| Purpose: The HMGI-C (high mobility group protein isoform I-C) protein is a member of the high-mobility
group AT-hook (HMGA) family of small non-histone chromosomal proteins that can modulate
transcription of an ample number of genes. Genome-wide studies reveal upregulation of the HMGI-C gene
in many human cancers, which suggests that HMGI-C might play a critical role in the progression of
various tumors. However, the exact role of HMGI-C in breast adenocarcinoma has not been made clear.
Methods: HMGI-C mRNA expression in breast cancer samples and marginal normal tissues was
characterized using qRT-PCR. The cytotoxic effects of HMGI-C siRNA on breast adenocarcinoma cells were
determined using MTT assay. Relative HMGI-C mRNA and protein levels were measured by quantitative
real-time PCR and western blotting, respectively. Apoptosis detection was done using TUNEL and
Annexin-V/PI assays, P53, caspase 3, 9, 8 and Bcl2 proteins evaluated by protein gel blot and miR34a, Let-
7a genes investigates by QRT-PCR assay. Cell cycle was analyzed by flow cytometry assay using propidium
iodide DNA staining. Results: An overexpression of HMGA2 was revealed with highly statistically
significant differences between breast cancer samples and marginal normal tissues (P < 0.0001). HMGI-C
siRNA significantly reduced both mRNA and protein expression levels in a 48-hour period after
transfection and in a dose-dependent manner. We observed that the knockdown of HMGI-C led to the
significant induction of apoptosis via mitochondrial pathway by inducing miR34a and cell cycle arrest in
MDA-MB-468 cells in vitro. Conclusions: These results propose that HMGI-C might play a critical role in the
progression of breast adenocarcinoma. Here we introduced HMGI-C as a potential therapeutic target for
trigger apoptosis and cell cycle arrest in human breast adenocarcinoma. Therefore HMGI-C siRNA may be
an effective adjuvant in human breast adenocarcinoma. |