Association of human herpes, papilloma and polyoma virus families with bladder cancer

Association of viral infection with bladder cancer: A systematic review and meta-analysis

BACKGROUND

Bladder cancer (BC) is the tenth most common cancer with the highest mortality rate. Since the etiological role of viral infection in the development of BC is less known, the aim of the present study was to examine the pooled prevalence and possible relationship between viral infection and BC.

METHODS

A systematic search of major online databases was conducted to investigate relevant studies. We estimated the pooled odds ratio (OR), 95 % confidence interval (CI), and heterogeneity for all studies by using meta-analysis and forest plots. All data were analyzed using Stata Software v.14.1.

RESULTS

We analyzed 87 articles (97 datasets), which included 59 case-control and 38 cross-sectional designs. The pooled prevalence of viral infection among BC patients was 17.59 % (95 % CI: 13.09-22.55 %; I2 = 96.34 %). Our subgroup analysis indicated that the pooled prevalence of human herpesvirus (HHV), papillomavirus (HPV), polyomavirus, and adenovirus was 33.67 %, 15.18 %, 7.46 %, and 30.14 %, respectively. We detected a significant relationship between viral infection and BC [summary OR 2.34 (95 % CI 1.56-3.51; I2 = 58.0 %)].

CONCLUSIONS

This possible association was exhibited for Epstein-Barr virus (EBV) and HPV. Our finding indicated that HPV and EBV infections with significant associations with BC can be considered as possible risk factors for BC. Although the specific molecular mechanism of the role of viruses in the development of BC has not been identified, persistent viral infection, oncogenic protein expression, apoptosis inhibition, cell cycle promotion, and disruption of signaling pathways in bladder tissue are possible pathways for the role of viruses in the development of BC.

Bladder cancer biomarkers: current approaches and future directions

Bladder cancer is a significant health concern worldwide, necessitating effective diagnostic and monitoring strategies. Biomarkers play a crucial role in the early detection, prognosis, and treatment of this disease. This review explores the current landscape of bladder cancer biomarkers, including FDA-approved molecular biomarkers and emerging ones. FDA-approved molecular biomarkers, such as BTA stat, BTA TRAK, and NMP22, have been instrumental in diagnosing and monitoring bladder cancer. These biomarkers are derived from urinary samples and are particularly useful due to their sensitivity and specificity. As we move forward, we should continue to seek ways to optimize our processes and outcomes, these markers remain seriously challenged in the detection of early bladder cancer due to their limited sensitivity and specificity. For instance, sensitivities of BTA stat in bladder tumor detection have varied between 40-72%, while its specificities vary from 29-96%. In the same way, 70% sensitivity and 80% specificity have been recorded for BTA TRAK, while 11-85.7% sensitivity and 77-100% specificity have been documented for NMP22 BladderChek. The given variations, especially the low sensitivity in the diagnosis of bladder cancer at an early stage call for the invention of better diagnostic systems. Moreover, different sample collection and handling procedures applied in different laboratories further contribute to inconsistent results obtained. Extracellular vesicles (EVs) and exosomes, which carry a vast number of proteins, are being considered as potential biomarkers. Although these markers show promise, challenges remain due to non-standardized isolation techniques and lack of reproducibility across studies. Moreover, the discovery of new potential biomarkers is ongoing. For instance, the UBC® Rapid test and UBC ELISA kit, the XPERT BC Monitor, BC UroMark, TaqMan® Arrays, Soluble FAS (sFAS), Bladder tumor fibronectin (BTF), and IGF2 and MAGE-A3 are among the newest biomarkers under investigation. In conclusion, while bladder cancer biomarkers have shown great promise, more research is needed to standardize the testing procedures and validate these biomarkers in a clinical setting. This will pave the way for more accurate and efficient diagnosis and monitoring of bladder cancer, ultimately improving patient outcomes.

PD-L1 Expression in Nonbacterial Chronic Cystitis and Bladder Cancer

INTRODUCTION AND HYPOTHESIS

The objective was to assess PD-L1 expression in nonbacterial chronic cystitis (NCC) and bladder cancer (BC).

METHODS

The present study included 20 NCC and 20 BC patients. The degree of inflammation of the bladder wall was assessed on slides stained with H&E. Viral pathogens (herpes simplex virus, Epstein-Barr virus, cytomegalovirus, and high-risk HPVs) were detected using real-time polymerase chain reaction analyses of the bladder specimens. Immunohistochemistry was performed to assess the PD-L1 expression in bladder tissue.

