GKAP1 functions as an anchoring protein for cGK-Iα and appears to be similar to AKAP (A kinase anchoring protein), which binds to cAK via its regulatory subunits. Hanafusa et al. performed SEREX analysis on colon cancer, and identified the novel CT antigen, Tektin 5 (TEKT5) [32]. TETKs are composed of a family of filament-forming proteins in the male germ cell-lineage in centrioles and basal bodies and within ciliary and flagellar doublet microtubules [64]. They were originally isolated from sea urchin sperm.
Five types of mammalian Tektins have been identified in various animals, including the mouse, rat, and human [65]. TEKT5 was initially identified in the rat. It is present in sperm flagella, plays an important role in flagella formation during spermiogenesis, buy Olaparib and has also been implicated in sperm motility. The human TEKT5 gene consists of 7 exons and is located on chromosome 16p13.13.
The expression of TEKT5 mRNA was restricted to the testis in normal adult tissues. It was detected in several types of cancers, including colon, gastric, liver, lung, and prostate cancers, but not in HNSCC. cDNA microarray analysis revealed that the expression of TEKT5 was higher in 2 of 3 colon cancer tissues than in normal tissue. It was selleck inhibitor also up-regulated by more than 3-fold in 50% of the lung cancer specimens examined. Thus, TEKT5 has a classical future as a Astemizole CT antigen. In our survey of 101 cancer patients with several types of cancer, 13 patients were found to have produced an antibody to the TEKT5 protein. No reactivity was observed in sera from healthy donors. TETK5
appears to have high immunogenic potential in terms of antibody frequency [32]. We evaluated the patterns and levels of expression of 8 CT genes by RT-PCR from a panel of primary HNSCC. Over 50% of the tumors examined expressed at least 1 CT gene. The coexpression of two or more genes was detected in 23% of HNSCC. The most frequently expressed gene was MAGE-A4 (32%), followed by MAGE-A3 (24%), GKAP1 (18%), MAGE-A1 (13%), CCDC62-2 (12%), SSX-2 (11%), XAGE-1b (7%), and NY-ESO-1 (3%) [31]. Using monoclonal antibodies, the expression of CT antigen proteins in multigene-expressed HNSCC tissue was analyzed using an immunohistochemical technique. The heterogeneous expression of CCDC62-2 and MAGE-A proteins was detected in HLA class I positive HNSCC ( Fig. 3). CD8 positive T cells were also occasionally observed. Humoral immune responses in cancer patients have been investigated broadly by ELISA against recombinant CT antigen proteins. The frequency of antibody responses to MAGE was shown to be low in these patients [7] and [45]. In contrast, the anti-NY-ESO-1 antibody has been detected in many cancer types, including melanoma, lung, ovarian, breast, and bladder cancer.