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Epigenetic mechanisms such as aberrant DNA methylation (DNAme) are known to drive esophageal squamous cell carcinoma (ESCC), yet they remain poorly understood. Here, we studied tumor-specific DNAme in ESCC cases from nine high-incidence countries of Africa, Asia, and South America. Infinium MethylationEPIC array was performed on 108 tumors and 51 normal tissues adjacent to the tumors (NAT) in the discovery phase, and targeted pyrosequencing was performed on 132 tumors and 36 NAT in the replication phase. Top genes for replication were prioritized by weighting methylation results using RNA-sequencing data from The Cancer Genome Atlas and GTEx and validated by qPCR. Methylome analysis comparing tumor and NAT identified 6,796 differentially methylated positions (DMP) and 866 differential methylated regions (DMR), with a 30% methylation (Δβ) difference. The majority of identified DMPs and DMRs were hypermethylated in tumors, particularly in promoters and gene-body regions of genes involved in transcription activation. The top three prioritized genes for replication, PAX9, SIM2 , and THSD4 , had similar methylation differences in the discovery and replication sets. These genes were exclusively expressed in normal esophageal tissues in GTEx and downregulated in tumors. The specificity and sensitivity of these DNAme events in discriminating tumors from NAT were assessed. Our study identified novel, robust, and crucial tumor-specific DNAme events in ESCC tumors across several high-incidence populations of the world. Methylome changes identified in this study may serve as potential targets for biomarker discovery and warrant further functional characterization. SIGNIFICANCE: This largest genome-wide DNA methylation study on ESCC from high-incidence populations of the world identifies functionally relevant and robust DNAme events that could serve as potential tumor-specific markers. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/10/2612/F1.large.jpg., (©2021 American Association for Cancer Research.)

Human papillomavirus (HPV) infections have been implicated in lung carcinogenesis, but causal associations remain uncertain. We evaluated a potential causal role for HPV infections in lung cancer through an analysis involving serology, tumor DNA, RNA, and p16 protein expression. Association between type-specific HPV antibodies and risk of lung cancer was examined among 3,083 cases and 4,328 controls in two case-control studies (retrospective) and one nested case-control study (prospective design). Three hundred and thirty-four available tumors were subjected to pathologic evaluation and subsequent HPV genotyping following stringent conditions to detect all high-risk and two low-risk HPV types. All HPV DNA-positive tumors were further tested for the expression of p16 protein and type-specific HPV mRNA. On the basis of the consistency of the results, although HPV11 and HPV31 E6 antibodies were associated with lung cancer risk in the retrospective study, no association was observed in the prospective design. Presence of type-specific antibodies correlated poorly with the presence of the corresponding HPV DNA in the tumor. Although nearly 10% of the lung tumors were positive for any HPV DNA (7% for HPV16 DNA), none expressed the viral oncogenes. No association was observed between HPV antibodies or DNA and lung cancer survival. In conclusion, we found no supportive evidence for the hypothesized causal association between HPV infections and lung cancer., (©2014 American Association for Cancer Research.)

Lymphatic vessel endothelial hyaluronan receptor (LYVE)-1 is thought to be restricted to lymph vessels and has been used as such to show that tumor lymphangiogenesis occurs on overexpression of lymphangiogenic factors in mouse tumor models. However, these studies have not yet been corroborated in human tumors. Here we show, first, that LYVE-1 is not exclusive to the lymph vessels. Indeed, LYVE-1 is also present in normal hepatic blood sinusoidal endothelial cells in mice and humans. Surprisingly, LYVE-1 is absent from the angiogenic blood vessels of human liver tumors and only weakly present in the microcirculation of regenerative hepatic nodules in cirrhosis, though both vessels are largely derived from the liver sinusoids. Second, we propose a novel approach to identify lymphatics in human and murine liver. By combining LYVE-1 and Prox 1 (a transcription factor) immunohistochemistry, we demonstrate that lymphatics are abundant in cirrhosis. In contrast, in human hepatocellular carcinoma and liver metastases, they are restricted to the tumor margin and surrounding liver. The absence of intratumor lymphatics in hepatocellular carcinomas and liver metastases may impair molecular and cellular transport in these tumors. Finally, the presence of LYVE-1 in liver sinusoidal endothelia suggests that LYVE-1 has functions beyond the lymph vascular system.