Detection of Merkel cell polyomavirus and human papillomavirus DNA in porocarcinoma

The HPV viral regulatory mechanism of TLRs and the related treatments for HPV-associated cancers

Infection with human papillomavirus (HPV) typically leads to cervical cancer, skin related cancers and many other tumors. HPV is mainly responsible for evading immune tumor monitoring in HPV related cancers. Toll like receptors (TLRs) are particular pattern recognition molecules. When the body is facing immune danger, it can lead to innate and direct adaptive immunity. TLR plays an important role in initiating antiviral immune responses. HPV can affect the expression level of TLR and interfere with TLR related signaling pathways, resulting in sustained viral infection and even carcinogenesis. This paper introduces the HPV virus and HPV related cancers. We discussed the present comprehension of TLR, its expression and signaling, as well as its role in HPV infection. We also provided a detailed introduction to immunotherapy methods for HPV related diseases based on TLR agonists. This will provide insights into methods that support the therapeutic method of HPV related conditions with TLR agonists.

Eccrine Porocarcinoma of the Vulva With Sarcomatoid Transformation, a New Human Papillomavirus-associated Malignancy? Case Report and Review of the Literature

Eccrine porocarcinoma is a rare cutaneous neoplasm, and rarer still in the anogenital region. In the vulva, the most common carcinoma by far is squamous cell carcinoma; however, eccrine porocarcinoma can arise at this site. As the distinction between porocarcinoma and squamous cell carcinoma has important prognostic implications at other cutaneous sites, it stands to reason that it may have these same implications in the vulva. We present a case of an eccrine porocarcinoma in the vulva of a 70-year-old woman that, in addition, showed sarcomatoid transformation. This tumor harbored human papillomavirus-18 DNA and mRNA, raising the question of the role of the oncogenic virus in sweat gland neoplasms of the vulva.

Merkel Cell Polyomavirus (MCPyV) and Cancers: Emergency Bell or False Alarm?

Merkel cell polyomavirus (MCPyV), the sole member of Polyomavirus associated with oncogenesis in humans, is the major causative factor of Merkel cell carcinoma (MCC), a rare, neuroendocrine neoplasia of the skin. Many aspects of MCPyV biology and oncogenic mechanisms remain poorly understood. However, it has been established that oncogenic transformation is the outcome of the integration of the viral genome into the host DNA. The high prevalence of MCPyV in the population, along with the detection of the virus in various human tissue samples and the strong association of MCPyV with the emergence of MCC, have prompted researchers to further investigate the role of MCPyV in malignancies other than MCC. MCPyV DNA has been detected in several different non-MCC tumour tissues but with significantly lower prevalence, viral load and protein expression. Moreover, the two hallmarks of MCPyV MCC have rarely been investigated and the studies have produced generally inconsistent results. Therefore, the outcomes of the studies are inadequate and unable to clearly demonstrate a direct correlation between cellular transformation and MCPyV. This review aims to present a comprehensive recapitulation of the available literature regarding the association of MCPyV with oncogenesis (MCC and non-MCC tumours).

Comparison of Quantitative Real-Time PCR and Digital PCR to Detect the Polyomavirus in Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) prevalence in Merkel cell carcinoma (MCC) cases is controversial. The detection and quantification of MCPyV DNA is mainly performed by PCR techniques using formalin-fixed, paraffin-embedded (FFPE) tissues. The aim of this study is to compare the performance of two different molecular techniques, specifically the quantitative Real-Time PCR (qPCR) and digital PCR (dPCR). Samples from 31 cases of MCC excisional surgical biopsies were analyzed. DNA extraction and purification from clinical samples were performed using the QIAcube Qiagen automated nucleic acid extractor. After the extraction, MCPyV was detected by qPCR and dPCR using specially designed primers and probes. Of the 31 MCC samples under study, the MCPyV genome was detected in 11 samples (35%) by qPCR compared with 20 samples (65%) detected by dPCR. Notably, 65% of primary tumors were positive for MCPyV (15/23). The viral genome was detected in 75% of tumors located at UV-exposed sites (6/8), 55% of tumors at partially UV-protected sites (5/9), and 67% of tumors at UV-protected sites (4/6). Our results showed a better sensitivity of dPCR in detecting the MCPyV genome in MCC samples compared with traditional qPCR techniques.

Combined Poroma and Verruca Plantaris

ABSTRACT

A 76-year-old female patient presented with a peculiar new exophytic-appearing, flesh-colored skin lesion on her left hallux. Owing to its atypical appearance, the neoplasm was biopsied. Histologic sections demonstrated numerous thickened, anastomosing cord-like structures composed of bland appearing adnexal keratinocytes attached to the epidermis and extending into the superficial dermis. Nearby areas exhibited papillomatosis, epidermal acanthosis, dense hyperparakeratosis, hypergranulosis, and superficial koilocytes, findings consistent with a verruca plantaris. A p16 stain was positive in many of the superficial epidermal keratinocytes. Human papillomavirus typing by in situ hybridization for the most common low-risk and high-risk types was also performed and was negative for these. We herein present an unusual case of a skin lesion which combines features of a poroma with a verruca plantaris. We further review what is known of the relationship between human papillomavirus and poroid neoplasms.

