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Rosiglitazone sensitizes hepatocellular carcinoma cell lines to 5-fluorouracil antitumor activity through activation of the PPARgamma signaling pathway.

Cao LQ, Wang XL, Wang Q, Xue P, Jiao XY, Peng HP, Lu HW, Zheng Q, Chen XL, Huang XH, Fu XH, Chen JS - Acta Pharmacol. Sin. (2009)

Bottom Line: Since distribution of PTEN in HCC tissues is significantly decreased compared with the paracancerous tissue, over-expression of PTEN by rosiglitazone enhances 5-FU-inhibited cell growth of HCC.Moreover, down-regulation of COX-2 is implicated in the synergistic effect of 5-FU.The results suggest potential novel therapies for the treatment of advanced liver cancer.

View Article: PubMed Central - PubMed

Affiliation: Department of Hepatobiliary Surgery, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, China.

ABSTRACT

Aim: Resistance to 5-fluorouracil (5-FU) is a major cause of chemotherapy failure in advanced hepatocellular carcinoma (HCC). Rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, has a crucial role in growth inhibition and induction of apoptosis in several carcinoma cell lines. In this study, we examine rosiglitazone-induced sensitization of HCC cell lines (BEL-7402 and Huh-7 cells) to 5-FU.

Methods: The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate cell viability. Western blotting analysis was performed to detect the protein expression (PPARgamma, PTEN, and COX-2) in BEL-7402 cells. Immunohistochemistry staining was used to examine the expression of PTEN in 100 advanced HCC tissues and paracancerous tissues. In addition, small interfering RNA was used to suppress PPARgamma, PTEN, and COX-2 expression.

Results: Rosiglitazone facilitates the anti-tumor effect of 5-FU in HCC cell lines, which is mediated by the PPARgamma signaling pathway. Activation of PPARgamma by rosiglitazone increases PTEN expression and decreases COX-2 expression. Since distribution of PTEN in HCC tissues is significantly decreased compared with the paracancerous tissue, over-expression of PTEN by rosiglitazone enhances 5-FU-inhibited cell growth of HCC. Moreover, down-regulation of COX-2 is implicated in the synergistic effect of 5-FU.

Conclusion: Rosiglitazone sensitizes hepatocellular carcinoma cell lines to 5-FU antitumor activity through the activation of PPARgamma. The results suggest potential novel therapies for the treatment of advanced liver cancer.

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Representative sections showing PTEN protein expression by immunohistochemical staining. (A-a) a negative control section of HCC (primary antibody substituted with PBS, original magnification, ×200); (A-b) the positive staining of PTEN was mainly observed in the cytoplasm of cells. The strong staining of PTEN protein was shown in paracancerous tissue (the long arrow), and the weak staining was shown in tumor tissue (the short arrow, original magnification, ×100); (A-c) PTEN protein was expressed in the cytoplasm of carcinoma cells (original magnification, ×200); (A-d) PTEN protein was expressed in the nuclei of carcinoma cells (original magnification, ×200); (B) Cellular protein was isolated from BEL-7402 cells transfected with control or PTEN siRNA for 48 h and was then subjected to Western blotting analysis for PTEN protein. PTEN siRNA inhibits PTEN protein expression. (C) BEL-7402 cells were transfected with control or PTEN siRNA for 48 h before exposing the cells to rosiglitazone (30 μmol/L) in the presence or absence of 5-FU (10 μmol/L). Afterwards, the cell viabilities were determined by MTT assay up to 48 h. Data are expressed as the mean±SD of three independent experiments. bP<0.05 vs control group; Con, cells treated with 0.1% DMSO; Con siRNA, non-specific siRNA, as a negative control.
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fig4: Representative sections showing PTEN protein expression by immunohistochemical staining. (A-a) a negative control section of HCC (primary antibody substituted with PBS, original magnification, ×200); (A-b) the positive staining of PTEN was mainly observed in the cytoplasm of cells. The strong staining of PTEN protein was shown in paracancerous tissue (the long arrow), and the weak staining was shown in tumor tissue (the short arrow, original magnification, ×100); (A-c) PTEN protein was expressed in the cytoplasm of carcinoma cells (original magnification, ×200); (A-d) PTEN protein was expressed in the nuclei of carcinoma cells (original magnification, ×200); (B) Cellular protein was isolated from BEL-7402 cells transfected with control or PTEN siRNA for 48 h and was then subjected to Western blotting analysis for PTEN protein. PTEN siRNA inhibits PTEN protein expression. (C) BEL-7402 cells were transfected with control or PTEN siRNA for 48 h before exposing the cells to rosiglitazone (30 μmol/L) in the presence or absence of 5-FU (10 μmol/L). Afterwards, the cell viabilities were determined by MTT assay up to 48 h. Data are expressed as the mean±SD of three independent experiments. bP<0.05 vs control group; Con, cells treated with 0.1% DMSO; Con siRNA, non-specific siRNA, as a negative control.

Mentions: 5-FU is widely used to treat advanced HCC, but chemo-resistance remains a major obstacle to its use in the clinical setting. To investigate the relationship between the expression of PTEN and advanced HCC, we examined the expression of PTEN in 100 advanced HCC tissues and paracancerous tissues. Of 100 cases of HCC, 62 cases were positive for PTEN, and 38 cases were negative. Ninety-two cases of adjacent non-tumor tissues were positive as a control. As shown in Figure 4A-b, the staining distribution of PTEN in HCC tissues was significantly decreased as compared with the paracancerous tissue (χ2=25.409, P<0.05). Furthermore, of the 62 positive samples, 45 showed staining in the cytoplasm of cancer cells (Figure 4A-c), and the other 17 exhibited intensive nuclear staining of cancer cells (Figure 4A-d).


