Latent infection of human cytomegalovirus is associated with the development of gastric cancer

Investigation of Epstein-Barr virus, Cytomegalovirus, Human herpesvirus 6, and Polyoma viruses (JC virus, BK virus) among Gastric cancer patients: A cross sectional study

Background and Aims

Gastric cancer is a significant global issue with a high death rate. This malignancy could be associated with several viral agents such as EBV, CMV, HHV-6, JCV, and BKV.

Objective

Evaluation of EBV, CMV, HHV-6 ,and JCV, BKV frequency among gastric cancer patients.

Methods

In this cross-sectional study, a total number of 60 gastric cancer specimens (32 male, 28 female) were retrieved from the pathology lab. Formalin-fixed paraffin-embedded tissue was used for molecular testing. DNA was extracted from samples, according to protocol, and used for PCR reaction. Polymerase chain reactions were used to assess CMV, EBV, HHV-6, JCV, and BKV frequency.

Results and Conclusion

The mean age of the participants was 61 years and 53.3% (32) of the participants were Male. A total number of 5 samples (8.34%) were infected with viral agents. Four male gastric samples were infected with EBV (6.67%) and only one female sample contained the BKV genome (1.67%). Totally 8.34% of the samples were infected with EBV and BKV. The CMV, HHV-6, and JCV genome was not detected in the samples. In conclusion, the presence of two viral agents including EBV and BKV among male and female samples respectively, and the genome of other viruses were not detected.

The role of gastric microecological dysbiosis in gastric carcinogenesis

Gastric cancer (GC) is the leading cause of cancer-related death worldwide, and reducing its mortality has become an urgent public health issue. Gastric microecological dysbiosis (including bacteria, fungi, viruses, acid suppressants, antibiotics, and surgery) can lead to gastric immune dysfunction or result in a decrease in dominant bacteria and an increase in the number and virulence of pathogenic microorganisms, which in turn promotes development of GC. This review analyzes the relationship between gastric microecological dysbiosis and GC, elucidates dynamic alterations of the microbiota in Correa's cascade, and identifies certain specific microorganisms as potential biomarkers of GC to aid in early screening and diagnosis. In addition, this paper presents the potential of gastric microbiota transplantation as a therapeutic target for gastric cancer, providing a new direction for future research in this field.

Microbiota and metabolites alterations in proximal and distal gastric cancer patients

Background

Globally, gastric cancer is the third most common cancer and the third leading cause of cancer death. Proximal and distal gastric cancers have distinct clinical and biological behaviors. The microbial composition and metabolic differences in proximal and distal gastric cancers have not been fully studied and discussed.

Methods

In this study, the gastric microbiome of 13 proximal gastric cancer tissues, 16 distal gastric cancer tissues, and their matched non-tumor tissues were characterized using 16S rRNA amplicon sequencing. Additionally, 10 proximal gastric cancer tissues, 11 distal gastric cancer tissues, and their matched non-tumor tissues were assessed by untargeted metabolomics.

Results

There was no significant difference in microbial diversity and richness between the proximal and distal gastric cancer tissues. At the genus level, the abundance of Rikenellaceae_RC9_gut_group, Porphyromonas, Catonella, Proteus, Oribacterium, and Moraxella were significantly increased in Proximal T, whereas that of Methylobacterium_Methylorubrum was significantly increased in Distal T. The untargeted metabolomics analysis revealed 30 discriminative metabolites between Distal T and Distal N. In contrast, there were only 4 discriminative metabolites between Proximal T and Proximal N. In distal gastric cancer, different metabolites were scattered through multiple pathway, including the sphingolipid signaling pathway, arginine biosynthesis, protein digestion and absorption, alanine, aspartate and, glutamate metabolism, etc.In proximal gastric cancer, differential microbial metabolites were mainly related to hormone metabolism.

Conclusion

Methylobacterium-Methylorubrum was significantly increased in Distal T, positively correlated with cancer-promoting metabolites, and negatively correlated with cancer-inhibiting metabolites. Rikenellaceae_RC_gut_group was significantly increased in Proximal T and positively correlated with cancer-promoting metabolites. Further studies regarding the functions of the above-mentioned microorganisms and metabolites were warranted as the results may reveal the different mechanisms underlying the occurrence and development of proximal and distal gastric cancers and provide a basis for future treatments.

