SV40 in human thyroid nodules

BK polyomavirus in Iranian patients with papillary thyroid cancer: Is it a major future challenge?

BK polyomavirus (BKPyV) is a well-known cause of nephropathy in renal transplant recipients. It has recently received much attention from researchers as a major predisposing factor for various cancers. This study aimed to investigate how BKPyV affected the advancement of papillary thyroid carcinoma (PTC). A total of 1057 samples were tested for BKPyV DNA and RNA, comprising 645 paraffin-embedded PTC biopsy samples (PEBS), 412 fresh biopsy samples (FBS), and 1057 adjacent noncancerous samples. The BKPyV DNA was found in 511 (48.3%) of the specimens, including 347 (84.2%) FBS and 164 (25.4%) PEBS. The mean BKPyV copy number was significantly lower in patients with PEBS (0.5 × 10-4  ± 0.1 × 10-4  copies/cell) than in FBS (1.3 × 10-1  ± 0.2 × 10-1  copies/cell) and non-PTC normal samples (0.3 × 10-5  ± 0.04 × 10-5  copies/cell). The PEBS had lower LT-Ag RNA expression than FBS, and no VP1 gene transcript expression was detected. In conclusion, although our findings indicated the presence of BKPyV in some Iranian PTC patients, more research is needed to corroborate these findings.

Traces of JC polyomavirus in papillary thyroid cancer: a comprehensive study in Iran

BACKGROUND

JC polyomavirus (JCPyV) is known to induce solid tumors such as astrocytomas, glioblastomas, and neuroblastomas in experimental animals, and recent studies have shown that the virus may be correlated with carcinogenesis. This study aimed to evaluate the impact of JCPyV on the progression of papillary thyroid cancer (PTC).

METHODS

A total of 1057 samples, including 645 paraffin-embedded PTC biopsy samples (PEBS) and 412 fresh biopsy samples (FBS), and 1057 adjacent non-cancerous samples were evaluated for the presence of JCPyV DNA and RNA.

RESULTS

We observed that 10.8% (114/1057) samples, including 17.5% (72/412) FBS and 6.5% (42/645) PEBS were positive for the JCPyV DNA. Among the JCPyV-positive samples, the mean JCPyV copy number was lower in patients with PEBS (0.3 × 10-4 ± 0.1 × 10-4 copies/cell) compared to FBS (1.8 × 10-1 ± 0.4 × 10-1 copies/cell) and non-PTC normal samples (0.2 × 10-5 ± 0.01 × 10-5 copies/cell), with a statistically significant difference (P < 0.001). The LT-Ag RNA expression was lower in PEBS than in FBS, while no VP1 gene transcript expression was found.

CONCLUSIONS

Although our results confirmed the presence of JCPyV in some Iranian patients with PTC, more research is needed to verify these results.

Evidencing the presence of merkel cell polyomavirus in papillary thyroid cancer

Merkel cell polyomavirus (MCPyV) infects most people asymptomatically, but recent reports indicate that the virus may be related to carcinogenesis. This study aimed to evaluate the impact of MCPyV on the development of papillary thyroid cancer (PTC). Totally, 1057 samples, including 412 fresh biopsy samples (FBS) and 645 paraffin-embedded PTC biopsy samples (PEBS), and 1057 adjacent non-cancerous samples were assessed for the presence of MCPyV DNA and RNA. MCPyV DNA was positive in 215 (20.3%) of samples, including 126 (30.6%) in FBS and 89 (13.8%) in PEBS. In MCPyV-positive samples, the mean MCPyV copy number was higher in the patients with FBS (2.3 × 10-1 ± 0.5 × 10-1 copies/cell) compared to PEBS (0.7 × 10-4 ± 0.1 × 10-4 copies/cell) and adjacent non-PTC normal samples (0.3 × 10-5 ± 0.02 × 10-5 copies/cell), indicating a statistically significant difference (P < 0.001). The LT-Ag RNA expression was higher in FBS compared to PEBS, while VP1 gene transcript was not detected in any samples. Although our findings showed the presence of MCPyV in a subset of PTC Iranian patients, further research is required to confirm these findings.

Viral infections and risk of thyroid cancer: A systematic review and empirical bayesian meta-analysis

OBJECTIVE

The associations between viruses and the cancer have been conducted in several studies while there has been no systematic review and meta-analysis about the association between viral infections and thyroid cancer (TC). Therefore, we investigated the association between viral infection and TC risk.

METHODS

Systematic search was done from 1994 to 2019 in Web of sciences (ISI), PubMed, and Scopus databases. Pooled logarithm of odds ratio (OR) and their corresponding 95 % confidence interval (CI) and pooled prevalence of viral infections were calculated to find the association between the viral infections and TC risk and overall prevalence of the viral infections in TC.

RESULTS

Twenty-three of 852 original articles were selected and included in the study. According to the results of the random effect meta-analysis, the pooled prevalence of viral infections in the TC patients was 37 % (95 % C. I = 22 %-55 %). In addition, there was a significant association between viral infections (log (OR) = 1.51, 95 % credible interval = 0.68-2.39) and TC risk. The highest associations were observed between TC risk and Simian Vacuolating Virus 40 (SV40) and B19 infections, respectively. The lowest non-significant association was found between TC risk and Poliovirus type 1 infection. The significantly heterogeneity was observed between included studies (Q test: p-value<0.001; I² = 73.82 %; τ² = 1.08, 95 % Cr. I = 0.47-1.94).

CONCLUSIONS

Results clearly demonstrated the potential pathogenetic association between viral infections and increased risk of TC.

