Interactions of chemical carcinogens and genetic variation in hepatocellular carcinoma

DNA mutilation: A telltale sign of cancer inception

DNA damage is a discrepancy in its chemical structure precipitated by a multitude of factors. Most DNA damages can be repaired efficiently through diverse restorative mechanisms subjective to the type of damage. DNA-damaging agents elicit a medley of cellular retorts like cell cycle arrest, followed by DNA repair mechanisms or apoptosis. An unrepaired DNA damage in a nonreplicating cell does not generally engender mutations but a similar scenario in replicating cell routes to permanent modification of genetic material shrugging to carcinogenesis. DNA mutilation can be allied to disarray in bases, debasement of backbone, or crosslinks. Base damages or backbone damages like single-strand and double-strand DNA breaks are usually produced by reactive oxygen species and ionizing radiation. This substantial DNA damage has broadly been considered to be caused by various exogenous and endogenous agents with variable rates of causality and decrees of risk, sourcing toward cancer or other diseases, necessitating furtherance in diagnostics at sequential points. The purpose of this article is to review in detail the various types of DNA damages, their contributory factors, and recent developments in their identification.

A bioinformatics analysis of zinc finger protein family reveals potential oncogenic biomarkers in breast cancer

BACKGROUND

Zinc finger protein family is the largest transcription factor family in the human genome. Studies have shown that the aberrant expression of zinc finger protein (ZNF) had a potential role in tumorigenesis. However, due to the high complexity of the ZNF family genes, the role of the ZNF family genes in breast cancer (BRCA) is still lacking in systematic understanding.

AIM

In the study, we aim to understand the expression profile, prognostic value, immune invasion pattern, tumor microenvironment, epigenetic and pathway relationships, and drug sensitivity of ZNFs using multi-omics data from public databases.

RESULTS

We focused on six members of ZNFs, which were upregulated in a variety of cancers. Notably, ZNF750 and ZNF224 were lower expressed in BRCA, and their expressions were significantly associated with BRCA prognosis. We confirmed the observations obtained by analyzing the clinic-pathological data. Otherwise, the expressions of ZNFs were significantly related to stromal and immune scores, and was significantly different among different immune subtypes in BRCA. Here, we found down-regulated methylation of ZNF217 and ZNF750. The relationship between methylation and survival showed the survival was worse for hypo-methylation of ZNF750 in BRCA, which is consistent with the correlation of high expression of ZNF750 in BRCA with worse survival.

CONCLUSIONS

Collectively, our results provide clues for a better understanding of the characterization of ZNF family genes in BRCA from a multi-omics perspective and show their potential for use as new tumor markers and therapeutic targets.

Etiology of Hepatocellular Carcinoma: Special Focus on Fatty Liver Disease

Hepatocellular Carcinoma (HCC) is a highly aggressive cancer with mortality running parallel to its incidence and has limited therapeutic options. Chronic liver inflammation and injury contribute significantly to the development and progression of HCC. Several factors such as gender, age, ethnicity, and demographic regions increase the HCC incidence rates and the major risk factors are chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV), carcinogens (food contaminants, tobacco smoking, and environmental toxins), and inherited diseases. In recent years evidence highlights the association of metabolic syndrome (diabetes and obesity), excessive alcohol consumption (alcoholic fatty liver disease), and high-calorie intake (nonalcoholic fatty liver disease) to be the prime causes for HCC in countries with a westernized sedentary lifestyle. HCC predominantly occurs in the setting of chronic liver disease and cirrhosis (80%), however, 20% of the cases have been known in patients with non-cirrhotic liver. It is widely believed that there exist possible interactions between different etiological agents leading to the involvement of diverse mechanisms in the pathogenesis of HCC. Understanding the molecular mechanisms of HCC development and progression is imperative in developing effective targeted therapies to combat this deadly disease. Noteworthy, a detailed understanding of the risk factors is also critical to improve the screening, early detection, prevention, and management of HCC. Thus, this review recapitulates the etiology of HCC focusing especially on the nonalcoholic fatty liver disease (NAFLD)- and alcoholic fatty liver disease (AFLD)-associated HCC.