RESULTS

Expression of PD-L1 was detected in 40% of NCC patients and 85% of BC patients. Viral pathogens were found in 50% of NCC patients and 60% of BC patients, with EBV being the most common. In NCC patients the immune cell score correlated strongly with the degree of inflammatory infiltration of the bladder wall (r = 0.867, p < 0.001), the presence of lymphoid aggregates in the submucosa (r = 0.804, p < 0.001), koilocytosis (r = 0.620, p = 0.004), and the presence of viral pathogens (r = 0.784, p < 0.001). In BC patients the immune cell score correlated with the degree of inflammatory infiltration of the bladder wall (r = 0.534, p = 0.015) and the presence of viral pathogens (r = 0.626, p = 0.003), but not with the presence of lymphoid aggregates in the submucosa (r = 0.083, p = 0.729), and koilocytosis (r = 0.366, p = 0.112).

CONCLUSIONS

Expression of PD-L1 was detected in a cohort of NCC patients, although the PD-L1 positivity rate was lower than that in BC. Our results demonstrate that the degree of PD-L1 expression in bladder tissue is associated with the presence of viral infections and with the degree of inflammatory infiltration of the bladder wall in both NCC and BC.

Role of human papillomavirus and associated viruses in bladder cancer: An updated review

Bladder cancer (BC) is a complex disease affecting the urinary system and is regulated by several carcinogenic factors. Viral infection is one such factor that has attracted extensive attention in BC. Human papillomavirus (HPV) is the most common sexually transmitted infection, and although multiple researchers have explored the role of HPV in BC, a consensus has not yet been reached. In addition, HPV-associated viruses (e.g., human immunodeficiency virus, herpes simplex virus, BK virus, and JC virus) appear to be responsible for the occurrence and progression of BC. This study systematically reviews the relationship between HPV-associated viruses and BC to elucidate the role of these viruses in the onset and progression of BC. In addition, the study aims to provide a greater insight into the biology of HPV-associated viruses, and assess potential strategies for treating virus-induced BC. The study additionally focuses on the rapid development of oncolytic viruses that provide a potentially novel option for the treatment of BC.

Human papillomaviruses and bladder cancer risk: first report in south of Iran

Information regarding the possible carcinogenicity of human papillomaviruses (HPVs) in bladder tissue might pave the way for the prevention of bladder cancer through improving HPV vaccination of the at-risk population. To address this, this study was conducted to detect HPVs in bladder cancer tissues in the South of Iran. Bladder biopsy samples of 181 patients with bladder cancer were included in this study. The detection of HPVs was performed by nested PCR assay, targeting the L1 region of the genome, and sequencing. HPV was detected in 0.55% of the bladder cancer samples, while the non-cancerous bladder samples were negative for HPV. HPV genotype 6 was detected in this study. The HPV-positive patient was a 55-year-old man with papillary urothelial neoplasms of low malignant in stage Ta-T1. This patient was resident of Dayer city. Overall, HPV prevalence among patients with bladder cancer was not statistically associated with place of residency, gender, age, stage, and grade of the tumor (P value > 0.05). The presence of HPV is extremely rare in bladder cancer biopsy specimens in the south of Iran. Therefore, the results of our study rule out the possible role of HPVs in the etiology of bladder cancer. Due to the increasing air pollution in this region and high-risk jobs, and habits such as cigarette smoking and hookah smoking, the role of these factors alongside genetic factors seems more prominent than the role of HPVs in causing bladder cancer in the south of Iran.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13337-023-00819-w.

The association between human papillomavirus and bladder cancer: Evidence from meta-analysis and two-sample mendelian randomization

INTRODUCTION

Bladder cancer (BCa) is the 10th most common type of cancer worldwide, and human papillomavirus (HPV) is the most common sexually transmitted infection. However, the relationship between HPV infection and the risk of BCa is still controversial and inconclusive.

METHODS

This systematic review and meta-analysis were conducted following the PRISMA 2020 reporting guideline. This study searched four bibliographic databases with no language limitation. The databases included PubMed (Medline), EMBASE, Cochrane Library, and Web of Science. Studies evaluating the interaction between HPV infection and the risk of BCa from inception through May 21, 2022, were identified and used in this study. This study estimated the overall and type-specific HPV prevalence and 95% confidence intervals (95% CI) using Random Effects models and Fixed Effects models. In addition, this study also calculated the pooled odds ratio and pooled risk ratio with 95% CI to assess the effect of HPV infection on the risk and prognosis of bladder cancer. Two-sample mendelian randomization (MR) study using genetic variants associated with HPV E7 protein as instrumental variables were also conducted.