Rosiglitazone sensitizes hepatocellular carcinoma cell lines to 5-fluorouracil antitumor activity through activation of the PPARgamma signaling pathway.

Cao LQ, Wang XL, Wang Q, Xue P, Jiao XY, Peng HP, Lu HW, Zheng Q, Chen XL, Huang XH, Fu XH, Chen JS - Acta Pharmacol. Sin. (2009)

Representative sections showing PTEN protein expression by immunohistochemical staining. (A-a) a negative control section of HCC (primary antibody substituted with PBS, original magnification, ×200); (A-b) the positive staining of PTEN was mainly observed in the cytoplasm of cells. The strong staining of PTEN protein was shown in paracancerous tissue (the long arrow), and the weak staining was shown in tumor tissue (the short arrow, original magnification, ×100); (A-c) PTEN protein was expressed in the cytoplasm of carcinoma cells (original magnification, ×200); (A-d) PTEN protein was expressed in the nuclei of carcinoma cells (original magnification, ×200); (B) Cellular protein was isolated from BEL-7402 cells transfected with control or PTEN siRNA for 48 h and was then subjected to Western blotting analysis for PTEN protein. PTEN siRNA inhibits PTEN protein expression. (C) BEL-7402 cells were transfected with control or PTEN siRNA for 48 h before exposing the cells to rosiglitazone (30 μmol/L) in the presence or absence of 5-FU (10 μmol/L). Afterwards, the cell viabilities were determined by MTT assay up to 48 h. Data are expressed as the mean±SD of three independent experiments. bP<0.05 vs control group; Con, cells treated with 0.1% DMSO; Con siRNA, non-specific siRNA, as a negative control.
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Related In: Results  -  Collection

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fig4: Representative sections showing PTEN protein expression by immunohistochemical staining. (A-a) a negative control section of HCC (primary antibody substituted with PBS, original magnification, ×200); (A-b) the positive staining of PTEN was mainly observed in the cytoplasm of cells. The strong staining of PTEN protein was shown in paracancerous tissue (the long arrow), and the weak staining was shown in tumor tissue (the short arrow, original magnification, ×100); (A-c) PTEN protein was expressed in the cytoplasm of carcinoma cells (original magnification, ×200); (A-d) PTEN protein was expressed in the nuclei of carcinoma cells (original magnification, ×200); (B) Cellular protein was isolated from BEL-7402 cells transfected with control or PTEN siRNA for 48 h and was then subjected to Western blotting analysis for PTEN protein. PTEN siRNA inhibits PTEN protein expression. (C) BEL-7402 cells were transfected with control or PTEN siRNA for 48 h before exposing the cells to rosiglitazone (30 μmol/L) in the presence or absence of 5-FU (10 μmol/L). Afterwards, the cell viabilities were determined by MTT assay up to 48 h. Data are expressed as the mean±SD of three independent experiments. bP<0.05 vs control group; Con, cells treated with 0.1% DMSO; Con siRNA, non-specific siRNA, as a negative control.
Mentions: 5-FU is widely used to treat advanced HCC, but chemo-resistance remains a major obstacle to its use in the clinical setting. To investigate the relationship between the expression of PTEN and advanced HCC, we examined the expression of PTEN in 100 advanced HCC tissues and paracancerous tissues. Of 100 cases of HCC, 62 cases were positive for PTEN, and 38 cases were negative. Ninety-two cases of adjacent non-tumor tissues were positive as a control. As shown in Figure 4A-b, the staining distribution of PTEN in HCC tissues was significantly decreased as compared with the paracancerous tissue (χ2=25.409, P<0.05). Furthermore, of the 62 positive samples, 45 showed staining in the cytoplasm of cancer cells (Figure 4A-c), and the other 17 exhibited intensive nuclear staining of cancer cells (Figure 4A-d).

Bottom Line: Since distribution of PTEN in HCC tissues is significantly decreased compared with the paracancerous tissue, over-expression of PTEN by rosiglitazone enhances 5-FU-inhibited cell growth of HCC.Moreover, down-regulation of COX-2 is implicated in the synergistic effect of 5-FU.The results suggest potential novel therapies for the treatment of advanced liver cancer.

View Article: PubMed Central - PubMed

Affiliation: Department of Hepatobiliary Surgery, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, China.

ABSTRACT

Aim: Resistance to 5-fluorouracil (5-FU) is a major cause of chemotherapy failure in advanced hepatocellular carcinoma (HCC). Rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, has a crucial role in growth inhibition and induction of apoptosis in several carcinoma cell lines. In this study, we examine rosiglitazone-induced sensitization of HCC cell lines (BEL-7402 and Huh-7 cells) to 5-FU.

Methods: The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate cell viability. Western blotting analysis was performed to detect the protein expression (PPARgamma, PTEN, and COX-2) in BEL-7402 cells. Immunohistochemistry staining was used to examine the expression of PTEN in 100 advanced HCC tissues and paracancerous tissues. In addition, small interfering RNA was used to suppress PPARgamma, PTEN, and COX-2 expression.

Results: Rosiglitazone facilitates the anti-tumor effect of 5-FU in HCC cell lines, which is mediated by the PPARgamma signaling pathway. Activation of PPARgamma by rosiglitazone increases PTEN expression and decreases COX-2 expression. Since distribution of PTEN in HCC tissues is significantly decreased compared with the paracancerous tissue, over-expression of PTEN by rosiglitazone enhances 5-FU-inhibited cell growth of HCC. Moreover, down-regulation of COX-2 is implicated in the synergistic effect of 5-FU.

Conclusion: Rosiglitazone sensitizes hepatocellular carcinoma cell lines to 5-FU antitumor activity through the activation of PPARgamma. The results suggest potential novel therapies for the treatment of advanced liver cancer.

Show MeSH
Related in: MedlinePlus