Does a new polyomavirus contribute to Merkel cell carcinoma?

Distinct Signatures of Genomic Copy Number Variants Define Subgroups of Merkel Cell Carcinoma Tumors

Simple Summary

Cancer results from genetic changes in cells. These changes are often mutations that alter the DNA sequence of critical genes. However, duplications and deletions in cancer-related genes can also contribute to malignant transformation. In this study we use Nanostring technology to assess DNA copy number changes in samples of Merkel cell carcinoma (MCC), a rare and aggressive neuroendocrine skin tumor. We were able to identify recurrent amplifications and deletions in cancer-related genes. We also found that MCC tumors grouped into three distinct copy number variant profiles. The first group consisted of tumors with multiple deletions. The second group contained tumors with low levels of genomic structural alterations. The last group comprised tumors containing multiple amplifications. Our study suggests that most MCC tumors are associated with deletions in cancer-related genes or are lacking in copy number changes, whereas a small percentage of tumors are associated with genomic amplifications.

Abstract

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer. Most MCC tumors contain integrated Merkel cell polyomavirus DNA (virus-positive MCC, VP-MCC) and carry a low somatic mutation burden whereas virus-negative MCC (VN-MCC) possess numerous ultraviolet-signature mutations. In contrast to viral oncogenes and sequence mutations, little is known about genomic structural variants in MCC. To identify copy number variants in commonly altered genes, we analyzed genomic DNA from 31 tumor samples using the Nanostring nCounter copy number cancer panel. Unsupervised clustering revealed three tumor groups with distinct genomic structural variant signatures. The first cluster was characterized by multiple recurrent deletions in genes such as RB1 and WT1. The second cluster contained eight VP-MCC and displayed very few structural variations. The final cluster contained one VP-MCC and four VN-MCC with predominantly genomic amplifications in genes like MDM4, SKP2, and KIT and deletions in TP53. Overall, VN-MCC contained more structure variation than VP-MCC but did not cluster separately from VP-MCC. The observation that most MCC tumors demonstrate a deletion-dominated structural group signature, independent of virus status, suggests a shared pathophysiology among most VP-MCC and VN-MCC tumors.

Emerging Evidence for Infectious Causes of Cancer in the United States

Worldwide, infectious agents currently contribute to an estimated 15% of new cancer cases. Most of these (92%, or 2 million new cancer cases) are attributable to 4 infectious agents: Helicobacter pylori, human papillomavirus, and hepatitis B and C viruses. A better understanding of how infectious agents relate to the US cancer burden may assist new diagnostic and treatment efforts. We review US-specific crude mortality rates from infection-associated cancers and describe temporal and spatial trends since 1999. We review the US-specific evidence for infection-cancer associations by reporting available estimates for attributable fractions for the infection-cancer associations. Death due to cancers with established infectious associations varies geographically, but estimates for the US attributable fraction are limited to a few observational studies. To describe the burden of infection-associated cancer in the United States, additional observational studies are necessary to estimate the prevalence of infection nationally and within subpopulations. As infectious associations emerge to explain cancer etiologies, new opportunities and challenges to reducing the burden arise. Improved estimates for the United States would help target interventions to higher-risk subpopulations.

De Novo Malignancies After Liver Transplantation With 14 Cases at a Single Center

OBJECTIVE

To analyze the clinical characteristics, risk factors, and prevention of de novo malignant tumors after liver transplantation.

METHODS

Fourteen patients who underwent liver transplantation were identified as having de novo malignancies. The clinical characteristics and survival of these patients were retrospectively reviewed.

RESULTS

Fourteen cases of de novo malignancies after liver transplantation occurred for an incidence rate of 1.94% (14/722), including 11 men (78.6%, mean age, 48 y) and 3 women (21.4%, mean age, 50 y). The mean period from transplantation to cancer diagnosis was 55 ± 35 months. The distribution of tumor histologic types included colon cancer, lung cancer, esophageal cancer, nasopharyngeal cancer, liver cancer, parotid carcinoma, bone cancer, post-transplantation lymphoproliferative disorder, stomach cancer, bladder cancer, and laryngeal cancer. Twelve cases (85.7%) had hepatitis B. Five patients (35.7%) underwent operations, and the other 9 patients underwent chemotherapy or radiotherapy. During a mean follow-up period of 37 ± 26 months after the diagnosis of de novo malignancy, 8 patients (57.1%) died, with only 1 dying of causes not related to the de novo malignancy. The survival analysis showed 1-, 5-, and 7-year survival rates of 85.7%, 71.4%, and 42.9%, respectively.

