Regulatory subunits of PKA define an axis of cellular proliferation/differentiation in ovarian cancer cells.

Background: The regulatory subunit of cAMP-dependent protein kinase (PKA) exists in two isoforms, RI and RII, which distinguish the PKA isozymes, type I (PKA-I) and type II (PKA-II). Evidence obtained from a variety of different experimental approaches has shown that the relative levels of type I and type II PKA in cells can play a major role in determining the balance between cell growth and differentiation. In order to characterize the effect of PKA type I and type II regulatory subunits on gene transcription at a global level, the PKA regulatory subunit genes for RIalpha and RIIbeta were stably transfected into cells of the ovarian cancer cell line (OVCAR8).

Autoantibody cancer biomarker: extracellular protein kinase A.

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 up-regulated in the sera of patients with cancer. The currently available tumor markers are based on the antigen determination method and lack specificity and sensitivity.

A rapid method for microarray cross platform comparisons using gene expression signatures.

Microarray technology has become highly valuable for identifying complex changes in global gene expression patterns. The inevitable use of a variety of different platforms has compounded the difficulty of effectively comparing data between projects, laboratories, and public access databases. The need for consistent, believable results across platforms is fundamental and methods for comparing results across platforms should be as straightforward as possible.

Autoantibody biomarkers in the detection of cancer.

By definition, tumor biomarkers are selective molecules that can distinguish between patients with cancer and controls. Serum tumor markers have been the most widely used approach for cancer detection. However, the limitations of these markers, which are based on the measurement of tumor antigens, preclude their general use in cancer screening and diagnosis.

Chemoprevention with protein kinase A RIalpha antisense in DMBA-mammary carcinogenesis.

Cancer is potentially preventable disease. A surprising variety of intracellular pathways can be a target for chemoprevention. Earlier it was discovered that cAMP-mediated system can play important role in prevention of DMBA-mammary carcinogenesis.

Stability regulation of mRNA and the control of gene expression.

Microarray technology has become highly valuable for identifying complex global changes in gene expression patterns. Standard techniques measure changes in total cellular poly(A) mRNA levels. The assumption that changes in gene expression as measured by these techniques are directly and well correlated with changes in rates of new gene synthesis form the basis of attempts to connect coordinated changes in gene expression with shared transcription regulatory elements.

Tumor reversion: protein kinase A isozyme switching.

The regulatory subunit of cAMP-dependent protein kinase (PKA) exists in the isoforms RI and RII, which distinguish PKA isozymes type I (PKA-I) and type II (PKA-II). Evidence obtained from different experimental approaches-such as site-selective cAMP analogs, antisense oligonucleotides, transcription factor decoys, cDNA microarrays, and gene transfer-has shown that PKA-I and -II are expressed in a balance of cell growth and differentiation. Loss of this balance may underlie cancer genesis and progression.

Effect of genistein on the expression of bone metabolism genes in ovariectomized mice using a cDNA microarray.

Osteoporosis associated with estrogen deficiency is defined as an abnormal decrease in bone mass leading to an increased fracture risk. Genistein (GEN), as a phytoestrogen, is a type of soybean-derived isoflavone that possesses structural similarity to estrogen. In this study, we assessed the effect of GEN in ovariectomized (OVX) mice.

CpG immunomer DNA enhances antisense protein kinase A RIalpha inhibition of multidrug-resistant colon carcinoma growth in nude mice: molecular basis for combinatorial therapy.

Purpose: CpG DNAs induce cytokines, activate natural killer cells, and elicit vigorous T-cell response leading to antitumor effects. Antisense oligodeoxynucleotides targeted against the RIalpha subunit of protein kinase A (antisense PKA RIalpha) 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 RIalpha and the CpG immunomer (CpG DNA linked through 3'-3' linkage containing two accessible 5' ends).

Control of gene expression during T cell activation: alternate regulation of mRNA transcription and mRNA stability.

Background: Microarray technology has become highly valuable for identifying complex global changes in gene expression patterns. The effective correlation of observed changes in gene expression with shared transcription regulatory elements remains difficult to demonstrate convincingly. One reason for this difficulty may result from the intricate convergence of both transcriptional and mRNA turnover events which, together, directly influence steady-state mRNA levels.

Down-regulation of regulatory subunit type 1A of protein kinase A leads to endocrine and other tumors.

Mutations of the human type Ialpha regulatory subunit (RIalpha) of cyclic AMP-dependent protein kinase (PKA; PRKAR1A) lead to altered kinase activity, primary pigmented nodular adrenocortical disease, and tumors of the thyroid and other tissues. To bypass the early embryonic lethality of Prkar1a(-/-) mice, we established transgenic mice carrying an antisense transgene for Prkar1a exon 2 (X2AS) under the control of a tetracycline-responsive promoter. Down-regulation of Prkar1a by up to 70% was achieved in transgenic mouse tissues and embryonic fibroblasts, with concomitant changes in kinase activity and increased cell proliferation, respectively.

Protein kinase A isozyme switching: eliciting differential cAMP signaling and tumor reversion.

The cAMP-dependent protein kinase types I (PKA-I) and II (PKA-II), composed of identical catalytic (C) subunits but distinct regulatory (R) subunits (RI versus RII), are expressed in a balance of cell growth and differentiation. Distortion of this balance may underlie tumorigenesis and tumor growth. Here, we used PC3M prostate carcinoma cells as a model to overexpress wild type and mutant R and C subunit genes and examined the effects of differential expression of these genes on tumor growth.

Antisense protein kinase A RIalpha inhibits 7,12-dimethylbenz(a)anthracene-induction of mammary cancer: blockade at the initial phase of carcinogenesis.

