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V Damiano

Publications and source records attributed to V Damiano.

At least 19 recordsLinked to original sources
PubMed2000

Gemcitabine combined with continuous infusion 5-fluorouracil in advanced and symptomatic pancreatic cancer: a clinical benefit-oriented phase II study.

Gemcitabine and 5-fluorouracil are the only two compounds with reproducible activity against advanced pancreatic cancer (APC). We have evaluated a novel combination of gemcitabine and 5-fluorouracil on the clinical benefit response (CBR) end point. Eleven consecutive patients with symptomatic APC were entered in a two-stage phase II trial. Gemcitabine was administered by intravenous (i.v.) bolus injection at the dose of 1,000 mg m(-2) on days 1, 8, 15 and 5-fluorouracil 500 mg m(-2) was given by continuous i.v. infusion on days 1-5. Treatment was repeated every 28 days. A CBR was achieved in 7/11 patients. The mean time to loss of CBR was 26.5 weeks (range 14-18, median 22). Toxicity was mild and no APC patient experienced WHO grade 3 toxicity. The gemcitabine/5-fluorouracil combination is well tolerated and produces a symptomatic relief in the majority of APC patients.

Adult↗
PubMed2000

Antitumor effect and potentiation of cytotoxic drugs activity in human cancer cells by ZD-1839 (Iressa), an epidermal growth factor receptor-selective tyrosine kinase inhibitor.

Transforming growth factor alpha (TGF-alpha) is an autocrine growth factor for human cancer. Overexpression of TGF-alpha and its specific receptor, the epidermal growth factor receptor (EGFR), is associated with aggressive disease and poor prognosis. The EGFR has been proposed as a target for anticancer therapy. Compounds that block ligand-induced EGFR activation have been developed. ZD-1839 (Iressa) is a p.o.-active, quinazoline derivative that selectively inhibits the EGFR tyrosine kinase and is under clinical development in cancer patients. The antiproliferative activity of ZD-1839 alone or in combination with cytotoxic drugs differing in mechanism(s) of action, such as cisplatin, carboplatin, oxaliplatin, paclitaxel, docetaxel, doxorubicin, etoposide, topotecan, and raltitrexed, was evaluated in human ovarian (OVCAR-3), breast (ZR-75-1, MCF-10A ras), and colon cancer (GEO) cells that coexpress EGFR and TGF-alpha. ZD-1839 inhibited colony formation in soft agar in a dose-dependent manner in all cancer cell lines. The antiproliferative effect was mainly cytostatic. However, treatment with higher doses resulted in a 2-4-fold increase in apoptosis. A dose-dependent supra-additive increase in growth inhibition was observed when cancer cells were treated with each cytotoxic drug and ZD-1839. The combined treatment markedly enhanced apoptotic cell death induced by single-agent treatment. ZD-1839 treatment of nude mice bearing established human GEO colon cancer xenografts revealed a reversible dose-dependent inhibition of tumor growth because GEO tumors resumed the growth rate of controls at the end of the treatment. In contrast, the combined treatment with a cytotoxic agent, such as topotecan, raltitrexed, or paclitaxel, and ZD-1839 produced tumor growth arrest in all mice. Tumors grew slowly for approximately 4-8 weeks after the end of treatment, when they finally resumed a growth rate similar to controls. GEO tumors reached a size not compatible with normal life in all control mice within 4-6 weeks and in all single agent-treated mice within 6-8 weeks after GEO cell injection. In contrast, 50% of mice treated with ZD-1839 plus topotecan, raltitrexed, or paclitaxel were still alive 10, 12, and 15 weeks after cancer cell injection, respectively. These results demonstrate the antitumor effect of this EGFR-selective tyrosine kinase inhibitor and provide a rationale for its clinical evaluation in combination with cytotoxic drugs.

Animals↗
PubMed2000

Oral antisense that targets protein kinase A cooperates with taxol and inhibits tumor growth, angiogenesis, and growth factor production.

