Human cytomegalovirus infection alters PC3 prostate carcinoma cell adhesion to endothelial cells and extracellular matrix

PRADclass: Hybrid Gleason Grade-Informed Computational Strategy Identifies Consensus Biomarker Features Predictive of Aggressive Prostate Adenocarcinoma

BACKGROUND

Prostate adenocarcinoma (PRAD) is a common cancer diagnosis among men globally, yet large gaps in our knowledge persist with respect to the molecular bases of its progression and aggression. It is mostly indolent and slow-growing, but aggressive prostate cancers need to be recognized early for optimising treatment, with a view to reducing mortality.

METHODS

Based on TCGA transcriptomic data pertaining to PRAD and the associated clinical metadata, we determined the sample Gleason grade, and used it to execute: (i) Gleason-grade wise linear modeling, followed by five contrasts against controls and ten contrasts between grades; and (ii) Gleason-grade wise network modeling via weighted gene correlation network analysis (WGCNA). Candidate biomarkers were obtained from the above analysis and the consensus found. The consensus biomarkers were used as the feature space to train ML models for classifying a sample as benign, indolent or aggressive.

RESULTS

The statistical modeling yielded 77 Gleason grade-salient genes while the WGCNA algorithm yielded 1003 trait-specific key genes in grade-wise significant modules. Consensus analysis of the two approaches identified two genes in Grade-1 (SLC43A1 and PHGR1), 26 genes in Grade-4 (including LOC100128675, PPP1R3C, NECAB1, UBXN10, SERPINA5, CLU, RASL12, DGKG, FHL1, NCAM1, and CEND1), and seven genes in Grade-5 (CBX2, DPYS, FAM72B, SHCBP1, TMEM132A, TPX2, UBE2C). A RandomForest model trained and optimized on these 35 biomarkers for the ternary classification problem yielded a balanced accuracy ∼ 86% on external validation.

CONCLUSIONS

The consensus of multiple parallel computational strategies has unmasked candidate Gleason grade-specific biomarkers. PRADclass, a validated AI model featurizing these biomarkers achieved good performance, and could be trialed to predict the differentiation of prostate cancers. PRADclass is available for academic use at: https://apalania.shinyapps.io/pradclass (online) and https://github.com/apalania/pradclass (command-line interface).

Polyploid Giant Cancer Cells Generated from Human Cytomegalovirus-Infected Prostate Epithelial Cells

BACKGROUND

Prostate cancer is the most commonly diagnosed malignancy and the sixth leading cause of cancer death in men worldwide. Chromosomal instability (CIN) and polyploid giant cancer cells (PGCCs) have been considered predominant hallmarks of cancer. Recent clinical studies have proven the association of CIN, aneuploidy, and PGCCs with poor prognosis of prostate cancer (PCa). Evidence of HCMV transforming potential might indicate that HCMV may be involved in PCa.

METHODS

Herein, we underline the role of the high-risk HCMV-DB and -BL clinical strains in transforming prostate epithelial cells and assess the molecular and cellular oncogenic processes associated with PCa.

RESULTS

Oncogenesis parallels a sustained growth of "CMV-Transformed Prostate epithelial cells" or CTP cells that highly express Myc and EZH2, forming soft agar colonies and displaying stemness as well as mesenchymal features, hence promoting EMT as well as PGCCs and a spheroid appearance.

CONCLUSIONS

HCMV-induced Myc and EZH2 upregulation coupled with stemness and EMT traits in IE1-expressing CTP might highlight the potential role of HCMV in PCa development and encourage the use of anti-EZH2 and anti-HCMV in PCa treatment.

Human microbiome and prostate cancer development: current insights into the prevention and treatment

The huge communities of microorganisms that symbiotically colonize humans are recognized as significant players in health and disease. The human microbiome may influence prostate cancer development. To date, several studies have focused on the effect of prostate infections as well as the composition of the human microbiome in relation to prostate cancer risk. Current studies suggest that the microbiota of men with prostate cancer significantly differs from that of healthy men, demonstrating that certain bacteria could be associated with cancer development as well as altered responses to treatment. In healthy individuals, the microbiome plays a crucial role in the maintenance of homeostasis of body metabolism. Dysbiosis may contribute to the emergence of health problems, including malignancy through affecting systemic immune responses and creating systemic inflammation, and changing serum hormone levels. In this review, we discuss recent data about how the microbes colonizing different parts of the human body including urinary tract, gastrointestinal tract, oral cavity, and skin might affect the risk of developing prostate cancer. Furthermore, we discuss strategies to target the microbiome for risk assessment, prevention, and treatment of prostate cancer.