Importance

First, the differences in microbial composition and metabolites between the proximal and distal gastric cancers were described; then, the correlation between microbiota and metabolites was preliminarily discussed. These microbes and metabolites deserve further investigations as they may reveal the different mechanisms involved in the occurrence and development of proximal and distal gastric cancers and provide a basis for future treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03650-x.

Identifying Potential miRNA Biomarkers for Gastric Cancer Diagnosis Using Machine Learning Variable Selection Approach

Aim: This study aimed to accurately identification of potential miRNAs for gastric cancer (GC) diagnosis at the early stages of the disease. Methods: We used GSE106817 data with 2,566 miRNAs to train the machine learning models. We used the Boruta machine learning variable selection approach to identify the strong miRNAs associated with GC in the training sample. We then validated the prediction models in the independent sample GSE113486 data. Finally, an ontological analysis was done on identified miRNAs to eliciting the relevant relationships. Results: Of those 2,874 patients in the training the model, there were 115 (4%) patients with GC. Boruta identified 30 miRNAs as potential biomarkers for GC diagnosis and hsa-miR-1343-3p was at the highest ranking. All of the machine learning algorithms showed that using hsa-miR-1343-3p as a biomarker, GC can be predicted with very high precision (AUC; 100%, sensitivity; 100%, specificity; 100% ROC; 100%, Kappa; 100) using with the cut-off point of 8.2 for hsa-miR-1343-3p. Also, ontological analysis of 30 identified miRNAs approved their strong relationship with cancer associated genes and molecular events. Conclusion: The hsa-miR-1343-3p could be introduced as a valuable target for studies on the GC diagnosis using reliable biomarkers.

Associations Between Gastric Cancer Risk and Virus Infection Other Than Epstein-Barr Virus: A Systematic Review and Meta-analysis Based on Epidemiological Studies

INTRODUCTION

Besides Helicobacter pylori and Epstein-Barr virus, other viruses might play potential roles in gastric carcinogenesis. This systematic review and meta-analysis was conducted to compare the prevalence of the viruses between gastric cancer (GC) and any controls.

METHODS

Comprehensive literature was searched up to January 25, 2019, and search was updated on April 6, 2020. The studies that compared the prevalence of viruses other than Epstein-Barr virus between GC and healthy or nonmalignant controls were eligible. Stata 12.0 software was used for heterogeneity tests and meta-analyses. Meanwhile, subgroup analysis, sensitivity analysis, and publication bias evaluation were performed where applicable. The power (1-β) was estimated by the PASS 11 software for each individual study.

RESULTS

A total of 41 eligible studies were included, concerning 11 kinds of viruses. Prevalence were significantly higher in GC for hepatitis B virus (odds ratio [OR] = 1.39, 95% confidence interval [CI] 1.11-1.75), human cytomegalovirus (OR = 2.25, 95% CI 1.14-4.43), human papillomavirus (HPV) (OR = 1.63, 95% CI 1.05-2.54), and John Cunningham virus (OR = 2.52, 95% CI 1.26-5.04). In subgroup analyses, HPV-16 infection was significantly associated with GC (OR = 2.42, 95% CI 1.00-5.83).

DISCUSSION

This study demonstrated that hepatitis B virus, human cytomegalovirus, HPV, and John Cunningham virus were more prevalent in GC. However, the causal relationship between their infection and risk of GC remains inconclusive, and further investigations are required.

The silent presence of Mycoplasma hominis in patients with prostate cancer

BACKGROUND

Mycoplasma hominis, an opportunistic pathogen in human genitourinary tract, can cause chronic infection in the prostate. Intracellular survival of M. hominis leads to a prolonged presence in the host cells that can affect the cell's biological cycle. In the present study, we aimed to evaluate the frequency of M. hominis DNA in prostate tissue of Iranian patients with prostate cancer (PCa) in comparison to a control group with benign prostatic hyperplasia (BPH).

METHODS

This research was a retrospective case-control study using 61 archived formalin-fixed paraffin-embedded (FFPE) blocks of prostate tissue from patients with PCa and 70 FFPE blocks of patients with BPH. Real-time PCR, targeting two different genes, 16S rRNA and yidC, in the M. hominis genome was performed for all specimens.