Protein kinase A type I (PKAI) transduces mitogenic signals from different growth factors and oncogenes and is overexpressed in the majority of human cancers. We and other investigators previously have reported that different PKAI inhibitors, including antisense oligonucleotides, have antitumor activity. In this study, we used a novel hybrid DNA/RNA mixed-backbone oligonucleotide (MBO) targeting the PKAI subunit RIalpha. We demonstrated that after oral administration, the MBO antisense RIalpha inhibited the growth of human colon cancer xenografts in nude mice and showed a cooperative antitumor effect with Taxol, which outlasted treatment withdrawal and significantly prolonged survival of mice compared with untreated controls or to single-agent-treated mice. Immunohistochemical analysis of tumor specimens showed inhibition of target protein RIalpha and of growth factor expression along with a marked inhibition of angiogenesis and an increase in p27 expression. In conclusion, a novel MBO that targets PKAI, administered p.o., is effective and cooperates with the anticancer drug Taxol on both tumor growth and expression of factors involved in the control of cell proliferation, cell cycle, and angiogenesis. Because the MBO described has completed a phase I trial involving i.v. injection in cancer patients, these results provide the biological rationale of its activity after oral administration and may be translated into a therapeutic strategy in a clinical setting.

Administration, Oral↗
PubMed2000

Antiangiogenic and antitumor activity of anti-epidermal growth factor receptor C225 monoclonal antibody in combination with vascular endothelial growth factor antisense oligonucleotide in human GEO colon cancer cells.

Angiogenesis plays a key role in tumor growth and metastasis. The transforming growth factor alpha (TGF-alpha)-epidermal growth factor receptor (EGFR) autocrine pathway controls in part the production of angiogenic factors such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in cancer cells. In this study, we have evaluated the antiangiogenic and antitumor activity of monoclonal antibody (MAb) C225, an anti-EGFR chimeric human-mouse MAb, alone and in combination with a human VEGF antisense (AS) 21-mer phosphorothioate oligonucleotide (VEGF-AS) in human GEO colon cancer cells. MAb C225 treatment determined a dose-dependent inhibition of VEGF, bFGF, and TGF-alpha production by GEO cells in vitro. Treatment with VEGF-AS caused a selective inhibition in VEGF expression by GEO cells in vitro. Treatment of immunodeficient mice bearing established, palpable GEO xenografts for 3 weeks with VEGF-AS or with MAb C225 determined a cytostatic reversible inhibition of tumor growth. In contrast, a prolonged inhibition of tumor growth was observed in all mice treated with the two agents, in combination with a significant improvement in mice survival compared with controls (P < .001), to MAb C225 (P < .001), or to VEGF-AS (P < .001) treated mice. All mice died within 4, 6, and 8 weeks after tumor cell injection in the control, VEGF-AS and MAb C225 groups, respectively. In contrast, 50% of mice treated with the combination of VEGF-AS and MAb C225 were alive at 13 weeks. Ten % of mice treated with VEGF-AS plus MAb C225 were alive at 20 weeks and had no histological evidence of GEO tumors. Immunohistochemical analysis of GEO tumor xenografts demonstrated a significant reduction of VEGF expression after treatment with VEGF-AS with a parallel reduction in microvessel count. MAb C225 treatment determined a reduction in the expression of VEGF, bFGF, and TGF-alpha with a reduction in microvessel count. Finally, a significant potentiation in inhibition of VEGF expression and little or no microvessels were observed in GEO tumors after the combined treatment with the two agents.

Animals↗
PubMed1999

Antitumor activity of sequential treatment with topotecan and anti-epidermal growth factor receptor monoclonal antibody C225.