CONCLUSIONS

De novo malignancies after organ transplantation have been suggested to be a major cause of late mortality. De novo malignancy after orthotopic liver transplantation was found to be related to smoking, sex, and low immune function due to immunosuppressive agents. Solid tumors should be removed, and the patient should receive chemotherapy or radiotherapy as early as possible. Early diagnosis and treatment are very important for improving the prognosis.

A Review of Functional Motifs Utilized by Viruses

Short linear motifs (SLiM) are short peptides that facilitate protein function and protein-protein interactions. Viruses utilize these motifs to enter into the host, interact with cellular proteins, or egress from host cells. Studying functional motifs may help to predict protein characteristics, interactions, or the putative cellular role of a protein. In virology, it may reveal aspects of the virus tropism and help find antiviral therapeutics. This review highlights the recent understanding of functional motifs utilized by viruses. Special attention was paid to the function of proteins harboring these motifs, and viruses encoding these proteins. The review highlights motifs involved in (i) immune response and post-translational modifications (e.g., ubiquitylation, SUMOylation or ISGylation); (ii) virus-host cell interactions, including virus attachment, entry, fusion, egress and nuclear trafficking; (iii) virulence and antiviral activities; (iv) virion structure; and (v) low-complexity regions (LCRs) or motifs enriched with residues (Xaa-rich motifs).

Primary Merkel Cell Carcinoma of the Submandibular Gland: When CK20 Status Complicates the Diagnosis

Merkel cell carcinoma is a neuroendocrine tumor that occurs predominantly on the sun-exposed skin, with rare cases in the extracutaneous sites. It represents one of the extremely rare malignant neuroendocrine tumors of the salivary glands. We report a case of primary Merkel cell carcinoma of the right submandibular gland. The preoperative diagnosis was doubtful and the definitive histological diagnosis proved to be very difficult considering the extreme rarity of this tumor. The intraoperative evaluation of the macroscopic characteristics of the lesion led to an elective lymph node dissection. The extreme aggressiveness of the disease has resulted in the necessity of a new post-operative staging and in a multimodal treatment. This is the first primary submandibular gland Merkel cell carcinoma described in the literature. Differential diagnosis may be challenging and proper hematoxylin-eosin staining and immunohistochemical studies are mandatory.

Merkel cell carcinoma with divergent differentiation: histopathological and immunohistochemical study of 15 cases with PCR analysis for Merkel cell polyomavirus

AIMS

To report on 15 cases of Merkel cell carcinoma (MCC) with divergent differentiation, to characterize its clinicopathological spectrum and its relationship with Merkel cell polyomavirus (MCV).

METHODS AND RESULTS

Fifteen patients with a mean age of 81 years were included. Follow-up was available for 13 cases (range 12 days to 6 years; median 6 months). Recurrence, metastasis and mortality rates were 15.4%, 53.8% and 61.5%, respectively. All tumours showed the typical histological and immunohistochemical features of MCC, with at least one additional divergent component. Eight cases had a single aberrant component (squamous in six cases, follicular in one case, and porocarcinoma in one case), six cases had two aberrant components (squamous and sarcomatous in three cases, glandular and squamous in two cases, and sarcomatous and neuroblastic in one case), and one case had three aberrant components (glandular, squamous, and sarcomatous). All cases had dysplastic changes in the overlying epithelium, and four of 15 showed epidermotropism. PCR analysis for Merkel cell polyomavirus (MCV) gave negative results in all 12 cases tested.

CONCLUSIONS

Merkel cell carcinoma with divergent differentiation is a highly aggressive tumour that might be difficult to recognize, owing to its wide histological variability. Negativity for MCV suggests that the virus is not implicated in the development of this subtype of MCC.