Porocarcinoma: an epidemiological, clinical, and dermoscopic 20-year study

BACKGROUND

Porocarcinoma (PC) is a rare cutaneous adnexal tumor with a variable metastatic potential. Given the paucity of data, guidelines and specific recommendations for PC are not yet well-established. In this study, we evaluate the disease-specific characteristics and outcome of this rare and often underestimated tumor.

MATERIALS AND METHOD

A retrospective study of the epidemiological, clinical, and dermoscopic characteristics among cases of histopathologically diagnosed PC, collected from the database of two skin cancer clinics in Italy (Firenze, Pistoia) from 2000 to 2020, was conducted.

RESULTS

Among the 52 patients with 53 tumors, 31 were men (59.6%) and 21 were women (40.4%) with an age range of 49-96 years (median age 82 years). The most common locations were the head/neck region in men (34% in men vs. 17% in women) and the lower limb in women (17% in women vs. 9% in men). Forty-eight cases (91%) underwent local excision. Of these patients, two (4%) experienced local recurrence, and one (2%) developed a second PC on a different anatomical site 1 month after the primary tumor's excision. Lymph node metastases were present in three cases (6%). Two of them have been treated surgically with adjuvant radiotherapy (both are disease-free after a 2-year follow-up period), whereas the third case developed visceral metastases followed by PC-related death.

CONCLUSIONS

This study, with 52 patients with 53 tumors covering a follow-up period of more than 5 years, shows a less aggressive behavior of PC with 4% local recurrence, 6% nodal metastases, and 2% mortality.

Merkel cell polyomavirus is a passenger virus in both poroma and porocarcinoma

BACKGROUND

Merkel cell polyomavirus (MCPyV) has been studied in several malignant and nonmalignant tissues. However, only in Merkel cell carcinoma (MCC) has the connection to tumorigenesis been established. Previously, eccrine porocarcinoma samples were shown to express MCPyV in the majority of samples. We aimed to examine MCPyV in porocarcinoma and poroma samples using MCC as the reference material.

METHODS

We analyzed 17 porocarcinoma and 50 poroma samples for the presence of MCPyV using LT antigen immunostaining and DNA detection methods. In addition, 180 MCC samples served as controls.

RESULTS

MCPyV LT antigen immunostaining was detected in 10% of poroma and 18% of porocarcinoma samples; on the other hand, it was present in 65% of MCC samples. MCPyV DNA was detected in only 10% of poroma and porocarcinoma samples compared with 96% of MCC samples. The viral DNA copy number in all MCPyV DNA-positive MCCs was at least 25 times higher than that in porocarcinoma or poroma samples with the highest MCPyV DNA-to-PTPRG ratio.

CONCLUSIONS

The low number of viral DNA copies in poroma and porocarcinoma samples, together with the negative LT expression of MCPyV DNA-positive tumors, indicates that MCPyV is simply a passenger virus rather than an oncogenic driver of porocarcinoma.

Droplet digital PCR of viral ‎DNA/RNA, current progress, challenges, and future perspectives

High-throughput droplet-based digital PCR (ddPCR) is a refinement of the conventional polymerase chain reaction (PCR)‎ methods. In ddPCR, DNA/RNA is encapsulated stochastically inside the microdroplets as reaction chambers. A small percentage of the reaction chamber contains one or fewer copies of the DNA or RNA. After PCR amplification, concentrations are determined based on the proportion of nonfluorescent partitions through the Poisson distribution. Some of the main features of ddPCR include high sensitivity and specificity, absolute quantification without a standard curve, high reproducibility, good tolerance to PCR inhibitor, and high efficacy compared to conventional molecular methods. These advantages make ddPCR a valuable addition to the virologist's toolbox. The following review outlines the recent technological advances in ddPCR methods and their applications in viral identification.

Merkel cell polyomavirus and non-Merkel cell carcinomas: guilty or circumstantial evidence?