Epidermal growth factor (EGF)-related proteins such as transforming growth factor alpha (TGF-alpha) control cancer cell growth through autocrine and paracrine pathways. Overexpression of TGF-alpha and/or its receptor (EGFR) has been associated with a more aggressive disease and a poor prognosis. The blockade of EGFR activation has been proposed as a target for anticancer therapy. Monoclonal antibody (MAb) C225 is an anti-EGFR humanized chimeric mouse MAb that is presently in Phase II clinical trials in cancer patients. Previous studies have suggested the potentiation of the antitumor activity of certain cytotoxic drugs, such as cisplatin and doxorubicin, in human cancer cell lines by treatment with anti-EGFR antibodies. We have evaluated in human ovarian, breast, and colon cancer cell lines, which express functional EGFR, the antiproliferative activity of MAb C225 in combination with topotecan, a cytotoxic drug that specifically inhibits topoisomerase I and that has shown antitumor activity in these malignancies. A dose-dependent supraadditive increase of growth inhibition in vitro was observed when cancer cells were treated with topotecan and MAb C225 in a sequential schedule. In this respect, the cooperativity quotient, defined as the ratio between the actual growth inhibition obtained by treatment with topotecan followed by MAb C225 and the sum of the growth inhibition achieved by each agent, ranged from 1.2 to 3, depending on drug concentration and cancer cell line. Treatment with MAb C225 also markedly enhanced apoptotic cell death induced by topotecan. For example, in GEO colon cancer cells, 5 nM topotecan, followed by 0.5 microg/ml MAb C225, induced apoptosis in 45% cells as compared with untreated cells (6%) or to 5 nM topotecan-treated cells (22%). Treatment of mice bearing established human GEO colon cancer xenografts with topotecan or with MAb C225 determined a transient inhibition of tumor growth because GEO tumors resumed the growth rate of untreated tumors at the end of the treatment period. In contrast, an almost complete tumor regression was observed in all mice treated with the two agents in combination. This determined a prolonged life span of the mice that was significantly different as compared with controls (P < 0.001), to MAb C225-treated group (P < 0.001), or to the topotecan-treated group (P < 0.001). All mice of the topotecan plus MAb C225 group were the only animals alive 14 weeks after tumor cell injection. Furthermore, 20% of mice in this group were still alive after 19 weeks. The combined treatment with MAb C225 and topotecan was well tolerated by mice with no signs of acute or delayed toxicity. These results provide a rationale for the evaluation of the anticancer activity of the combination of topoisomerase I inhibitors and anti-EGFR blocking MAbs in clinical trials.

Animals↗
PubMed1998

Cooperative inhibition of renal cancer growth by anti-epidermal growth factor receptor antibody and protein kinase A antisense oligonucleotide.

BACKGROUND: The expression of epidermal growth factor receptor (EGFR) and type I cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKAI) is associated with neoplastic transformation. By use of human renal cancer cell lines (i.e., 769-P, ACHN, A498, and SW839), we investigated the antiproliferative activity and the antitumor activity of an anti-EGFR humanized chimeric mouse monoclonal antibody, MAb C225, and a novel mixed backbone 18-mer antisense oligonucleotide, HYB 190, that targets expression of the RIalpha regulatory subunit of PKAI. METHODS: The antiproliferative activity of MAb C225 and oligonucleotide HYB 190, alone or in combination, on different renal cancer cell lines was determined by monitoring cell growth in soft agar. In addition, the induction of apoptosis by treatment with the anti-EGFR antibody and/or antisense PKAI oligonucleotides was evaluated by flow cytometric analysis of fragmented DNA. The antitumor activity of MAb C225 and oligonucleotide HYB 190 was determined in athymic mice bearing established ACHN tumor xenografts. Cell proliferation and tumor growth data were evaluated for statistical significance using Student's t test; reported P values are two-sided. RESULTS: MAb C225 and oligonucleotide HYB 190 inhibited colony formation in soft agar in a dose-dependent manner for all renal cancer cell lines tested. We observed a potentiation of growth inhibition and induction of apoptosis when 769-P cells and ACHN cells were treated with both agents. Combination treatment with MAb C225 and oligonucleotide HYB 190 caused regression of ACHN tumor xenografts, whereas single-agent treatment only delayed tumor growth. CONCLUSION: The combination of anti-EGFR MAb C225 and ited cooperative antiproliferative effects and cooperative antitumor effects on EGFR and PKAI-expressing human renal cancer cell lines.