RESULTS

This study retrieved 80 articles from the four bibliographic databases. Of the total, 27 were case-control studies, and 53 were cross-sectional studies. The results showed that the prevalence of HPV was 16% (95% CI: 11%-21%) among the BCa patients, most of which were HPV-16 (5.99% [95% CI: 3.03%-9.69%]) and HPV-18 (3.68% [95% CI: 1.72%-6.16%]) subtypes. However, the study found that the prevalence varied by region, detection method, BCa histological type, and sample source. A significantly increased risk of BCa was shown for the positivity of overall HPV (odds ratio [OR], 3.35 [95% CI: 1.75-6.43]), which was also influenced by study region, detection method, histological type, and sample source. In addition, the study found that HPV infection was significantly associated with the progression of BCa (RR, 1.73 [95% CI: 1.39-2.15]). The two-sample MR analysis found that both HPV 16 and 18 E7 protein exposure increased the risk of BCa (HPV 16 E7 protein: IVW OR per unit increase in protein level = 1.0004 [95% CI: 1.0002-1.0006]; p = 0.0011; HPV 18 E7 protein: IVW OR per unit increase in protein level = 1.0003 [95% CI: 1.0001-1.0005]; p = 0.0089).

CONCLUSION

In conclusion, HPV may play a role in bladder carcinogenesis and contribute to a worse prognosis for patients with BCa. Therefore, it is necessary for people, especially men, to get vaccinated for HPV vaccination to prevent bladder cancer.

Human herpesvirus 6A and 6B and polyomavirus JC and BK infections in renal cell carcinoma and their relationship with p53, p16INK4a, Ki-67, and nuclear factor-kappa B expression

There are a limited number of studies regarding the involvement of viruses in the development and pathogenesis of renal cell carcinoma (RCC). In this study, we aimed to discover whether human herpesvirus 6A (HHV-6A) and 6B (HHV-6B) and human polyomavirus JC (JCV) and BK (BKV) are associated with RCC and the expression of p53, p16INK4a, Ki-67, and nuclear factor-κB (NF-κB) in patients with RCC. A total of 122 histologically confirmed RCC tissue specimens and 96 specimens of their corresponding peritumoral tissues were included in this prospective study. Nested PCR was performed to amplify viral DNA sequences. Restriction endonuclease analysis was carried out to discriminate between HHV-6A and HHV-6B. p53, p16INK4a, Ki-67, and NF-κB immunostaining data of the studied tissue specimens were available from our previous study. Statistical analysis was performed to demonstrate the potential associations. HHV-6B and JCV were detected in 10.7% and 13.9% of patients with RCC, respectively. We did not detect HHV-6A and BKV in any of RCC tissue specimens. Moreover, no association was found between either of these viruses and RCC. Our study revealed a significant association between HHV-6B and p53 overexpression. No other associations were found between cellular biomarkers p53, p16INK4a, Ki-67, and NF-κB and the studied viruses. The data of this study, though very limited, disprove the involvement of HHV-6A, HHV-6B, BKV, and JCV in the initiation or progression of RCC.

Bladder cancer and human papillomavirus association: a systematic review and meta-analysis

BACKGROUND

The possible association of human papillomavirus (HPV) and bladder cancer has been controversial. Older findings suggest a significant association between the virus and bladder cancer. The aim of this study was to evaluate the data from the last ten years to estimate the prevalence of the virus in bladder cancer patients and to assess the association between the virus and cancer.

METHOD

A search of major databases was conducted to retrieve published English language studies between January 2011 and March 2021. In the present study overall prevalence of the virus in bladder cancer patients was estimated along with the prevalence of subgroups. Also, the possible associations between the prevalence of the virus and bladder cancer and the possible impact of variables in the geographical area and the type of sample were measured by comprehensive meta-analysis software (V2.2, BIOSTAT).

RESULTS

Unlike previous studies, despite the relatively high prevalence of the virus [pooled prevalence: 14.3% (95% CI 8.9-22.2%)] no significant association was found between HPV and bladder cancer (OR 2.077, 95% CI 0.940-4.587). No significant association was found between geographical area (except Asia) and type of sample with bladder cancer.

CONCLUSIONS

Given the significant prevalence, despite the insignificance of the association between virus and cancer, it seems that more studies with case-control design are needed to elucidate this association.

High cytomegalovirus serology and subsequent COPD-related mortality: a longitudinal study

Background

Positive serology for cytomegalovirus (CMV) has been associated with all-cause mortality risk but its role in COPD mortality is unknown. The objective of the present study was to assess the relationship between CMV serology and COPD mortality.

