Analysis of prostate tissue DNA for the presence of human papillomavirus by polymerase chain reaction, cloning, and automated sequencing

Does Human Papillomavirus Play a Causative Role in Prostate Cancer? A Systematic Review Using Bradford Hill's Criteria

Globally, prostate cancer is the fifth most common cause of cancer-related death among men, and metastatic castration-resistant prostate cancer has a high cancer-related mortality rate. However, the aetiology of this disease is not yet fully understood. While human papillomavirus (HPV) has been associated with several types of cancer, including cervical, anal, and oropharyngeal cancers, studies investigating the relationship between HPV and prostate cancer have shown mixed results. This systematic review aimed to evaluate the causative association between HPV and prostate cancer using Bradford Hill's criteria. A comprehensive search of PubMed was conducted, and 60 out of 482 studies were included in the review. The included studies were evaluated based on nine Bradford Hill criteria, and information on the identification and transmission of the virus and potential oncogenic mechanisms was also extracted. The strength of association criterion was not met, and other criteria, such as consistency and coherence, were not fulfilled. However, biological plausibility was supported, and potential oncogenic mechanisms were identified. While some studies have reported the presence of HPV in prostate cancer tissues, the overall quality of evidence remains low, and the association between HPV and prostate cancer is weak. Nevertheless, the prostate is a potential reservoir for the transmission of HPV, and the HPV E6 and E7 oncoproteins and inflammation are likely to be involved in any oncogenic mechanisms. Further studies with a higher level of evidence are needed to establish a definitive link between HPV and prostate cancer.

Evidence for a causal role by human papillomaviruses in prostate cancer - a systematic review

It is hypothesised that high risk for cancer human papillomaviruses (HPVs) have a causal role in prostate cancer.

In 26 case control studies, high risk HPVs have been identified in benign and prostate cancers. High risk HPVs were identified in 325 (22.6%) of 1284 prostate cancers and in 113 (8.6%) of 1313 normal or benign prostate controls (p = 0.001).

High risk HPVs of the same type have been identified in both normal and benign prostate tissues prior to the development of HPV positive prostate cancer. High risk HPVs can be associated with inflammatory prostatitis leading to benign prostate hyperplasia and later prostate cancer. Normal human prostate epithelial cells can be immortalised by experimental exposure to HPVs. HPVs are probably sexually transmitted.

The role of HPVs in prostate cancer is complex and differs from HPVs associated cervical cancer. HPV infections may initiate prostate oncogenesis directly and influence oncogenesis indirectly via APOBEC enzymes. HPVs may collaborate with other pathogens in prostate oncogenesis.

Although HPVs are only one of many pathogens that have been identified in prostate cancer, they are the only infectious pathogen which can be prevented by vaccination.

A causal role for HPVs in prostate cancer is highly likely.

Association between human papillomavirus and prostate cancer: A meta-analysis

Observational studies have suggested an association between human papillomavirus (HPV) infection and the risk of prostate cancer (PCa). However, the association between HPV infection and the risk of PCa remains unclear. The aim of the present meta-analysis study was to investigate whether HPV serves a role in increasing the risk of PCa. Relevant previous studies up to May 2015 were searched in PubMed, Web of Science, Cochrane library, Chinese National Knowledge Infrastructure, China Wan Fang database and China Biomedical Literature Database. A random-effects model or fixed-effects model was employed to determine odds ratios (ORs) with 95% confidence intervals (CIs), when appropriate. Heterogeneity was evaluated using Q and I2 statistical analysis. A total of 24 case-control studies involving 971 patients and 1,085 controls were investigated to estimate the association between HPV infection and PCa risk. The pooled estimate for OR was 2.27 (95% CI, 1.40-3.69). Stratified pooled analyses were subsequently performed according to the HPV detection methods, geographical regions, publication years and types of tissue. Sensitivity analysis based on various exclusion criteria maintained the significance with respect to PCa individually. Little evidence of publication bias was observed. The meta-analysis suggested that HPV infection is associated with increasing risk of PCa, which indicated a potential pathogenetic link between HPV and PCa.

