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Cytochrome P450 1A2 Metabolizes 17β-Estradiol to Suppress Hepatocellular Carcinoma.

Ren J, Chen GG, Liu Y, Su X, Hu B, Leung BC, Wang Y, Ho RL, Yang S, Lu G, Lee CG, Lai PB - PLoS ONE (2016)

Bottom Line: The inhibitory effect was significantly enhanced in cells with CYP1A2 overexpression, which effectively conversed E2 to the cytotoxic 2-ME.The anti-HCC effect of E2 was not associated with estrogen receptors ERα and ERβ as well as tumor suppressor P53 but enhanced by the approved anti-HCC drug sorafenib.The reduction of CYP1A2 significantly disrupts this metabolic pathway, contributing the progression and growth of HCC and the gender disparity of this malignancy.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, Faculty of Medicine, The Chinese University of Hong Kong; New Territories, Hong Kong, China.

ABSTRACT
Hepatocellular carcinoma (HCC) occurs more frequently in men than in women. It is commonly agreed that estrogen plays important roles in suppressing HCC development, however, the underlying mechanism remains largely unknown. Since estrogen is mainly metabolized in liver and its metabolites affect cell proliferation, we sought to investigate if the liver-specific cytochrome P450 1A2 (CYP1A2) mediated the inhibitory effect of estrogen on HCC. In this study, the expression of estrogen-metabolizing enzyme CYP1A2 was determined in HCC tissues and cell lines. Cell proliferation and apoptosis were assessed in cells with or without CYP1A2 overexpression. The levels of 17β-estradiol (E2) and its metabolite 2-methoxyestradiol (2-ME) were determined. A xenograft tumor model in mice was established to confirm the findings. It was found that CYP1A2 expression was greatly repressed in HCC. E2 suppressed HCC cell proliferation and xenograft tumor development by inducing apoptosis. The inhibitory effect was significantly enhanced in cells with CYP1A2 overexpression, which effectively conversed E2 to the cytotoxic 2-ME. E2 in combination with sorafenib showed an additive effect on HCC. The anti-HCC effect of E2 was not associated with estrogen receptors ERα and ERβ as well as tumor suppressor P53 but enhanced by the approved anti-HCC drug sorafenib. In addition, HDAC inhibitors greatly induced CYP1A2 promoter activities in cancer cells, especially liver cancer cells, but not in non-tumorigenic cells. Collectively, CYP1A2 metabolizes E2 to generate the potent anti-tumor agent 2-ME in HCC. The reduction of CYP1A2 significantly disrupts this metabolic pathway, contributing the progression and growth of HCC and the gender disparity of this malignancy.

No MeSH data available.


Related in: MedlinePlus

Expression of ERα, ERβ, GPR30, CYP1A2, CYP3A4 and COMT in HCC.Total RNA was extracted from 12 pairs of human HCC samples (tumorous (T) and adjacent non-tumorous (N) tissues) and human HCC cell lines. Among the tissue samples, HCC1, 3, 5, 7 and 10 were obtained from female patients, the rest were obtained from male patients (S1 Table). The mRNA levels of ERα (A), ERβ (B), GPR30 (C), CYP1A2 (D), CYP3A4 (E) and COMT (F) were analyzed by RT-qPCR. The expression levels were normalized with β-Actin mRNA levels. The data are expressed as fold changes relative to the expression level in the tumor of HCC1. Each column represents the mean ± s.d. of four technical replicates.
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pone.0153863.g002: Expression of ERα, ERβ, GPR30, CYP1A2, CYP3A4 and COMT in HCC.Total RNA was extracted from 12 pairs of human HCC samples (tumorous (T) and adjacent non-tumorous (N) tissues) and human HCC cell lines. Among the tissue samples, HCC1, 3, 5, 7 and 10 were obtained from female patients, the rest were obtained from male patients (S1 Table). The mRNA levels of ERα (A), ERβ (B), GPR30 (C), CYP1A2 (D), CYP3A4 (E) and COMT (F) were analyzed by RT-qPCR. The expression levels were normalized with β-Actin mRNA levels. The data are expressed as fold changes relative to the expression level in the tumor of HCC1. Each column represents the mean ± s.d. of four technical replicates.

Mentions: The obvious difference between Hep3B and HepG2 is that the former is a p53-defecient cell line where the latter contains wide-type p53. In order to check whether p53 is a factor causing the different responses to E2 in various cell lines, we transfected Hep3B with wide-type p53, followed by E2 treatment. Fig 2C shows that p53 did not affect the estrogen inhibitory effect on Hep3B growth. Our finding further suggested that the inhibitory effect of E2 might not be related to ERα because the degree of E2-mediated inhibition relative to non-E2 treatment remained almost the same along the increasing dose of fulvestrant “Fig 1D”, which may downregulate and degrade ERα [27]. Sorafenib is the only approved systemic anti-HCC for patients at advanced stages and current studies have suggested that sorafenib be used together with other anti-tumor agents to increase the efficacy [28]. It will thus be interesting to find out whether E2 can be a potential agent to be used in combination with sorafenib. To this end, we found that E2 could significantly enhance the effectiveness of sorafenib, compared with either agent alone “Fig 1E”. Both E2 and 2-ME were found to induce apoptosis in HCC cells, which was reflected by significant increase of cell population in sub-G1 “Fig 1F”. It was noted that the most significant increase of Sub-G1 population was caused by 10μM 2-ME treatment.