Methods

We analysed data from 806 participants in the Tucson Epidemiological Study of Airway Obstructive Disease who, at enrolment, were aged 28–70 years and had completed lung function tests. We tested CMV serology in sera from enrolment and defined “high CMV serology” as being in the highest tertile. Vital status, date and cause of death were assessed through death certificates and/or linkage with the National Death Index up to January 2017. The association of CMV serology with all-cause and cause-specific mortality risk was tested in Cox models adjusted for age, sex, level of education, body mass index, smoking status and pack-years.

Results

High CMV serology was marginally associated with all-cause mortality (p=0.071) but the effect was inversely dependent on age, with the association being much stronger among participants <55 years than among participants ≥55 years at enrolment (p-value for CMV-by-age interaction <0.001). Compared with low CMV serology, high CMV serology was associated with mortality from COPD among all subjects (adjusted hazard ratio (HR) 2.38, 95% CI 1.11–5.08; p=0.025) and particularly in subjects <55 years old at enrolment (HR 5.40, 95% CI 1.73–16.9; p=0.004). Consistent with these results, high CMV serology also predicted mortality risk among subjects who already had airflow limitation at enrolment (HR 2.10, 95% CI 1.20–3.68; p=0.009).

Conclusions

We report a strong relationship between CMV serology and the risk of dying from COPD, and thus identify a novel risk factor for COPD mortality.

Using a 45-year longitudinal population-based cohort, it was demonstrated for the first time that high CMV serology predicts COPD mortality risk, particularly in younger subjects, identifying a novel and early risk factor for COPD mortalityhttp://bit.ly/32odP0Q

From trash to treasure: detecting unexpected contamination in unmapped NGS data

Background

Next Generation Sequencing (NGS) experiments produce millions of short sequences that, mapped to a reference genome, provide biological insights at genomic, transcriptomic and epigenomic level. Typically the amount of reads that correctly maps to the reference genome ranges between 70% and 90%, leaving in some cases a consistent fraction of unmapped sequences. This ’misalignment’ can be ascribed to low quality bases or sequence differences between the sample reads and the reference genome. Investigating the source of the unmapped reads is definitely important to better assess the quality of the whole experiment and to check for possible downstream or upstream ’contamination’ from exogenous nucleic acids.

Results

Here we propose DecontaMiner, a tool to unravel the presence of contaminating sequences among the unmapped reads. It uses a subtraction approach to identify bacteria, fungi and viruses genome contamination. DecontaMiner generates several output files to track all the processed reads, and to provide a complete report of their characteristics. The good quality matches on microorganism genomes are counted and compared among samples. DecontaMiner builds an offline HTML page containing summary statistics and plots. The latter are obtained using the state-of-the-art D3 javascript libraries. DecontaMiner has been mainly used to detect contamination in human RNA-Seq data. The software is freely available at http://www-labgtp.na.icar.cnr.it/decontaminer.

Conclusions

DecontaMiner is a tool designed and developed to investigate the presence of contaminating sequences in unmapped NGS data. It can suggest the presence of contaminating organisms in sequenced samples, that might derive either from laboratory contamination or from their biological source, and in both cases can be considered as worthy of further investigation and experimental validation. The novelty of DecontaMiner is mainly represented by its easy integration with the standard procedures of NGS data analysis, while providing a complete, reliable, and automatic pipeline.

Electronic supplementary material

The online version of this article (10.1186/s12859-019-2684-x) contains supplementary material, which is available to authorized users.

Human Herpesvirus 6 and Malignancy: A Review

In order to determine the role of human herpesvirus 6 (HHV-6) in human disease, several confounding factors, including methods of detection, types of controls, and the ubiquitous nature of the virus, must be considered. This is particularly problematic in the case of cancer, in which rates of detection vary greatly among studies. To determine what part, if any, HHV-6 plays in oncogenesis, a review of the literature was performed. There is evidence that HHV-6 is present in certain types of cancer; however, detection of the virus within tumor cells is insufficient for assigning a direct role of HHV-6 in tumorigenesis. Findings supportive of a causal role for a virus in cancer include presence of the virus in a large proportion of cases, presence of the virus in most tumor cells, and virus-induced in-vitro cell transformation. HHV-6, if not directly oncogenic, may act as a contributory factor that indirectly enhances tumor cell growth, in some cases by cooperation with other viruses. Another possibility is that HHV-6 may merely be an opportunistic virus that thrives in the immunodeficient tumor microenvironment. Although many studies have been carried out, it is still premature to definitively implicate HHV-6 in several human cancers. In some instances, evidence suggests that HHV-6 may cooperate with other viruses, including EBV, HPV, and HHV-8, in the development of cancer, and HHV-6 may have a role in such conditions as nodular sclerosis Hodgkin lymphoma, gastrointestinal cancer, glial tumors, and oral cancers. However, further studies will be required to determine the exact contributions of HHV-6 to tumorigenesis.