RESULTS

Out of 61 blocks of prostate biopsy from patients with PCa, eight samples (13%) were positive for M. hominis, while the bacterium was not detected in any of the 70 blocks of patients with BPH (P value, 0.002).

CONCLUSIONS

The high frequency of M. hominis in patients with PCa likely shows a hidden role of the organism in prostate cancer during its chronic, apparently silent and asymptomatic colonization in prostate.

Patients with Helicobacter pylori-positive gastric cancer with human cytomegalovirus infection have a low tendency of advanced lymphatic metastasis in a Chinese population

Recognized as a group I carcinogen for gastric cancer (GC) and a factor involved in the development of GC, Helicobacter pylori serves a major part in GC research. However, most studies have focused on H. pylori itself, ignoring the complicated pathogenic microbiological environment of GC and neglecting the synergistic or antagonistic effects of H. pylori with other pathogenic microorganisms. Increasing evidence has revealed that the human cytomegalovirus (HCMV) is present in several types of tumors and serves an important role in the neoplastic process of certain human malignant tumors, including GC. The aim of the present study was to explore the role of HCMV and H. pylori co-infection in GC. HCMV and H. pylori infection was analyzed in paired gastric tumor and peri-tumoral tissues from 134 (98 male and 36 female) patients using PCR. The results revealed that a total of 74 (55.2%) patients had H. pylori infection, 58 patients (43.3%) had HCMV infection, and 34 (25.4%) patients had both HCMV and H. pylori infection. Univariate and multivariate analyses demonstrated that H. pylori infection was independently associated with advanced lymphatic metastasis [P=0.007; odds ratio (OR)=3.51]. Furthermore, compared with HCMV-/H. pylori -, neither HCMV+/H. pylori - nor HCMV+/H. pylori + were associated with metastasis, but HCMV-/H. pylori + co-infection status was an independent risk factor for advanced lymphatic metastasis (P=0.005; OR=6.00). In conclusion, GC co-infected with HCMV and H. pylori exhibited a low tendency of lymph node metastasis. HCMV may interact with H. pylori to inhibit the process of lymphatic metastasis, and the mechanism requires further investigation.

The Human Cytomegalovirus US31 Gene Predicts Favorable Survival and Regulates the Tumor Microenvironment in Gastric Cancer

Human cytomegalovirus (HCMV) is an oncogenic virus associated with tumorigenesis. Our previous study revealed that the HCMV US31 gene interacted with NF-κB2 and mediated inflammation through macrophages. However, there are few reports on the role of US31 in gastric cancer (GC). The aim of this study was to investigate the expression of the US31 gene in GC tissue and assess its role in the occurrence and development of GC. US31 expression in 573 cancer tissues was analyzed using immunohistochemistry. Results showed that US31 was significantly associated with tumor size (P = 0.005) and distant metastasis (P < 0.001). Higher US31 expression indicated better overall survival in GC patients. Overexpression of US31 significantly inhibited the proliferation, migration, and invasion of GC cells in vitro (P < 0.05). Furthermore, expression levels of CD4, CD66b, and CD166 were positively correlated with US31, suggesting that it was involved in regulating the tumor immune microenvironment of GC. RNA sequencing, along with quantitative real-time polymerase chain reaction, confirmed that the expression of US31 promoted immune activation and secretion of inflammatory cytokines. Overall, US31 inhibited the malignant phenotype and regulated tumor immune cell infiltration in GC; these results suggest that US31 could be a potential prognostic factor for GC and may open the door for a new immunotherapy strategy.

Role of Bacterial and Viral Pathogens in Gastric Carcinogenesis

Simple Summary

Stomach cancer is one of the most common cancers in the world, with over one million new cases diagnosed in 2020. Despite recent advances in cancer treatments, gastric cancer remains a serious clinical problem. This disease is tightly linked to gastric infections with Helicobacter pylori bacterium, Epstein–Barr virus, and some other less known pathogens. Here, we discuss how gastric pathogens induce tumorigenic changes in the stomach.

Abstract

Gastric cancer (GC) is one of the deadliest malignancies worldwide. In contrast to many other tumor types, gastric carcinogenesis is tightly linked to infectious events. Infections with Helicobacter pylori (H. pylori) bacterium and Epstein–Barr virus (EBV) are the two most investigated risk factors for GC. These pathogens infect more than half of the world’s population. Fortunately, only a small fraction of infected individuals develops GC, suggesting high complexity of tumorigenic processes in the human stomach. Recent studies suggest that the multifaceted interplay between microbial, environmental, and host genetic factors underlies gastric tumorigenesis. Many aspects of these interactions still remain unclear. In this review, we update on recent discoveries, focusing on the roles of various gastric pathogens and gastric microbiome in tumorigenesis.

