Correlation between serum prolactin levels and hepatocellular tumorigenesis induced by 3'-methyl-4-dimethylaminoazobenzene in mice

Estrogen Receptor-α Suppresses Liver Carcinogenesis and Establishes Sex-Specific Gene Expression

Estrogen protects females from hepatocellular carcinoma (HCC). To determine whether this protection is mediated by classic estrogen receptors, we tested HCC susceptibility in estrogen receptor-deficient mice. In contrast to a previous study, we found that diethylnitrosamine induces hepatocarcinogenesis to a significantly greater extent when females lack Esr1, which encodes Estrogen Receptor-α. Relative to wild-type littermates, Esr1 knockout females developed 9-fold more tumors. Deficiency of Esr2, which encodes Estrogen Receptor-β, did not affect liver carcinogenesis in females. Using microarrays and QPCR to examine estrogen receptor effects on hepatic gene expression patterns, we found that germline Esr1 deficiency resulted in the masculinization of gene expression in the female liver. Six of the most dysregulated genes have previously been implicated in HCC. In contrast, Esr1 deletion specifically in hepatocytes of Esr1 conditional null female mice (in which Cre was expressed from the albumin promoter) resulted in the maintenance of female-specific liver gene expression. Wild-type adult females lacking ovarian estrogen due to ovariectomy, which is known to make females susceptible to HCC, also maintained female-specific expression in the liver of females. These studies indicate that Esr1 mediates liver cancer risk, and its control of sex-specific liver gene expression involves cells other than hepatocytes.

Domperidone use and risk of primary liver cancer in the Clinical Practice Research Datalink

BACKGROUND

Pronounced sex-disparity in liver cancer suggests a role for hormones, one of which could be prolactin. Stimulation of prolactin production in mice via domperidone has been reported to decrease hepatocarcinogenesis, thus may have chemopreventive potential. To study the effect of domperidone in humans, a large medical records study was conducted.

METHODS

Based in the Clinical Practice Research Datalink, 1921 liver cancer cases and 7681 controls were identified. Conditional logistic regression was employed to estimate odds ratios (OR) and 95% confidence intervals (CI). Domperidone use was analyzed overall, and by number of prescriptions and cumulative dose.

RESULTS

Comparing ever- versus never-use, there was no association between domperidone and liver cancer among men (OR = 1.06, 95% CI: 0.76-1.48) or women (OR = 1.21, 95% CI: 0.82-1.76). Among men, there was no association with dose or number of prescriptions, while among women who received the highest doses (OR_{2700 mg vs. 0 mg} = 2.52, 95% CI: 1.18-5.41, p-trend = 0.02) and greatest number of prescriptions (OR_{≥11 Rx vs. 0 Rx} = 3.17, 95% CI: 1.07-9.40, p-trend = 0.02) there was a significantly increased risk, although there was no evidence of heterogeneity in the results by gender.

CONCLUSION

Domperidone use was not associated with decreased liver cancer risk among all study participants. Among women, an increased risk at highest levels of exposure warrants further study.

Reproductive factors, menopausal hormone therapies and primary liver cancer risk: a systematic review and dose-response meta-analysis of observational studies

BACKGROUND

A striking gender disparity in the incidence and outcome of primary liver cancer (PLC) has been well recognized. Mounting evidence from basic research suggests that hormonal factors may be involved in the gender disparity of PLC. Whether hormonal exposures in human subjects are associated with PLC risk is largely unknown.

OBJECTIVE AND RATIONALE

Whether reproductive factors and use of menopausal hormone therapies (MHTs) in women are associated with PLC risk remains controversial. We conducted this study to clarify this issue.

SEARCH METHODS

PubMed and EMBASE were searched to July, 2016 for studies published in English or Chinese. Observational studies (cohort, nested case-control and case-control) that provided risk estimates of reproductive factors, MHTs and PLC risk were eligible. The quality of included studies was determined based on the Newcastle-Ottawa quality assessment scale. Summary risk ratios (RRs) were calculated using a random-effects model. Dose-response analysis was conducted where possible.

OUTCOMES

Fifteen peer-reviewed studies, involving 1795 PLC cases and 2 256 686 women, were included. Overall meta-analyses on parity and PLC risk did not find any significant associations; however, when restricting to studies with PLC cases ≥100, increasing parity was found to be significantly associated with a decreased risk of PLC [RR for the highest versus lowest parity 0.67, 95% CI 0.52, 0.88; RR for parous versus nulliparous 0.71, 95% CI 0.53, 0.94; RR per one live birth increase 0.93, 95% CI 0.88, 0.99]. A J-shaped relationship between parity and PLC risk was identified (P_{non-linearity} < 0.01). Compared with never users, the pooled RRs of PLC were 0.60 (95% CI 0.37, 0.96) for ever users of MHT, 0.73 (95% CI 0.46, 1.17) for ever users of estrogen-only therapy (ET) and 0.67 (95% CI 0.45, 1.02) for ever users of estrogen-progestin therapy (EPT). The pooled RR of PLC for the oldest versus youngest category of menarcheal age was 0.50 (95% CI 0.32, 0.79). Oophorectomy was significantly associated with an increased risk of PLC (RR 2.23, 95% CI 1.46, 3.41). No significant association of age at first birth, and spontaneous or induced abortion with PLC risk was found. No meta-analysis was performed for the association of age at menopause, breastfeeding, hysterectomy, menopausal status and stillbirth with PLC risk owing to huge methodological heterogeneity and/or very limited studies.