Defining the frequency of human papillomavirus and polyomavirus infection in urothelial bladder tumours

Given the contradictory nature of the literature regarding the role of human papillomaviruses and polyomaviruses in the pathogenesis of urothelial bladder cancer (UBC), we sought to investigate the frequency of their involvement in a large cohort of primary UBCs. DNA was extracted from 689 fresh-frozen UBC tissues and screened for the presence of high-risk human papillomavirus (HPV) types 16 and 18 and BKV/JCV genomic DNA by qPCR. In positive cases, viral identity was confirmed by Sanger sequencing and viral gene expression was analysed by RT-PCR or immunohistochemistry. All 689 UBCs were negative for HPV18. One UBC from a female patient with areas of squamous differentiation was positive for HPV16. The qPCR data indicated variable levels of polyomavirus in 49 UBCs. In the UBCs with low C_ts we were able to confirm that 23 were BKV and 6 were JCV by Sanger sequencing. Polyomavirus large T antigen expression was low but detectable in 70% of the sequencing-confirmed polyomavirus positive samples. Thus, in United Kingdom patients, the presence of HPV DNA sequences is extremely rare in UBC (<1% of cases). Polyomavirus DNA (predominantly BKV) is more common in UBC, but still only detectable in 7% of cases and in many of these cases at low copy number. We have performed the largest virus screening to date in UBC, finding that HPV16, HPV18 and HPyV are unlikely to be common causative agents in UBC.

Analysis of cervical lesions for presence of HSV-2 and HPV-16 and HPV-18 in Iranian patients by PCR

Objective Cervical cancer (CC) is one of the leading causes of deaths from cancer among women worldwide. Viral infections is now one of the known risk factors for CC. The aim of this study was to investigate the presence of herpes simplex virus type 2 (HSV-2), human papilloma virus types 16 (HPV-16) and human papilloma virus types 18 (HPV-18) in Iranian patients with CC using the polymerase chain reaction (PCR). Materials and methods This case-control study was conducted on a total of 45 patients with CC from Khatam-Al-Anbiya Hospital, Hamadan, Iran during 2014, and 30 samples from healthy subjects as controls. The presence of HSV-2 and HPV-16/18 DNA sequences was detected by PCR. Results Eight of CC patients (17.77%) had HPV-16/18 DNA and only one patient (2.22%) with HSV-2 was identified. These viruses were not detected in control cases. Among HPV-16/18 positive patients, 62.5% and 37.5% biopsies were positive for HPV-16 and HPV-18, respectively. On the other hand, only one case (2.22%) was positive for HPV-16/18, but HSV-2 and this co-infection was not detected in the control group. Conclusion Our results demonstrate that there was no direct molecular evidence to support a cofactor relationship between HSV-2 and HPV-16/18 in cervical malignancies. However, the results about HPV-16/18 was in accordance with previous studies.

Latent Kaposi's sarcoma-associated herpesvirus infection in bladder cancer cells promotes drug resistance by reducing reactive oxygen species

Kaposi's sarcoma-associated herpesvirus (KSHV) is the major etiologic agent of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. Recent studies have indicated that KSHV can be detected at high frequency in patient-derived bladder cancer tissue and might be associated with the pathogenesis of bladder cancer. Bladder cancer is the second most common cancer of the genitourinary tract, and it has a high rate of recurrence. Because drug resistance is closely related to chemotherapy failure and cancer recurrence, we investigated whether KSHV infection is associated with drug resistance of bladder cancer cells. Some KSHV-infected bladder cancer cell lines showed resistance to an anti-cancer drug, cisplatin, possibly as a result of down-regulation of reactive oxygen species. Additionally, drug resistance acquired from KSHV infection could partly be overcome by HDAC1 inhibitors. Taken together, the data suggest the possible role of KSHV in chemo-resistant bladder cancer, and indicate the therapeutic potential of HDAC1 inhibitors in drug-resistant bladder cancers associated with KSHV infection.