Herpes and polyoma family viruses in thyroid cancer

Thyroid cancer is considered the most common malignancy that affects the endocrine system. Generally, thyroid cancer derives from follicular epithelial cells, and thyroid cancer is divided into well-differentiated papillary (80% of cases) and follicular (15% of cases) carcinoma. Follicular thyroid cancer is further divided into the conventional and oncocytic (Hürthle cell) type, poorly differentiated carcinoma and anaplastic carcinoma. Both poorly differentiated and anaplastic carcinoma can arise either de novo, or secondarily from papillary and follicular thyroid cancer. The incidence of thyroid cancer has significantly increased for both males and females of all ages, particularly for females between 55–64 years of age, from 1999 through 2008. The increased rates refer to tumors of all stages, though they were mostly noted in localized disease. Recently, viruses have been implicated in the direct regulation of epithelial-mesenchymal transition (EMT) and the development of metastases. More specifically, Epstein-Barr virus (EBV) proteins may potentially lead to the development of metastasis through the regulation of the metastasis suppressor, Nm23, and the control of Twist expression. The significant enhancement of the metastatic potential, through the induction of angiogenesis and changes to the tumor microenvironment, subsequent to viral infection, has been documented, while EMT also contributes to cancer cell permissiveness to viruses. A number of viruses have been identified to be associated with carcinogenesis, and these include lymphotropic herpesviruses, namely EBV and Kaposi's sarcoma-associated herpesvirus [KSHV, also known as human herpesvirus type 8 (HHV8)]; two hepatitis viruses, hepatitis B virus (HBV) and hepatitis C virus (HCV); human papillomaviruses (HPVs); human T cell lymphoma virus (HTLV); and a new polyomavirus, Merkel cell polyomavirus identified in 2008. In this review, we examined the association between thyroid cancer and two oncogenic virus families, the herpes and polyoma family viruses, and we discuss their potential role as causative agents in thyroid carcinogenesis.

Investigation of BK virus, Epstein-Barr virus and human papillomavirus sequences in postoperative thyroid gland specimens

BACKGROUND

Although recent evidence has implicated viruses in the regulation of epithelial-to-mesenchymal transition and tumor progression, little is known regarding viral infections in thyroid malignancies. Thus the aim of this study was to detect sequences of 3 potentially oncogenic viruses - BK virus (BKV), Epstein-Barr virus (EBV) and human papillomavirus (HPV) - in a series of postoperative thyroid gland specimens.

METHODS

Thirty patients with thyroid nodules who underwent surgery for thyroid disease within a 3-year period were enrolled. Both nodular and adjacent normal thyroid tissue was surgically excised from each patient. Viral gene sequences of BKV (VP1), EBV (LMP1, EBNA2 and EBER1) and HPV were amplified by PCR. The PCR results were confirmed by direct sequencing analysis.

RESULTS

VP1 gene sequences were detected in 60% (18/30) of thyroid cancer or multinodular hyperplasia lesions compared with in 43.3% (13/30) of adjacent normal thyroid tissue specimens. Fifteen of thirty (50%) of thyroid cancer or multinodular hyperplasia samples revealed LMP1 sequences compared with 46.7% (14/30) of corresponding normal thyroid tissues. EBNA2 gene sequences were detected in 90% (27/30) of thyroid cancer or multinodular hyperplasia samples, compared with 90% (27/30) of adjacent normal thyroid tissue specimens. All samples were negative for EBER1 sequences, while HPV DNA was not detected in either nodular or normal thyroid tissue.

CONCLUSIONS

This study suggests that BKV and EBV "infection" is an early event, occurring within normal tissue. Our findings do not show a clear role for the viruses examined, instead they suggest an "endemicity" pattern rather than a causal effect.

The influence of the environment on the development of thyroid tumors: a new appraisal

Most epidemiological studies concerning differentiated thyroid cancers (DTC) indicate an increasing incidence over the last two decades. This increase might be partially explained by the better access to health services worldwide, but clinicopathological analyses do not fully support this hypothesis, indicating that there are carcinogenetic factors behind this noticeable increasing incidence. Although we have undoubtedly understood the biology and molecular pathways underlying thyroid carcinogenesis in a better way, we have made very little progresses in identifying a risk profile for DTC, and our knowledge of risk factors is very similar to what we knew 30-40 years ago. In addition to ionizing radiation exposure, the most documented and established risk factor for DTC, we also investigated the role of other factors, including eating habits, tobacco smoking, living in a volcanic area, xenobiotics, and viruses, which could be involved in thyroid carcinogenesis, thus, contributing to the increase in DTC incidence rates observed.

SV40 and human cancer: A review of recent data

An unknown proportion of formalin-inactivated poliovirus vaccine lots administered to millions of US residents between 1955 and 1963 was contaminated with small amounts of infectious simian virus 40 (SV40), a polyomavirus of the rhesus macaque. It has been reported that mesothelioma, brain tumors, osteosarcoma and non-Hodgkin lymphoma (NHL) contain SV40 DNA sequences and that SV40 infection introduced into humans by the vaccine probably contributed to the development of these cancers. The Immunization Safety Review Committee of the Institute of Medicine (IOM) reviewed this topic in 2002. The present review of recent studies showed that the earlier results describing the recovery of SV40 DNA sequences from a large proportion of the above tumors were not reproducible and that most studies were negative. Contamination with laboratory plasmids was identified as a possible source of false positive results in some previous studies. The low-level immunoreactivity of human sera to SV40 was very likely the result of cross-reactivity with antibodies to the SV40-related human polyomaviruses BKV and JCV, rather than of authentic SV40 infection. SV40 sero-reactivity in patients with the suspect tumors was no greater than that in controls. In epidemiologic studies, the increased incidence of some of the suspect tumors in the 1970s to 1980s was not related to the risk of exposure to SV40-contaminated vaccines. In summary, the most recent evidence does not support the notion that SV40 contributed to the development of human cancers.