Expression and immunogenicity of a tumor-associated antigen, 90K/Mac-2 binding protein, in lung carcinoma
Yoshitomo Ozaki1, Keiichi Kontani, Jun Hanaoka
1Second Department of Surgery, Shiga University of Medical Science, Otsu, Japan.
Background:
The authors attempted to obtain shared proteins among lung carcinoma cells by column chromatographies. A glycoprotein with approximately 500 kDa isolated from QG56 cells showed an identical amino acid sequence to 90K/Mac-2 binding protein (M2BP). This protein has been reported to be highly expressed and to modulate the expression of surface molecules involved in immune responses on cultured cancer cells. Therefore, it would be beneficial for M2BP to be targeted in cancer immunotherapy.
Methods:
The authors analyzed the expression of M2BP in lung carcinoma cells and M2BP's immunogenicity as a tumor antigen. Eight cultured lung carcinoma cell lines and 28 tumor tissues from patients with lung carcinoma were examined for the expression of M2BP mRNA and protein. Sera from cancer patients (n = 23) and healthy donors (n = 19) were studied for their reactivity to M2BP peptides by enzyme-linked immunosorbent assay.
Results:
Seven of the 8 (87.5%) lung carcinoma cell lines and 17 of the 28 (60.7%) tumor tissues expressed high levels of M2BP mRNA. Most of the M2BP mRNA-positive cancer cell lines and tumors also showed M2BP protein expression. The serum levels of antibodies to M2BP were elevated in 30.4% of the patients. In addition, M2BP-specific immunoglobulin G was observed in all patients with anti-M2BP antibodies.
Conclusions:
M2BP is highly expressed in lung carcinoma cells and is sufficiently immunogenic to elicit specific immunity to this molecule in patients with lung carcinoma. M2BP is expected to be useful as a tumor marker and a target antigen in cancer immunotherapy.