Apoptosis induction and ERK/NF-κB inactivation are associated with magnolol-inhibited tumor progression in hepatocellular carcinoma in vivo

Although hepatitis B and/or hepatitis C virus were recognized as major risk factor for the development of hepatocellular carcinoma (HCC), certain occupational, environmental, and lifestyle factors also play key roles in HCC tumorigenesis. Moreover, in molecular signaling route, extracellular signal-regulated kinase (ERK)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling was found to be overexpressed and linked to poor prognosis in HCC. Thus, to identify possible nature compound that can suppress ERK/NF-κB may be benefit to HCC patient. Magnolol, a natural compound derived from herbal plant Magnolia officinalis, has been recognized as a liver protection and antitumor reagent. However, whether magnolol-inhibited HCC progression correlates with disruption of ERK/NF-κB signaling is remained unclear. In this studies, we performed SK-Hep1/luc2 HCC bearing animal model to investigate the anticancer efficacy and mechanism of magnolol on tumor progression. Tumor size and tumor growth rate were dramatically suppressed after treatment of magnolol. In addition, expression of phospho-ERK (p-ERK), NF-κB p65 (Ser536), and tumor progression-associated proteins, such as matrix metallopeptidase 9 (MMP-9), vascular endothelial growth factor (VEGF), X-linked inhibitor of apoptosis protein (XIAP), and CyclinD1 were all significantly decreased by magnolol. Most important, major extrinsic and intrinsic apoptosis signaling factors, including active caspase-8 and caspase-9 were both enhanced by magnolol. This study indicated that apoptosis induction through extrinsic/intrinsic pathways and blockage of ERK/NF-κB activation were associated with magnolol-inhibited tumor progression in HCC in vivo.

MicroRNA-548b inhibits proliferation and invasion of hepatocellular carcinoma cells by directly targeting specificity protein 1

Emerging studies have revealed that microRNAs (miRNAs) are aberrantly expressed in hepatocellular carcinoma (HCC), and the dysregulation of miRNAs exerts crucial roles in the carcinogenesis and development of HCC. Therefore, elucidating the relationship between miRNAs and HCC progression is of great importance to develop novel therapeutic techniques and to improve the prognosis of patients with this malignancy. Recently, miR-548b-3p (miR-548b) has been demonstrated to be a cancer-associated miRNA in tongue squamous cell carcinoma and glioma. However, the expression and function of miR-548b in HCC remain poorly understood. In the present study, it was found that miR-548b is expressed at low levels in HCC tissues and cell lines. Decreased miR-548b expression was found to be positively associated with the clinical features of HCC, including the TNM stage and lymph node metastasis. Functional experiments revealed that upregulation of miR-548b expression decreased proliferation and invasion of HCC cells. Specificity protein 1 (SP1) was verified to be a direct target of miR-548b in HCC cells; as Spearman's correlation analysis identified miR-548b expression to be negatively correlated with that of SP1 expression in HCC tissue specimens. In addition, SP1 inhibition exhibited similar effects as miR-548b overexpression in HCC cells. SP1 reintroduction significantly reversed the suppressive effects of miR-548b upregulation on the proliferation and invasion of HCC cells. In conclusion, the results presented in the present study demonstrated that miR-548b may serve as a tumor suppressive miRNA that inhibits the proliferation and invasion of HCC cells by directly targeting SP1. Consequently, miR-548b can be exploited as a novel therapeutic target for treating patients with HCC in the future, but this needs to be investigated further.

microRNA-548b suppresses aggressive phenotypes of hepatocellular carcinoma by directly targeting high-mobility group box 1 mRNA

Background and purpose: An increasing number of studies have revealed that microRNAs (miRNAs) are the main drivers of hepatocarcinogenesis including progression to later stages of liver cancer. Recently, miR-548b was identified as a cancer-related miRNA in glioma and tongue squamous cell carcinoma. Nonetheless, the expression pattern and specific roles of miR-548b in hepatocellular carcinoma (HCC) have not yet been clarified.

Methods: Expression levels of miR-548b in HCC tissues and cell lines were measured by reverse-transcription quantitative PCR. In vitro and in vivo functional assays were performed to determine the effects of miR-548b on the malignant phenotypes of HCC cells. In addition, the molecular mechanisms by which miR-548b regulates the initiation and progression of HCC were investigated in detail.

Results: miR-548b expression was weak in HCC tissues and cell lines. The low miR-548b expression significantly correlated with tumor size, TNM stage, and venous infiltration of HCC. In addition, exogenous miR-548b expression suppressed HCC cell proliferation, colony formation, and metastasis and induced apoptosis in vitro. Silencing of miR-548b exerted an opposite effect on these characteristics of HCC cells. Furthermore, miR-548b overexpression hindered tumor growth in vivo. Mechanistic analysis identified high-mobility group box 1 (HMGB1) as a direct target gene of miR-548b in HCC cells. Moreover, an HMGB1 knockdown reproduced the effects of miR-548b upregulation on HCC cells. Recovered HMGB1 expression reversed the effects of miR-548b on HCC cells. Notably, miR-548b overexpression deactivated the PI3K–AKT pathway in HCC cells in vitro and in vivo.