First description of Merkel Cell polyomavirus DNA detection in a patient with Stevens-Johnson syndrome

Merkel Cell polyomavirus (MCPyV), a ubiquitous DNA tumor virus, has been found to be associated with Merkel cell carcinoma and chronic lymphocytic leukaemia while other associations are still being explored. MCPyV sequences have also been detected in normal tissues of tumor patients and in the blood of healthy donors. This report documents a new MCPyV association with the Stevens-Johnson syndrome, a rare immune-modulated mucocutaneous process particularly associated with specific drugs and infective agents. A high MCPyV viral load was detected simultaneously in fluid from skin lesions (2.0 × 10(4) copies/ml) and in matched blood (7.4 × 10(5) copies/ml) from a young adult patient after bone marrow transplant for a relapsed T-cell acute lymphatic leukaemia. MCPyV clearance concurred with the complete resolution of skin lesions after 5 days of cidofovir treatment. DNA sequencing classified the amplicons as the European/Italian MKL-1 strain. Given its ubiquitous nature, MCPyV could account for part of Stevens-Johnson syndrome idiopathic cases.

Merkel cell polyomavirus large T antigen has growth-promoting and inhibitory activities

Merkel cell carcinoma (MCC) is a rare and aggressive form of skin cancer. In at least 80% of all MCC, Merkel cell polyomavirus (MCPyV) DNA has undergone clonal integration into the host cell genome, and most tumors express the MCPyV large and small T antigens. In all cases of MCC reported to date, the integrated MCPyV genome has undergone mutations in the large T antigen. These mutations result in expression of a truncated large T antigen that retains the Rb binding or LXCXE motif but deletes the DNA binding and helicase domains. However, the transforming functions of full-length and truncated MCPyV large T antigen are unknown. We compared the transforming activities of full-length, truncated, and alternatively spliced 57kT forms of MCPyV large T antigen. MCPyV large T antigen could bind to Rb but was unable to bind to p53. Furthermore, MCPyV-truncated large T antigen was more effective than full-length and 57kT large T antigen in promoting the growth of human and mouse fibroblasts. In contrast, expression of the MCPyV large T antigen C-terminal 100 residues could inhibit the growth of several different cell types. These data imply that the deletion of the C terminus of MCPyV large T antigen found in MCC serves not only to disrupt viral replication but also results in the loss of a distinct growth-inhibitory function intrinsic to this region.

Dermatology clinics: what's new in dermatopathology: news in nonmelanocytic neoplasia

This article reviews the recent dermatopathology literature involving nonmelanocytic neoplasia, with a focus on important work done over the last 5 years. The discussion includes advances in the understanding of Merkel cell carcinoma pathogenesis and prognosis; changes in the seventh edition of the American Joint Committee of Cancer staging manual in reference to staging of squamous cell carcinoma and Merkel cell carcinoma; newly described or rare histopathologic patterns and entities including squamoid eccrine ductal carcinoma, rippled-pattern adnexal neoplasms, onychomatricoma, spindle cell predominant trichodiscoma/neurofollicular hamartoma, and myoepithelioma; and microsatellite instability in sebaceous neoplasms of Muir-Torre syndrome and other tumors.

Rising incidence of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive, skin cancer of obscure histogenesis, the incidence of which is rising. There is no consensus on the optimal treatment. Our aim was to evaluate the staging, investigation, treatment, and follow-up of MCC in eastern Denmark, and to investigate the incidence. We suggest guidelines for treatment. First we reviewed the medical records of 51 patients diagnosed with MCC from 1995 until 2006 in eastern Denmark. The nation-wide incidence of MCC was extracted from the Danish Cancer Registry for the calculations for the period 1986-2003. We reviwed published papers about MCC based on a MEDLINE search. Fourteen of the 51 patients developed recurrence, and 37 (73%) died during the study period. Mean follow-up was 13 months (range 1-122). A total of 153 patients were identified in the Danish Cancer Registry, and showed that incidence rates had increased 5.4 fold over the 18 year period from 1986 until 2003. Rates were highest in people over the age of 65. Recommended treatment with curative intent includes excision of the primary tumour with wide margins, excision of the sentinel node, computed tomogram (CT) or positron emission tomography (PET) of the thorax and abdomen, and adjuvant radiotherapy to the surgical bed. In the case of advanced disease, systemic palliative chemotherapy remains a possibility. There is a need for prospective multicentre evaluation of staging investigations and treatment of MCC.