Human cytomegalovirus protein UL136 activates the IL-6/STAT3 signal through MiR-138 and MiR-34c in gastric cancer cells

BACKGROUND

Accumulating evidences have indicated that human cytomegalovirus (HCMV) may link to multiple human malignancies, including gastric cancer. However, the mechanistic role of HCMV in GC remains largely unknown.

METHODS

In this study, we have successfully established HCMV latent gene UL-136-expressing gastric cancer cells. We measured cell proliferation of GC cells, MNK-45 and SGC-7901, with stable UL136 expression or paired control cells by using CCK-8 assay. We have showed that GC cells with stable UL136 expression had a rapid cell growth. Furthermore, our data from matrigel-coated transwell assay have demonstrated that UL136 expressing GC cells showed an enhanced invasion capacity compared to control cells. Furthermore, ectopic expression of UL136 inhibits tumorigenicity in an animal model.

RESULTS

We observed that IL-6/STAT3 was stimulated by UL136 overexpression. Also, miR-138 is consistently up-regulated, while miR-34 down-regulated by UL136 in either MNK-45 or SGC-7901 cells. Our mechanistic study showed that treatment of miR-138 mimics in MNK-45 cells indeed inhibited SIRT1 expression to increase phosphorylation level of STAT3. MiR-34c suppressed expression of IL6R through direct binding with the putative 3'UTR binding sites of this gene. UL136 regulate IL6/STAT3 pathway, at least in part, through down-regulation of miR-34c in GC cells.

CONCLUSION

In conclusion, HCMV-induced miR-34c or miR-138 involves in the activation of IL6/STAT3 signaling. Targeting the IL6-STAT3 axis or miRNAs represent a promising strategy for HCMV-related tumor formation.

Overexpression of the human cytomegalovirus UL111A is correlated with favorable survival of patients with gastric cancer and changes T-cell infiltration and suppresses carcinogenesis

Purpose

We previously found that human cytomegalovirus (HCMV) infection is associated with gastric cancer (GC) development. UL111A plays a role during HCMV productive or latent infection. However, UL111A expression profiles in GC tissues and their relationship with this disease are unknown.

Methods

PCR and nested RT-PCR were performed to verify UL111A expression in 71 GC tissues and its transcripts in 16 UL111A-positive GC samples. UL111A expression levels in GC patients were evaluated by immunohistochemistry on a tissue microarray for 620 GC patients. The correlations among UL111A expression levels, clinicopathological characteristics, and prognosis were analyzed. Further, the effects of overexpression of latency-associated viral interleukin-10 (LAcmvIL-10) and cmvIL-10 on GC cell proliferation, colony formation, migration, and invasion were assessed.

Results

The UL111A detection rate in GC tissues was 32.4% (23/71) and that of its mRNA expression was 68.75% (11/16). High expression of UL111A was also related to better overall and disease-free survival in GC patients. GC patients with TNM II/III stage expressing higher UL111A levels might benefit from adjuvant chemotherapy (ACT) after surgery. Moreover, high UL111A expression was also associated with increased CD4+ , CD8+ T-lymphocyte and Foxp3+ T-cell infiltration. In vitro assays further demonstrated that LAcmvIL-10 and cmvIL-10 overexpression inhibits GC cell line proliferation, colony formation, migration, and invasion.

Conclusions

High UL111A expression changes the number of infiltrating T cells and is associated with favorable survival. Therefore, UL111A could be used as an independent prognostic biomarker and might be a potential therapeutic target for GC.

Electronic supplementary material

The online version of this article (10.1007/s00432-019-03092-x) contains supplementary material, which is available to authorized users.