Worldwide Prevalence of Human Papillomavirus and Relative Risk of Prostate Cancer: A Meta-analysis

Despite the increasing number of studies conducted recently to evaluate the association between HPV infections and the risk of prostate cancer, the results remain inconclusive. Furthermore, the prevalence and distribution of overall and individual HPV types worldwide in prostate cancer has not been reported until now. Therefore, we estimated the prevalence of HPV in prostate cancer by pooling data of 46 studies with 4919 prostate cancer cases, taking into account the heterogeneity of major related parameters, including study region, specimen type, HPV DNA source, detection method, publication calendar period and Gleason score. Moreover, we tested the association of HPV infections with prostate cancer risks by a meta-analysis of 26 tissue-based case-control studies. We found that the prevalence of HPV infection was 18.93% (95% CI = 17.84-20.05%) in prostate cancer cases, and most of which were high-risk HPV types (17.73%, 95% CI = 16.52-18.99%). The prevalence varied by region, PCR primers used, publication calendar period and Gleason score. Our study also showed a significantly increased risk of prostate cancer with the positivity of overall HPV detected in prostate tissues (OR = 1.79, 95% CI = 1.29-2.49) and revealed the geographic variation of association strength (P < 0.001). In conclusion, HPV infections may contribute to the risk of prostate cancer.

Human papillomavirus 16 infection as a potential risk factor for prostate cancer: an adaptive meta-analysis

OBJECTIVES

Although an expert review published in 2013 concluded that an association between human papillomavirus (HPV) infection and prostate cancer (PCa) risk had not yet been firmly established, a 2011 systematic review of 14 articles revealed an increased prevalence of HPV-16 DNA in PCa tissues. Another meta-analysis of the related articles is needed to evaluate the potential link between HPV infection and PCa risk.

METHODS

A snowballing search strategy was applied to the previously cited articles in the above-mentioned expert review and systematic review. Additional articles selected for this meta-analysis should fulfill all following inclusion criteria: (a) evaluation of detected HPV-16 DNA in tissue samples and the PCa risk and (b) report of the HPV-16 prevalence in both cancer and control tissues. Estimated summary odds ratios (sOR) with 95% confidence intervals (CI) were calculated using fixed effect or random-effect models.

RESULTS

Hand searching identified 16 new articles. The sOR of the total 30 articles indicated a significant HPV-16 infection-related increase in the PCa risk (sOR, 1.851; 95% CI, 1.353 to 2.532, I(2)=37.82%).

CONCLUSIONS

These facts provide additional supportive evidence for a causal role of HPV-16 infection in prostate carcinogenesis. As the PCa incidence rates have increased rapidly in Asian countries, including Korea, during the last several decades, further studies of HPV-related PCa carcinogenesis may be necessary.

Thirty years of research on infection and prostate cancer: no conclusive evidence for a link. A systematic review

BACKGROUND

The potential role of genitourinary infection in the etiology of prostate cancer (CaP) has been extensively investigated for 30 years. Two basic approaches have been used: tissue-based methods (polymerase chain reaction, immunohistochemistry, and in situ hybridization) and serologic assays (enzyme-linked immunosorbent assay, immunofluorescence, etc.). The objective of this review was to answer the question of whether infection of the male genitourinary tract may have a role in the etiology of CaP.

MATERIALS AND METHODS

We have carried out a systematic review of the evidence that was published in the MEDLINE/PubMed database until December 2011. The search terms included "prostate cancer," "infection," and the explicit names of the various infectious agents. Additional studies were identified using a reference search. A total of 74 papers were included in the review, which cover the following infectious agents: human papillomavirus, cytomegalovirus, herpes simplex virus, Epstein-Barr virus, human herpesvirus, BK virus, JC virus, chlamydia, mycoplasma, ureaplasma, trichomonas, neisseria, treponema, Propionibacterium acnes, xenotropic murine leukemia virus-related virus and Candida albicans.