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.

How does cytomegalovirus factor into diseases of aging and vaccine responses, and by what mechanisms?

Cytomegalovirus (CMV) is an important pathogen for both clinical and population settings. There is a growing body of research implicating CMV in multiple health outcomes across the life course. At the same time, there is mounting evidence that individuals living in poverty are more likely to be exposed to CMV and more likely to experience many of the chronic conditions for which CMV has been implicated. Further research on the causal role of CMV for health and well-being is needed. However, the strong evidence implicating CMV in type 2 diabetes, autoimmunity, cancer, cardiovascular disease, vaccination, and age-related alterations in immune function warrants clinical and public health action. This imperative is even higher among individuals living in socioeconomically disadvantaged settings and those exposed to high levels of chronic psychosocial stress.

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.

Anti-inflammatory drugs and uterine cervical cancer cells: Antineoplastic effect of meclofenamic acid

Uterine cervical cancer (UCC) is one of the main causes of cancer-associated mortality in women. Inflammation has been identified as an important component of this neoplasia; in this context, anti-inflammatory drugs represent possible prophylactic and/or therapeutic alternatives that require further investigation. Anti-inflammatory drugs are common and each one may exhibit a different antineoplastic effect. As a result, the present study investigated different anti-inflammatory models of UCC in vitro and in vivo. Celecoxib, sulindac, nimesulide, dexamethasone, meclofenamic acid, flufenamic acid and mefenamic acid were tested in UCC HeLa, VIPA, INBL and SiHa cell lines. The cytotoxicity of the drugs was evaluated in vitro. Celecoxib, sulindac, nimesulide, mefenamic acid and flufenamic acid presented with slight to moderate toxicity (10-40% of cell death corresponding to 100 µM) in certain cell lines, while meclofenamic acid exhibited significant cytotoxicity in all essayed cell lines (50-90% of cell death corresponding to 100 µM). The meclofenamic acid was tested in murine models (immunodeficient and immunocompetent) of UCC, which manifested a significant reduction in tumor growth and increased mouse survival. It was demonstrated that of the evaluated anti-inflammatory drugs, meclofenamic acid was the most cytotoxic, with a significant antitumor effect in murine models. Subsequent studies are necessary to evaluate the clinical utility of this drug.

Identification of Pathogen Signatures in Prostate Cancer Using RNA-seq

Infections of the prostate by bacteria, human papillomaviruses, polyomaviruses, xenotropic murine leukemia virus (MLV)-related gammaretroviruses, human cytomegaloviruses and other members of the herpesvirus family have been widely researched. However, many studies have yielded conflicting and controversial results. In this study, we systematically investigated the transcriptomes of human prostate samples for the unique genomic signatures of these pathogens using RNA-seq data from both western and Chinese patients. Human and nonhuman RNA-seq reads were mapped onto human and pathogen reference genomes respectively using alignment tools Bowtie and BLAT. Pathogen infections and integrations were analyzed in adherence with the standards from published studies. Among the nine pathogens (Propionibacterium acnes, HPV, HCMV, XMRV, BKV, JCV, SV40, EBV, and HBV) we analyzed, Propionibacterium acnes genes were detected in all prostate tumor samples and all adjacent samples, but not in prostate samples from healthy individuals. SV40, HCMV, EBV and low-risk HPVs transcripts were detected in one tumor sample and two adjacent samples from Chinese prostate cancer patients, but not in any samples of western prostate cancer patients; XMRV, BKV and JCV sequences were not identified in our work; HBV, as a negative control, was absent from any samples. Moreover, no pathogen integration was identified in our study. While further validation is required, our analysis provides evidence of Propionibacterium acnes infections in human prostate tumors. Noted differences in viral infections across ethnicity remain to be confirmed with other large prostate cancer data sets. The effects of bacterial and viral infections and their contributions to prostate cancer pathogenesis will require continuous research on associated pathogens.

