erucylphospho-n-n-n-trimethylpropylammonium and Prostatic-Neoplasms

Integrin-dependent adhesion of tumor cells to extracellular matrix proteins provides anchorage-dependent protection from cell death. In the present investigation we aimed to understand whether and how the paradigmatic membrane-targeted synthetic phospholipid analog erufosine is relevant for tumor cell adhesion to extracellular matrix proteins, cell survival and migration. The antineoplastic action of erufosine was analyzed with glioblastoma and prostate cancer cells adhering to fibronectin or collagen I using proliferation, adhesion and migration assays. The composition of adhesion contacts containing activated β1 integrins was studied using immunofluorescence. The importance of β1 integrins for the observed effects was analyzed in fibroblasts proficient or deficient in β1 integrin expression. Adhesion to collagen I and fibronectin increased the death threshold in serum-deprived tumor cells. Moreover, β1 integrin-deficient cells were more sensitive to erufosine-treatment compared to β1 integrin proficient cells suggesting a role of β1 integrins for matrix-mediated death resistance. Most importantly, erufosine disturbed the maturation of the cell adhesion complexes containing paxillin, activated β1 integrins and phosphorylated FAK, leading to a reduction of survival signals and inhibition of tumor cell adhesion and migration. These findings suggest that membrane-targeted synthetic phospholipids analogs may be of value for counteracting matrix-mediated treatment resistance in combined treatment approaches with radiotherapy or chemotherapy.

Topics: Animals; Antineoplastic Agents; Cell Adhesion; Cell Line, Tumor; Cell Membrane; Cell Movement; Cell Survival; Collagen Type I; Extracellular Matrix; Fibroblasts; Fibronectins; Focal Adhesion Kinase 1; Focal Adhesion Protein-Tyrosine Kinases; Glioblastoma; Humans; Integrin beta1; Male; Mice; Organophosphates; Paxillin; Phosphorylation; Prostatic Neoplasms; Quaternary Ammonium Compounds

The phosphatidylinositol-3-kinase (PI3K)/Akt pathway is frequently deregulated in prostate cancer and associated with neoplastic transformation, malignant progression, and enhanced resistance to classical chemotherapy and radiotherapy. Thus, it is a promising target for therapeutic intervention. In the present study, the cytotoxic action of the Akt inhibitor Erufosine (ErPC3) was analyzed in prostate cancer cells and compared to the cytotoxicity of the PI3K inhibitor LY294002. Moreover, the efficacy of combined treatment with Akt inhibitors and ionizing radiation in prostate cancer cells was examined.. Prostate cancer cell lines PC3, DU145, and LNCaP were treated with ErPC3 (1-100 µM), LY294002 (25-100 µM), irradiated (0-10 Gy), or subjected to combined treatments. Cell viability was determined by the WST-1 assay. Apoptosis induction was analyzed by flow cytometry after staining with propidium iodide in a hypotonic citrate buffer, and by Western blotting using antibodies against caspase-3 and its substrate PARP. Akt activity and regulation of the expression of Bcl-2 family members and key downstream effectors involved in apoptosis regulation were examined by Western blot analysis.. The Akt inhibitor ErPC3 exerted anti-neoplastic effects in prostate cancer cells, however with different potency. The anti-neoplastic action of ErPC3 was associated with reduced phosphoserine 473-Akt levels and induction of apoptosis. PC3 and LNCaP prostate cancer cells were also sensitive to treatment with the PI3K inhibitor LY294002. However, the ErPC3-sensitive PC3-cells were less susceptible to LY294002 than the ErPC3-refractory LNCaP cells. Although both cell lines were largely resistant to radiation-induced apoptosis, both cell lines showed higher levels of apoptotic cell death when ErPC3 was combined with radiotherapy.. Our data suggest that constitutive Akt activation and survival are controlled by different different molecular mechanisms in the two prostate cancer cell lines - one which is sensitive to the Akt-inhibitor ErPC3 and one which is more sensitive to the PI3K-inhibitor LY294002. Our findings underline the importance for the definition of predictive biomarkers that allow the selection patients that may benefit from the treatment with a specific signal transduction modifier.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma; Cell Death; Cell Line, Tumor; Chromones; Humans; Male; Morpholines; Organophosphates; Prostatic Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Quaternary Ammonium Compounds; Radiation-Sensitizing Agents; Radiation, Ionizing; Time Factors; Treatment Outcome