Functional Profile of Human Cytomegalovirus Genes and Their Associated Diseases: A Review

The human cytomegalovirus (HCMV), whose genome is 235 ± 1.9 kbp long, is a common herpesvirus. However, the functions of many of its genes are still unknown. HCMV is closely associated with various human diseases and infects 60-90% of the global population. It can infect various human cells, including fibroblasts, epithelial cells, endothelial cells, smooth muscle cells, and monocytes. Although HCMV infection is generally asymptomatic and causes subtle clinical symptoms, it can generate a robust immune response and establish a latent infection in immunocompromised individuals, including those with AIDS, transplant recipients, and developing fetuses. Currently available antivirals approved for the treatment of HCMV-associated diseases are limited by dose-limiting toxicity and the emergence of resistance; however, vaccines and immunoglobulins are unavailable. In this review, we have summarized the recent literature on 43 newly identified HCMV genes. We have described their novel functions on the viral replication cycle, latency, and host immune evasion. Further, we have discussed HCMV-associated diseases and current therapeutic targets. Our review may provide a foundational basis for studies aiming to prevent and develop targeted therapies for HCMV-associated diseases.

Multiple infections by EBV, HCMV and Helicobacter pylori are highly frequent in patients with chronic gastritis and gastric cancer from Southwest Mexico: An observational study

The chronic inflammation and damage to the gastric epithelium induced by Helicobacter pylori (H. pylori) are the main risk factors for gastric cancer development. Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) induce chronic inflammation and have been found in gastric tumors. The objectives this observational study were to determine the frequency of multiple infections by Helicobacter pylori, Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) and to relate the infection by EBV and HCMV with H. pylori vacA/cagA genotypes in patients with chronic gastritis or gastric cancer. DNA from H. pylori, EBV and HCMV was detected by PCR in biopsies from 106 Mexican patients with chronic gastritis and 32 from gastric cancer. The cagA status and the vacA genotypes of H. pylori were determined by PCR. In chronic gastritis and gastric cancer EBV was found in 69.8% and 87.5%, HCMV in 52.8% and 53.1%, and H. pylori in 48.1% and 40.6%, respectively. In chronic gastritis, 53% of H. pylori patients were EBV and 33% were both EBV/HCMV; in gastric cancer, 92.3% of H. pylori-infected individuals were EBV and 46.1% were EVB/HCMV. All the intestinal- and mixed-type tumors and the 83.3% of diffuse-type tumors were EBV. No significant differences were found between single infections or coinfections with the diagnosis or the cancer type. The H. pylori genotypes were not related to EBV or HCMV infection. The frequency of dual infections by H. pylori, EBV and HCMV is higher in patients from southwest Mexico than other populations. It is likely that these pathogens act synergistically to induce inflammation and gastric cancer.

A viral map of gastrointestinal cancers

Cancers of the gastrointestinal tract (GIT) are expected to account for approximately 20% of all cancers in 2017. Apart from their high incidence, GIT cancers show high mortality rates, placing these malignancies among the most prominent public health issues of our time. Cancers of the GIT are the result of a complex interplay between host genetic factors and environmental factors and frequently arise in the context of a continued active inflammatory response. Several tumor viruses are able to elicit such chronic inflammatory responses. In fact, several viruses have an impact on GIT tumor initiation and progression, as well as on patients' response to therapy and prognosis, through direct and indirect mechanisms. In this review, we have gathered information on different viruses' rates of infection, viral-driven specific carcinogenesis mechanisms and viral-related impact on the prognosis of cancers of the GIT (specifically in organs that have an interface with the environment - esophagus, stomach, intestines and anus). Overall, while some viral infections show a strong causal relation with specific gastrointestinal cancers, these represent a relatively small fraction of GIT malignancies. Other types of cancer, like Esophageal Squamous Cell Carcinoma, require further studies to confirm the carcinogenic role of some viral agents.

Does Regular Exercise Counter T Cell Immunosenescence Reducing the Risk of Developing Cancer and Promoting Successful Treatment of Malignancies?

Moderate intensity aerobic exercise training or regular physical activity is beneficial for immune function. For example, some evidence shows that individuals with an active lifestyle exhibit stronger immune responses to vaccination compared to those who are inactive. Encouragingly, poor vaccine responses, which are characteristic of an ageing immune system, can be improved by single or repeated bouts of exercise. In addition, exercise-induced lymphocytosis, and the subsequent lymphocytopenia, is thought to facilitate immune surveillance, whereby lymphocytes search tissues for antigens derived from viruses, bacteria, or malignant transformation. Aerobic exercise training is anti-inflammatory and is linked to lower morbidity and mortality from diseases with infectious, immunological, and inflammatory aetiologies, including cancer. These observations have led to the view that aerobic exercise training might counter the age-associated decline in immune function, referred to as immunosenescence. This article summarises the aspects of immune function that are sensitive to exercise-induced change, highlighting the observations which have stimulated the idea that aerobic exercise training could prevent, limit, or delay immunosenescence, perhaps even restoring aged immune profiles. These potential exercise-induced anti-immunosenescence effects might contribute to the mechanisms by which active lifestyles reduce the risk of developing cancer and perhaps benefit patients undergoing cancer therapy.

