Levels of vitamin A and cellular retinol binding protein in human hepatocellular carcinoma and adjacent normal tissue

Potential Molecular Targeted Therapy for Unresectable Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent and lethal cancers, representing a serious worldwide health concern. The recurrence incidence of hepatocellular carcinoma (HCC) following surgery or ablation is as high as 70%. Thus, the clinical applicability of standard surgery and other locoregional therapy to improve the outcomes of advanced HCC is restricted and far from ideal. The registered trials did not identify a treatment that prolonged recurrence-free survival, the primary outcome of the majority of research. Several investigator-initiated trials have demonstrated that various treatments extend patients' recurrence-free or overall survival after curative therapies. In the past decade, targeted therapy has made significant strides in the treatment of advanced HCC. These targeted medicines produce antitumour effects via specific signals, such as anti-angiogenesis or advancement of the cell cycle. As a typical systemic treatment option, it significantly improves the prognosis of this fatal disease. In addition, the combination of targeted therapy with an immune checkpoint inhibitor is redefining the paradigm of advanced HCC treatment. In this review, we focused on the role of approved targeted medicines and potential therapeutic targets in unresectable HCC.

A systematic review and meta-analysis of the association between vitamin A intake, serum vitamin A, and risk of liver cancer

BACKGROUND

Previous evidence supports that vitamin A decreases the risk of several types of cancer. However, the association between vitamin A and liver cancer is inconclusive.

AIM

This systematic review and meta-analysis summarizes the existing literature, discussing the association between vitamin A intake, serum vitamin A, and liver cancer in adult populations.

METHODS

A systematic literature review was performed by searching the EMBASE, PubMed, Scopus and International Pharmaceutical Abstract databases using terms related to vitamin A (e.g. retinol, α-carotene, β-carotene, and β-cryptoxanthin) and hepatic cancer without applying any time restriction. A meta-analysis was performed using random effect models.

RESULTS

The meta-analysis of five studies showed no association between serum retinol and liver cancer (pooled risk ratio = 1.90 (0.40-9.02); n = 5 studies, I² = 92%). In addition, the systematic review of studies from 1955 to July 2017 found studies that indicated no association between the intake and serum level of α-carotene ( n = 2) and β-cryptoxanthin ( n = 1) and the risk of liver cancer. Further, the associations between retinol intake ( n = 3), β-carotene intake ( n = 3), or serum β-carotene ( n = 3) and liver cancer were inconclusive.

CONCLUSIONS

Current information on the association between vitamin A intake and liver cancer or serum vitamin A and liver cancer are limited. Most studies demonstrated no association between dietary vitamin A and the risk of liver cancer. However, the finding was based on a small number of studies with potential publication bias. Therefore, large observational studies should be conducted to confirm these associations.

Dietary antioxidants in the prevention of hepatocarcinogenesis: a review

In this review, the role of dietary antioxidants in the prevention of hepatocarcinogenesis is examined. Both human and animal models are discussed. Vitamin C, vitamin E, and selenium are antioxidants that are essential in the human diet. A number of non-essential chemicals also contain antioxidant activity and are consumed in the human diet, mainly as plants or as supplements, including beta-carotene, ellagic acid, curcumin, lycopene, coenzyme Q(10), epigallocatechin gallate, N-acetyl cysteine, and resveratrol. Although some human and animal studies show protection against carcinogenesis with the consumption of higher amounts of antioxidants, many studies show no effect or an enhancement of carcinogenesis. Because of the conflicting results from these studies, it is difficult to make dietary recommendations as to whether consuming higher amounts of specific antioxidants will decrease the risk of developing hepatocellular carcinoma.

Chemoprevention of hepatocellular carcinoma: Use of tamoxifen in an animal model of hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is common worldwide and growing in importance in the West. HCC often occurs against a background of liver disease, tends to present at an advanced stage, and has a poor prognosis, suggesting that it is an ideal target for chemoprevention. We sought to identify in an animal model chemopreventive agents for HCC that might be tested in human subjects. To this end, we induced liver tumors by injecting ethyl-nitrosourea in 6-week-old male B6C3F1 mice. Two chemopreventive agents were administered over a period of 60 weeks: tamoxifen (420 mg/kg feed) and a retinoid, 13-cis-retinoic acid (200 mg/kg feed). Animals were killed at 60 weeks and their livers examined for HCC and premalignant lesions. All liver lesions (altered foci, adenomata, HCC) occurred significantly less frequently in the tamoxifen-treated group than the group given only ethylnitrosourea (HCC developed in 2 of 47 (4%) vs 11 of 44 (25%); P < .001). On the other hand, retinoic acid appeared to increase the number of liver tumors, and in 2 animals angiosarcoma developed. Tamoxifen significantly decreased the incidence of chemical hepatocarcinogenesis in this model, suggesting an important role for estrogens in the pathogenesis of HCC and suggesting that it should be tested in human beings as a chemopreventive agent against HCC.

