pancreatic ductal epithelial cells. CSF1R was not upregulated in hTERT immortalized epithelial clones that subsequently underwent senescence or in immortalized fibroblasts. Upon stimulation by the CSF1R ligand CSF1, the immortalized epithelial cell lines showed rapid internalization of CSF1R with concomitant down-modulation and colocalization of phosphorylated NFjBp65 with hTERT protein, hTERT translocation into the nucleus and the binding of c-Myc to the hTERT promoter region. Reducing the expression of CSF1R using short hairpin interfering RNA abolished these effects and also decreased cell survival and the number of population doublings under suboptimal culture conditions. The telomerase inhibitor GRN163L confirmed a role for telomerase in the cleavage of the intracellular domain of CSF1R. On the basis of these findings, we suggest that CSF1R may be a critical factor facilitating hTERT immortalization of epithelial cells.

Transcription Regulation of the Human Telomerase Reverse Transcriptase (hTERT) Gene

“…ETS Proto-Oncogene 2 (Ets2) interacts with c-Myc and together they bind to hTERT promoter sequence and mediate breast cancer proliferation [52]. Colony Stimulating Factor 1 Receptor (CSF1R), upon induction by its ligand Colony Stimulating Factor 1 (CSF1), gets internalised into activated immortalized epithelial cells which lead to elevated binding of c-Myc to hTERT promoter [68]. Protein deglycase DJ-1 regulates c-Myc expression and thus hTERT promoter activity in renal and ovarian carcinoma cells [70].…”

Novel Role for Matricellular Proteins in the Regulation of Islet β Cell Survival

“…PS-1 cells are previously described human pancreatic stellate cells (24,25). They were maintained in high glucose DMEM: Ham's F12 medium (1:1, both from PAA) supplemented with 10% FBS, 1 g/ml puromycin (Sigma), 1 mM sodium pyruvate, 100 unit/ml penicillin and 100 g/ml streptomycin, or in RPMI 1640 supplemented with 10% FBS, 0.1% L-glutamine, 100 unit/ml penicillin, and 100 g/ml streptomycin.…”

Current Status and Evolution of Preclinical Drug Development Models of Epithelial Ovarian Cancer

“…Retroviral transduction of either the human papilloma virus E6/E7 oncogenes or the simian virus 40 T-Antigen (SV40-TAg) in human OSE cells leads to increased and sustained proliferation even after multiple passages but does not induce transformation (19, 20). For immortalization to occur, additional retroviral constructs targeting TP53, hTERT, or RB are required (21, 22). Besides retroviral transduction, RNA interference technology has been successful in immortalizing human OSE cells as exemplified by the work of Yang and colleagues who successfully immortalized OSE cells via siRNA knockdown of p53 and Rb (23, 24).…”