CpG Immunomer DNA Enhances Antisense Protein Kinase A RIα Inhibition of Multidrug-Resistant Colon Carcinoma Growth in Nude Mice: Molecular Basis for Combinatorial Therapy

Abstract

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.

Lung Cancer Signature Biomarkers: tissue specific semantic similarity based clustering of Digital Differential Display (DDD) data

“…But increased level of copper in lewis lung carcinoma cells were related with the development of multi drug resistance [24]. The PRKAR1A down-regulation also linked to multidrug-resistant (MDR) in colon carcinoma cells [25]. The COPB1 was an essential component for the coatomer formation [26].…”

The Ile646Val (2073A>G) Polymorphism in the Kinase-Binding Domain of A-Kinase Anchoring Protein 10 and the Risk of Colorectal Cancer

“…Furthermore, Cho et al [3] have provided evidence that the extracellular PKA is up-regulated in colon carcinoma cells, which suggests that PKA could be used as a diagnostic and prognostic biomarker for CRC. Using an antisense oligonucleotide targeting the PKA-RIα, several therapeutic strategies for treating cancers, including CRC, have been developed [19,20,21,22,23]. The increased ability of the AKAP10 Val646 variant to bind and localize PKA to its subcellular substrates may be a disadvantage for the cell in carcinogenesis, resulting in a stronger mitogen effect of PKA [12].…”

Dichotomous role of protein kinase A type I (PKAI) in the tumor microenvironment: A potential target for ‘two-in-one’ cancer chemoimmunotherapeutics

“…Similarly, AS-PKAI inhibited HCT-15 multidrug resistant colon carcinoma growth in nude mice involving modulation of apoptotic proteins in correlation to RIα to RIIβ switching. Proapoptotic proteins BAX and BAK increased, whereas Bcl-2 (anti-apoptotic) and RIα levels decreased [50]. The above described findings indicate that PKA isozyme switching via selective RI/PKAI inhibition may reverse MDR.…”

“…1 in reference [39]), and is also downstream to various hormones and growth factors (EGF, transforming growth factor (TGF)-α, etc. ), cooperating in the transduction and amplification of their mitogenic signals in neoplastic transformation [39][40][41][42][43]; e RI/PKAI, through its propagative interaction with EGFR signaling system, may have a role in tumor-associated angiogenesis by controlling the expression of angiogenic growth factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) [41][42][43][44]; f RI/PKAI has a structural association with apoptotic machinery, including cytochrome c oxidase and anti-apoptotic Bcl-2 family, and its pharmacological inhibition may trigger the apoptosis and suppress the transduction of survival signals in cancer cells, indicating an anti-apoptotic role of RIα/PKAI in tumorigenesis and tumor growth [42,[45][46][47][48][49]; g Pharmacological inhibition of RI/PKAI may revert multidrug resistance (MDR) in a variety of multidrug resistant cancer cell lines, suggesting RI/PKAI is associated with multidrug resistant phenotypes of cancer [50][51][52][53]; and h The synthesis and the relative abundance of RIα/PKAI isoform in relevance to RIIβ/PKAII is differentially regulated during cellular proliferation/differentiation and neoplastic transformation [22].…”