WIDER IMPLICATIONS

Parity is associated with PLC risk in a J-shaped dose-response pattern. Late age at menarche and ever use of MHT are associated with a reduced risk of PLC, whereas there is no association of ever use of ET and EPT, age at first birth, or spontaneous and induced abortion with PLC risk. Compared to women with no history of oophorectomy, those with a history of oophorectomy are at an increased risk of PLC. Our findings provide some epidemiological support for a role of hormonal exposures in the development of PLC in women. However, these findings should be interpreted with much caution because of the limited number of studies and potential biases, and need to be validated by studies with good design and large sample size.

Sexual dimorphism in cancer

The incidence of many types of cancer arising in organs with non-reproductive functions is significantly higher in male populations than in female populations, with associated differences in survival. Occupational and/or behavioural factors are well-known underlying determinants. However, cellular and molecular differences between the two sexes are also likely to be important. In this Opinion article, we focus on the complex interplay that sex hormones and sex chromosomes can have in intrinsic control of cancer-initiating cell populations, the tumour microenvironment and systemic determinants of cancer development, such as the immune system and metabolism. A better appreciation of these differences between the two sexes could be of substantial value for cancer prevention as well as treatment.

Menopausal hormone therapy use and risk of primary liver cancer in the clinical practice research datalink

Primary liver cancer occurs less commonly among women than men in almost all countries. This discrepancy has suggested that hormone levels and/or exogenous hormone use could have an effect on risk, although prior studies have reached inconsistent conclusions. Thus, the current study was conducted to examine the relationship between menopausal hormone therapy (MHT) use and development of liver cancer. A nested case-control study was conducted within the United Kingdom's Clinical Practice Research Datalink (CPRD). Controls were matched, at a 4-to-1 ratio, to women diagnosed with primary liver cancer between 1988 and 2011. A second match, based on whether the cases and controls had diabetes, was also conducted. Odds ratios (OR) and 95% confidence intervals (95%CI) for associations of MHT with liver cancer were estimated using conditional logistic regression adjusted for known risk factors. In the overall match, 339 women with liver cancer were matched to 1318 controls. MHT use was associated with a significantly lower risk of liver cancer (ORadj  = 0.58, 95%CI = 0.37-0.90) especially among users of estrogen-only MHT (ORadj = 0.44, 95%CI = 0.22-0.88) and among past users (ORadj  = 0.53, 95%CI = 0.32-0.88). Among the matched cases (n = 58) and controls (n = 232) with diabetes, the odds ratios were similar to the overall analysis (ORadj  = 0.57, 95%CI = 0.09-3.53), but did not attain statistical significance. In the current study, MHT use, especially estrogen-only MHT use, was associated with a significantly lower risk of liver cancer. These results support the need of further investigation into whether hormonal etiologies can explain the variation in liver cancer incidence between men and women.

Prolactin prevents hepatocellular carcinoma by restricting innate immune activation of c-Myc in mice

Women are more resistant to hepatocellular carcinoma (HCC) than men despite equal exposure to major risk factors, such as hepatitis B or C virus infection. Female resistance is hormone-dependent, as evidenced by the sharp increase in HCC incidence in postmenopausal women who do not take hormone replacement therapy. In rodent models sex-dimorphic HCC phenotypes are pituitary-dependent, suggesting that sex hormones act via the gonadal-hypophyseal axis. We found that the estrogen-responsive pituitary hormone prolactin (PRL), signaling through hepatocyte-predominant short-form prolactin receptors (PRLR-S), constrained TNF receptor-associated factor (TRAF)-dependent innate immune responses invoked by IL-1β, TNF-α, and LPS/Toll-like receptor 4 (TLR4), but not TRIF-dependent poly(I:C)/TLR3. PRL ubiquitinated and accelerated poststimulatory decay of a "trafasome" comprised of IRAK1, TRAF6, and MAP3K proteins, abrogating downstream activation of c-Myc-interacting pathways, including PI3K/AKT, mTORC1, p38 MAPK, and NF-κB. Consistent with this finding, we documented exaggerated male liver responses to immune stimuli in mice and humans. Tumor promotion through, but regulation above, the level of c-Myc was demonstrated by sex-independent HCC eruption in Alb-Myc transgenic mice. PRL deficiency accelerated liver carcinogenesis in Prl(-/-) mice of both sexes. Conversely, pharmacologic PRL mobilization using the dopamine D2 receptor antagonist domperidone prevented HCC in tumor-prone C3H/HeN males. Viewed together, our results demonstrate that PRL constrains tumor-promoting liver inflammation by inhibiting MAP3K-dependent activation of c-Myc at the level of the trafasome. PRL-targeted therapy may hold promise for reducing the burden of liver cancer in high-risk men and women.