Purpose: There are two types of cyclic AMP (cAMP)-dependent protein kinase (PKA), type I (PKA-I) and type II (PKA-II), which share a common catalytic (C) subunit but contain distinct regulatory (R) subunits, RI versus RII, respectively. Evidence suggests that increased expression of PKA-I and its regulatory subunit (RIalpha) correlates with tumorigenesis and tumor growth. We investigated the effect of sequence-specific inhibition of RIalpha gene expression at the initial phase of 7,12-dimethylbenz(alphaa)anthracene (DMBA)-induced mammary carcinogenesis.

Application of z-score transformation to Affymetrix data.

Z-score transformation has been successfully used as a normalisation procedure for microarray data generated using radioactively labelled probes with spotted cDNA arrays. One of the advantages of the z-score transformation method is that it provides a way of standardising data across a wide range of experiments and allows the comparison of microarray data independent of the original hybridisation intensities. The feasibility of applying z-score transformation to other types of linear microarray data, specifically that generated using fluorescently labelled probes with Affymetrix chips, was tested in three separate scenarios and is discussed here.

Antisense protein kinase A RI alpha-induced tumor reversion: portrait of a microarray.

Antisense oligonucleotides can selectively block disease-causing genes due to the specificity of the Watson-Crick base-pairing mechanism of action. A genome-wide view of antisense technology is illustrated via protein kinase A RI alpha antisense. Complementary DNA microarray analysis of the RI alpha antisense-induced expression profile shows the up- and down-regulation of clusters of coordinately expressed genes that define the molecular portrait of a reverted tumor cell phenotype.

CRE-enhancer DNA decoy: a tumor target-based genetic tool.

Enhancer DNA decoy oligonucleotides (ODNs) inhibit transcription by competing for transcription factors. A decoy ODN composed of the cAMP response element (CRE) inhibits CRE-directed gene transcription and tumor growth without affecting normal cell growth. We used DNA microarrays to analyze the global gene expression in tumors exposed to the CRE-decoy ODN.

Gene expression profiling of oxidative stress on atrial fibrillation in humans.

Atrial Fibrillation (AF) is thought be caused by oxidative stress. Oxidative stress at the cellular level results from many factors, including exposure to alcohol, medications, cold, toxins or radiation. In this study we investigated gene transcriptional profiles on the human myocardial tissues from AF and oxidative stress conditions.

Antisense DNAs as targeted genetic medicine to treat cancer.

Nucleic acid therapies represent a direct genetic approach for cancer treatment. Such an approach takes advantage of mechanisms that activate genes known to confer a growth advantage to neoplastic cells. The ability to block the expression of these genes allows exploration of normal growth regulation.

Antisense protein kinase A RIalpha acts synergistically with hydroxycamptothecin to inhibit growth and induce apoptosis in human cancer cells: molecular basis for combinatorial therapy.

Purpose: The increased expression of RIalpha, the regulatory subunit of cyclic AMP (cAMP)-dependent protein kinase type I (PKA-I), has been correlated with cancer cell growth. An antisense oligonucleotide targeting the RIalpha subunit of PKA (antisense RIalpha) induces cell growth arrest, apoptosis, and differentiation in a variety of cancer cell lines in vitro and in tumors in vivo. This study investigated the utility of a combinatorial therapy consisting of the RNA-DNA second-generation RIalpha antisense HYB0165 (Gem231) and the cytotoxic drug hydroxycamptothecin (HCPT), which inhibits topoisomerase I.

A genomic-scale view of the cAMP response element-enhancer decoy: a tumor target-based genetic tool.

Enhancer DNA decoy oligodeoxynucleotides (ODNs) inhibit transcription by competing for transcription factors. A decoy ODN composed of the cAMP response element (CRE) inhibits CRE-directed gene transcription and tumor growth without affecting normal cell growth. Here, we use DNA microarrays to analyze the global effects of the CRE-decoy ODN in cancer cell lines and in tumors grown in nude mice.

Antisense DNAs as targeted therapeutics for cancer: no longer a dream.

Progress in antisense technology has been rapid, and the traditional antisense inhibition of gene expression has now been viewed at a genomic scale. This global view has led to a deeper understanding of the mechanism of action, the elimination of non-specific and undesirable side effects and, ultimately, greater efficacy and reduced toxicity for nucleic acid medicines. Several antisense oligonucleotides are in clinical trials; these are well tolerated and have therapeutic potential.

Dissecting the circuitry of protein kinase A and cAMP signaling in cancer genesis: antisense, microarray, gene overexpression, and transcription factor decoy.

Expression of the RI alpha subunit of the cAMP-dependent protein kinase type I (PKA-I) is enhanced in human cancer cell lines, in primary tumors, in transformed cells, and in cells upon stimulation of growth. Signaling via the cAMP pathway may be complex, and the biological effects of the pathway in normal cells may depend upon the physiological state of the cells. However, results of different experimental approaches such as antisense exposure, 8-Cl-cAMP treatment, and gene overexpression have shown that the inhibition of RI alpha/PKA-I exerts antitumor activity in a wide variety of tumor-derived cell lines examined in vitro and in vivo.

7-Benzylamino-6-chloro-2-piperazino-4-pyrrolidino-pteridine, a potent inhibitor of cAMP-specific phosphodiesterase, enhancing nuclear protein binding to the CRE consensus sequence in human tumour cells.

The cAMP-specific phosphodiesterase isoenzyme family PDE4 represents the highest cAMP-hydrolysing activity in many human cancer cell lines including the human large cell lung carcinoma cell line LXFL529L. Treatment of LXFL529L cells with the potent PDE4 inhibitor 7-benzylamino-6-chloro-2-piperazino-4-pyrrolidino-pteridine (DC-TA-46) induces dose-dependent growth inhibition. Cells are arrested in the G(1)-phase of the cell cycle and the induction of apoptosis is observed.