siRNA-Mediated Silencing of HMGA2 Induces Apoptosis and Cell Cycle Arrest in Human Colorectal Carcinoma

Abstract

Purpose: Overexpression of HMGA2, known as small non-histone chromosomal protein, is associated with progression of various tumors, including colorectal cancers. The aim of this study was to investigate the effect of a specific HMGA2 siRNA on apoptosis and cell cycle of HCT-116 (colorectal carcinoma) cells.

Methods: The cells were transfected with siRNAs using a transfection reagent. The cytotoxic effects of HMGA2 siRNA on colorectal carcinoma cells were determined using MTT assay. Relative HMGA2 mRNA and protein levels were measured by QRT-PCR and western blotting, respectively. Apoptosis was measured by a TUNEL test based on labeling of DNA strand breaks. We also evaluated caspase-3, caspase-8, and caspase-9 expression by QRTPCR to determine which pathway is involved in apoptosis. Cell cycle was assessed by FACS and cell cycle analysis using PI DNA staining.

Results: HMGA2 siRNA significantly reduced both mRNA and protein expression levels 48 h after transfection and dose-dependent manner in colorectal carcinoma cells. We also showed that the silencing of HMGA2 led to the induction of apoptosis through intrinsic pathway and cell cycle arrest in G2/M phases of interphase in HCT-116 cells in vitro.

Conclusions: These results propose that HMGA2 might play an important role in the progression of colorectal carcinoma and might be a potential therapeutic target for trigger apoptosis and cell cycle arrest in colorectal carcinoma.

Keywords: Apoptosis; Cell cycle; Colorectal carcinoma; HMGA2 (high mobility group A2); Small interference RNA (siRNA).