Human Cytomegalovirus interleukin-10 promotes proliferation and migration of MCF-7 breast cancer cells

Breast cancer is the most common malignancy affecting women worldwide. While a small fraction of breast cancers have a hereditary component, environmental and behavioral factors also impact the development of cancer. Human cytomegalovirus (HCMV) is a member of the Herpesviridae family that is widespread in the general population and has been linked to several forms of cancer. While HCMV DNA has been found in some breast cancer tissue specimens, we wanted to investigate whether a secreted viral cytokine might have an effect on cancerous or even pre-cancerous cells. HCMV encodes an ortholog of the human cellular cytokine interleukin-10 (IL-10). The HCMV UL111A gene product is cmvIL-10, which has 27% sequence identity to IL-10 and binds the cellular IL-10 receptor (IL-10R) to induce downstream cell signaling. We found that MCF-7 human breast cancer cells express IL-10R and that exposure to cmvIL-10 results in enhanced proliferation and increased chemotaxis of MCF-7 cells. PCR arrays revealed that treatment with cmvIL-10 alters expression of cell adhesion molecules and increases MMP gene expression. In particular, MMP-10 gene expression was found to be significantly up-regulated and this correlated with an increase in cell-associated MMP-10 protein produced by MCF-7 cells exposed to cmvIL-10. These results suggest that the presence of cmvIL-10 in the tumor microenvironment could contribute to the development of more invasive tumors.

cmvIL-10 stimulates the invasive potential of MDA-MB-231 breast cancer cells

Cancer is the result of unregulated cell growth that leads to tumor formation, and in many cases, metastases. Although there are several risk factors associated with cancer, one area that remains poorly understood is the impact of infectious disease. Human cytomegalovirus (HCMV) is a member of the herpesvirus family that is highly prevalent in the population. HCMV usually causes clinical disease only in immune compromised individuals, but recent evidence suggests that HCMV may be strongly associated with some forms of cancer, particularly glioblastoma and breast cancer. We investigated the possibility that cmvIL-10, a viral cytokine with homology to human IL-10 that is secreted from infected cells, could act in a paracrine manner to alter the tumor microenvironment, induce cell signaling, and increase the invasive potential of cancer cells. We found that human MDA-MB-231 breast cancer cells express the IL-10 receptor and that exposure to cmvIL-10 results in activation of Stat3, a transcription factor strongly associated with enhanced metastatic potential and chemo-resistance. In addition, cmvIL-10 stimulated an increase in DNA synthesis and cell proliferation, protected MDA-MB-231 cells from etoposide-induced apoptosis, and also greatly enhanced chemotaxis toward epidermal growth factor (EGF). These results suggest a significant and wide-ranging role for cmvIL-10 in the progression of breast cancer and could have broad implications for the diagnosis and treatment of cancer in HCMV-positive patients.

Human cytomegalovirus infection enhances NF-κB/p65 signaling in inflammatory breast cancer patients

Human Cytomegalovirus (HCMV) is an endemic herpes virus that re-emerges in cancer patients enhancing oncogenic potential. Recent studies have shown that HCMV infection is associated with certain types of cancer morbidity such as glioblastoma. Although HCMV has been detected in breast cancer tissues, its role, if any, in the etiology of specific forms of breast cancer has not been investigated. In the present study we investigated the presence of HCMV infection in inflammatory breast cancer (IBC), a rapidly progressing form of breast cancer characterized by specific molecular signature. We screened for anti-CMV IgG antibodies in peripheral blood of 49 non-IBC invasive ductal carcinoma (IDC) and 28 IBC patients. In addition, we screened for HCMV-DNA in postsurgical cancer and non-cancer breast tissues of non-IBC and IBC patients. We also tested whether HCMV infection can modulate the expression and activation of transcriptional factor NF-κB/p65, a hallmark of IBC. Our results reveal that IBC patients are characterized by a statistically significant increase in HCMV IgG antibody titers compared to non-IBC patients. HCMV-DNA was significantly detected in cancer tissues than in the adjacent non-carcinoma tissues of IBC and IDC, and IBC cancer tissues were significantly more infected with HCMV-DNA compared to IDC. Further, HCMV sequence analysis detected different HCMV strains in IBC patients tissues, but not in the IDC specimens. Moreover, HCMV-infected IBC cancer tissues were found to be enhanced in NF-κB/p65 signaling compared to non-IBC patients. The present results demonstrated a correlation between HCMV infection and IBC. Etiology and causality of HCMV infection with IBC now needs to be rigorously examined.