Merkel cell polyomavirus (MCPyV) is the major causative factor of the rare but aggressive cancer, Merkel cell carcinoma (MCC). Two characteristics of MCPyV-positive MCCs are integration of the viral genome and expression of a truncated version of one of its oncogenic proteins, namely large T antigen. The strong association of MCPyV with MCC development has incited researchers to further investigate a possible role of this virus in other cancers. However, many of the examples displaying the presence of the virus in the various non-MCC cancers are not able to clearly demonstrate a direct connection between cellular transformation and the presence of the virus. The prevalence of the virus is significantly lower in non-MCC cancers compared to MCCs, with a lower level of viral load and sparse viral protein expression. Moreover, the state of the viral genome, and whether a truncated large T antigen is expressed, has rarely been investigated. Nonetheless, considering the strong oncogenic potential of MCPyV proteins in MCC, the plausible contribution of MCPyV to transformation and cancer growth in non-MCC tumors cannot be ruled out. Furthermore, the absence of MCPyV in cancers does not exclude a hit-and-run mechanism, or the oncoproteins of MCPyV may potentiate the neoplastic process mediated by co-infecting oncoviruses such as high-risk human papillomaviruses and Epstein-Barr virus. The current review is focusing on the available data describing the presence of MCPyV in non-MCC tumors, with an aim to provide a comprehensive overview of the corresponding literature and to discuss the potential contribution of MCPyV to non-MCC cancer in light of this.

Merkel Cell Polyomavirus Small T Antigen Induces DNA Damage Response

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine cancer of the skin with high rates of metastasis and mortality. Besides well-established factors including genetic mutations and UV-induced DNA damage in Merkel cell carcinogenesis, the recent discovery of the Merkel cell polyomavirus (MCPyV) has shed light on the viral etiology of MCC. In the current study, we provide novel evidence that MCPyV small T (sT) antigen induces the DNA damage response (DDR) pathway. Our data show that in human MCC cells, the presence of MCPyV is associated with hyperphosphorylation of histone H2AX, a marker for DNA damage. We observed that overexpression of MCPyV sT antigen induced the phosphorylation of histone H2AX as well as the activation of ataxia telangiectasia mutant (ATM), an upstream kinase important for H2AX phosphorylation. Moreover, we observed that MCPyV sT expression also induced the hyperphosphorylation of other ATM downstream molecules (including 53BP1 and CHK2) as well as the hypermethylation of histone 3 and histone 4. These findings disclose a novel link between MCPyV sT and the DDR pathway in MCC. Given that measurement of DDR is clinically useful for evaluating treatment response to radio- and chemotherapy, our findings warrant further investigation to evaluate the potential implications of this pathway for MCC management.

Merkel Cell Polyomavirus: A New DNA Virus Associated with Human Cancer

Merkel cell polyomavirus (MCPyV or MCV) is a novel human polyomavirus that has been discovered in Merkel cell carcinoma (MCC), a highly aggressive skin cancer. MCPyV infection is widespread in the general population. MCPyV-associated MCC is one of the most aggressive skin cancers, killing more patients than other well-known cancers such as cutaneous T-cell lymphoma and chronic myelogenous leukemia (CML). Currently, however, there is no effective drug for curing this cancer. The incidence of MCC has tripled over the past two decades. With the widespread infection of MCPyV and the increase in MCC diagnoses, it is critical to better understand the biology of MCPyV and its oncogenic potential. In this chapter, we summarize recent discoveries regarding MCPyV molecular virology, host cellular tropism, mechanisms of MCPyV oncoprotein-mediated oncogenesis, and current therapeutic strategies for MCPyV-associated MCC. We also present epidemiological evidence for MCPyV infection in HIV patients and links between MCPyV and non-MCC human cancers.

Droplet digital PCR (ddPCR) vs quantitative real-time PCR (qPCR) approach for detection and quantification of Merkel cell polyomavirus (MCPyV) DNA in formalin fixed paraffin embedded (FFPE) cutaneous biopsies

BACKGROUND

Merkel cell polyomavirus (MCPyV) is associated with Merkel cell carcinoma and high viral load in the skin was proposed as a risk factor for the occurrence of this tumour. MCPyV DNA was detected, with lower frequency, in different skin cancers but since the viral load was usually low, the real prevalence of viral DNA could be underestimated.

OBJECTIVE

To evaluate the performance of two assays (qPCR and ddPCR) for MCPyV detection and quantification in formalin fixed paraffin embedded (FFPE) tissue samples.

METHODS

Both assays were designed to simultaneous detection and quantification of both MCPyV as well as house-keeping DNA in clinical samples. The performance of MCPyV quantification was investigated using serial dilutions of cloned target DNA. We also evaluated the applicability of both tests for the analysis of 76 FFPE cutaneous biopsies.

RESULTS

The two approaches resulted equivalent with regard to the reproducibility and repeatability and showed a high degree of linearity in the dynamic range tested in the present study. Moreover, qPCR was able to quantify ≥10⁵ copies per reaction, while the upper limit of ddPCR was 10⁴ copies. There was not significant difference between viral load measured by the two methods The detection limit of both tests was 0,15 copies per reaction, however, the number of positive samples obtained by ddPCR was higher than that obtained by qPCR (45% and 37% respectively).

CONCLUSIONS

The ddPCR represents a better method for detection of MCPyV in FFPE biopsies, mostly these containing low copies number of viral genome.