Antibodies to merkel cell polyomavirus T antigen oncoproteins reflect tumor burden in merkel cell carcinoma patients

Merkel cell polyomavirus (MCPyV) is a common infectious agent that is likely involved in the etiology of most Merkel cell carcinomas (MCC). Serum antibodies recognizing the MCPyV capsid protein VP1 are detectable at high titer in nearly all MCC patients and remain stable over time. Although antibodies to the viral capsid indicate prior MCPyV infection, they provide limited clinical insight into MCC because they are also detected in more than half of the general population. We investigated whether antibodies recognizing MCPyV large and small tumor-associated antigens (T-Ag) would be more specifically associated with MCC. Among 530 population control subjects, these antibodies were present in only 0.9% and were of low titer. In contrast, among 205 MCC cases, 40.5% had serum IgG antibodies that recognize a portion of T-Ag shared between small and large T-Ags. Among cases, titers of T-Ag antibodies fell rapidly (∼8-fold per year) in patients whose cancer did not recur, whereas they rose rapidly in those with progressive disease. Importantly, in several patients who developed metastases, the rise in T-Ag titer preceded clinical detection of disease spread. These results suggest that antibodies recognizing T-Ag are relatively specifically associated with MCC, do not effectively protect against disease progression, and may serve as a clinically useful indicator of disease status.

Colorectal and anal neoplasms following liver transplantation

OBJECTIVE

Liver transplantation (LT) is the treatment of choice for end-stage liver disease. The required immunosuppression increases the risk for developing malignancies. Some viruses play a crucial role. Data on neoplasms of the colon, rectum and anus in LT are limited.

METHOD

A retrospective evaluation of the incidence and clinical course of colorectal and anal malignancies and colonic polyps in a series of 467 consecutive LTs in 402 individuals between 1998 and 2001 was performed. Standard immunosuppression included Tacrolimus, Mycophenolic acid and steroids.

RESULTS

During a median follow up of 5.2 years, three colon adenocarcinomas, one EBV associated cecal posttransplant lymphoproliferative tumour and two HPV associated anal tumours were identified. Pre-LT colonoscopy was performed in 161 patients (40%), and of 153 evaluable individuals, 53 (34.9%) had polyps. Colonoscopy was performed in 186 patients (46.3%) median 14.8 (range 0.2-77.8) months post-LT and 55 (29.3%) had polyps. Post-LT adenomatous polyps were detected in 47.3% of patients with pre-LT polyps vs 6.7% of patients without pre-LT polyps (P < 0.001). Patients with alcoholic liver disease had a significantly higher rate of adenoma formation (50.0% vs 11.1%, P < 0.001). No patient died from colorectal/anal malignancy.

CONCLUSION

The incidence of metachronous and new polyp formation in our study is similar to people who are not immunocompromised, but subgroups are at increased risk. Viral-associated malignancies, including post-transplant lymphoproliferative disorders and anal cancer, are important entities in the LT population suggesting that complete screening of the colon, rectum and anus including pre-LT and post-LT colonoscopy should be utilized.

Chronic lymphocytic leukaemia patients have a high risk of Merkel-cell polyomavirus DNA-positive Merkel-cell carcinoma

Background:

Immunosuppression and Merkel-cell polyomavirus (MCPyV) infection may have a role in the pathogenesis of Merkel-cell carcinoma (MCC), a rare neuroendocrine carcinoma of the skin.

Methods:

We studied incidence of chronic lymphocytic leukaemia (CLL) and MCC from the files of the Finnish Cancer Registry and the largest hospital of Finland, Helsinki University Central Hospital, from 1979 to 2006. Presence of MCPyV DNA in MCCs was investigated by quantitative PCR.

