15 Shen and colleagues used a reliable model for studying the cellular and molecular mechanisms involved in carcinogenesis of esophageal carcinomas. In order to demonstrate the effect of viruses and tumor promoters on the tumorigenicity, human embryonic esophageal cells were infected with HPV-18 E6 E7-AAV in synergy with exposure to 12-o-tetradecanoyl phorbol 13-acetate (TPA). Malignant transformation of human embryonic epithelial cells was induced in vitro by HPV-18 E6E7 in synergy with TPA. This is a good evidence for the close relationship between HPV-18 as

an etiologic factor and pathogenesis of esophageal carcinoma.16 In contrast to the above mentioned studies, there are several reports originating mainly from western Inhibitors,research,lifescience,medical European countries and United States of America that show the absence of HPV DNA in ESCCs. Some of these studies show only rare association of HPV DNA with ESCCs. Morgan

and colleagues used PCR to Inhibitors,research,lifescience,medical examine frozen tissue from 22 cases of ESCCs for the presence of specific DNA sequences from oncogenic strains of HPV. The products of PCR were further analyzed by southern blot hybridization (SBH). No HPV sequences were detected in any tumor, suggesting it is unlikely, therefore, that HPV plays a significant role in the pathogenesis of Inhibitors,research,lifescience,medical ESCCs in the United Kingdom.17 Saegusa and colleagues examined 103 esophageal carcinomas by PCR method using two consensus (targeting either the L1 or the E6-E7 regions) and two type specific (type 16 and type 18) primer sets. However, the entire series

of tumor DNA were negative for HPV sequences by PCR assays using all four primer sets.18 This study was designed to evaluate prevalence of HPV in ESCC cases diagnosed in Pathology Department, Medical School, Shiraz University of Inhibitors,research,lifescience,medical Inhibitors,research,lifescience,medical Medical Sciences. Materials and Methods All cases of ESCC that were Tyrphostin B42 reported between years 1982 to 2002 in the Pathology Department, Medical School were identified. All slides of ESCC cases (n=92) available in the departmental archive were reviewed, and the best slides and their paraffin-embedded tissue blocks were extracted. In addition, slides and paraffin-embedded tissue blocks of normal esophagus from 20 autopsy cases (15-80 years), who referred to the Department between 1996 to 2000, were extracted. To prepare DNA sample from each block one section for hematyoxyllin eosin (H&E) staining and 15 sections for DNA extraction were prepared. second All sections had a thickness of 5 µm. The sections for DNA extraction placed in two microfuge tubes. Another section was prepared for H&E staining, and was used to confirm the presence of tumor tissue in all previous sections taken for DNA extraction. In order to prevent cross contamination and pick up of sectioned tissues from previous blocks, blade of microtome, working instruments, and surfaces were cleaned by Xylol and HCL 1N before starting with another block.