Liver Tumor Promoter Research Articles

Hepatitis B virus X protein differentially regulates the angiogenesis of Hepatocellular Carcinoma through p53-VEGF axis according to glucose levels

Introduction and ObjectivesBlood glucose fluctuates severely in the diabetes (DM) and tumor microenvironment. Our previous works have found Hepatitis B virus X protein (HBx) differentially regulated metastasis and apoptosis of hepatoma cells depending on glucose concentration. We here aimed to explore whether HBx played dual roles in the angiogenesis of hepatocellular carcinoma varying on different glucose levels. Materials and MethodsWe collected conditioned medium from HBx-overexpressing cells cultured with two solubilities of glucose, and then applied to EA.hy926 cells. Alternatively, a co-culture cell system was established with hepatoma cells and EA.hy926 cells. We analyzed the angiogenesis of EA.hy926 cells with CCK8, wound-healing, transwell-migartion and tube formation experiment. ELISA was conducted to detect the secretion levels of angiogenesis-related factors. siRNAs were used to detect the P53-VEGF axis. ResultsHBx expressed in hepatoma cells suppressed VEGF secretion, and subsequently inhibited the proliferation, migration and tube formation of EA.hy926 cells in a high glucose condition, while attenuating these in the lower glucose condition. Furthermore, the p53-VEGF axis was required for the dual role of HBx in angiogenesis. Additionally, HBx mainly regulated the nuclear p53. ConclusionsThese data suggest that the dual roles of HBx confer hepatoma cells to remain in a glucose-rich environment and escape from the glucose-low milieu through tumor vessels, promoting liver tumor progression overall. We exclusively revealed the dual role of HBx on the angiogenesis of liver tumors, which may shed new light on the mechanism and management strategy of HBV- and DM-related hepatocellular carcinoma.

Histone methyltransferase KMT5C drives liver cancer progression and directs therapeutic response to PARP inhibitors.

Epigenetic plasticity is a major challenge in cancer-targeted therapy. However, the molecular basis governing this process has not yet been clearly defined. Despite the considerable success of poly(ADP-ribose) polymerase inhibitors (PARPi) in cancer therapy, the limited response to PARPi, especially in HCC, has been a bottleneck in its clinical implications. Herein, we investigated the molecular basis of the histone methyltransferase KMT5C (lysine methyltransferase 5C) that governs PARPi sensitivity and explored a potential therapeutic strategy for enhancing PARPi efficacy. We identified KMT5C, a trimethyltransferase of H4K20, as a targetable epigenetic factor that promoted liver tumor growth in mouse de novo MYC/Trp53-/- and xenograft liver tumor models. Notably, induction of KMT5C by environmental stress was crucial for DNA repair and HCC cell survival. Mechanistically, KMT5C interacted with the pivotal component of homologous recombination repair, RAD51, and promoted RAD51/RAD54 complex formation, which was essential for the activation of dsDNA breaks repair. This effect depended on the methyltransferase activity of KMT5C. We further demonstrated that the function of KMT5C in promoting HCC progression was dependent on RAD51. Importantly, either a pharmacological inhibitor (A196) or genetic inhibition of KMT5C sensitized liver cancer cells to PARPi. KMT5C played a vital role in promoting liver cancer progression by activating the DNA repair response. Our results revealed a novel therapeutic approach using the KMT5C inhibitor A196, concurrent with olaparib, as a potential HCC therapy.

LANCL1, a cell surface protein, promotes liver tumor initiation through FAM49B-Rac1 axis to suppress oxidative stress.