Results:

We identified 4164 patients diagnosed with CLL and 172 diagnosed with MCC. Six patients diagnosed with both diseases were found; CLL was the first diagnosis in four cases and MCC in two. The standardised incidence ratio (SIR) for CLL after the diagnosis of MCC was highly elevated, 17.9 (95% confidence interval (CI), 2.2–64.6; P<0.001), and the SIR for MCC after the diagnosis of CLL was also elevated, 15.7 (3.2–46.0, P<0.01). Merkel-cell polyomavirus DNA was present in all five MCCs with tumour tissue available for analysis.

Conclusions:

We conclude that patients diagnosed with CLL have a substantially increased risk for MCC, and vice versa. Merkel-cell polyomavirus DNA is frequently present in MCCs that occur in CLL patients. Immunosuppression related with CLL and viral infection might explain the association between CLL and MCC.

Human Merkel cell polyomavirus infection II. MCV is a common human infection that can be detected by conformational capsid epitope immunoassays

Merkel cell polyomavirus (MCV) is a newly-discovered human tumor virus found in approximately 80% of Merkel cell carcinoma (MCC). The rate of MCV infection among persons without MCC is unknown. We developed a MCV virus-like particle (VLP) enzyme-linked immunoassay (EIA) that does not cross-react with human BK or murine polyomaviruses. Peptide mapping of the MCV VP1 gene and immunoblotting with denatured MCV VLP are less sensitive than the MCV EIA in detecting MCV antibodies suggesting antibody reactivity in this assay primarily targets conformational but not linear epitopes. Among MCC patients, all 21 (100%) patients tested with MCV-positive tumors had high serum MCV IgG but not high MCV IgM levels. Only 3 of 6 (50%) MCC patients with MCV-negative tumors were positive for MCV antibodies. Sera from most adults, including 107 of 166 (64%) blood donors, 63 of 100 (63%) commercial donors and 37 of 50 (74%) systemic lupus erythematosus patients, show evidence for prior MCV exposure. Age-specific MCV prevalence was determined by examining a cross-sectional distribution of 150 Langerhans cell histiocytosis (an unrelated neoplasm) patient sera. MCV prevalence increases from 50% among children age 15 years or younger to 80% among persons older than 50 years. We did not find evidence for vertical transmission among infants. Although past exposure to MCV is common among all adult groups, MCC patients have a markedly elevated MCV IgG response compared with control patients. Our study demonstrates that MCV is a widespread but previously unrecognized human infection.

Array-CGH reveals recurrent genomic changes in Merkel cell carcinoma including amplification of L-Myc

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer with poorly characterized genetics. We performed high resolution comparative genomic hybridization on 25 MCC specimens using a high-density oligonucleotide microarray. Tumors frequently carried extra copies of chromosomes 1, 3q, 5p, and 6 and lost chromosomes 3p, 4, 5q, 7, 10, and 13. MCC tumors with less genomic aberration were associated with improved survival (P=0.04). Tumors from 13 of 22 MCC patients had detectable Merkel cell polyomavirus DNA, and these tumors had fewer genomic deletions. Three regions of genomic alteration were of particular interest: a deletion of 5q12-21 occurred in 26% of tumors, a deletion of 13q14-21 was recurrent in 26% of tumors and contains the well-characterized tumor suppressor RB1, and a previously unreported focal amplification at 1p34 was present in 39% of tumors and centers on L-Myc (MYCL1). L-Myc is related to the c-Myc proto-oncogene, has transforming activity, and is amplified in the closely related small cell lung cancer. Normal skin showed no L-Myc expression, whereas 4/4 MCC specimens tested expressed L-Myc RNA in relative proportion to the DNA copy number gain. These findings suggest several genes that may contribute to MCC pathogenesis, most notably L-Myc.

The role of polyomaviruses in human disease

The human polyomaviruses, BK virus and JC virus, have long been associated with serious diseases including polyomavirus nephropathy and progressive multifocal leukoencephalopathy. Both viruses establish ubiquitous, persistent infections in healthy individuals. Reactivation can occur when the immune system is impaired, leading to disease progression. Recently, the human polyomavirus family has expanded with the identification of three new viruses (KI, WU and Merkel cell polyomavirus), all of which may prove to be involved in human disease. This review describes the general aspects of human polyomavirus infections and pathogenicity. Current topics of investigation and future directions in the field are also discussed.