Role of infectious agents in the carcinogenesis of brain and head and neck cancers

This review concentrates on tumours that are anatomically localised in head and neck regions. Brain cancers and head and neck cancers together account for more than 873,000 cases annually worldwide, with an increasing incidence each year. With poor survival rates at late stages, brain and head and neck cancers represent serious conditions. Carcinogenesis is a multi-step process and the role of infectious agents in this progression has not been fully identified. A major problem with such research is that the role of many infectious agents may be underestimated due to the lack of or inconsistency in experimental data obtained globally. In the case of brain cancer, no infection has been accepted as directly oncogenic, although a number of viruses and parasites are associated with the malignancy. Our analysis of the literature showed the presence of human cytomegalovirus (HCMV) in distinct types of brain tumour, namely glioblastoma multiforme (GBM) and medulloblastoma. In particular, there are reports of viral protein in up to 100% of GBM specimens. Several epidemiological studies reported associations of brain cancer and toxoplasmosis seropositivity. In head and neck cancers, there is a distinct correlation between Epstein-Barr virus (EBV) and nasopharyngeal carcinoma (NPC). Considering that almost every undifferentiated NPC is EBV-positive, virus titer levels can be measured to screen high-risk populations. In addition there is an apparent association between human papilloma virus (HPV) and head and neck squamous cell carcinoma (HNSCC); specifically, 26% of HNSCCs are positive for HPV. HPV type 16 was the most common type detected in HNSCCs (90%) and its dominance is even greater than that reported in cervical carcinoma. Although there are many studies showing an association of infectious agents with cancer, with various levels of involvement and either a direct or indirect causative effect, there is a scarcity of articles covering the role of infection in carcinogenesis of brain and head and neck cancers. We review recent studies on the infectious origin of these cancers and present our current understanding of carcinogenic mechanisms, thereby providing possible novel approaches to cancer treatment.

Viruses and metabolism: alterations of glucose and glutamine metabolism mediated by human cytomegalovirus

Recent studies of human cytomegalovirus (HCMV) infection have demonstrated that the virus significantly alters cellular metabolism, especially the utilization of glucose and glutamine. Glucose is not broken down by the tricarboxylic acid (TCA) cycle in infected cells; instead, it is used biosynthetically for fatty acid synthesis for membranes needed during the infection. In this chapter, we discuss the possibility that HCMV integrates its mechanisms for manipulating cellular signaling and stress responses to induce novel adipocyte-like differentiation in order to alter metabolism so that glucose can be used synthetically, that is, for fatty acids and lipids. This process diverts glucose from the TCA cycle and requires induction of enzymes that can convert glutamine to α-ketoglutarate to maintain the TCA cycle (anaplerosis). We discuss data proposing that the anaplerotic utilization of glutamine may be mediated, in part, by c-Myc activation, and the induction of adipocyte-like differentiation may result from the activation of the endoplasmic reticulum resident kinase PKR-like ER kinase. These alterations in metabolism during HCMV infection are comparable to those seen in many tumor cells. Indeed, the alterations in cellular signaling, stress responses, and metabolism that have been characterized could result in unexpected pathogenesis, potentially implicating HCMV as an agent or subtle cofactor in many maladies. Better understanding of HCMV's effects on cell signaling and metabolism will show how HCMV-mediated modifications of cellular processes relate to pathogenesis and will suggest novel avenues for antiviral therapy.

Viral effects on metabolism: changes in glucose and glutamine utilization during human cytomegalovirus infection

Human cytomegalovirus (HCMV) infection causes dramatic alterations of intermediary metabolism, similar to those found in tumor cells. In infected cells, glucose carbon is not completely broken down by the tricarboxylic acid (TCA) cycle for energy; instead, it is used biosynthetically. This process requires increased glucose uptake, increased glycolysis and the diversion of glucose carbon, in the form of citrate, from the TCA cycle for use in HCMV-induced fatty acid biosynthesis. The diversion of citrate from the TCA cycle (cataplerosis) requires induction of enzymes to promote glutaminolysis, the conversion of glutamine to α-ketoglutarate to maintain the TCA cycle (anaplerosis) and ATP production. Such changes could result in heretofore uncharacterized pathogenesis, potentially implicating HCMV as a subtle cofactor in many maladies, including oncogenesis. Recognition of the effects of HCMV, and other viruses, on host cell metabolism will provide new understanding of viral pathogenesis and novel avenues for antiviral therapy.

Is HCMV a tumor promoter?

