Does Simian Virus 40 (SV40) Have a Role in UK Malignant Pleural Mesothelioma? No Role is Identified in a Sensitive RNA In Situ Hybridization Study on Potentially Affected Birth Cohorts.

BACKGROUND: Simian virus 40 (SV40)-contaminated polio vaccine was accidentally administered to about one-third of the UK population receiving polio vaccines between 1956 and 1962. SV40 was subsequently demonstrated to be a carcinogenic virus in experimental and animal models. Since then, the SV40 oncogenic protein large T antigen (SV40 Tag) has been shown to cause malignant transformation of asbestos-treated human pleural mesothelial cells and malignant pleural mesotheliomas in asbestos-exposed SV40 Tag transgenic mice. The present study was designed to investigate the possible association of SV40 Tag with human malignant pleural mesothelioma samples from birth cohorts of the UK population exposed to combined peak levels of asbestos and SV40-contaminated polio vaccines. MATERIALS AND METHODS: Tumor and background lung tissue microarrays prepared from archival surgical specimens of 139 pleural mesothelioma cases, collected over a period of 8 years (1998 to 2005), were analyzed. These represented birth cohorts overlapping with the period 1950 to 1960, exposed to a high level of both asbestos and SV40-contaminated live polio vaccines. SV40 Tag mRNA expression was investigated using a highly sensitive and specific SV40 Tag RNA in situ hybridization detection method on the basis of the novel RNAscope technology. RESULTS: SV40 Tag RNA was not detected in any of the 127 evaluable tumor cases, despite appropriate results obtained for the external positive and negative controls included. CONCLUSION: The complete absence of SV40 Tag mRNA in this large series of cases contradicts experimental evidence suggestive of SV40 link with asbestos-exposed malignant pleural mesotheliomas in the UK population. Alternative explanations of the negative findings are discussed to exclude possible confounding factors.

Nuclear grade and necrosis predict prognosis in malignant epithelioid pleural mesothelioma: a multi-institutional study.

A recently described nuclear grading system predicted survival in patients with epithelioid malignant pleural mesothelioma. The current study was undertaken to validate the grading system and to identify additional prognostic factors. We analyzed cases of epithelioid malignant pleural mesothelioma from 17 institutions across the globe from 1998 to 2014. Nuclear grade was computed combining nuclear atypia and mitotic count into a grade of I-III using the published system. Nuclear grade was assessed by one pathologist for three institutions, the remaining were scored independently. The presence or absence of necrosis and predominant growth pattern were also evaluated. Two additional scoring systems were evaluated, one combining nuclear grade and necrosis and the other mitotic count and necrosis. Median overall survival was the primary endpoint. A total of 776 cases were identified including 301 (39%) nuclear grade I tumors, 354 (45%) grade II tumors and 121 (16%) grade III tumors. The overall survival was 16 months, and correlated independently with age (P=0.006), sex (0.015), necrosis (0.030), mitotic count (0.001), nuclear atypia (0.009), nuclear grade (<0.0001), and mitosis and necrosis score (<0.0001). The addition of necrosis to nuclear grade further stratified overall survival, allowing classification of epithelioid malignant pleural mesothelioma into four distinct prognostic groups: nuclear grade I tumors without necrosis (29 months), nuclear grade I tumors with necrosis and grade II tumors without necrosis (16 months), nuclear grade II tumors with necrosis (10 months) and nuclear grade III tumors (8 months). The mitosis-necrosis score stratified patients by survival, but not as well as the combination of necrosis and nuclear grade. This study confirms that nuclear grade predicts survival in epithelioid malignant pleural mesothelioma, identifies necrosis as factor that further stratifies overall survival, and validates the grading system across multiple institutions and among both biopsy and resection specimens. An alternative scoring system, the mitosis-necrosis score is also proposed.

Synergistic targeting of breast cancer stem-like cells by human γδ T cells and CD8+ T cells.

The inherent resistance of cancer stem cells (CSCs) to existing therapies has largely hampered the development of effective treatments for advanced malignancy. To help develop novel immunotherapy approaches that efficiently target CSCs, an experimental model allowing reliable distinction of CSCs and non-CSCs was set up to study their interaction with non-MHC-restricted γδ T cells and antigen-specific CD8+ T cells. Stable lines with characteristics of breast CSC-like cells were generated from ras-transformed human mammary epithelial (HMLER) cells as confirmed by their CD44hi CD24lo GD2+ phenotype, their mesenchymal morphology in culture and their capacity to form mammospheres under non-adherent conditions, as well as their potent tumorigenicity, self-renewal and differentiation in xenografted mice. The resistance of CSC-like cells to γδ T cells could be overcome by inhibition of farnesyl pyrophosphate synthase (FPPS) through pretreatment with zoledronate or with FPPS-targeting short hairpin RNA. γδ T cells induced upregulation of MHC class I and CD54/ICAM-1 on CSC-like cells and thereby increased the susceptibility to antigen-specific killing by CD8+ T cells. Alternatively, γδ T-cell responses could be specifically directed against CSC-like cells using the humanised anti-GD2 monoclonal antibody hu14.18K322A. Our findings identify a powerful synergism between MHC-restricted and non-MHC-restricted T cells in the eradication of cancer cells including breast CSCs. Our research suggests that novel immunotherapies may benefit from a two-pronged approach combining γδ T-cell and CD8+ T-cell targeting strategies that triggers effective innate-like and tumour-specific adaptive responses.

Usual interstitial pneumonia in asbestos-exposed cohorts - concurrent idiopathic pulmonary fibrosis or atypical asbestosis?

AIMS: To determine whether usual interstitial pneumonia (UIP) pattern fibrosis is seen in asbestosis. METHODS AND RESULTS: The occurrence of UIP pattern fibrosis was studied in four asbestos cohorts systematically referred following postmortem to the UK Pneumoconiosis Unit, Cardiff. The combined exposed workforce comprised >25 000 persons. Over the 17-year period, 233 subjects were identified; 210 had degrees of interstitial fibrosis with a fibrotic non-specific interstitial pneumonia pattern and subpleural accentuation, and three showed UIP pattern fibrosis. All three of these cases showed grade 4 fibrosis (honeycombing) with no asbestos fibre dose-response correlation. A Poisson distribution of probability analysis indicated that the observed cases of UIP in this workforce could be wholly accounted for by the prevalence of idiopathic pulmonary fibrosis (IPF) in the population. CONCLUSIONS: UIP pattern fibrosis is rarely observed in asbestos-exposed subjects, and shows no dose-response correlation with asbestos fibres on mineral analysis; this points to an alternative disease, such as IPF. The results indicate that UIP pattern fibrosis should not be regarded as genuine asbestosis, irrespective of the status of asbestos biomarkers, and this impacts upon the postmortem handling of asbestos-related deaths.