Animals↗
PubMed1998

Down-regulation of type I protein kinase A by transfection of human breast cancer cells with an epidermal growth factor receptor antisense expression vector.

MDA-468 human breast cancer cells overexpress the EGFR and exhibit a functional TGFalpha-EGFR autocrine pathway. Loss of EGFR expression following stable transfection with an antisense EGFR cDNA containing plasmid down-regulates type I cAMP-dependent protein kinase (PKAI) expression with acquisition of cell growth resistance to the PKAI inhibitor 8-Cl-cAMP. These results suggest that PKAI expression and function are controlled by a TGFalpha-EGFR autocrine pathway in human breast cancer cells overexpressing the EGFR.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1997

Synergistic inhibition of human cancer cell growth by cytotoxic drugs and mixed backbone antisense oligonucleotide targeting protein kinase A.

Protein kinase A type I plays a key role in neoplastic transformation, conveying mitogenic signals of different growth factors and oncogenes. Inhibition of protein kinase A type I by antisense oligonucleotides targeting its RIalpha regulatory subunit results in cancer cell growth inhibition in vitro and in vivo. A novel mixed backbone oligonucleotide HYB 190 and its mismatched control HYB 239 were tested on soft agar growth of several human cancer cell types. HYB 190 demonstrated a dose-dependent inhibition of colony formation in all cell lines whereas the HYB 239 at the same doses caused a modest or no growth inhibition. A noninhibitory dose of each mixed backbone oligonucleotide was used in OVCAR-3 ovarian and GEO colon cancer cells to study whether any cooperative effect may occur between the antisense and a series of cytotoxic drugs acting by different mechanisms. Treatment with HYB 190 resulted in an additive growth inhibitory effect with several cytotoxic drugs when measured by soft agar colony formation. A synergistic growth inhibition, which correlated with increased apoptosis, was observed when HYB 190 was added to cancer cells treated with taxanes, platinum-based compounds, and topoisomerase II selective drugs. This synergistic effect was also observed in breast cancer cells and was obtained with other related drugs such as docetaxel and carboplatin. Combination of HYB 190 and paclitaxel resulted in an accumulation of cells in late S-G2 phases of cell cycle and marked induction of apoptosis. A cooperative effect of HYB 190 and paclitaxel was also obtained in vivo in nude mice bearing human GEO colon cancer xenografts. These results are the first report of a cooperative growth inhibitory effect obtained in a variety of human cancer cell lines by antisense mixed backbone oligonucleotide targeting protein kinase A type I-mediated mitogenic signals and specific cytotoxic drugs.

Animals↗
PubMed1997

Simplified determination of combined residues of prochloraz and its metabolites in vegetable, fruit and wheat samples by gas chromatography.

This paper describes a gas chromatographic method for the determination of combined residues of prochloraz and its metabolites in various plant materials, including vegetables, fruits, seeds, grains and roots. The method is much simpler than previous ones as it does not require steam distillation; it consists of preliminary extraction of the sample, hydrolysis with pyridine hydrochloride in a test tube, extraction of the 2,4,6-trichlorophenol without the aid of steam distillation/continuous extraction, derivatization with diazomethane and gas chromatographic determination using electron-capture detection. The method is very rapid and can be done in a test tube; detection limit is from 0.01 to 0.50 mg/kg; recoveries are dependent on concentration of analyte and sample matrix; the determined values were found in the region of 72-102%.

Chromatography, Gas↗
PubMed1997

The RIalpha subunit of protein kinase A (PKA) binds to Grb2 and allows PKA interaction with the activated EGF-receptor.