The role for estrogen receptor-alpha and prolactin receptor in sex-dependent DEN-induced liver tumorigenesis

Mice treated neonatally with diethylnitrosamine (DEN) develop liver tumors in a male-dominant manner, reflecting the male bias in human hepatocellular carcinoma. Evidence suggests that estrogen, androgen, prolactin (PRL) and growth hormone (GH) modify liver tumorigenesis. We determined the roles of estrogen receptor-α (ERα) and prolactin receptor (PRLR) using receptor null mice, ERαKO (C57Bl/6J) and PRLR-KO (129Ola-X-C57BL/6), in the neonatal-DEN model of liver tumorigenesis. In both mouse strains, females had reduced tumorigenesis compared with males (P < 0.01), regardless of ERα or PRLR status. Tumorigenesis was not affected by ovariectomy in C57Bl/6J mice but it was increased by ovariectomy in the mixed strain, 129Ola-X-C57BL/6, regardless of PRLR status. ERαKO males had 47% fewer tumors than ERα wild-type males (P < 0.01). On the other hand, estradiol treatment protected against tumorigenesis in males only in the presence of ERα. As evidenced by liver gene expression, lack of ERα did not alter the pattern of GH secretion in males but resulted in the male GH pattern in females. These observations indicate that ERα is not required for lower tumorigenesis in females, but it is required for the protective effects of exogenously delivered estradiol. Unexpectedly, the results indicate that ERα plays a role in promotion of liver tumors in males. In addition, it can be concluded that sex differences in liver tumorigenesis cannot be explained by the sexually dimorphic pattern of GH secretion. The results also rule out PRL as the mediator of the protective effect of the ovaries.

Supportive evidence for the anticancerous potential of alternative medicine against hepatocarcinogenesis in mice

INTRODUCTION

The present study examines if Lycopodium 200 (Lyco-200) has demonstrable anti-cancer activities in mice which are chronically fed carcinogens, p-dimethylaminoazobenzene (p-DAB) and phenobarbital (PB) to induce liver cancer.

MATERIALS AND METHODS

Mice in 5 different groups were chronically fed for varying periods of time: group I: normal diet; group II: normal diet + alcohol 200); group III: p-DAB + PB; group IV: p-DAB + PB + alcohol 200 (vehicle of Lyco-200 being ethyl alcohol); group V: p-DAB + PB + Lyco-200. They were sacrificed at day 7, 15, 30, 60, 90 or 120, and the following parameters were assessed: cytogenetic endpoints like chromosome aberrations, micronuclei, mitotic index and sperm-head anomaly; toxicity biomarkers like acid and alkaline phosphatases, alanine and aspartate amino transferase, glutathione reductase, succinate dehydrogenase and catalase activities, lipid peroxidation and reduced glutathione content. Additionally, scanning and transmission electron microscopic analyses of liver tissues were made at day 90 and 120, and immunodetection of p53 protein as well as gelatin zymography for matrix metalloproteinases in liver tissue were performed. Furthermore, studies were conducted on blood glucose, hemoglobin and cholesterol, estradiol, testosterone and cortisol, and lymphocyte and hepatic cell viabilities. Physical properties of Lyco-200 and potentized alcohol 200 were analyzed by using methods such as UV, Fourier Transform Infrared Spectroscopy (FTIR), Fluorescence Spectroscopy, 1H-NMR and 13C-NMR (Nuclear Magnetic Resonance Spectroscopy).

RESULTS

Lyco-200 reduced cytogenetic damages yielding positive modulations of all biochemical, pathological and other risk factors, cell viability and expression of p53 protein and matrix metalloproteinases as compared to controls.

CONCLUSION

Studies on other mammals are recommended to further investigate the potential of Lyco-200 in liver cancer.

The later administration of progesterone more rapidly activates dormant mouse mammary tumor cells initiated by 3'-methyl-4-dimethylaminoazobenzene

Implantation of progesterone at 1 month of age induced the development of mammary tumors in female C57BL/6 x DS-F1 mice that had been treated with 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) neonatally, and that had undergone ovariectomy and received implants of estradiol-17beta (E2) pellets at 1 month of age, and the incidence of mammary tumors became 100% at 15 months of age. On the other hand, no mammary tumors developed in these mice with implants of E2 pellets alone. Implantation of progesterone alone also induced no mammary tumors in mice that had been treated with 3'-Me-DAB neonatally, and had undergone ovariectomy at 1 month of age. Implantation of progesterone at 4, 6, 8, and 10 months of age also caused the prompt development of mammary tumors as implantation of progesterone at 1 month of age. When ages at which the incidence became 50% were estimated on curves of the incidences, these ages on implantation of progesterone at 1, 4, 6, 8, and 10 were about 11, 13, 14, 14, and 14 months of age. These results suggest that progesterone together with estrogen promotes the development of mammary tumors induced by 3'-Me-DAB, and that the later progesterone is administered, the more rapidly it activates dormant mammary tumor cells initiated by 3'-Me-DAB.