In cancer cells, cyclic AMP-dependent protein kinase (PKA) is secreted into the conditioned medium. This PKA, designated as extracellular protein kinase A (ECPKA), is markedly upregulated in the sera of patients with cancer. The currently available tumor markers are based on the antigen determination method and lack specificity and sensitivity. Here, we present an ECPKA autoantibody detection method for a universal biomarker that detects cancer of various cell types. We tested sera from 295 patients with cancers of various cell types, 155 normal controls, and 55 patients without cancer. The specificity and sensitivity of this autoantibody enzyme immunoassay method were compared with the conventional antigen determination method by receiver-operating characteristic plots. In the sera, the presence of autoantibody directed against ECPKA was highly correlated with cancer. High anti-ECPKA autoantibody titers ( frequency, 90%; mean titer, 3.0) were found in the sera of patients with various cancers, whereas low or negative titers ( frequency, 12%; mean titer, 1.0) were found in the control group. The receiver-operating characteristic plot showed that autoantibody enzyme immunoassay exhibited 90% sensitivity and 88% specificity, whereas the enzymatic assay exhibited 83% sensitivity and 80% specificity. These results show that the autoantibody method distinguished between patients with cancer and controls better than the antigen method could. Our results show that autoantibody ECPKA is a universal serum biomarker for cancers of various cell types. (Cancer Res 2006; 66(18): 8971-4)

The serum of a Wr(a+) woman has becn found to contain an antibody reacting with an antigen of very high incidence. Preliminary tests on the rtrcngth of the Wra antigen on the cella of the antibody forma and the variation of reactions of the antibody with the cells of nonrelated Wr(a+) and Wr(a-) individuals suggest that the antibody may be detecting the antithetical antigen to Wra.

Purpose: CpG DNAs induce cytokines, activate natural killer cells, and elicit vigorous T-cell response leading to antitumor effects. Antisense oligodeoxynucleotides targeted against the RIa subunit of protein kinase A (antisense PKA RIa) induce growth arrest, apoptosis, and differentiation in a variety of cancer cell lines in vitro and in vivo. This study investigated the use of a combinatorial therapy consisting of the RNA-DNA second-generation antisense PKA RIa and the CpG immunomer (CpG DNA linked through 3V -3Vlinkage containing two accessible 5Vends). Experimental Design: HCT-15 multidrug-resistant colon carcinoma growth in nude mice was used as an experimental model. The inhibitory effect on tumor growth and apoptotic activity of antisense RIa and CpG immunomer, singly and in combination, were measured by tumor growth, levels of RIa subunit, and antiapoptotic and proapoptotic proteins. Effect on host-immune system was measured by mouse spleen size, interleukin-6 (IL-6) levels in mouse blood, and nuclear factor-nB (NF-nB) transcription activity in mouse spleen cells. Results: In combination, CpG immunomer and antisense PKA RIa induced additive/supraadditive effect on the inhibition of tumor growth. Antisense RIabut not CpGimmunomer increased Bax and Bak proapoptotic protein levels and decreased Bcl-2 and RIa protein levels in tumor cells. CpG immunomer but not antisense RIa induced an enlargement of mouse spleen, increased IL-6 levels in mouse blood, and increased NF-nB transcription activity in mouse spleen cells. Conclusions: These results show that type IPKA down-regulation and induction of apoptosis in tumor cells by antisense PKA RIa, and host-immune stimulation by CpG immunomer are responsible at the molecular level for the supra-additive effects of tumor growth inhibition. Thus, antisense PKA RIa and CpG immunomer in combination work cooperatively and as tumor-targeted therapeutics to treat human cancer.