Functional interactions between protein kinase A (PKA) and epidermal growth factor receptor (EGF-R) signalling pathways have been suggested. Unlike the type II isoform of PKA (PKAII), the type I (PKAI) and/or its regulatory subunit RIalpha are generally overexpressed in cancer cells and are induced following transforming growth factor alpha (TGF alpha)/EGF-R-dependent transformation. Downregulation of RIalpha/PKAI inhibits TGF alpha expression and EGF-R-dependent signalling. We have previously shown that addition of EGF to quiescent human normal epithelial MCF-10A cells determines PKAI expression and cell membrane translocation before cells enter S phase, while PKAI inhibition prevents S phase entry. Constitutive overexpression of PKAI confers the ability to grow in serum free medium, bypassing EGF requirement. Here we demonstrate a direct interaction of PKAI, but not of PKAII, with the activated EGF-R, that occurs within 5 min following EGF treatment of MCF-10A cells. Moreover, induction of mitogen-activated protein kinase (MAPK) activity following EGF-R activation is mimicked by PKAI overexpression and inhibited by downregulators of PKAI. Finally, the PKAI-EGF-R association occurs through the binding of RIalpha to the SH3 domain(s) of Grb2 adaptor protein, thus allowing the recruitment of the PKAI holoenzyme to the activated EGF-R. This is the first demonstration of a direct interaction of PKAI with the activated EGF-R macromolecular signalling complex.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Antitumor activity of combined blockade of epidermal growth factor receptor and protein kinase A.

BACKGROUND: Epidermal growth factor (EGF)-related proteins, such as transforming growth factor-alpha (TGF-alpha), control cancer cell growth through hormonal pathways (i.e., autocrine [hormone acts on cell that produces it] and paracrine [hormone acts on nearby cells] pathways). Overexpression of TGF-alpha and/or its receptor (EGFR) has been detected in human cancers. The blockade of EGFR activation by the use of anti-EGFR monoclonal antibodies (MAbs) has been proposed as a potential anticancer therapy. The type I cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKAI) is generally overexpressed in human cancer cells and is involved in neoplastic transformation. Inhibition of PKAI by selective cAMP analogues, such as 8-chloro-cAMP (8-CI-cAMP), induces growth inhibition in various human cancer cell lines. PURPOSE: On the basis of our previous observations of a cooperative anti-proliferative effect of anti-EGFR Mab 528 and 8-Cl-cAMP in human cancer cell lines in vitro, we evaluated the anticancer activity in vivo of the combination of an anti-EGFR MAb (MAb C225) and 8-Cl-cAMP. METHODS: Athymic mice were injected subcutaneously with 10(7) human colon carcinoma GEO cells. After 7 days, when established tumor xenografts of 0.30-0.35 cm3 were detectable, 10-15 mice per group were treated intraperitoneally twice weekly with different doses of 8-Cl-cAMP and/or MAb C225. Cancer cell expression of various growth factors was evaluated by immunohistochemical analysis in tumors obtained from control and treated mice. Data were evaluated for statistical significance using the Student's t test and the Mantel-Cox logrank test. All P values represent two-sided tests of statistical significance. RESULTS: A 5-week treatment with low doses of 8-Cl-cAMP (0.5 mg/dose) and MAb C225 (0.25 mg/dose) blocked GEO tumor growth (compared with that in control mice; P < .00001) and suppressed cancer cell production of autocrine growth factors, such as TGF-alpha, amphiregulin, and CRIPTO, and of angiogenic (promotes new blood vessel formation) factors, such as vascular endothelial growth factor and basic fibroblast growth factor, with no signs of toxicity. Control and 8-Cl-cAMP (0.5 mg/dose)-treated mice died within 9-10 weeks after tumor cell injection. In MAb C225 (0.25 mg/dose)-treated mice, GEO tumors resumed a growth rate comparable to that in control animals within 3 weeks following the end of treatment and the mice died between 11 and 20 weeks after tumor cell injection. GEO tumor growth was significantly delayed in the MAb C225 plus 8-Cl-cAMP treatment group (P < .00001) and was accompanied by a prolonged survival of mice (P < .00001) as compared with the control group. CONCLUSIONS: Long-term treatment with a combination of agents that selectively inhibit two intracellular signal-transduction enzymes, such as the PKAI serine-threonine kinase and the EGFR tyrosine kinase, has anticancer activity in vivo, reflected by suppression of tumor proliferation and angiogenesis, with no signs of toxicity. IMPLICATIONS: Since these inhibitors of intracellular mitogenic (growth-stimulating) signaling have a different mechanism(s) of action and do not antagonize the effects of cytotoxic therapy, a combination of anti-EGFR MAb C225 and 8-Cl-cAMP should be investigated as a nontoxic, long-term treatment for cancer patients following chemotherapy.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Differential sensitivity to non-major histocompatibility complex-restricted recombinant interleukin 2-activated lymphocyte killing of human mammary epithelial MCF-10A cells overexpressing oncogenes or protein kinase A subunits.