No Evidence of Human Polyomavirus 9, WU and KI DNA in Kidney and Urinary Bladder Tumour Tissue Samples

BACKGROUND/AIMS

The oncogenic potential of human polyomaviruses (HPyVs) has been proposed, but so far only Merkel cell carcinoma polyomavirus seems to be associated with a human tumour. The role of BK polyomavirus (BKPyV) in human tumourigenesis remains controversial. BKPyV establishes persistent infection in the urinary tract, and renal and bladder neoplasms have been studied extensively, but conflicting prevalence data are reported. KI, WU and HPyV9 were detected in urine samples suggesting that these viruses may also infect the urinary tract, but their presence in urinary tract tumours has not been studied. The aim of this work was to examine the prevalence of KIPyV, WUPyV, HPyV9 and BKPyV by PCR in renal and bladder neoplasms.

METHODS

A total of 190 formalin-fixed paraffin-embedded renal neoplasms, bladder cancer and kidney biopsy samples were analysed for the presence of BKPyV, KIPyV, WUPyV and HPyV9 DNA by real-time and nested PCR.

RESULTS

Amplifiable DNA was extracted from all the samples, but none of the studied viruses were detected in benign renal neoplasia (0/23), malignant renal tumours (0/89) or bladder cancer (0/76).

CONCLUSION

Our study did not find any evidence that BKPyV, KIPyV, WUPyV or HPyV9 are associated with bladder and renal tumours.

The role of Kaposi's sarcoma-associated herpesvirus infection in the proliferation of human bladder cancer cells

Existing evidence suggests a possible role of viruses in human bladder cancer development. Recently, Kaposi's sarcoma-associated herpesvirus (KSHV) was reported to be the most frequently detected virus in bladder cancer tissue from Croatian patients on screening with the Lawrence Livermore Microbial Detection Array. In the current study, to investigate the functional roles of KSHV in bladder cancer, five bladder cancer cell lines were infected with KSHV and their tumour progression-associated changes investigated. Four KSHV-infected bladder cancer cell lines were established; two invasive bladder cancer cell lines showed higher proliferation rates than uninfected cells. Additionally, these KSHV-infected invasive bladder cancer cells showed a greater number of colonies, which were also significantly larger than those of uninfected cells, in a soft agar colony formation assay. cDNA microarray analysis showed that various genes associated with cell proliferation and cancer development were upregulated in these KSHV-infected bladder cancer cells. Taken together, we suggest that KSHV infection affects the proliferation of a subset of invasive bladder cancer cells and may therefore play a role in their oncogenic progression. Further studies are required to elucidate the exact mechanism used by KSHV to promote bladder cancer progression.

Site of infections associated with human papillomavirus

INTRODUCTION

Human papillomavirus (HPV) is the most clinically common sexually transmitted infection due to its carcinogenic power and the high number of lesions that it causes at different sites of the human body.

MATERIAL AND METHODS

Genital tract organs are the most common sites where the virus can be found, but by increasing the sensitivity of diagnostic technique, it is possible to identify viral presence in different regions of the body such as the stomach, the lung, and the urinary tract. These findings break with the traditional HPV skin/genital tropic profile and demonstrate that the virus is capable of infecting a wide variety of cells, tissues, and organs or can, at least, survive in these areas. The widespread presence of the HPV in the human body, often in latent form, led us to consider the hypothesis that HPV latency may be associated with no disease.

CONCLUSION

This observation raises further questions about the possibility of the virus not causing disease in specific sites of the human body, but rather, behaving like a commensal/opportunistic microorganism.

Breast cancer: is there a viral connection?

Viruses are known to be etiologically related to several types of human cancer. In several published studies, viruses such as human mammary tumor virus, human papillomaviruses, Epstein-Barr virus, human cytomegalovirus, herpes simplex virus, and measles virus have been implicated in the pathogenesis of a subset of breast cancers (BC). However, these studies have produced conflicting results, causing considerable controversy. In this context, recent demonstration of elevated levels of mutagenic antiviral enzyme APOBEC3B in a majority of BCs is a highly significant development, as it provides a possible mechanism for development of large numbers of mutations (kataegis) that characterize many of the BCs. It has also provided further impetus for revaluating the role of viruses in the pathogenesis of BC.

Are human polyomaviruses co-factors for cancers induced by other oncoviruses?