Cytochrome P450 1A2 Metabolizes 17β-Estradiol to Suppress Hepatocellular Carcinoma.

Ren J, Chen GG, Liu Y, Su X, Hu B, Leung BC, Wang Y, Ho RL, Yang S, Lu G, Lee CG, Lai PB - PLoS ONE (2016)

Expression of ERα, ERβ, GPR30, CYP1A2, CYP3A4 and COMT in HCC.Total RNA was extracted from 12 pairs of human HCC samples (tumorous (T) and adjacent non-tumorous (N) tissues) and human HCC cell lines. Among the tissue samples, HCC1, 3, 5, 7 and 10 were obtained from female patients, the rest were obtained from male patients (S1 Table). The mRNA levels of ERα (A), ERβ (B), GPR30 (C), CYP1A2 (D), CYP3A4 (E) and COMT (F) were analyzed by RT-qPCR. The expression levels were normalized with β-Actin mRNA levels. The data are expressed as fold changes relative to the expression level in the tumor of HCC1. Each column represents the mean ± s.d. of four technical replicates.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4836701&req=5

pone.0153863.g002: Expression of ERα, ERβ, GPR30, CYP1A2, CYP3A4 and COMT in HCC.Total RNA was extracted from 12 pairs of human HCC samples (tumorous (T) and adjacent non-tumorous (N) tissues) and human HCC cell lines. Among the tissue samples, HCC1, 3, 5, 7 and 10 were obtained from female patients, the rest were obtained from male patients (S1 Table). The mRNA levels of ERα (A), ERβ (B), GPR30 (C), CYP1A2 (D), CYP3A4 (E) and COMT (F) were analyzed by RT-qPCR. The expression levels were normalized with β-Actin mRNA levels. The data are expressed as fold changes relative to the expression level in the tumor of HCC1. Each column represents the mean ± s.d. of four technical replicates.
Mentions: The obvious difference between Hep3B and HepG2 is that the former is a p53-defecient cell line where the latter contains wide-type p53. In order to check whether p53 is a factor causing the different responses to E2 in various cell lines, we transfected Hep3B with wide-type p53, followed by E2 treatment. Fig 2C shows that p53 did not affect the estrogen inhibitory effect on Hep3B growth. Our finding further suggested that the inhibitory effect of E2 might not be related to ERα because the degree of E2-mediated inhibition relative to non-E2 treatment remained almost the same along the increasing dose of fulvestrant “Fig 1D”, which may downregulate and degrade ERα [27]. Sorafenib is the only approved systemic anti-HCC for patients at advanced stages and current studies have suggested that sorafenib be used together with other anti-tumor agents to increase the efficacy [28]. It will thus be interesting to find out whether E2 can be a potential agent to be used in combination with sorafenib. To this end, we found that E2 could significantly enhance the effectiveness of sorafenib, compared with either agent alone “Fig 1E”. Both E2 and 2-ME were found to induce apoptosis in HCC cells, which was reflected by significant increase of cell population in sub-G1 “Fig 1F”. It was noted that the most significant increase of Sub-G1 population was caused by 10μM 2-ME treatment.

Bottom Line: The inhibitory effect was significantly enhanced in cells with CYP1A2 overexpression, which effectively conversed E2 to the cytotoxic 2-ME.The anti-HCC effect of E2 was not associated with estrogen receptors ERα and ERβ as well as tumor suppressor P53 but enhanced by the approved anti-HCC drug sorafenib.The reduction of CYP1A2 significantly disrupts this metabolic pathway, contributing the progression and growth of HCC and the gender disparity of this malignancy.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, Faculty of Medicine, The Chinese University of Hong Kong; New Territories, Hong Kong, China.

ABSTRACT
Hepatocellular carcinoma (HCC) occurs more frequently in men than in women. It is commonly agreed that estrogen plays important roles in suppressing HCC development, however, the underlying mechanism remains largely unknown. Since estrogen is mainly metabolized in liver and its metabolites affect cell proliferation, we sought to investigate if the liver-specific cytochrome P450 1A2 (CYP1A2) mediated the inhibitory effect of estrogen on HCC. In this study, the expression of estrogen-metabolizing enzyme CYP1A2 was determined in HCC tissues and cell lines. Cell proliferation and apoptosis were assessed in cells with or without CYP1A2 overexpression. The levels of 17β-estradiol (E2) and its metabolite 2-methoxyestradiol (2-ME) were determined. A xenograft tumor model in mice was established to confirm the findings. It was found that CYP1A2 expression was greatly repressed in HCC. E2 suppressed HCC cell proliferation and xenograft tumor development by inducing apoptosis. The inhibitory effect was significantly enhanced in cells with CYP1A2 overexpression, which effectively conversed E2 to the cytotoxic 2-ME. E2 in combination with sorafenib showed an additive effect on HCC. The anti-HCC effect of E2 was not associated with estrogen receptors ERα and ERβ as well as tumor suppressor P53 but enhanced by the approved anti-HCC drug sorafenib. In addition, HDAC inhibitors greatly induced CYP1A2 promoter activities in cancer cells, especially liver cancer cells, but not in non-tumorigenic cells. Collectively, CYP1A2 metabolizes E2 to generate the potent anti-tumor agent 2-ME in HCC. The reduction of CYP1A2 significantly disrupts this metabolic pathway, contributing the progression and growth of HCC and the gender disparity of this malignancy.

No MeSH data available.


Related in: MedlinePlus