The sensitivity of human tumor cells to activated lymphocytes is considered to play an essential role in the antitumor activity of recombinant interleukin-2 (rIL-2)-based immunotherapy. We have investigated the effects of several genes involved in the regulation of cell growth and transformation on the sensitivity of human mammary epithelial MCF-10A cells to non-MHC-restricted, rIL-2-activated lymphocytes. Therefore, the lysability of MCF-10A cells overexpressing activated oncogenes (Ha-ras, erbB-2, and a mutated p53), growth factors [transforming growth factor alpha (TGFalpha)], or cAMP-dependent protein kinase A subunits (RIalpha, RIIbeta, and Calpha) was evaluated comparatively at different effector:target ratios by a 51Cr release assay. Parental MCF-10A, MCF-10A p53-mutated, and MCF-10A RIIbeta cells showed an intermediate sensitivity. Lysability was increased significantly in MCF-10A Ha-ras, MCF-10A TGFalpha, and MCF-10A RIalpha cells, reduced in MCF-10A Calpha cells, and completely abrogated in MCF-10A erbB-2 cells. These differences could not be explained by simple changes in the cell surface expression of MHC class I and intercellular adhesion molecule-1 proteins or by secretion of TGFbeta. Treatment with TAb 250, a mouse anti-p185(erbB-2) monoclonal antibody, or down-regulation of p185(erbB-2) expression resulted in circumvention of MCF-10A erbB-2 cell resistance. We conclude that molecular changes at the single-gene level resulting in alterations of intracellular signaling and/or cell transformation modulate sensitivity of human mammary epithelial cells to non-MHC-restricted, rIL-2-induced cytotoxicity, regardless of MHC class I and/or intercellular adhesion molecule-1 expression or TGFbeta secretion. Furthermore, anti-p185(erbB-2) monoclonal antibodies may be useful as adjuncts to rIL-2 treatment in patients with erbB-2-overexpressing tumors.

Animals↗
PubMed1996

Growth inhibition of human colon carcinoma cells by combinations of anti-epidermal growth factor-related growth factor antisense oligonucleotides.