RESULTS

Despite the variable study designs and methodological approaches that were used, most of the pathogens that were studied were unlikely to be directly involved in prostate carcinogenesis.

CONCLUSIONS

The role of infection in the etiology of CaP has yet to be determined despite 30 years of research efforts. A discovery of an infectious agent that is associated with CaP would be of great medical importance; however, such a link would have to be firmly established before impacting on patient care.

Protocol for the use of a bead array for the multiple detection of genotype of Chlamydia trachomatis

The identification of Chlamydia trachomatis genotypes is important for both molecular epidemiology and infection control such as contact tracing and identification of high-risk groups. Currently, at least 19 human serovars have been recognized by using polyclonal and monoclonal antibodies against the major outer membrane protein. In sexually transmitted diseases, multiple pathogens or genotype infections are not uncommon. Hence, detection of multiple gene targets in one reaction is becoming increasingly important. Here, we describe the multiplex detection of eight genotypes of C. trachomatis by a combination of a PCR amplification with a multiplex bead array detection. The bead array system comprises distinct bead sets, which are color coded by different fluorescent intensities and a dual-laser flow cytometer analyzer to identify the identity of the bead and the intensity of the reporter dye that binds to the target molecules. The DNA sequences of the variable segments (VS2 or VS1-VS2) in outer membrane protein (omp1) gene are PCR amplified and biotin labeled and used as a gene target for the genotyping of C. trachomatis. Genotype-specific probes coupled to beads are used for capturing the labeled target amplicons through specific hybridization. Thus, multiple genotypes are detected and differentiated simultaneously by yielding quantitative data.

Human papillomavirus 16 or 18 infection and prostate cancer risk: a meta-analysis

OBJECTIVE

Whether the oncogenic human papillomavirus (HPV) infection, especially infection with the most common subtypes 16 or 18, is related to prostate carcinogenesis remains conflicting. A meta-analysis with updated data was performed to obtain a more precise estimate of the association between them.

METHODS

Eligible studies were retrieved via both computer searches and review of references. The relation of HPV-16 or HPV-18 infection to prostate cancer (PC) was quantified separately. Stratified analyses based on HPV detection methods and geographic regions were also performed. Estimates of OR with 95% CI were summarized using the fixed-effect or random-effect models as appropriate.

RESULTS

Twenty-five eligible studies were retrieved. All the 25 studies were assigned for exploring the relation of HPV-16 infection to PC, while 13 studies provided additional information on HPV-18 simultaneously. In the overall estimates, the pooled OR indicated no significant increase of PC risk related with either HPV-16 (OR 1.09; 95% CI 0.97-1.23; P(heterogeneity) = 0.135) or HPV-18 (OR 1.05; 95% CI 0.89-1.24; P(heterogeneity) = 0.314) infection. Further quantitative assay of stratified data could also not yield any significant result, except the stratified analysis on HPV-16 DNA detection, which revealed higher HPV-16 DNA prevalence in PC cases (OR 1.54; 95% CI 1.07-2.20; P(heterogeneity) = 0.130).

CONCLUSIONS

Even though the overall estimates did not provide a supportive evidence for the causal role of HPV in prostate carcinogenesis, higher HPV-16 DNA prevalence in PC cases from the stratified analysis still indicated a potential association between HPV infection and PC risk in our meta-analysis.

Genotyping of Chlamydia trachomatis by microsphere suspension array

The identification of Chlamydia trachomatis genotypes is important for both the study of molecular epidemiology and infection control. We have developed a microsphere suspension array assay that can identify C. trachomatis genotypes rapidly and accurately and also discriminate among multiple genotypes in one clinical specimen.

