Role of HSP27 in the multidrug sensitivity and resistance of colon cancer cells

Abstract

Multidrug resistance in cancer cells is a primary factor affecting therapeutic efficacy. Heat shock 27 kD protein 1 (HSP27) is associated with cell apoptosis and resistance to chemotherapy. However, the mechanisms underlying HSP27-associated pathways in colon cancer cells remain unclear. Therefore, the present study used short hairpin (sh) RNA to inhibit HSP27 expression in colon cancer cells in order to investigate the effects in vitro and in vivo. Flow cytometry was used to investigate cell apoptosis and a xenograft model was employed to examine the tumorigenesis. Protein expression was measured by Western blotting. The results revealed that suppression of HSP27 expression significantly increased cell apoptosis, inhibited tumor growth and enhanced sensitivity to the anti-cancer agents 5-fluorouracil (5-FU) and vincristine (VCR). shHSP27 significantly decreased the expression of notch receptor 1 and the phosphorylation level of Akt and mTOR, and enhanced the effect of 5-FU and VCR. In conclusion, HSP27 suppression enhanced the sensitivity of colon cancer cells to 5-FU and VCR, and increased colon cancer cell apoptosis with and without chemotherapy. Therefore, the development of novel therapeutic agents that inhibit the expression of HSP27 may offer a new treatment option for colon cancer.

Keywords: colon cancer; heat shock 27 kD protein 1; multidrug sensitivity; notch receptor 1-Akt-mTOR pathway.

Figure 1.

Effect of shHSP27 on HSP27 expression (A) in vitro and (B) in vivo. Results are expressed as the ratio of HSP27 and β-actin. *P<0.05 vs. the others. n=4 in each group. sh, short hairpin; HSP27, heat shock 27 kD protein 1; NC, negative control.

Figure 2.

Annexin V-FITC/PI staining of SW480 cells with/without shHSP27 and chemotherapy. *P<0.05 vs. the other groups, ^#P<0.05 vs. control + 5-FU group, ^&P<0.05 vs. control + VCR group. n=5 in each group. sh, short hairpin; HSP27, heat shock 27 kD protein 1; 5-FU, 5-fluorouracil; VCR, vincristine.

Figure 3.

Tumor sizes in the xenograft model. *P<0.05 vs. the other groups, ^#P<0.05 vs. control, ^&P<0.05 vs. control + 5-FU or control + VCR. n=4 in each group. sh, short hairpin; HSP27, heat shock 27 kD protein 1; 5-FU, 5-fluorouracil; VCR, vincristine. Scale bar=100 mm.

Figure 4.

Effect of shHSP27 and chemotherapy on the phosphorylation and expression of the NOTCH1-Akt-mTOR pathway in vitro. *P<0.05 vs. the other groups, ^#P<0.05 vs. control + 5-FU group, ^&P<0.05 vs. control + VCR group. n=4 in each group. sh, short hairpin; HSP27, heat shock 27 kD protein 1; NOTCH1, notch receptor 1; 5-FU, 5-fluorouracil; VCR, vincristine; p, phosphorylated.

Figure 5.

Effect of shHSP27 and chemotherapy on the phosphorylation and expression of the NOTCH1-Akt-mTOR pathway in vivo. *P<0.05 vs. the others, ^#P<0.05 vs. control + 5-FU group, ^&P<0.05 vs. control + VCR group. n=4 in each group. sh, short hairpin; HSP27, heat shock 27 kD protein 1; NOTCH1, notch receptor 1; 5-FU, 5-fluorouracil; VCR, vincristine.