GEO is a well-differentiated colon cancer cell line that coexpresses the epidermal growth factor-like growth factors CRIPTO (CR), amphiregulin (AR), and transforming growth factor alpha (TGF-alpha). Antisense 20-mer phosphorothioate oligodeoxynucleotides (AS S-oligos) directed against CR, AR, and TGF-alpha mRNAs were equipotent in their ability to inhibit both the anchorage-dependent growth and the anchorage-independent growth (AIG) of GEO cells, with a 50% inhibitory concentration of about 5 micrometer in the AIG assay. A supraadditive effect was observed when a combination of S-oligos was used. For example, a combination of two different AS S-oligos (either AR + CR, or TGF-alpha + CR, or TGF-alpha + AR) at a concentration of 1 micrometer each (total concentration, 2 micrometer) resulted in 50% inhibition of GEO cells AIG, whereas the use of each AS S-Oligo at a 1 or 2 micrometer concentration resulted respectively in about 10 and 20% growth inhibition. A combination of the three AS S-oligos was even more effective, resulting in about 60% inhibition of GEO cells AIG at a concentration of 1 micrometer each (3 micrometer total concentration). The AS S-oligos were also able to inhibit specifically the expression of either AR, CR, or TGF-alpha proteins in GEO cells, as assessed using immunocytochemistry or Western blot analysis. Finally, a supraadditive growth inhibitory effect of the AS S-oligos and an epidermal growth factor receptor-blocking antibody (monoclonal antibody 528) was observed. These data suggest that the use of a combination of AS S-oligos directed against different growth factors and antibodies directed against their receptors might result in an efficient inhibition of colon carcinoma cell growth.

Amphiregulin↗
PubMed1995

Amphiregulin anti-sense oligodeoxynucleotides inhibit growth and transformation of a human colon carcinoma cell line.

Amphiregulin (AR) is a secreted heparin-binding growth factor that is structurally and functionally related to epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha). GEO cells are from a human colon cancer cell line that expresses high levels of AR protein and mRNA. To assess the role of AR in colon-cancer cell proliferation and transformation, 2 different anti-sense 20-mer phosphorothioate oligodeoxynucleotides (AR AS-1 and AR AS-2 S-oligos) complementary to the 5' sequence of AR mRNA were synthesized. Both AR AS S-oligos were able to inhibit the anchorage-dependent growth (ADG) of GEO cells. The 2 AR AS S-oligos were equipotent when used in equimolar concentrations. In particular, a 40% growth inhibition was observed at a concentration of 10 microM, while a mis-sense S-oligo used as control had no effect on GEO cell growth. The AR AS-1 S-oligo used at the same concentration also inhibited by 40% the 3H-thymidine incorporation by DNA of GEO cells. The anchorage-independent growth (AIG) of GEO cells was even more significantly affected by AR AS S-oligo treatment. In fact, up to 80% inhibition of the AIG of GEO cells was observed when cells were treated with 10 microM of both AR AS S-oligos. Finally, the AR AS S-oligos were able to specifically inhibit AR protein expression in GEO cells, as assessed by immunocytochemistry. These data suggest that AR is involved in colon-cancer cell transformation, and that AR may represent a suitable target for gene therapy in human colon carcinomas.

Amphiregulin↗
PubMed1995

Cyclic AMP-dependent protein kinase type I is involved in hypersensitivity of human breast cells to topoisomerase II inhibitors.

Topoisomerase II (Topo II) is an essential enzyme that catalyzes the breakage of double-strand DNA and is the target of several effective anticancer drugs, including the epipodophyllotoxins. The regulatory subunits of the cyclic AMP-dependent protein kinase are differentially expressed in normal and cancer cells. The RIalpha subunit is overexpressed in cells transformed by transforming growth factor-alpha (TGF-alpha) or Ha-ras oncogene. It has been shown that murine cells transformed by Ha-ras become hypersensitive to Topo II-targeting anticancer drugs. In this report we have tested whether any correlation exists between the expression of RIalpha protein and cellular sensitivity of Topo II-targeting drugs. Normal human breast MCF-10A cells and their derivatives overexpressing TGF-alpha, Ha-ras, or the different protein kinase subunits were treated with either Topo II inhibitors, such as etoposide, teniposide, or amsacrine, or with drugs which act independently of Topo II, such as bleomycin. Here we show that MCF-10A TGF-alpha and MCF-10A Ha-ras cells overexpress the RIalpha protein and become hypersensitive to epypodophyllotoxins and amsacrine but not to bleomycin. Direct introduction of the RIalpha gene into MCF-10A induces hypersensitivity to Topo II inhibitor drugs. In contrast, the overexpression of the other protein kinase subunits, RIIbeta or Calpha, does not modify the drug sensitivity of MCF-10A cells. No differences in the mRNA/protein content or in the activity of Topo II were found between hypersensitive cells and parental MCF-10A cells, suggesting that RIalpha may influence drug sensitivity via modulation of events downstream of the Topo II-DNA cleavable complex.