Human cytomegalovirus (HCMV) is a beta-herpesvirus that causes persistent infection in humans and can cause severe disease in fetuses and immunocompromised individuals. Although HCMV is not currently causally implicated in human cancer, emerging evidence suggests that HCMV infection and expression may be specifically associated with human malignancies including malignant glioma, colon, and prostate cancer. In addition, multiple investigators have demonstrated that HCMV can dysregulate signaling pathways involved in initiation and promotion of malignancy, including tumor suppressor, mitogenic signaling, inflammatory, immune regulation, angiogenesis and invasion, and epigenetic mechanisms. This review highlights some of the recent evidence that HCMV might play a role in modulating the tumor microenvironment as well as in the initiation and promotion of tumor cells themselves.

Tumor cells infected with oncolytic influenza A virus prime natural killer cells for lysis of resistant tumor cells

Tumor resistance to lysis by resting natural killer (NK) cells may be overcome by priming of NK cells with cytokines or by binding of NK activating receptors to ligands expressed on target cells. In this study, major histocompatibility complex class I (MHC-I)-negative LNCaP and MHC-I-positive DU145 cells were infected with genetically modified influenza A virus lacking the non-structural gene 1 (NS1 IAV). The cells were used to investigate the influence of NS1 IAV infection on NK cell lysis of tumor cells as well as to prime NK cells for lysis of LNCaP and DU145 cells. While LNCaP cells infected with DeltaNS1 IAV showed enhanced lysis when compared with mock-infected cells (93% +/- 1.47 vs. 52% +/- 0.74), both mock-infected and DeltaNS1 IAV-infected DU145 cells were resistant to NK cell lysis. Moreover, NK cells primed with DeltaNS1 IAV-infected LNCaP/DU145 cells effectively lysed resistant DU145 and sensitive LNCaP cells to a greater extent than NK cells primed with mock-infected LNCaP/DU145 or non-primed NK cells. Also, NK cell priming with DeltaNS1 IAV-infected tumor cells enhanced extracellular signal-regulated kinase phosphorylation and increased granule release in NK cells. The increased granule release was specifically mediated by NKp46, which eventually potentiated NK cells primed with DeltaNS1 IAV-infected tumor cells to overcome the inhibitory effects posed by MHC-I expression on DU145 cells. These findings show that in addition to direct lytic activity of NK cells, DeltaNS1 IAV may influence anti-tumoral responses by priming NK cells.

Neoplasia: the second decade

This issue marks the end of the 10-year anniversary of Neoplasia where we have seen exciting growth in both number of submitted and published articles in Neoplasia. Neoplasia was first published in 1999. During the past 10 years, Neoplasia has dynamically adapted to the needs of the cancer research community as technologies have advanced. Neoplasia is currently providing access to articles through PubMed Central to continue to facilitate rapid broad-based dissemination of published findings to the scientific community through an Open Access model. This has in part helped Neoplasia to achieve an improved impact factor this past year, demonstrating that the manuscripts published by Neoplasia are of great interest to the overall cancer research community. This past year, Neoplasia received a record number of articles for review and has had a 21% increase in the number of published articles.

Resistance to cytarabine induces the up-regulation of NKG2D ligands and enhances natural killer cell lysis of leukemic cells

Prolonged treatment of leukemic cells with chemotherapeutic agents frequently results in development of drug resistance. Moreover, selection of drug-resistant cell populations may be associated with changes in malignant properties such as proliferation rate, invasiveness, and immunogenicity. In the present study, the sensitivity of cytarabine (1-beta-D-arabinofuranosylcytosine, araC)-resistant and parental human leukemic cell lines (T-lymphoid H9 and acute T-lymphoblastic leukemia Molt-4) to natural killer (NK) cell-mediated killing was investigated. The results obtained demonstrate that araC-resistant H9 and Molt-4 (H9(r)ARAC(100) and Molt-4(r)ARAC(100)) cell lines are more sensitive to NK cell-mediated lysis than their respective parental cell lines. This increased sensitivity was associated with a higher surface expression of ligands for the NK cell-activating receptor NKG2D, notably UL16 binding protein-2 (ULBP-2) and ULBP-3 in H9(r)ARAC(100) and Molt-4(r)ARAC(100) cell lines. Blocking ULBP-2 and ULBP-3 or NKG2D with monoclonal antibody completely abrogated NK cell lysis. Constitutive phosphorylated extracellular signal-regulated kinase (ERK) but not pAKT was higher in araC-resistant cells than in parental cell lines. Inhibition of ERK using ERK inhibitor PD98059 decreased both ULBP-2/ULBP-3 expression and NK cell cytotoxicity. Furthermore, overexpression of constitutively active ERK in H9 parental cells resulted in increased ULBP-2/ULBP-3 expression and enhanced NK cell lysis. These results demonstrate that increased sensitivity of araC-resistant leukemic cells to NK cell lysis is caused by higher NKG2D ligand expression, resulting from more active ERK signaling pathway.