Presently, 12 human polyomaviruses are known: BK polyomavirus (BKPyV), JCPyV, KIPyV, WUPyV, Merkel cell polyomavirus (MCPyV), HPyV6, HPyV7, Trichodysplasia spinulosa-associated polyomavirus, HPyV9, HPyV10, STLPyV and HPyV12. In addition, the non-human primate polyomavirus simian virus 40 (SV40) seems to circulate in the human population. MCPyV was first described in 2008 and is now accepted to be an etiological factor in about 80% of the rare but aggressive skin cancer Merkel cell carcinoma. SV40, BKPyV and JCPyV or part of their genomes can transform cells, including human cells, and induce tumours in animal models. Moreover, DNA and RNA sequences and proteins of these three viruses have been discovered in tumour tissue. Despite these observations, their role in cancer remains controversial. So far, an association between cancer and the other human polyomaviruses is lacking. Because human polyomavirus DNA has been found in a broad spectrum of cell types, simultaneous dwelling with other oncogenic viruses is possible. Co-infecting human polyomaviruses may therefore act as a co-factor in the development of cancer, including those induced by other oncoviruses. Reviewing studies that report co-infection with human polyomaviruses and other tumour viruses in cancer tissue fail to detect a clear link between co-infection and cancer. Directions for future studies to elaborate on a possible auxiliary role of human polyomaviruses in cancer are suggested, and the mechanisms by which human polyomaviruses may synergize with other viruses in oncogenic transformation are discussed.

Identification of genomic alterations in oesophageal squamous cell cancer

Oesophageal cancer is one of the most aggressive cancers and is the sixth leading cause of cancer death worldwide. Approximately 70% of global oesophageal cancer cases occur in China, with oesophageal squamous cell carcinoma (ESCC) being the histopathological form in the vast majority of cases (>90%). Currently, there are limited clinical approaches for the early diagnosis and treatment of ESCC, resulting in a 10% five-year survival rate for patients. However, the full repertoire of genomic events leading to the pathogenesis of ESCC remains unclear. Here we describe a comprehensive genomic analysis of 158 ESCC cases, as part of the International Cancer Genome Consortium research project. We conducted whole-genome sequencing in 17 ESCC cases and whole-exome sequencing in 71 cases, of which 53 cases, plus an additional 70 ESCC cases not used in the whole-genome and whole-exome sequencing, were subjected to array comparative genomic hybridization analysis. We identified eight significantly mutated genes, of which six are well known tumour-associated genes (TP53, RB1, CDKN2A, PIK3CA, NOTCH1, NFE2L2), and two have not previously been described in ESCC (ADAM29 and FAM135B). Notably, FAM135B is identified as a novel cancer-implicated gene as assayed for its ability to promote malignancy of ESCC cells. Additionally, MIR548K, a microRNA encoded in the amplified 11q13.3-13.4 region, is characterized as a novel oncogene, and functional assays demonstrate that MIR548K enhances malignant phenotypes of ESCC cells. Moreover, we have found that several important histone regulator genes (MLL2 (also called KMT2D), ASH1L, MLL3 (KMT2C), SETD1B, CREBBP and EP300) are frequently altered in ESCC. Pathway assessment reveals that somatic aberrations are mainly involved in the Wnt, cell cycle and Notch pathways. Genomic analyses suggest that ESCC and head and neck squamous cell carcinoma share some common pathogenic mechanisms, and ESCC development is associated with alcohol drinking. This study has explored novel biological markers and tumorigenic pathways that would greatly improve therapeutic strategies for ESCC.

Joint infectious causation of human cancers

Joint infectious causation of cancer has been accepted in a few well-studied instances, including Burkitt's lymphoma and liver cancer. In general, evidence for the involvement of parasitic agents in oncogenesis has expanded, and recent advances in the application of molecular techniques have revealed specific mechanisms by which host cells are transformed. Many parasites evolve to circumvent immune-mediated detection and destruction and to control critical aspects of host cell reproduction and survival: cell proliferation, apoptosis, adhesion, and immortalization. The host has evolved tight regulation of these cellular processes-the control of each represents a barrier to cancer. These barriers need to be compromised for oncogenesis to occur. The abrogation of a barrier is therefore referred to as an essential cause of cancer. Alternatively, some aspects of cellular regulation restrain but do not block oncogenesis. Relaxation of a restraint is therefore referred to as an exacerbating cause of cancer. In this chapter, we explore past and current evidence for joint infectious causation of cancer in the context of essential and exacerbating causes. We stress that discovery of joint infectious causation may provide great improvements in controlling cancer, particularly through the identification of many additional nonhuman targets for synergistic interventions for prevention and treatment.