Association of Human Cytomegalovirus with Hodgkin’s Disease and Non-Hodgkin’s lymphomas

Background and Objective:

The human cytomegalovirus (HCMV) can persist lifelong as a latent infection and may result in a series of disorders. Associations with both Hodgkin’s disease and non-Hodgkin´s lymphomas have been reported. Expression of the unique long (UL)138 gene of HCMV is linked with the viral latency phase while that of the immediate-early (IE)1 gene is typical of the viral replication phase in patients. This study conducted to determine the prevalence of CMV latent infection in histological tissue samples from patients with Hodgkin’s and Non-Hodgkin´s lymphomas.

Material and Methods:

A cross sectional study was carried out with a total of 50 paraffin embedded tissues blocks, including 25 samples for Hodgkin’s disease and 25 samples for non-Hodgkin´s lymphomas. After RNA extraction and cDNA preparation, detection of IE1 mRNA was conducted by RT-PCR and identification of mRNA UL138 was achieved by nested PCR.

Results:

Among 25 cases of Non-Hodgkin´s lymphoma, 5 (20%) were positive for UL 138 and 1 (4%) for both IE1 and UL 138. Among 25 cases of Hodgkin only 1 (4%) was positive for UL 138 and all were negative for IE1

Conclusion:

A relatively high 20% rate of expression of UL 138 was detected in patients with non-Hodgkin´s lymphoma, so that latent CMV infection may play a role in development of the disease.

Human cytomegalovirus detection in gastric cancer and its possible association with lymphatic metastasis

Increasing evidence suggests that human cytomegalovirus (HCMV) is associated with many human malignancies. However, its prevalence in gastric cancer (GC) and clinical association remain unknown. HCMV IgG and IgM antibodies in the sera of 80 GC patients and 80 healthy controls were detected using a microparticle enzyme immunoassay. The prevalence of HCMV UL47, UL55, UL56, and UL77 genes among 102 GC tumor tissues and adjacent normal specimens was measured by polymerase chain reaction (PCR) or nested PCR. Quantitative real-time PCR (Q-PCR) was used to determine viral load. Virus localization in neoplastic tissues was determined by immunohistochemistry. No significant difference of HCMV IgG and IgM seropositivity was found between GC patients and the healthy group. However, the overall HCMV DNA positivity rate was significantly higher in GC cancerous tissue compared with in paired normal tissue (P<0.01). HCMV infection was mainly localized in the tumorous epithelium. Q-PCR in HCMV-positive specimens indicated that the viral copy number was notably higher in GC tissues than in adjacent normal specimens (P<0.001). Clinical statistical analysis indicated that HCMV load in GC tumor tissue was positively associated with lymphatic metastasis (P=0.043), the area under the receiver operating characteristic (ROC) curve was 0.6638. Our data clearly provide the prevalence of HCMV in GC patients. We conclude that HCMV infection in malignant tissues might be associated with carcinogenesis or progression of GC and possibly relates to lymphatic metastasis.

The cytomegalovirus protein UL138 induces apoptosis of gastric cancer cells by binding to heat shock protein 70