HCC is an aggressive cancer with a poor clinical outcome. Understanding the mechanisms that drive tumor initiation is important for improving treatment strategy. This study aimed to identify functional cell membrane proteins that promote HCC tumor initiation. Tailor-made siRNA library screening was performed for all membrane protein-encoding genes that are upregulated in human HCC (n = 134), with sphere formation as a surrogate readout for tumor initiation. Upon confirmation of membranous localization by immunofluorescence and tumor initiation ability by limiting dilution assay in vivo, LanC-like protein-1 (LANCL1) was selected for further characterization. LANCL1 suppressed intracellular reactive oxygen species (ROS) and promoted tumorigenicity both in vitro and in vivo. Mechanistically, with mass spectrometry, FAM49B was identified as a downstream binding partner of LANCL1. LANCL1 stabilized FAM49B by blocking the interaction of FAM49B with the specific E3 ubiquitin ligase TRIM21, thus protecting FAM49B from ubiquitin-proteasome degradation. The LANCL1-FAM49B axis suppressed the Rac1-NADPH oxidase-driven ROS production, but this suppression of ROS was independent of the glutathione transferase function of LANCL1. Clinically, HCCs with high co-expression of LANCL1 and FAM49B were associated with more advanced tumor stage, poorer overall survival, and disease-free survival. In addition, anti-LANCL1 antibodies targeting the extracellular N-terminal domain were able to suppress the self-renewal ability, as demonstrated by the sphere formation ability of HCC cells. Our data showed that LANCL1 is a cell surface protein and a key contributor to HCC initiation. Targeting the LANCL1-FAM49B-Rac1-NADPH oxidase-ROS signaling axis may be a promising therapeutic strategy for HCC.

Abstract 6458: Maternal and paternal alcohol exposures program higher incidence of hepatocellular carcinoma in offspring

Abstract Environmental exposures during development are known to influence adult health and disease. Specifically, early developmental exposures have been shown to increase susceptibility to cancer in adults through epigenetic mechanisms. Alcohol is a potent environmental carcinogen and teratogen, causing a wide range of health problems across the life course of an individual. Current literature examining early life exposures solely focuses on maternal exposures despite recent efforts to recognize paternal epigenetic contributions. Thus, we investigated the influence of preconception paternal, maternal, and dual parental alcohol exposures on offspring’s predisposition to develop liver disease and hepatocellular carcinoma (HCC). We hypothesized that dual-parental alcohol exposure would exacerbate the incidence of liver cancer in adult offspring. Using an established mouse model, we exposed male and female adult C57BL/6J mice to control (0% EtOH) or alcohol (10% EtOH) preconception treatments. Next, we randomly assigned pups from each treatment to either a single injection of Diethylnitrosamine (DEN; 25mg/kg) to promote liver tumors, or saline control. Finally, we sacrificed offspring on postnatal day 182 and collected organs and blood for enzyme analysis. DEN-treated males display an increased liver-to-body weight ratio compared to saline males while also exhibiting lower body weight. The male progeny from the dual-parental treatment group exhibited a significant increase in tumor incidence and burden in DEN-treated males, exceeding those measured for the maternal and paternal treatments. Further, offspring from the dual-parental group had high levels of alanine transaminase (ALT) and aspartate transaminase (AST) compared to the other treatment groups. Oil Red-O and Sirius Red staining of liver sections revealed increased hepatic steatosis and fibrosis in DEN males compared to saline males. Again, the dual-parental exposed offspring exhibited the most aberrant phenotype. Blind scoring of H&E-stained liver sections identified increases in steatosis, fibrosis, and HCC lesions, with the highest scores emerging in DEN-treated dual-parental offspring. These findings demonstrate that preconception paternal and gestational maternal alcohol exposures program a predisposition to adult-onset chronic diseases including alcoholic fatty liver disease, hepatic fibrosis, and HCC. These experiments not only confirm our hypothesis that dual-parental exposed offspring exhibit an exacerbated hepatic abnormality phenotype, but also highlight the importance of both maternal and paternal environmental exposures on disease risk in offspring. While the negative effects of maternal alcohol consumption have been well established, our novel finding that paternal alcohol exposure also promotes hepatocellular carcinoma in offspring has potentially profound clinical implications. Citation Format: Alison Basel, Sanat S. Bhadsavle, Kara N. Thomas, Katherine N. Zimmel, Alexis N. Roach, Matthew Gaytan, Grace Parkey, Michael C. Golding. Maternal and paternal alcohol exposures program higher incidence of hepatocellular carcinoma in offspring. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6458.

Glycogen overload transforms the liver.

Glycogen is a fast and accessible form of energy. Glycogen accumulation occurs when it is synthesized excessively or is not broken down, and it plays an important role in many physiological processes. In addition, the accumulated glycogen may provide nourishment or serve as a mediator in nutrient-poor tumor environments thereby potentiating tumor growth. Liu et al. reveal that accumulated glycogen promotes liver tumor initiation by inhibiting the Hippo signaling pathway. Furthermore, it spontaneously undergoes liquid-liquid phase separation (LLPS). The retention of Mst1/2 in glycogen droplets formed by LLPS subsequently blocks the Hippo pathway, activates YAP and promotes liver tumorigenesis. This study highlights the importance of glycogen accumulation in liver tumorigenesis and expands the drugs targeting accumulated glycogen, which may open a new avenue for the early detection and treatment of liver tumors.

Human constitutive androstane receptor represses liver cancer development and hepatoma cell proliferation by inhibiting erythropoietin signaling

The constitutive androstane receptor (CAR) is a nuclear receptor that plays a crucial role in regulating xenobiotic metabolism and detoxification, energy homeostasis, and cell proliferation by modulating the transcription of numerous target genes. CAR activation has been established as the mode of action by which phenobarbital-like nongenotoxic carcinogens promote liver tumor formation in rodents. This paradigm, however, appears to be unrelated to the function of human CAR (hCAR) in hepatocellular carcinoma (HCC), which remains poorly understood. Here, we show that hCAR expression is significantly lower in HCC than that in adjacent nontumor tissues and, importantly, reduced hCAR expression is associated with a worse HCC prognosis. We also show overexpression of hCAR in human hepatoma cells (HepG2 and Hep3B) profoundly suppressed cell proliferation, cell cycle progression, soft-agar colony formation, and the growth of xenografts in nude mice. RNA-Seq analysis revealed that the expression of erythropoietin (EPO), a pleiotropic growth factor, was markedly repressed by hCAR in hepatoma cells. Addition of recombinant EPO in HepG2 cells partially rescued hCAR-suppressed cell viability. Mechanistically, we showed that overexpressing hCAR repressed mitogenic EPO–EPO receptor signaling through dephosphorylation of signal transducer and activator of transcription 3, AKT, and extracellular signal–regulated kinase 1/2. Furthermore, we found that hCAR downregulates EPO expression by repressing the expression and activity of hepatocyte nuclear factor 4 alpha, a key transcription factor regulating EPO expression. Collectively, our results suggest that hCAR plays a tumor suppressive role in HCC development, which differs from that of rodent CAR and offers insight into the hCAR–hepatocyte nuclear factor 4 alpha–EPO axis in human liver tumorigenesis.

A high-throughput screening assay for identification of chemicals with liver tumor promoting potential using a transgenic zebrafish line

Traditional high-throughput methods for identification of chemicals with liver tumor promotion potentials are based on established cancer cell lines, and rapid and cost-effective high-throughput screening assays in whole organisms are presently lacking. In this study, a transgenic zebrafish liver cancer model was employed to develop a method that could be used to identify chemicals with liver tumor promotion effect quickly and accurately. The method consisted of three parts, including exposure preparation, exposure process and image acquisition. In brief, after chemical exposure for 7 days, 96-well plate exposure system for zebrafish larvae was assessed by microplate reader. Then, the liver cancer promoting potential chemicals were evaluated by field area and field average intensity of fluorescence. The results were further validated by conducting histopathological examination. Our data demonstrated that the high-throughput screening assay developed in this study was reproducible and could be used to rapidly screen chemicals with liver tumor promoting potentials by using tris-(2-chloropropyl)-phosphate (TDCIPP) as a positive control. Furthermore, some other positive chemicals found in previous studies and environmental compounds were assessed using the established method. Results indicated that 86.7% of the positive chemicals and five environmental compounds out of seventeen compounds could enhance liver tumor progression.

Distinct Roles of the Sister Nuclear Receptors PXR and CAR in Liver Cancer Development

Pregnane X receptor (PXR) and constitutively active receptor/constitutive androstane receptor (CAR) are xenobiotic-responsible transcription factors belonging to the same nuclear receptor gene subfamily (NR1I) and highly expressed in the liver. These receptors are activated by a variety of chemicals and play pivotal roles in many liver functions,including xenobiotic metabolism and disposition. Phenobarbital, an enzyme inducer and liver tumor promoter, activates both rodent and human CAR but causes liver tumors only in rodents. Although the precise mechanism for phenobarbital/CAR-mediated liver tumor formation remains to be established, intracellular pathways, including the Hippo pathway/YAP-TEAD system and β-catenin signaling, seem to be involved. In contrast to CAR, previous findings by our group suggest that PXR activation does not promote hepatocyte proliferation but it enhances the proliferation induced by various stimuli. Moreover, and surprisingly, PXR may have antitumor effects in both rodents and humansby targeting inflammatory cytokine signals, angiogenesis and epithelial-mesenchymal transition. In this review, we summarize the current knowledge on the associations of PXR and CAR with hepatocyte proliferation and liver tumorigenesis and their molecular mechanisms and species differences. <b>Significance Statement</b> Pregnane X receptor (PXR) and constitutively active receptor/constitutive androstane receptor (CAR) have very similar functions in the gene regulation associated with xenobiotic disposition, as suggested by their identification as xenosensors for enzyme induction. In contrast, recent reports clearly suggest that these receptors play distinct roles in the control of hepatocyte proliferation and liver cancer development. Understanding these differences at the molecular level may help us evaluate the human safety of chemical compounds and develop novel drugs targeting liver cancers.

CD169-positive macrophages enhance abscopal effect of radiofrequency ablation therapy in liver cancer

Radiofrequency ablation (RFA) is a widely used and effective treatment for primary or metastatic liver cancer with small-size lesions. However, the therapeutic effectiveness of RFA in controlling metastatic lesion or recurrence is still limited. As the major cell population in tumor microenvironment (TME), macrophages have been reported to be recruited to RFA-treated lesion, but their roles are still unclear. Herein, we successfully established the mouse model mimicking RFA-induced abscopal effect, in which RFA eliminated the local orthotopic liver tumor but failed to control growth of distant tumor. Correspondently, RFA suppressed protumoral activation of local tumor-associated macrophages (TAMs), but failed to reprogram TAMs in distance. Importantly, although RFA led to reduced proportion of hepatic CD169+ macrophages in local and decreased expression of immune inhibitory molecules Tim-3 and PD-L1, these alterations were not observed for CD169+ macrophages in distant TME. Further RNA-seq and flow cytometry analysis showed that hepatic CD169+ macrophages contributed to reprograming TME through recruiting CD8+ T/NK cells and suppressing accumulation of MDSCs/Tregs. Consistently, depletion of CD169+ macrophages in CD169-DTR mouse greatly promoted liver tumor progression and largely dampened RFA-induced tumor suppression. Notably, transfer of CD169+ macrophages synergistically enhanced RFA-induced inhibition of distant tumor. To our knowledge, this is the first study which demonstrates hepatic CD169+ macrophages as a key factor responsible for RFA-induced abscopal effect. Our data suggest RFA with transfer of CD169+ macrophages as a promising combination therapy to lessen metastasis or recurrence of liver cancer in patients.

Antitumor effects of cadmium against diethylnitrosamine-induced liver tumors in mice.

Cadmium (Cd) has been reported to exhibit antitumor effects against chemically induced liver tumors. However, the antitumor effects of Cd are not completely understood. Metallotherapy, the use of a toxic metal to attack liver tumors, could be a viable strategy. In the present study, 8-week old, male, C57BL/6 mice were administered injections of diethylnitrosamine (DEN) (90 mg/kg, and then 50 mg/kg 2 weeks later), followed by liver tumor promotion with carbon tetrachloride. Cadmium chloride was administered in the drinking water (1000 ppm) from 21–40 weeks after DEN initiation. Body weights were recorded and liver tumor formation was monitored via ultrasound. At the end of experiments, livers were removed, weighed, and the tumor incidence, tumor numbers and tumor size scores were recorded. Liver histology and metallothionein (MT) immunostaining were performed. After DEN injection, animal body weight decreased, and then slowly recovered with time. Cd treatment did not affect animal body weight gain. Ultrasound analysis detected liver tumors 35 weeks after DEN injection, and the mice were necropsied at 40 weeks. Liver/body weight ratios increased in the DEN and DEN + Cd groups. Cd treatment decreased the tumor incidence (71 vs. 17%), tumor numbers (15 vs. 2) and tumor scores (22 vs. 3) when compared with the DEN only group. Histopathology showed hepatocyte degeneration in all groups, and immunohistochemistry showed MT-deficiency in the liver tumors, while MT staining was intensified in the surrounding tissues. Reverse transcription-quantitative PCR showed increases in α-fetoprotein level in DEN-treated livers, and increases in MT-2 and tumor necrosis factor α (TNFα) levels in Cd-treated livers. Thus, it was concluded that Cd is effective in the suppression of DEN-induced liver tumors, and that the mechanisms may be related to MT-deficiency in tumors and the induction of TNFα to kill tumor cells.

Suppression of apoptotic signaling in rat hepatocytes by non-dioxin-like polychlorinated biphenyls depends on the receptors CAR and PXR

Non-dioxin-like polychlorinated biphenyls (NDL-PCBs) represent a sub-group of persistent organic pollutants found in food, environmental samples and human and animal tissues. Promotion of pre-neoplastic lesions in rodent liver has been suggested as an indicator for a possible increased risk of liver cancer in humans exposed to NDL-PCBs. In rodent hepatocytes, suppression of DNA damage-triggered apoptosis is a typical mode of action of liver tumor promoters. Here, we report that NDL-PCBs suppress apoptosis in rat hepatocytes treated in culture with an apoptogenic dose of UV light. Suppression became less pronounced when the constitutive androstane receptor (CAR) and/or the pregnane-X-receptor (PXR) where knocked-out using siRNAs, while knocking-out both receptors led to a full reconstitution of apoptosis. In contrast, suppression of apoptosis by the CAR or PXR activators phenobarbital or dexamethasone were CAR- or PXR-specific. Induction and suppression of apoptosis were paralleled by changes in caspase 3/7, 8 and 9 activities. Our findings indicate that NDL-PCBs can suppress UV-induced apoptosis in rat hepatocytes by activating CAR and PXR. It needs further investigation if these mechanisms of action are also of relevance for human liver.

Microcystins can be extracted from Microcystis aeruginosa using amino acid-derived biosurfactants.

Microcystin, a cyanotoxin produced by Microcystis aeruginosa growing in eutrophic waters, can promote liver tumors in people ingesting contaminated water. To date, water treatment systems have not been effective in removing or degrading these cyanotoxins. In this work, we investigated the inhibitory activity of surfactants on the growth of M. aeruginosa and their application to extract the intracellular produced cyanotoxins. The experiments involving growth inhibition and extraction of cyanotoxins were carried out using the non-biodegradable surfactant cetyl trimethyl ammonium bromide (CTAB) in addition to other biodegradable surfactants. These were Tween 80 and surfactants derived from amino acids and peptides, respectively, from arginine, SDA, and hydrolyzed peptone, SDP. We demonstrated that the tested surfactants could be used to inhibit the growth of M. aeruginosa. At this point, CTAB and SDA proved to be the most competent surfactants in reducing cyanobacterial growth. Moreover, microcystins have been successfully removed from the water employing a cloud point extraction protocol based on the use of these surfactants and ammonium sulfate.

Insights into Growth Factors in Liver Carcinogenesis and Regeneration: An Ongoing Debate on Minimizing Cancer Recurrence after Liver Resection.

Hepatocellular carcinoma has become a leading cause of cancer-associated mortality throughout the world, and is of great concern. Currently used chemotherapeutic drugs in the treatment of hepatocellular carcinoma lead to severe side effects, thus underscoring the need for further research to develop novel and safer therapies. Liver resection in cancer patients is routinely performed. After partial resection, liver regeneration is a perfectly calibrated response apparently sensed by the body’s required liver function. This process hinges on the effect of several growth factors, among other molecules. However, dysregulation of growth factor signals also leads to growth signaling autonomy and tumor progression, so control of growth factor expression may prevent tumor progression. This review describes the role of some of the main growth factors whose dysregulation promotes liver tumor progression, and are also key in regenerating the remaining liver following resection. We herein summarize and discuss studies focused on partial hepatectomy and liver carcinogenesis, referring to hepatocyte growth factor, insulin-like growth factor, and epidermal growth factor, as well as their suitability as targets in the treatment of hepatocellular carcinoma. Finally, and given that drugs remain one of the mainstay treatment options in liver carcinogenesis, we have reviewed the current pharmacological approaches approved for clinical use or research targeting these factors.

Exacerbation of Liver Tumor Metastasis in twist1a+/xmrk+ Double Transgenic Zebrafish following Lipopolysaccharide or Dextran Sulphate Sodium Exposure.

The poor prognosis for patients with hepatocellular carcinoma (HCC) is related directly to metastasis. The Twist1 gene encodes for a transcription factor essential to embryogenesis. It has also been shown to promote epithelial-to-mesenchymal transition (EMT), invasion, and metastasis; however, there is currently no in vivo evidence that Twist1 plays a role in the metastasis of liver tumors. Zebrafish are increasingly being used as an alternative cancer model. In the current study, an adult-stage zebrafish HCC model was used to examine the synergistic effects of twist1a and xmrk, a well characterized oncogene, during HCC metastasis. We also examined the effects of two inflammatory agents, lipopolysaccharides (LPS) and dextran sulfate sodium (DSS), on the hepatocyte-specific expression of transgenic twist1a and xmrk. The conditional overexpression of twist1a and xmrk was shown to promote liver tumor metastasis in zebrafish, resulting in increased apoptosis and cell proliferation as well as tumor maintenance and propagation independent of the inherent EMT-inducing activity of xmrk. Exposing twist1a+/xmrk+ transgenic zebrafish to LPS or DSS was shown to promote metastasis, indicating that the overexpression of twist1a and xmrk led to crosstalk between the signaling pathways involved in EMT. This study provides important evidence pertaining to the largely overlooked effects of signaling crosstalk between twist1a and xmrk in regulating HCC metastasis. Our results also suggest that the co-expression of twist1a/xmrk in conjunction with exposure to LPS or DSS enhances HCC metastasis, and provides a valuable in vivo platform by which to investigate tumor initiation and metastasis in the study of liver cancer.

Promotion effect of microcystin-LR on liver tumor progression in krasV12 transgenic zebrafish following acute or subacute exposure

Microcystin-LR (MC-LR) is widely distributed in the natural environment and causes hepatotoxicity. However, whether MC-LR promotes liver tumor progression remains controversial. krasV12 transgenic zebrafish were used as an inducible liver tumor model to evaluate the potential tumor-promoting effect of MC-LR. First, krasV12 transgenic larvae were exposed to 0, 0.1 and 1 mg/L MC-LR with 20 mg/L doxycycline (Dox) for 4 d. The gray values and histopathological examinations of the liver demonstrated that MC-LR aggravated liver tumor progression, which could be inhibited by the Protein arginine methyltransferase 5 (Prmt5) inhibitor compound 5 (CMP5). Second, 1-month-old juvenile transgenic zebrafish were exposed to 0, 20 mg/L Dox, 1 μg/L MC-LR, and 20 mg/L Dox with 0.1 or 1 μg/L MC-LR for 15 d to determine whether the exposure to environmental concentrations of MC-LR promoted hepatocellular carcinoma (HCC) progression. We found that environmental concentrations of MC-LR increased the hepatosomatic index (HSI) and gray value (intensity/area) and promoted HCC progression. The results indicate that environmental concentrations of MC-LR have the potential to promote liver tumor progression. Taken together, the present study demonstrates that MC-LR can promote tumor in krasV12 transgenic zebrafish and that the upregulation of prmt5 expression might contribute to MC-LR-mediated promotion of liver tumorigenesis.

Knockout of Putative Tumor Suppressor Aldh1l1 in Mice Reprograms Metabolism to Accelerate Growth of Tumors in a Diethylnitrosamine (DEN) Model of Liver Carcinogenesis.

Simple SummaryCancers often loose the enzyme of folate metabolism ALDH1L1. We proposed that such loss is advantageous for the malignant tumor growth and tested this hypothesis in mice proficient or deficient (gene knockout) in ALDH1L1 expression. Liver cancer in both groups was induced by injection of chemical carcinogen diethylnitrosamine. While the number of tumors observed in ALDH1L1 proficient and deficient mice was similar, tumors grew faster and to a larger size in the knockout mice. We conclude that the ALDH1L1 loss promotes liver tumor growth without affecting tumor initiation or multiplicity. Accelerated growth of tumors lacking the enzyme was linked to several metabolic pathways, which are beneficial for rapid proliferation.Cytosolic 10-formyltetrahydrofolate dehydrogenase (ALDH1L1) is commonly downregulated in human cancers through promoter methylation. We proposed that ALDH1L1 loss promotes malignant tumor growth. Here, we investigated the effect of the Aldh1l1 mouse knockout (Aldh1l1−/−) on hepatocellular carcinoma using a chemical carcinogenesis model. Fifteen-day-old male Aldh1l1 knockout mice and their wild-type littermate controls (Aldh1l1+/+) were injected intraperitoneally with 20 μg/g body weight of DEN (diethylnitrosamine). Mice were sacrificed 10, 20, 28, and 36 weeks post-DEN injection, and livers were examined for tumor multiplicity and size. We observed that while tumor multiplicity did not differ between Aldh1l1−/− and Aldh1l1+/+ animals, larger tumors grew in Aldh1l1−/− compared to Aldh1l1+/+ mice at 28 and 36 weeks. Profound differences between Aldh1l1−/− and Aldh1l1+/+ mice in the expression of inflammation-related genes were seen at 10 and 20 weeks. Of note, large tumors from wild-type mice showed a strong decrease of ALDH1L1 protein at 36 weeks. Metabolomic analysis of liver tissues at 20 weeks showed stronger differences in Aldh1l1+/+ versus Aldh1l1−/− metabotypes than at 10 weeks, which underscores metabolic pathways that respond to DEN in an ALDH1L1-dependent manner. Our study indicates that Aldh1l1 knockout promoted liver tumor growth without affecting tumor initiation or multiplicity.

Maternal metabolic syndrome induces liver injury and promotes tumor growth in the offspring

Abstract Objective Obesity is a growing disease entity affecting a third of women of reproductive age. Epidemiological studies show that children of obese mothers suffer from obesity, long-term morbidity and an increased rate of childhood cancers. However, the mechanisms of disease transmission remain unknown. The aim of this study is to test this hypothesis in a mouse model and shed light on the involved mechanisms of vertical transmission. Methods Female mice were fed a high fat or standard diet (HFD/SD) for 16 weeks before being mated with mice fed a normal diet. Corresponding diet was continued until weaning, all offspring were thereafter fed a SD. Metabolic profile, weight gain, liver enzymes and the gut microbiota profile were assessed in the offspring (n = 24). Additional groups of offspring (n = 48) were injected with a carcinogen (diethylnitrosamine) at week two, tumor characteristics were assessed by computed tomography scan at week 36. Results Mothers fed HFD developed obesity and non-alcoholic fatty liver disease (NAFLD). Female offspring of mothers fed HFD gained significantly more weight (+33.7%, p = 0.001), had increased alanine transaminase levels (62 vs 18 IU/L, p = 0.003) and a significantly altered liver histology exemplified by an increased NAFLD activity score (3.8 vs 0.6, p = 0.016). Expression levels of several candidate genes were studied of which FGF21 showed the largest differential expression between HFD and SD offspring (9 vs 1 2^ΔΔCT, p = &amp;lt;0.001). However, epigenetic analysis of FGF21 in the liver revealed no changes in methylation level between HFD and SD offspring. Furthermore, offspring of HFD mothers had a distinctly altered gut microbiome with lower proportions of Bacteroides caccae, Bacteroidales and Parasutterella excrementihominis. Interestingly, the proportion of female offspring developing tumors was significantly higher in offspring of HFD mothers (83 vs 44%, p = 0.011), the average total tumor volume was larger (234 vs 3.5mm3, p = 0.022) and the offspring developed more tumors (3.5 vs 0.6, p = 0.010). Conclusion Maternal obesity promotes liver tumor growth in the offspring, alters metabolic patterns and induces liver suffering in the progeny in a sex-dependent manner. The gut microbiome seems to play a role in this transmission of disease. Yet further research is needed to determine the vectors of transmission and evaluate preventive interventions in obese mothers.

Perfluorooctane sulfonate promotes doxycycline-induced liver tumor progression in male Krasv12 transgenic zebrafish

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant that has been widely detected in the environment and has caused growing international concern. The liver is the main target organ of PFOS exposure. Animal experiments have shown that PFOS exposure can increase the risk of liver tumorigenesis. However, whether PFOS can accelerate liver tumor progression is still unclear. In this study, transgenic zebrafish Tg(fabp10:rtTA2s-M2; TRE2:EGFP-KRASG12V), a hepatocellular carcinoma (HCC) model that can cause liver tumorigenesis by doxycycline (DOX) induction, was used to investigate the effect of PFOS exposure in HCC progression. The male krasV12 transgenic zebrafish were exposed to 20 mg/L DOX, 500 μg/L PFOS or combined 20 mg/L DOX and 500 μg/L PFOS for 10 d. The results showed that co-treated with PFOS and DOX caused oncogenic Kras-induced liver enlargement, increased the percentages of zebrafish with HCC, and aggravated metabolic reprogramming of liver. To the best of our knowledge, this study for the first proved that PFOS could promote liver tumor progression. Decreased vitamin D level and increased fatty acid intake caused by PFOS might be responsible for the tumor-promoting effects. The results suggest that attention should be paid to the tumor-promoting effects of PFOS when assessing its environmental health risks, and these findings provide new insights into the toxicity of PFOS.

APOBEC3A catalyzes mutation and drives carcinogenesis in vivo.

The APOBEC3 family of antiviral DNA cytosine deaminases is implicated as the second largest source of mutation in cancer. This mutational process may be a causal driver or inconsequential passenger to the overall tumor phenotype. We show that human APOBEC3A expression in murine colon and liver tissues increases tumorigenesis. All other APOBEC3 family members, including APOBEC3B, fail to promote liver tumor formation. Tumor DNA sequences from APOBEC3A-expressing animals display hallmark APOBEC signature mutations in TCA/T motifs. Bioinformatic comparisons of the observed APOBEC3A mutation signature in murine tumors, previously reported APOBEC3A and APOBEC3B mutation signatures in yeast, and reanalyzed APOBEC mutation signatures in human tumor datasets support cause-and-effect relationships for APOBEC3A-catalyzed deamination and mutagenesis in driving multiple human cancers.

Structure-Dependent Effects of Phthalates on Intercellular and Intracellular Communication in Liver Oval Cells.

Humans are exposed to phthalates released from plastics, cosmetics, or food on a daily basis. Phthalates have low acute liver toxicity, but their chronic exposures could induce molecular and cellular effects linked to adverse health outcomes, such as liver tumor promotion or chronic liver diseases. The alternation of gap junctional intercellular communication (GJIC) and MAPK-Erk1/2 pathways in liver progenitor or oval cells can disrupt liver tissue homeostatic mechanisms and affect the development and severity of these adverse outcomes. Our study with 20 different phthalates revealed their structurally dependent effects on liver GJIC and MAPK-Erk1/2 signaling in rat liver WB-F344 cell line with characteristics of liver oval cells. The phthalates with a medium-length side chain (3–6 C) were the most potent dysregulators of GJIC and activators of MAPK-Erk1/2. The effects occurred rapidly, suggesting the activation of non-genomic (non-transcriptional) mechanisms directly by the parental compounds. Short-chain phthalates (1–2 C) did not dysregulate GJIC even after longer exposures and did not activate MAPK-Erk1/2. Longer chain (≥7 C) phthalates, such as DEHP or DINP, moderately activated MAPK-Erk1/2, but inhibited GJIC only after prolonged exposures (>12 h), suggesting that GJIC dysregulation occurs via genomic mechanisms, or (bio)transformation. Overall, medium-chain phthalates rapidly affected the key tissue homeostatic mechanisms in the liver oval cell population via non-genomic pathways, which might contribute to the development of chronic liver toxicity and diseases.