Association of Kaposi’s sarcoma-associated herpesvirus (KSHV) with bladder cancer in Croatian patients

As the seventh most common human malignancy, bladder cancer represents a global health problem. In addition to well-recognized risk factors such as smoking and exposure to chemicals, various infectious agents have been implicated as cofactors in the pathogenesis of urothelial malignancies. The aim of the present study was to assess the possible association of viral infection and bladder cancer in Croatian patients. Biopsy specimens were collected from a total of 55 patients diagnosed with different stages of bladder cancer. Initial screening of DNA extracts for the presence of viruses on Lawrence Livermore Microbial Detection Array revealed Kaposi’s sarcoma-associated herpesvirus (KSHV) in each of three randomly chosen biopsy specimens. The prevalence of infection with KSHV among study population was then examined by KSHV-specific polymerase chain reaction (PCR) and immunoblotting. By nested PCR, KSHV DNA was detected in 55% of patients. KSHV, also known as human herpesvirus 8, is an infectious agent known to cause cancer. Its oncogenic potential is primarily recognized from its role in Kaposi’s sarcoma, but it has also been involved in pathogenesis of two lymphoproliferative disorders. A high prevalence of KSHV infection in our study indicates that KSHV may play a role in tumorigenesis of bladder cancer and warrants further studies.

Association between NQO1 C609T polymorphism and bladder cancer susceptibility: a systemic review and meta-analysis

There is growing evidence for the important roles of genetic factors in the host's susceptibility to bladder cancer. NAD(P)H:quinone oxidoreductase 1 (NQO1) is a cytosolic enzyme that catalyzes the two-electron reduction of quinoid compounds into hydroquinones. Since the NQO1 C609T polymorphism is linked to enzymatic activity of NQO1, it has also been hypothesized that NQO1 C609T polymorphism may affect the host's susceptibility to bladder cancer by modifying the exposure to carcinogens. There were many studies carried out to assess the association between NQO1 C609T polymorphism and bladder cancer risk, but they reported contradictory results. We conducted a meta-analysis to examine the hypotheses that the NQO1 C609T polymorphism modifies the risk of bladder cancer. Eleven case-control studies with 2,937 bladder cancer cases and 3,008 controls were included in the meta-analysis. Overall, there was no obvious association between NQO1 C609T polymorphism and bladder cancer susceptibility (for T versus C: odds ratio (OR) = 1.12, 95 % confidence interval (95 %CI) 0.99-1.26, P OR = 0.069; for TT versus CC: OR = 1.31, 95 %CI 0.95-1.81, P OR = 0.100; for TT/CT versus CC: OR = 1.06, 95 %CI 0.95-1.18, P OR = 0.304; for TT versus CT/CC: OR = 1.29, 95 %CI 0.94-1.77, P OR = 0.112). After adjusting for heterogeneity, meta-analysis of those left 10 studies showed that there was an obvious association between NQO1 C609T polymorphism and bladder cancer susceptibility (for T versus C: OR = 1.18, 95 %CI 1.06-1.31, P OR = 0.003; for TT versus CC: OR = 1.47, 95 %CI 1.14-1.90, P OR = 0.003; for TT/CT versus CC: OR = 1.16, 95 %CI 1.01-1.34, P OR = 0.036; for TT versus CT/CC: OR = 1.39, 95 %CI 1.10-1.75, P OR = 0.006). There was low risk of publication bias. Therefore, our meta-analysis suggests that NQO1 C609T polymorphism is associated with bladder cancer susceptibility.

Association between the cytotoxic T-lymphocyte antigen 4 +49A/G polymorphism and bladder cancer risk

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a potent immunoregulatory molecule that suppresses antitumor response by downregulating T cell activation. The most studied CTLA-4 +49A/G polymorphism has been associated with various cancers risks. However, little is known about the association between CTLA-4 +49A/G polymorphism and bladder cancer risk. A hospital-based case-control study was conducted in 300 patients with bladder cancer and 300 healthy controls matched with age and sex. The CTLA-4 +49A/G polymorphism was genotyped using polymerase chain reaction-restriction fragment length polymorphism. Patients with bladder cancer had a significantly lower frequency of CTLA-4 +49GG genotype [odds ratio (OR) = 0.44, 95 % confidence interval (CI) = 0.23, 0.85; P = 0.01] and G allele (OR = 0.73, 95 % CI = 0.56, 0.96; P = 0.02) than healthy controls. When stratifying by the stage, grade, and histological type of bladder cancer, we found no statistical association. This is the first study to highlight the significant association between CTLA-4 +49A/G polymorphism and bladder cancer risk. Additional studies are needed to confirm this finding.