Cooperatively transcriptional and epigenetic regulation of sonic hedgehog overexpression drives malignant potential of breast cancer.
Bottom Line: Comprehensive understanding of the regulation mechanism of Shh in cancer cells is necessary to find an effective approach to selectively block its tumorigenic function.Moreover, in vitro data demonstrated that both NF-κB activation and hypomethylation in promoter region were positively associated with the overexpression of Shh.Furthermore, the biological function data indicated that overexpressed Shh enhanced the self-renewal capacity and migration ability of breast cancer cells, which could be augmented by promoter demethylation and NF-κB activation.
Affiliation: Department of Pharmacology, College of Life Science and Biopharmaceutical of Shenyang Pharmaceutical University, Shenyang, China.Show MeSH
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Mentions: It is well known that the activation of Shh signaling would result in a malignant potential of cancer cells.3,4 Therefore, we next investigated whether hypomethylation, NF-κB and Shh cooperate to drive the malignant potential of breast cancer cells. As shown in Figure4a, the overexpression of Shh led to an increase in the colony formation rate of MDA-MB-231 cells. Similarly, there was a significant increase in the number of colony-forming cells after treatment with TNF-α or 5-Aza. In addition, triple combination resulted in a significant increase in the colony formation rate, indicating an enhanced self-renewal capacity of these breast cancer cells. Interestingly, pretreatment with cyclopamine, a specific inhibitor of Shh signaling, led to an obvious decrease in the number of colony-forming cells, suggesting that the induction of Shh expression by 5-Aza and NF-κB is critical in the self-renewal of breast cancer cells. Moreover, the migration ability of Bcap37 cells was also measured. In agreement with the data obtained from the colony formation assay, the migration cells were increased after being treated with overexpressed Shh, TNF-α or 5-Aza (see Fig.4b). Meanwhile, the number of invasion cells was significantly increased after the combination, but obviously reversed by cyclopamine (see Fig.4b). Furthermore, we also assessed the effect of Shh signaling on cell proliferation. As shown in Figure S1, overexpression of Shh resulted in an increase in the cell viability of MDA-MB-231 cells, whereas pretreatment with cyclopamine reversed Shh-mediated cell proliferation. In contrast to colony formation and migration results, a slight reduction of cell viability was shown after treatment with TNF-α or 5-Aza. Taken together, our data showed that hypomethylation, NF-κB and Shh cooperate to drive self-renewal capacity and migration ability of breast cancer cells.
Affiliation: Department of Pharmacology, College of Life Science and Biopharmaceutical of Shenyang Pharmaceutical University, Shenyang, China.