Conclusion: Our findings provide the first evidence that miR-548b restrains HCC progression, at least partially, by downregulating HMGB1 and deactivating the PI3K–AKT pathway. Thus, miR-548b might be a novel target for the development of new therapies for HCC.

Hepatocellular carcinoma in non-cirrhotic liver: A comprehensive review

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, which in turns accounts for the sixth most common cancer worldwide. Despite being the 6^th most common cancer it is the second leading cause of cancer related deaths. HCC typically arises in the background of cirrhosis, however, about 20% of cases can develop in a non-cirrhotic liver. This particular subgroup of HCC generally presents at an advanced stage as surveillance is not performed in a non-cirrhotic liver. HCC in non-cirrhotic patients is clinically silent in its early stages because of lack of symptoms and surveillance imaging; and higher hepatic reserve in this population. Interestingly, F3 fibrosis in non-alcoholic fatty liver disease, hepatitis B virus and hepatitis C virus infections are associated with high risk of developing HCC. Even though considerable progress has been made in the management of this entity, there is a dire need for implementation of surveillance strategies in the patient population at risk, to decrease the disease burden at presentation and improve the prognosis of these patients. This comprehensive review details the epidemiology, risk factors, clinical features, diagnosis and management of HCC in non-cirrhotic patients and provides future directions for research.

A curcumin derivative, WZ35, suppresses hepatocellular cancer cell growthviadownregulating YAP-mediated autophagy

HCC is a common cancer type in the world. Here, we found WZ35, a novel derivative of curcumin, could notably suppress HCC cell growthviainhibiting YAP controlled autophagy, highlighting the potent anti-tumor activity of WZ35 in liver cancer therapy.

MicroRNA-504 functions as a tumor suppressor in hepatocellular carcinoma through inhibiting Frizzled-7-mediated-Wnt/β-catenin signaling

Accumulating evidence suggests that microRNAs (miRNAs) are critical regulators in the development and progression of various malignant tumors, including hepatocellular carcinoma (HCC). Multiple findings have indicated that miRNA-504 (miR-504) is dysregulated in several types of cancers, functioning as an oncogenic miRNA or a tumor suppressive miRNA. However, the role of miR-504 in HCC remains unknown. In this study, we aimed to detect the expression pattern of miR-504 in HCC tissues and cell lines and investigate the precise biological function in HCC cells. Our results showed that miR-504 expression levels were frequently downregulated in both HCC tissues and cell lines. Gain-of-function experiments demonstrated that miR-504 overexpression inhibited the proliferation and invasion in HCC cell lines. By contrast, miR-504 inhibition had the opposite effect. Interestingly, bioinformatics analysis predicted that Frizzled-7 (FZD7) was a potential target gene of miR-504. Dual-luciferase reporter assays confirmed that miR-504 directly targeted the 3'-untranslated region of FZD7 mRNA. In addition, our results showed that miR-504 negatively regulated the mRNA and protein expression of FZD7 in HCC cell lines. Moreover, miR-540 overexpression inhibited the cellular expression of β-catenin and blocked the activation of Wnt signaling in HCC cells. Notably, restoration of FZD7 expression significantly reversed the inhibitory effect of miR-504 on proliferation, invasion, and Wnt/β-catenin signaling in HCC cells. In conclusion, our results demonstrate that miR-504 functions as a tumor suppressive miRNA that inhibits the proliferation and invasion of HCC cells by targeting FZD7 and inhibiting Wnt/β-catenin signaling. Our study provides evidence that miR-504-meidated FZD7/Wnt/β-catenin signaling pathway plays an important role in HCC development and progression and suggests miR-504 as a novel future therapeutic target for treatment of HCC.

Droplet digital PCR detects high rate of TP53 R249S mutants in cell-free DNA of middle African patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is still a major killing malignancy in sub-Saharan Africa. Lifelong intoxication with aflatoxin B1 is considered as one of the primary causes of this situation. The role of aflatoxin in HCC from a given population is commonly estimated through the prevalence of R249S mutation of TP53, a hallmark for previous exposure to the mycotoxin. However, the role of AFB1 is barely known in large part of Africa. We conducted a survey on circulating cell-free DNA from 149 patients with HCC and 213 control subjects with and without liver diseases from Cameroon and Central African Republic using droplet digital PCR technique. We observed a mutation prevalence of 24.8% (n = 37/149) in patients with tumor and 5.6% (n = 12/213) in controls (P = 2.2E-07). Patients with mutations usually displayed significantly increased circulating alpha-fetoprotein (AFP) values, high hepatitis B virus (HBV) DNA loads as well as worsened values of blood cells count. Interestingly, the fraction of droplets positive for R249S was significantly larger in patients with liver cancer (15.3 ± 3.7%) than in controls (0.5 ± 0.3%, P = 7.1E-04). Our survey indicates that AFB1 is instrumental for HCC development in Middle Africa and that droplet digital PCR might be used in the region both to diagnose HCC and to conduct public health surveys on populations at risk of chronic aflatoxin intoxication.

Non‑infective occupational risk factors for hepatocellular carcinoma: A review (Review)

Liver cancer is the second leading worldwide cause of cancer‑associated mortalities. Hepatocellular carcinoma, which accounts for the majority of liver tumors, ranks fifth among types of human cancer. Well‑established risk factors for liver cancer include the hepatitis B and C viruses, aflatoxins, alcohol consumption, and oral contraceptives. Tobacco smoking, androgenic steroids, and diabetes mellitus are suspected risk factors. Current knowledge regarding non‑infective occupational risk factors for liver cancer is inconclusive. The relevance of liver disorders to occupational medicine lies in the fact that the majority of chemicals are metabolized in the liver, and toxic metabolites generated via metabolism are the predominant cause of liver damage. However, their non‑specific clinical manifestations that are similar in a number of liver diseases make diagnosis difficult. Furthermore, concomitant conditions, such as viral hepatitis and alcohol or drug abuse, may mask liver disorders that result from occupational hepatotoxic agents and block the demonstration of an occupational cause. The identification of environmental agents that result in human cancer is a long and often difficult process. The purpose of the present review is to summarize current knowledge regarding the association of non‑infective occupational risk exposure and HCC, to encourage further research and draw attention to this global occupational public health problem.

Hepatocellular carcinoma and the risk of occupational exposure

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. The main risk factors for HCC are alcoholism, hepatitis B virus, hepatitis C virus, nonalcoholic steatohepatitis, obesity, type 2 diabetes, cirrhosis, aflatoxin, hemochromatosis, Wilson's disease and hemophilia. Occupational exposure to chemicals is another risk factor for HCC. Often the relationship between occupational risk and HCC is unclear and the reports are fragmented and inconsistent. This review aims to summarize the current knowledge regarding the association of infective and non-infective occupational risk exposure and HCC in order to encourage further research and draw attention to this global occupational public health problem.

Effect of GSTM1 and GSTT1 Polymorphisms on Genetic Damage in Humans Populations Exposed to Radiation From Mobile Towers

All over the world, people have been debating about associated health risks due to radiation from mobile phones and mobile towers. The carcinogenicity of this nonionizing radiation has been the greatest health concern associated with mobile towers exposure until recently. The objective of our study was to evaluate the genetic damage caused by radiation from mobile towers and to find an association between genetic polymorphism of GSTM1 and GSTT1 genes and DNA damage. In our study, 116 persons exposed to radiation from mobile towers and 106 control subjects were genotyped for polymorphisms in the GSTM1 and GSTT1 genes by multiplex polymerase chain reaction method. DNA damage in peripheral blood lymphocytes was determined using alkaline comet assay in terms of tail moment (TM) value and micronucleus assay in buccal cells (BMN). There was a significant increase in BMN frequency and TM value in exposed subjects (3.65 ± 2.44 and 6.63 ± 2.32) compared with control subjects (1.23 ± 0.97 and 0.26 ± 0.27). However, there was no association of GSTM1 and GSTT1 polymorphisms with the level of DNA damage in both exposed and control groups.

Identification of AFB1-interacting proteins and interactions between RPSA and AFB1

A method using immobilized affinity chromatography (IAC) was developed to screen for aflatoxin B1 (AFB1)-binding proteins. AFB1 and bovine serum albumin (BSA) coupled protein (BSA-AFB1) was prepared using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The resulting coupled compound was immobilized onto PVDF transfer membranes, which were then incubated with total protein from mouse liver. AFB1-binding proteins were eluted, after non-specific washing, by specific elution, and the eluted proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two candidate AFB1-binding proteins were identified by liquid chromatography-tandem mass spectrometry as the 40S ribosomal protein SA (RPSA) and a putative uncharacterized protein. RPSA and AFB1 interactions were further analyzed by ELISA in vitro and laser confocal immunofluorescence analysis in vivo. The results from ELISA and immunofluorescence showed that RPSA efficiently bound AFB1 in vitro and in vivo. This study's conclusion laid the foundation for further exploration of the role of AFB1-binding proteins in AFB1 toxicology towards hepatocytes and the entry pathway of AFB1 into hepatocytes.

Involvement of DNA damage response pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has been known as one of the most lethal human malignancies, due to the difficulty of early detection, chemoresistance, and radioresistance, and is characterized by active angiogenesis and metastasis, which account for rapid recurrence and poor survival. Its development has been closely associated with multiple risk factors, including hepatitis B and C virus infection, alcohol consumption, obesity, and diet contamination. Genetic alterations and genomic instability, probably resulted from unrepaired DNA lesions, are increasingly recognized as a common feature of human HCC. Dysregulation of DNA damage repair and signaling to cell cycle checkpoints, known as the DNA damage response (DDR), is associated with a predisposition to cancer and affects responses to DNA-damaging anticancer therapy. It has been demonstrated that various HCC-associated risk factors are able to promote DNA damages, formation of DNA adducts, and chromosomal aberrations. Hence, alterations in the DDR pathways may accumulate these lesions to trigger hepatocarcinogenesis and also to facilitate advanced HCC progression. This review collects some of the most known information about the link between HCC-associated risk factors and DDR pathways in HCC. Hopefully, the review will remind the researchers and clinicians of further characterizing and validating the roles of these DDR pathways in HCC.

Anticarcinogenic effect of brucine in diethylnitrosamine initiated and phenobarbital-promoted hepatocarcinogenesis in rats

We evaluated the effects of brucine on N-nitrosodiethylamine (DENA)-induced hepatocarcinogenesis in rats. Initiation of hepatocarcinogenesis was done by intraperitoneal injection of diethylnitrosamine (DENA) followed by promotion with phenobarbital. The rats were exposed to dietary brucine for 4 weeks prior to initiation, and the treatment was continued for 22 consecutive weeks. Brucine decreased the incidence, total number, multiplicity, size and volume of preneoplastic hepatic nodules in a dose-dependent manner. Administration of DENA induced hepatocellular carcinoma (HCC), as evidenced by changes in histopathological architecture, increased activity of cytochrome P450, decreased activity of glutathione Stransferase (GST) as well as decreased antioxidant status, enhanced lipid peroxidation, increased liver marker enzymes. Western blot analysis showed decreased expression of cyclin D1 and Bcl-2 with activation of caspase-3 and increased expression of Bax. Immunohistochemical demonstrated the decreased expression of the PCNA and VEGF. These results indicate that brucine prevents lipid peroxidation and hepatic cell damage and also protects the antioxidant system in DENA-induced hepatocarcinogenesis.

Serum anti-P53 antibodies and alpha-fetoprotein in patients with non-B non-C hepatocellular carcinoma

The rate of hepatocellular carcinoma (HCC) is increasing worldwide including Egypt. Non-B non-C HCC was reported in some countries. We aimed to investigate P53 antibodies and alpha-fetoprotein in patients with non-B non-C HCC in our region. In a case series study, included 281 patients with HCC and 20 patients with liver cirrhosis of matched age, sex and social factors were received for management at Tanta University Hospitals. Sera were tested for HCV and HBV markers by ELISA/PCR, alpha-fetoprotein (AFP) level and anti-p53 antibody were evaluated by ELISA. Antinuclear antibody, serum copper and iron were assessed in non-viral HCC. Liver scanning and biopsy were evaluated. Non-B non-C HCC patients were 13.87% of total. P53 antibody serum level in non-B non-C HCC patients showed insignificant difference (p>0.05) as compared to viral-associated HCC, while significant as compared to cirrhosis. They had significant decrease in serum AFP level (p<0.001) as compared to viral-associated HCC. Their tumors were mainly solitary, and have smaller-sizes. Sensitivity, specificity, PPV, NPV and accuracy test of anti P53 antibody positive patients were 91.52%, 84.63%, 90.34%, 80.2% and 74.8% respectively. It correlates positively with AFP, tumor size and staging, MELD score and Child-Pugh score. Non-B non-C HCC showed high serum prevalence of anti-p53 as viral-associated HCC suggesting an evidence of high onchogenecity. It appears of much benefit in diagnosis, follow up and differentiation from cirrhosis in presence of low levels of alpha-fetoprotein.