Transcription profiling of irradiated non-adherent anoikis-resistant DU145 and MCF-7 cells and 5-azacytidine-treated non-adherent anoikis-resistant HeLa cells in contrast to control (non-irradiated, non-treated) cells.

ABSTRACT: Radiation and chemotherapy represent standard-of-care cancer treatments, however most treated patients eventually experience tumor recurrence, treatment failure and metastatic dissemination with fatal consequences. To elucidate molecular mechanisms of resistance to radio- and chemo-therapy, we exposed human cancer cell lines (HeLa, MCF-7, and DU145) to clinically relevant doses of 5-azacytidine or ionizing radiation and compared the transcript profiles of all surviving cell subpopulations including non-adherent fraction. Stress-mobilized non-adherent cell fractions differed from other survivors in deregulation of hundreds of genes including those involved in interferon response. Exposure of cancer cells to interferon-gamma but not interferon-beta resulted in development of a heterogeneous non-adherent fraction comprising, besides apoptotic/necrotic cells, also live cells featuring active Notch signaling and expressing stem cell markers. Interferon-gamma-mediated loss of adhesion and anoikis-resistance required active Erk pathway interlinked with interferon signaling by IRF1, as chemical inhibition of MEK or siRNA-mediated knockdown of Erk1/2 and IRF1 prevented mobilization of the surviving non-adherent population. Noteworthy, among the top scoring genes upregulated in surviving non-adherent tumor cells induced by 5-azacytidine or irradiation was a skin-specific protein suprabasin (SBSN), a recently identified oncoprotein. SBSN expression required the activity of the MEK/Erk pathway, and siRNA-mediated knockdown of SBSN resulted in suppression of the non-adherent fraction in irradiated, interferon-gamma- and 5-azacytidine-treated cells, respectively. Consistently, ectopic expression of SBSN isoforms enhanced the non-adherent phenotype, suggesting functional participation of SBSN in genotoxic stress-induced phenotypic plasticity and stress resistance. The stress-induced expression of skin protein(s) in a subset of cancer cells indicates partial induction of a keratinocyte-like expression program. Overall, we propose that IFN and Erk signaling drive the heterogeneous response of cancer cells to genotoxic therapies and expression of keratinocyte-specific genes as key players in mobilization and survival of cancer stem-like cells, with implications for cancer evolution and therapy resistance.

ORGANISM(S): Homo sapiens

SUBMITTER: Lenka Kyjacova 

PROVIDER: E-MTAB-6062 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress