Infrequent widespread microsatellite instability in hepatocellular carcinomas

DNA methylation alterations of ADCY5, MICAL2, and PLEKHG2 during the developmental stage of cryptogenic hepatocellular carcinoma

AIM

The aim of this study was to clarify the significance of DNA methylation alterations of cryptogenic hepatocellular carcinomas (HCCs).

METHODS

Using the Infinium assay, we performed genome-wide DNA methylation analysis of 250 liver tissue samples, including noncancerous liver tissue (U-N) and corresponding cancerous tissue (U-T) from patients with cryptogenic HCC without a history of excessive alcohol use and hepatitis virus infection, and whose U-N samples showed no remarkable histological features (no microscopic evidence of simple steatosis, any form of hepatitis including nonalcoholic steatohepatitis, or liver cirrhosis).

RESULTS

We identified 3272 probes that showed significant differences of DNA methylation levels between U-N and normal liver tissue samples from patients without HCC, indicating that a distinct DNA methylation profile had already been established at the precancerous U-N stage. U-Ns have a DNA methylation profile differing from that of noncancerous liver tissue of patients with nonalcoholic steatohepatitis-related, viral hepatitis-related, and alcoholic liver disease-related HCCs. Such DNA methylation alterations in U-Ns were inherited by U-Ts. The U-Ns showed DNA methylation alteration of ADCY5, resulting in alteration of its mRNA expression, whereas noncancerous liver tissue of patients with nonalcoholic steatohepatitis-, viral hepatitis-, or alcoholic liver disease-related HCCs did not. DNA methylation levels of MICAL2 and PLEKHG2 in U-Ts were correlated with larger tumor diameter and portal vein involvement, respectively.

CONCLUSIONS

U-N-specific DNA hypermethylation of ADCY5 may have significance, even from the precancerous stage in liver showing no remarkable histological features. DNA hypomethylation of MICAL2 and PLEKHG2 may determine the clinicopathological features of cryptogenic HCC.

Protein profiles reveal MSH6/MSH2 as a potential biomarker for hepatocellular carcinoma with microvascular invasion

AIM

Microvascular invasion (MVI) is an independent risk factor for postoperative recurrence and metastasis in hepatocellular carcinoma (HCC). However, the specific protein expression profiles that differentiate HCC with MVI from those without MVI remain unclear.

METHODS

The profiles of proteins in early-stage HCC tissues and normal liver tissues were characterized by quantitative proteomics techniques. Immunohistochemical (IHC) staining was undertaken on tissue microarrays from 80 HCC patients to assess the expression of MSH2 and MSH6. Cell counting, colony formation, migration, and invasion assays were carried out in vitro.

RESULTS

We identified 5164 proteins in both HCC tissues and adjacent normal liver tissues. Compared to HCC without MVI, 148 upregulated proteins and 97 downregulated proteins were found in HCC with MVI. Particularly noteworthy was the remarkable upregulation of MSH6/MSH2 among these dysregulated proteins in HCC with MVI. Further validation through bioinformatics prediction and IHC confirmed the elevated expression of MSH6/MSH2, which correlated with aggressive disease characteristics and poor prognosis. Receiver operating characteristic curve analyses revealed a substantial area under the curve of 0.761 (specificity 71.79%, sensitivity 73.17%) for the combined use of MSH6/MSH2. Knockdown of MSH6/MSH2 significantly inhibited HCC cell proliferation and invasion in vitro.

CONCLUSIONS

Our study establishes MSH6 or MSH2 as an oncogene that is prominently overexpressed during HCC progression, which provides new targets for HCC with MVI.

The Systemic Inflammatory Response Identifies Patients with Adverse Clinical Outcome from Immunotherapy in Hepatocellular Carcinoma

Systemic inflammation is a hallmark of cancer, and it has a pivotal role in hepatocellular carcinoma (HCC) development and progression. We conducted a retrospective study including 362 patients receiving immune check-point inhibitors (ICIs) across three continents, evaluating the influence of neutrophiles to lymphocytes ratio (NLR), platelets to lymphocytes ratio (PLR), and prognostic nutritional index (PNI) on overall (OS), progression free survival (PFS), and radiologic responses. In our 362 patients treated with immunotherapy, median OS and PFS were 9 and 3.5 months, respectively. Amongst tested inflammatory biomarkers, patients with NLR ≥ 5 had shorter OS (7.7 vs. 17.6 months, p < 0.0001), PFS (2.1 vs. 3.8 months, p = 0.025), and lower objective response rate (ORR) (12% vs. 22%, p = 0.034); similarly, patients with PLR ≥ 300 reported shorter OS (6.4 vs. 16.5 months, p < 0.0001) and PFS (1.8 vs. 3.7 months, p = 0.0006). NLR emerged as independent prognostic factors for OS in univariate and multivariate analysis (HR 1.95, 95%CI 1.45-2.64, p < 0.001; HR 1.73, 95%CI 1.23-2.42, p = 0.002) and PLR remained an independent prognostic factor for both OS and PFS in multivariate analysis (HR 1.60, 95%CI 1.6-2.40, p = 0.020; HR 1.99, 95%CI 1.11-3.49, p = 0.021). Systemic inflammation measured by NLR and PLR is an independent negative prognostic factor in HCC patients undergoing ICI therapy. Further studies are required to understand the biological mechanisms underlying this association and to investigate the predictive significance of circulating inflammatory biomarkers in HCC patients treated with ICIs.

Biomarkers and Future Perspectives for Hepatocellular Carcinoma Immunotherapy

Hepatocellular cancer is the sixth most frequently diagnosed malignant disease worldwide, and was responsible for tens of millions of deaths in 2020; however, treatment options for patients with advanced hepatocellular carcinoma remain limited. Immunotherapy has undergone rapid development over recent years, especially in the field of immune checkpoint inhibitors (ICIs). These drugs aim to activate and enhance antitumor immunity and represent a new prospect for the treatment of patients with advanced cancer. Nevertheless, only a small proportion of liver cancer patients currently benefit from ICI-based treatment, highlighting the need to better understand how ICIs and tumors interact, as well as identify predictive biomarkers for immunotherapeutic responses. In this review, we highlight clinical trials and basic research in hepatocellular carcinoma, with a particular focus on predictive biomarkers for the therapeutic efficacy of ICIs. Predictive biomarkers for immune-related adverse events are also discussed.

Immune-based therapies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third most frequent cause of cancer-related death. The immune-rich contexture of the HCC microenvironment makes this tumour an appealing target for immune-based therapies. Here, we discuss how the functional characteristics of the liver microenvironment can potentially be harnessed for the treatment of HCC. We will review the evidence supporting a therapeutic role for vaccines, cell-based therapies and immune-checkpoint inhibitors and discuss the potential for patient stratification in an attempt to overcome the series of failures that has characterised drug development in this disease area.

Low Levels of Microsatellite Instability at Simple Repeated Sequences Commonly Occur in Human Hepatocellular Carcinoma

BACKGROUND/AIM

The aim of this study was to assess the incidence of MSI in a large series of human hepatocellular carcinomas (HCC) with various etiologies.

MATERIALS AND METHODS

The MSI status was determined by polymerase chain reaction (PCR) using 5 mononucleotide and 13 CAn dinucleotide repeats.

RESULTS

None of the 122 HCC samples displayed an MSI-High phenotype, as defined by the presence of alterations at more than 30% of the microsatellite markers analyzed. Yet, limited microsatellite instability consisting in the insertion or deletion of a few repeat motifs was detected in 32 tumor samples (26.2%), regardless of the etiology of the underlying liver disease. MSI tended to be higher in patients with cirrhosis (p=0.051), possibly reflecting an impact of the inflammatory context in this process.

CONCLUSION

Based on a large series of HCC with various etiologies, our study allowed us to definitely conclude that MSI is not a hallmark of HCC.

Hypermutation and microsatellite instability in gastrointestinal cancers

Recent progress in cancer genome analysis using next-generation sequencing has revealed a high mutation burden in some tumors. The particularly high rate of somatic mutation in these tumors correlates with the generation of neo-antigens capable of eliciting an immune response. Identification of hypermutated tumors is therefore clinically valuable for selecting patients suitable for immunotherapy treatment. There are several known causes of hypermutation in tumors, such as ultraviolet light in melanoma, tobacco smoke in lung cancer, and excessive APOBEC (apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like) activity in breast and gastric cancer. In gastrointestinal cancers, one of the leading causes of hypermutation is a defect in DNA mismatch repair, which results in microsatellite instability (MSI). This review will focus on the frequency, characteristics and genomic signature of hypermutated gastrointestinal cancers with MSI. Detection of tumor hypermutation in cancer is expected to not only predict the clinical benefit of immune checkpoint inhibitor treatment, but also to provide better surgical strategies for the patients with hypermutated tumors. Thus, in an era of precision medicine, identification of hypermutation and MSI will play an important role directing surgical and chemotherapeutic treatment.

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.

Disruption of transforming growth factor-beta signaling through beta-spectrin ELF leads to hepatocellular cancer through cyclin D1 activation

Transforming growth factor-beta (TGF-beta) signaling members, TGF-beta receptor type II (TBRII), Smad2, Smad4 and Smad adaptor, embryonic liver fodrin (ELF), are prominent tumor suppressors in gastrointestinal cancers. Here, we show that 40% of elf(+/-) mice spontaneously develop hepatocellular cancer (HCC) with markedly increased cyclin D1, cyclin-dependent kinase 4 (Cdk4), c-Myc and MDM2 expression. Reduced ELF but not TBRII, or Smad4 was observed in 8 of 9 human HCCs (P<0.017). ELF and TBRII are also markedly decreased in human HCC cell lines SNU-398 and SNU-475. Restoration of ELF and TBRII in SNU-398 cells markedly decreases cyclin D1 as well as hyperphosphorylated-retinoblastoma (hyperphosphorylated-pRb). Thus, we show that TGF-beta signaling and Smad adaptor ELF suppress human hepatocarcinogenesis, potentially through cyclin D1 deregulation. Loss of ELF could serve as a primary event in progression toward a fully transformed phenotype and could hold promise for new therapeutic approaches in human HCCs.

A Dose-Dependent Decrease in the Fraction of Cases Harboring M6P/IGF2R Mutations in Hepatocellular Carcinomas from the Atomic Bomb Survivors

The risk for hepatocellular carcinoma (HCC) development is significantly heightened in the atomic bomb survivors, but the mechanism is unclear. We have previously reported finding a radiation dose-dependent increase in HCCs with TP53 mutations from the survivors. We now show that, in the same HCC samples, the frequency of 3'-untranslated region (3'UTR) mutations in M6P/IGF2R, a candidate HCC tumor suppressor gene, decreases with dose (P = 0.0091), implying a radiation dose-dependent negative selection of cells harboring such mutations. The fact that they were in the 3'UTR implicates changes in transcript stability rather than in protein function as the mechanism. Moreover, these M6P/IGF2R 3'UTR mutations and the TP53 mutations detected previously were mutually exclusive in most of the tumors, suggesting two independent pathways to HCC development, with the TP53 pathway being more favored with increasing radiation dose than the M6P/IGF2R pathway. These results suggest that tumors attributable to radiation may be genotypically different from tumors of other etiologies and hence may provide a way of distinguishing radiation-induced cancers from "background" cancers--a shift from the current paradigm.

Clinicopathological significance of loss of heterozygosity and microsatellite instability in hepatocellular carcinoma in China

AIM: To determine the features of microsatellite alterations and their association with clinicopathological characteristics of hepatocellular carcinoma (HCC).

METHODS: Loss of heterozygosity (LOH) and microsatellite instability (MSI) of 55 microsatellite loci were detected with PCR-based microsatellite polymorphism analyses in tumors and corresponding noncancerous liver tissues of 56 surgically resected HCCs using the MegaBACE 500 automatic DNA analysis system.

RESULTS: LOH was found in 44 of 56 HCCs (78.6%) at one or several loci. Frequencies of LOH on 1p, 4q, 8p, 16q, and 17p were 69.6% (39/56), 71.4% (40/56), 66.1% (37/56), 66.1% (37/56), and 64.3% (36/56), respectively. MSI was found in 18 of 56 HCCs (32.1%) at one or several loci. Ten of fifty-six (17.9%) HCCs had MSI-H. Serum HBV infection, alpha-fetoprotein concentration, tumor size, cirrhosis, histological grade, tumor capsule, as well as tumor intrahepatic metastasis, might be correlated with LOH on certain chromosome regions.

CONCLUSION: Frequent microsatellite alterations exist in HCC. LOH, which represents a tumor suppressor gene pathway, plays a more important role in hepatocarcin-ogenesis. MSI, which represents a mismatch repair gene pathway, is a rare event during liver carcinogenesis. Furthermore, LOH on certain chromosome regions may be correlated with clinicopathological characteristics in HCC.

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Mutations in the ST7/RAY1/HELG locus rarely occur in primary colorectal, gastric, and hepatocellular carcinomas

Human cancers frequently show a loss of heterozygosity on chromosome 7q31, which indicates the existence of broad-range tumour-suppressor gene(s) at this locus. Truncating mutations in the ST7 gene at this locus are seen frequently in primary colon cancer and breast cancer cell lines. Therefore, the ST7 gene represents a novel candidate gene for the tumour suppressor at this locus. However, more recent studies have reported that ST7 mutations are infrequent or absent in primary cancer and cell lines. To ascertain the frequency of mutations of the ST7 gene in cancer cells, we examined mutations in the ST7 coding sequence in 48 colorectal, 48 gastric, and 48 hepatocellular carcinomas using polymerase chain reaction-single-strand conformational polymorphism and direct sequencing. We detected somatic mutations, which were located near the exon-intron junction in intron 8, in only three out of 144 cases. We conclude that mutations in the ST7 gene are rare in primary colorectal, gastric, and hepatocellular carcinomas.