Amsacrine↗
PubMed1995

Cooperative antiproliferative effects of 8-chloro-cyclic AMP and 528 anti-epidermal growth factor receptor monoclonal antibody on human cancer cells.

8-Chloro-cyclic AMP (8-Cl-cAMP), a site-selective cAMP analogue, is a specific inhibitor of type I cAMP-dependent protein kinase (PKAI) and induces growth inhibition in several human and rodent tumor cell lines. The anti-epidermal growth factor receptor (EGFR) mAb 528 is a blocking antibody able to inhibit the in vitro and in vivo growth of several human cancer cell lines that express functional EGFRs. Since enhanced levels of PKAI are generally found in tumor cells and an increase in PKAI expression is induced by transformation through a transforming growth factor alpha/EGFR autocrine pathway, we have evaluated whether treatment with mAb 528 in combination with 8-Cl-cAMP may have an additive or synergistic growth inhibitory effect on human cancer cells. A dose-dependent inhibition of monolayer cell growth was observed in two human colon cancer cell lines (GEO and CBS) and in a human breast cancer cell line (MDA-468) by treatment with either mAb 528 or 8-Cl-cAMP with 50% inhibitory concentration of 2-10 microgram/ml or 20-25 micrometer, respectively. The combined treatment with low noninhibitory doses of mAb 528 (0.25 microgram/ml) and with 8-Cl-cAMP had a more than additive growth inhibitory effect with a 3- to 5-fold reduction in the 8-Cl-cAMP 50% inhibitory concentration in all cell lines tested. This combined treatment was similarly effective in inhibiting the soft agar cloning efficiency of GEO cells. 8-Cl-cAMP treatment of GEO cells induced a dose-dependent increase in cell membrane-associated EGFRs with a maximum 3- to 4-fold increase within 48-72 h of treatment. These results suggest that a double blockade of the PKAI serine-threonine kinase-dependent and of the EGFR tyrosine kinase-dependent pathways is potentially useful in cancer therapy.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1994

Differential effects of protein kinase A sub-units on Chinese-hamster-ovary cell cycle and proliferation.

It has been shown that a marked increase in the levels of RI alpha sub-units and a decrease in RII beta sub-unit levels correlate with neoplastic transformation or with the mitogenic response of normal cells to hormones and growth factors. The selective down-regulation of RI alpha and the following induction of RII beta determine cell-growth arrest and differentiation of several cancer cells. To directly address the question whether the 2 protein-kinase-A(PKA) isoforms play different roles in the control of proliferation and cell-cycle distribution, we introduced and over-expressed the different PKA sub-units in Chinese-hamster-ovary (CHO) cells via retroviral-vector-mediated gene transfer. Whereas CHO cells treated with RI alpha anti-sense oligodeoxynucleotides were growth arrested and accumulated in the G0/G1 phases of the cell cycle, infection of CHO cells with a retroviral vector in order to over-express RI alpha determined growth advantages in monolayer conditions and substantially increased their cloning efficiency in soft agar. These events correlated with a sustained percentage of cells in S phase induced by RI alpha over-expression in the infected cells. In contrast, CHO cells infected with retroviral vectors over-expressing either a RII beta sub-unit or a C alpha catalytic sub-unit of PKA exhibited growth arrest within a few days of culture and accumulated in the G2-M phase of the cell cycle. The results of our study demonstrate that the different PKA sub-units play different and specific roles in the control of cell growth and cell-cycle distribution.

Animals↗