Polymerase chain reaction-based fluorescent Luminex assay to detect the presence of human papillomavirus types

Becuase 40% of human papillomavirus (HPV) infections are mixed infections, the accurate identification of high-risk HPV genotypes in mixed infections is important for defining a woman's risk for progression to cervical cancer. Thus, advanced Luminex-based HPV genotyping has been developed to simultaneously detect the presence of multiple HPV types. Here, we describe the development of a Luminex-based HPV genotyping that combines polymerase chain reaction amplification with hybridization to fluorescence-labeled polystyrene bead microarrays (Luminex suspension array technology). New HPV type-specific oligonucleotide probes and YBT L1/GP6-1 primers were used to detect the HPV types in 132 clinical samples. We simultaneously evaluated the usefulness of this technique on clinical samples. We detected 15 specific HPV types (6, 16, 18, 31, 35, 42, 51, 52, 55, 56, 58, 59, 66, 67 and 68) examined with specificity without known cross-reaction to other HPV types. The detection limit for the different HPV types was above 500 plasmids. We compared the performance of the Luminex-based assay to the established HPV DNA microarray chip for polymerase chain reaction products derived from 53 clinical samples. The evaluation showed excellent agreement. The Luminex-based HPV genotyping was a sensitive, reproducible technique for the simultaneous genotyping of all clinically relevant genital HPV types. This assay system may be used to provide critical clinical information for early detection of HPV, especially in cases where the HPV copy numbers are low and the latency period of HPV infection is prolonged.

Viruses in the mammalian male genital tract and their effects on the reproductive system

This review describes the various viruses identified in the semen and reproductive tracts of mammals (including humans), their distribution in tissues and fluids, their possible cell targets, and the functional consequences of their infectivity on the reproductive and endocrine systems. The consequences of these viral infections on the reproductive tract and semen can be extremely serious in terms of organ integrity, development of pathological and cancerous processes, and transmission of diseases. Furthermore, of essential importance is the fact that viral infection of the testicular cells may result not only in changes in testicular function, a serious risk for the fertility and general health of the individual (such as a fall in testosteronemia leading to cachexia), but also in the possible transmission of virus-induced mutations to subsequent generations. In addition to providing an exhaustive account of the data available in these domains, this review focuses attention on the fact that the interface between endocrinology and virology has so far been poorly explored, particularly when major health, social and economical problems are posed. Our conclusions highlight the research strategies that need to be developed. Progress in all these domains is essential for the development of new treatment strategies to eradicate viruses and to correct the virus-induced dysfunction of the endocrine system.

Mutations within the tumour suppressor gene p53 are not confined to a late event in prostate cancer progression. a review of the evidence

Mutations in the p53 tumour suppressor gene are generally believed to be a late event in the progression of prostate cancer, and are associated with androgen independence, metastasis, and a worse prognosis. In this review, we examine the current literature available on p53 mutations and focus on stages A (T1) and B (T2) of prostate cancer. We report here that p53 mutations can be found in approximately one third of prostate cancers that are clinically localized to the prostate. In addition, high levels of p53 mutation are found in normal prostate tissue of prostate cancer patients, prostatic intraepithelial neoplasia, and benign prostatic hyperplasia. The limitations of techniques used to determine p53 mutations are discussed, as well as other modes of p53 loss in early stage prostate cancer.

Co-ordinated changes in expression of cell adhesion molecules in prostate cancer

The expressions of E-cadherin, the integrin subunits beta 1, beta 2, beta 3, CD44 and alpha-catenin were studied in parallel by immunohistochemistry in a series of 40 prostate biopsies comprising one normal, 11 benign prostatic hyperplasia (BPH), and 28 prostatic adenocarcinomas. As reported by others, there was a consistent loss of E-cadherin expression with increasing tumour grade and de-differentiation. However, a significant proportion of losses occurred at earlier grades than previously reported. The parallel nature of this study showed, for the first time in human prostate carcinoma, a reciprocal expression pattern of E-cadherin and beta 1 integrin in the higher grades of prostate cancer. A reciprocal expression pattern was also found for E-cadherin and CD44 between moderately and poorly differentiated tumours. alpha-Catenin expression was downregulated only in those cells which had previously lost E-cadherin expression, and beta 2 and beta 3 integrin were rarely expressed in prostate tumours. A loss of expression of the luminal epithelial specific keratins CK8 and CK18 was also observed in advanced stage, poorly differentiated carcinomas.