Difference in expression level and localization of DNA polymerase beta among human esophageal cancer focus, adjacent and corresponding normal tissues

Abstract

The aim of this paper was to study the expression level and localization of DNA polymerase beta (polbeta) and the difference in those among the human esophageal cancer focus, cancer adjacent and corresponding normal esophageal tissues. These three kinds of tissues were collected from surgically resected tissues in 17 patients with esophageal carcinoma in Linzhou, China. Each of a total of 51 tissue pieces was divided into two aliquots: one aliquot for detection of polbeta expression by in situ hybridization and by immunohistochemistry; another for detection of polbeta expression by RNA dot blot and immunoblotting. In the tissue specimens detected by in situ hybridization and immunohistochemistry, the cancer focus tissue had much stronger polbeta expression signals localized in the scattered heteromorphologic cancer cells. The cancer adjacent tissue exhibited slightly stronger polbeta signals mainly localized in the epithelial proliferating cells and the corresponding normal tissue displayed weak polbeta signals basically located in the epithelial basal cells. The difference in expression level of polbeta among the three kinds of tissues detected by RNA dot blot and immunoblotting was similar to the above results. Further, the truncated POLB could be demonstrated in both cancer focus and cancer adjacent tissues, but could not be found in the corresponding normal tissue in immunoblotting. The results suggest that the overexpression of polbeta with truncated form may be a potential biomarker for early diagnosis of human esophageal carcinoma.

RETRACTED ARTICLE: HAX-1 Promotes the Chemoresistance, Invasion, and Tumorigenicity of Esophageal Squamous Carcinoma Cells

“…Previous studies have shown that pol b is up-regulated in ovarian, prostate, breast, and colon cancer tissues compared to adjacent normal tissues [9][10][11]. Moreover, pol b overexpression has been detected in esophageal carcinoma by in situ hybridization and immunohistochemistry [12]. pol b overexpression in cancer cells has been shown to be regulated at post-transcriptional level by HCLS1-associated protein X-1 (HAX-1), because the 3 0 UTR of the pol b mRNA contains three stem-loop structures that modulates gene expression [13].…”

A platinum agent resistance gene, POLB, is a prognostic indicator in colorectal cancer

“…Srivastava et al [9] found elevated levels of POLB expression in breast, colon and prostate cancers, and speculated that the more advanced tumors may have increased amounts of damaged DNA requiring repair by the higher levels of POLB. Dong et al [10] examined expression of POLB in surgically resected specimens in 17 patients with esophageal cancer, and found that POLB expression in tumor tissue was higher than in the corresponding normal tissue. At present, there is little information regarding POLB expression and its clinicopathologic significance in CRC.…”

DNA polymerase beta overexpression correlates with poor prognosis in esophageal cancer patients

“…They found that the major BER DNA polymerase, pol, was overexpressed in approximately one-third of all tumors sampled and pol was most frequently overexpressed in cancers in vivo of uterus, ovary, prostate and stomach. Our group has carried out series of researches focused on expression of DNA pol in esophageal cancer, and one of our findings is the high expression of pol in esophageal tumors, which correlates to drug-resistance of this malignancy [19][20][21][22]. In this research, we analyzed the clinical and pathological significance of pol as well as its correlation to survival of the patients, through testing its expression in both esophageal tumors and the matched normal tissues adjacent to tumor.…”