The story of human cytomegalovirus and cancer: increasing evidence and open questions

Although human cytomegalovirus (HCMV) is generally not regarded to be an oncogenic virus, HCMV infection has been implicated in malignant diseases from different cancer entities. On the basis of our experimental findings, we developed the concept of "oncomodulation" to better explain the role of HCMV in cancer. Oncomodulation means that HCMV infects tumor cells and increases their malignancy. By this concept, HCMV was proposed to be a therapeutic target in a fraction of cancer patients. However, the clinical relevance of HCMV-induced oncomodulation remains to be clarified. One central question that has to be definitively answered is if HCMV establishes persistent virus replication in tumor cells or not. In our eyes, recent clinical findings from different groups in glioblastoma patients and especially the detection of a correlation between the numbers of HCMV-infected glioblastoma cells and tumor stage (malignancy) strongly increase the evidence that HCMV may exert oncomodulatory effects. Here, we summarize the currently available knowledge about the molecular mechanisms that may contribute to oncomodulation by HCMV as well as the clinical findings that suggest that a fraction of tumors from different entities is indeed infected with HCMV.

Androgen-dependent activation of human cytomegalovirus major immediate-early promoter in prostate cancer cells

BACKGROUND

Human cytomegalovirus (HCMV) major immediate early (MIE) promoter, which is involved in viral reactivation, is specifically activated by androgen in LNCaP prostate cancer cells.

METHODS

Androgen-dependent transcriptional activities of the HCMV MIE promoter were measured by transient transfection assay. Expression levels of genes related to protein kinase A (PKA)-signaling pathway was measured by RT-PCR.

RESULTS

Activation of the HCMV MIE promoter by androgen results from an increase in PKA activities. The expression level of PKA catalytic (C) subunit beta transcript variant 2 (PKA-C beta 2) was decreased by serum deprivation and was increased by R1881 treatment, in a pattern similar to changes of the HCMV MIE promoter activities. Furthermore the exogenous expression of PKA-C beta 2 strongly activated the HCMV MIE promoter, indicating that regulation of the PKA-C beta 2 expression might be a direct upstream factor in the HCMV MIE promoter regulation by androgen in LNCaP cells.

CONCLUSIONS

The data elucidated the mechanisms by which androgen activates PKA in androgen-dependent prostate cancer cells, resulting in activation of the HCMV MIE promoter. These results support the possibility that activation of the HCMV MIE promoter by androgen in the prostate could cause the productive infection, which might contribute to oncomodulation in prostate cancers.

Rotavirus replication in intestinal cells differentially regulates integrin expression by a phosphatidylinositol 3-kinase-dependent pathway, resulting in increased cell adhesion and virus yield

Changes in the interactions between intestinal cells and their surrounding environment during virus infection have not been well documented. The growth and survival of intestinal epithelial cells, the main targets of rotavirus infection, are largely dependent on the interaction of cell surface integrins with the extracellular matrix. In this study, we detected alterations in cellular integrin expression following rotavirus infection, identified the signaling components required, and analyzed the subsequent effects on cell binding to the matrix component collagen. After rotavirus infection of intestinal cells, expression of alpha2beta1 and beta2 integrins was up-regulated, whereas that of alphaVbeta3, alphaVbeta5, and alpha5beta1 integrins, if present, was down-regulated. This differential regulation of integrins was reflected at the transcriptional level. It was unrelated to the use of integrins as rotavirus receptors, as both integrin-using and integrin-independent viruses induced integrin regulation. Using pharmacological agents that inhibit kinase activity, integrin regulation was shown to be dependent on phosphatidylinositol 3-kinase (PI3K) but independent of the activities of the mitogen-activated protein kinases p38 and ERK1/2, and cyclooxygenase-2. Replication-dependent activation of the PI3K/Akt pathway was observed following infection of intestinal and nonintestinal cell lines. Rotavirus activation of PI3K was important for regulation of alpha2beta1 expression. Blockade of integrin regulation by PI3K inhibition led to decreased adherence of infected intestinal cells to collagen and a concomitant decrease in virus titer. These findings indicate that rotavirus-induced PI3K activation causes regulation of integrin expression in intestinal cells, leading to prolonged adherence of infected cells to collagen and increased virus production.