ARID3A inhibits colorectal cancer cell stemness and drug-resistance by targeting a multitude of stemness-associated genes

Abstract

Aims

ARID3A is highly expressed in CRC patients. However, the functional role of ARID3A in CRC remains unexplored. We sought to demonstrate ARID3A function in CRC.

Materials and methods

ARID3A was knocked-down using lentiviruses harboring shRNA. CRC patients' tissue cDNA array was used to assess expression of ARID3A. Effect of ARID3A on CSC-associated genes was analysed using real-time PCR array. Western-blot analysis and ChIP assay were used to validate the role of ARID3A. Paclitaxel-resistant CSC-enriched cell population was used to assess correlation between ARID3A, stemness and drug resistance potential. Ex vivo findings were corroborated on preclinical mouse model.

Key findings

ARID3A expression was significantly higher throughout CRC stages than normal individuals. ARID3A expression was significantly higher in the aggressive CRC cell line HCT116 compared to HT29, which expressed higher levels of CD44, CD133, and EpCAM, suggesting a reciprocal relationship between ARID3A expression and CRC stemness. Real-time PCR-based stem cell array using ARID3A-knockdown HCT116 cells showed upregulation of 9 cancer stem cell (CSC)-associated genes. ChIP-assay verified binding of ARID3A on transcriptionally active promoter regions of CSC associated genes. ARID3A depletion led to enhanced proliferation, anchorage-independent growth, and ABCG2 upregulation in HCT116 cells. In paclitaxel-resistant HCT116 cells, ARID3A expression was dampened, whereas, CD44 and CD133 increased. ARID3A knockdown accelerated tumor growth and promoted larger tumor formation in nude-mouse xenograft model. Ki67, CD44 and CD133 were highly upregulated in knockdown tumors.

Significance

This study demonstrated that ARID3A inhibits CRC stemness, anchorage-independent growth, self-renewal, anti-cancer drug resistance of CRC cells and tumor growth in vivo.