Specific immunotherapy targeting MN/CA9 tumor-associated antigen for renal cell carcinoma

MN/CAIX抗原是一种质膜糖蛋白，表达于多种类型的恶性肿瘤中。我们先前的研究表明，大多数肾细胞癌(RCC)都表达这种抗原。我们已经合成了9聚体抗原肽，并将它们用作肿瘤疫苗来研究诱导这种抗原特异性反应的能力。本实验室建立了转导MN/CA9的小鼠肾细胞癌和胚胎成纤维细胞系MN-RencA和MN-3T3。用这些细胞株检测抗原肽免疫BALB/c小鼠后是否能诱导出特异性CTL。用人类白细胞抗原-A24和H-2K^d限制性免疫优势肽免疫BALB/c小鼠，每周免疫一次。第四次免疫后，用肿瘤坏死因子释放法和乳酸脱氢酶释放法检测MN特异性CTL活性。此外，在同基因动物模型上观察了抗原肽疫苗的治疗效果。免疫BALB/c小鼠的脾细胞对MN-RencA和MN-3T3细胞有反应性，即MN抗原肽诱导产生MN特异性CD8CTL前体细胞。在MN-RencA接种后，这种CTL前体被转移到幼小鼠体内，与对照组相比，这些小鼠的荷瘤率显著降低。提示MN抗原肽免疫治疗肾癌可能是一种潜在的治疗方法。

MN/CA IX antigen is a plasma membrane glycoprotein expressed in several types of malignancies. Our previous study revealed that majority of renal cell carcinomas (RCC) express this antigen. We have synthesized 9mer antigen peptides and employed them as tumor vaccines to investigate the ability to induce this antiger specific responses. MN-RenCa and MN-3T3, MN/CA9 transfectant mouse renal cell carcinoma and embryofibroblast cell lines, have been established in our laboratory. Using these cell lines, we examined whether vaccination with the antigen peptides could induce specific CTL.Vaccines were made with HLA-A24 as well as H-2K^d restricted immunodominant peptides, and administrated into BALB/c mice with IFA every week. After the fourth vaccination, MN specific CTL activity was tested by TNF release assay and LDH release assay against MN-3T3. Furthermore, therapeutic efficacy of vaccination with the antigen peptides was investigated in syngeneic animal model. Spleen cells derived from BALB/c mouse vaccinated with antigen peptides showed reactivity against MN-RenCa and MN-3T3 cells, i.e., vaccination with MN antigen peptides resulted in the induction of MN specific CD8+ CTL precursor. This CTL precursor were transferred into naive mice after MN-RenCa inoculation and significantly low tumor-take was observed in these mice compared to control mice. These findings suggest that vaccination with MN antigen peptides may be potential therapeutic approach for RCC.