It has been hypothesized that human cytomegalovirus (HCMV) could act as a tumor promoter and play an “oncomodulatory” role in the neoplastic process of several human malignancies. However, we demonstrate for the first time that UL138, a HCMV latency-associated gene, could act as a tumor inhibitor in gastric cancer (GC). The expression of UL138 is down-regulated in HCMV positive gastric adenocarcinoma tissues, especially in poorly or none differentiated tumors. Overexpression of UL138 in several human GC cell lines inhibits cell viability and induces apoptosis, in association with the reduction of an anti-apoptotic Bcl-2 protein and the induction of cleaved caspase-3 and caspase-9. Moreover, protein array analysis reveals that UL138 interacts with a chaperone protein, heat shock protein 70 (HSP70). This interaction is confirmed by immunoprecipitation and immunostaining in situ in GC cell lines. In addition, this UL138-mediated cancer cell death could efficiently lead to suppression of human tumor growth in a xenograft animal model of GC. In conclusion, these results uncover a previously unknown role of the cytomegalovirus protein UL138 in inducing GC cells apoptosis, which might imply a general mechanism that viral proteins inhibit cancer growth in interactions with both chaperones and apoptosis-related proteins. Our findings might provide a potential target for new therapeutic strategies of GC treatment.

Clinical significance of expression of human cytomegalovirus genes in colorectal cancer

AIM: To detect the expression of human cytomegalovirus (HCMV) infection related genes in colorectal cancer tissues and their relationship with clinicopathological features of colorectal cancer.

METHODS: HCMV UL135, UL136, US28 and IE1 gene expression in colorectal cancer tissues and corresponding adjacent normal samples was determined by nested PCR. The accuracy of nested PCR results was confirmed by SDS-PAGE and DNA sequencing analysis. The relationship between HCMV gene expression and clinicopathological features of patients with colorectal cancer was also analyzed. Statistical methods included Chi-square test or Fisher exact probability test and logistic regression model analysis.

RESULTS: The results of nested PCR were confirmed to be reliable. The positive expression rates of UL135, UL136 and US28 genes in the colorectal cancer tissues were 35.0%, 15.0% and 60.0%, respectively; and they were 16.7%, 1.7% and 18.3% in corresponding normal tissues. The positive expression rates of UL135, UL136 and US28 genes in the colorectal cancer tissues were significantly higher than those in corresponding normal tissues (P < 0.05 for all). There was no significant difference in the positive expression rate of IE1 between colorectal cancer tissues (13.3%) and corresponding normal tissues (10%). The expression of UL135, ULi136 and IE1 genes had no significant association with gender, age, tumor size, histological differentiation, metastasis or Dukes stage. The expression of US28 had a significant association with lymph node metastasis and Dukes stage, but not with age, gender, tumor size or histological differentiation.

CONCLUSION: UL135, UL136 and US28 gene expression is more often found in colorectal cancer tissues than in corresponding normal tissues, among which US28 has a significant association with lymph node metastasis and Dukes stage of colorectal cancer. Our findings suggest that some HCMV genes may play a role in the occurrence and development of colorectal cancer.

Clinical relevance between human cytomegalovirus infection and colorectal cancer

AIM: To investigate the clinical relevance between human cytomegalovirus (HCMV) infection and colorectal cancer.

METHODS: The specific immunoglobulin G (IgG) and IgM antibodies against HCMV in sera of colorectal cancer patients (n = 60), patients with colorectal polyps (n = 60) and health controls (n = 60) were detected by chemiluminescence immunoassay. HCMV infection in colorectal cancer tissues and corresponding adjacent normal samples were determined through the detection of UL138 gene by nested PCR and in situ hybridization. The relationships between HCMV infection and clinical features of colorectal cancer were analyzed.

RESULTS: The positive rates of HCMV-IgG in the colorectal cancer group, colorectal polyps group and healthy control group were 95.0% (57/60), 98.3% (59/60), and 96.7% (58/60), respectively; the positive rates of HCMV-IgM were 5.0% (3/60), 1.7% (1/60) and 1.7% (1/60), respectively. There were no statistically significant differences in the positive rates of HCMV-IgG and HCMV-IgM among the three groups. However, there was a significant difference between colorectal cancer tissues and corresponding normal tissues in HCMV-UL138 detection. The positive rates of HCMV-UL138 were 65.6% (19/32) and 62.5% (20/32) in colorectal cancer tissues samples, and 12.5% (4/32) and 9.4% (3/32) in corresponding normal tissues as revealed by nested PCR detection and in situ hybridization, respectively. HCMV infection had no significant association with age, gender, location of mass, tumor size, histological differentiation, metastasis or Dukes stage.

CONCLUSION: HCMV infection is associated with colorectal cancer. Compared with corresponding normal epithelium, the neoplastic epithelium may be preferentially infected by the HCMV. This research suggests that HCMV infection may play a role in the occurrence and development of colorectal cancer.