Cellular retinol-binding protein-1 in hepatocellular carcinoma correlates with beta-catenin, Ki-67 index, and patient survival

The cellular retinol-binding protein-1 (CRBP-1) plays a key role in the esterification and intercellular transfer of retinol. By in situ hybridization, immunohistochemistry, and confocal laser scanning microscopy (CLSM), we show that, in normal liver, CRBP-1 is strongly expressed in the cytoplasm of hepatic stellate cells (HSCs) and myofibroblasts (MFs) with only low CRBP-1 levels in hepatocytes. By contrast, in 196 hepatocellular carcinoma (HCC) specimens CRBP-1 expression in MFs was down-regulated in 83%. Patients with high CRBP-1 expression in MFs had a significantly higher 2-year survival as compared with patients with low CRBP-1 expression (52% vs. 29%, respectively; P =.034). An aberrant nuclear CRBP-1 accumulation resulting from cytoplasmic invagination was found in 29% of HCCs. Nuclear CRBP-1 staining correlated positively with a favorable tumor stage (Okuda stage I; P =.01) and negatively with the Ki-67(+) proliferation fraction (PF). A Ki-67(+) PF of > or =10% was associated with a lower 2-year survival probability as compared with patients with a Ki-67(+) PF of <10% (12% vs. 40%, respectively; P =.015). Prognosis did not correlate with the nuclear beta-catenin expression. There was, however, a close correlation between nuclear CRBP-1 inclusions and nuclear beta-catenin staining in HCCs (P =.008), suggesting a cross talk between CRBP-1 and the Wnt/wingless signal transduction pathway. In conclusion, our findings demonstrate that CRBP-1 detection may be useful for the discrimination between nonneoplastic and neoplastic liver cells and suggest that modulation of CRBP-1 expression in HCCs contributes to tumor growth and progression via retinoid-mediated signaling and disruption of cellular vitamin A homeostasis.

Underexpression of mRNA in human hepatocellular carcinoma focusing on eight loci

Genetic alterations associated with human hepatocellular carcinoma (HCC) have been reported previously, but are not sufficient to specify differences of HCCs from precancerous diseases of the liver, such as hepatitis, hepatic fibrosis, and cirrhosis. In the present study, we performed differential gene display analysis (DGDA) to clarify the specific genetic alterations associated with gene expression changes in the course of development of HCC from chronic viral hepatitis. Four pairs of surgically resected HCCs and hepatitis tissues were investigated. We found 1,028 expression sequence tags (ESTs) that were decreased or increased in HCC tissues compared with hepatitis tissues in the same patient. Nucleotide sequencing showed that they included 55 EST clones in the GenBank database, which were considered candidates for specific messenger RNA (mRNA) expression alterations in HCCs. After excluding 9 ESTs that code mitochondrial DNA, we performed quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) for the 46 remaining EST clones. We found 8 mRNAs underexpressed in primary HCC tissues in 20 patients in higher percentages than found in previous studies, including 18 cases (90%) for aldolase B (ALDOB), 15 cases (75%) for carbamyl phosphate synthetase 1 (CPS1), albumin (ALB), plasminogen (PLG), and EST 51549, 13 cases (65%) for cytochrome P450 subfamily 2E1 (CYP2E1), 12 cases (60%) for human retinol-binding protein 4 (RBP4), and 11 cases (55%) for human organic anion transporter C (OATP-C) gene. In conclusion, underexpression of key gene products may be important in the development and/or progression of HCC.

Serum retinol and risk of hepatocellular carcinoma in patients with child-Pugh class A cirrhosis

Liver cirrhosis is the main risk factor for the development of human hepatocellular carcinoma (HCC). In this condition, the liver and plasma suffer a drastic depletion of retinoids. This study was conducted to investigate whether any relation exists between serum retinol levels and HCC development in cirrhotics. Seventy child-Pugh class A cirrhotic patients, 16 child-Pugh class A cirrhotic patients with HCC, and 140 age- and sex-matched subjects were included in this study. At the time of enrollment, fasting blood samples were taken to determine serum retinol levels. For the following 7 years, the 70 cirrhotic patients were also followed up for the occurrence of HCC by periodic screening with ultrasonography and serum alpha-fetoprotein assays. The serum retinol levels in both cirrhotic patients and HCC patients were significantly lower than those in healthy subjects. Among the 70 cirrhotic patients, 14 HCC were detected during follow-up. The prediagnostic retinol levels were significantly lower in cirrhotic patients who developed HCC compared with patients who did not. The odds ratio of cirrhotic patients who developed HCC in the lowest tertile to highest tertile of retinol status was 6.75 (95% CI=1.26--36.0; P=0.015). Our results suggest that a state of retinoid deficiency may promote hepatocarcinogenesis in patients at high risk such as cirrhotics.