Comparisons for detecting NY-ESO-1 mRNA expression levels in hepatocellular carcinoma tissues

Abstract

Abstract. NY-ESO-1 is a cancer/testis (CT) antigen expressed in normal adult tissues solely in the testicular germ cells of normal adults and in various cancers. It induces specific humoral and cellular immunity in patients with NY-ESO-1-expressing cancer. We compared the expression of NY-ESO-1 mRNA in hepatocellular carcinoma (HCC) patients by using various primers and DNA polymerases to optimize RT-PCR conditions and to evaluate the correlations among the expression levels of NY-ESO-1, LAGE-1 and SSX-1 and clinical parameters. We determined differences in the abilities of the various primers and DNA polymerases to amplify the NY-ESO-1 gene at different exons. Primers designated as P3 detected targeted sequences better than primers P1 and P2; AmpliTaq Gold ® DNA polymerase was more effective than Platinum ® pfx DNA polymerase and Taq DNA polymerase. NY-ESO-1, LAGE-1 and SSX-1 mRNAs were detected in 29.7, 45.3 and 37.5%, respectively, of the 64 HCC specimens. No CT antigen mRNAs were detected in the 64-paired adjacent non-cancerous tissues. The frequency for the coexpression of one, two or three antigens of NY-ESO-1, LAGE-1 and SSX-1 was 57.8, 35.9 and 18.8%, respectively. We also analyzed the relationships among the CT antigen expression levels and several clinical parameters. There were no significant differences between CT antigen expression levels and clinical parameters, except the correlations between the expression of SSX-1 and the age of the patients. IntroductionHepatocellular carcinoma (HCC) is the sixth most common cancer worldwide; because of its poor prognosis, the number of HCC-related deaths is almost identical. Thus, HCC represents the third most common cause of cancer-related deaths world-wide. Eighty-two percent of all cases (and hence deaths) are in developing countries (55% in P.R. China alone) (1). The mortality of HCC is the second highest among that caused by malignant tumors in P.R. China. The annual death toll for HCC in P.R. China is ranked at number one in the world. Hepatic surgery is a principal treatment for HCC and has achieved significant advances in recent years; however, the recurrence and metastasis of HCC are still the major problems associated with its high mortality (2,3).Ideally, cancer therapy should possess sufficient potency to eradicate systemic tumors in multiple body sites and the specificity to discriminate between neoplastic and nonneoplastic cells. In both of these respects, immunotherapy is an attractive approach. The first step of active immunotherapy is to identify cogent antigen targets for HCC. Among tumor antigens identified to date, cancer/testis (CT) antigens have been recognized as a group of highly attractive targets for cancer vaccine development. CT antigen-encoding genes comprise 44 families, including the NY-ESO-1 (4), MAGE (5) and SSX (6) gene groups. In view of the expanding list of CT genes and their significance to antigen-specific cancer vaccine development, a CT gene database to accumulate relevant data at a single web interface has been created...