Protein kinase C-α mediates epidermal growth factor receptor transactivation in human prostate cancer cells

Progression of human prostate cancer to a malignancy that is refractory to androgen-ablation therapy renders the disease resistant to available treatment options and accounts for the high prostate cancer mortality rate. Epidermal growth factor receptor (EGFR) expression in human prostate cancer specimens increases with disease progression to androgen-refractory prostate cancer, and experimental models implicate EGFR-dependent signaling to Erk1/2 activation in the androgen-refractory prostate cancer phenotype. 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced Erk1/2 activation in human prostate cancer PC-3 cells is a paradigm of diacylglycerol-induced EGFR transactivation in androgen-independent prostate cancer. In this report, we establish an obligatory role for TPA-induced protein kinase C (PKC)-α activation in EGFR transactivation and signaling to Erk1/2 activation in PC-3 cells. TPA-regulated molecules include PKCs, PKDs, and Ras guanyl nucleotide-releasing proteins. The PKC-selective inhibitors GF109203X and Gö6983 each blocked TPA-induced EGFR transactivation, indicating a requirement for PKC. PC-3 cells express four PKC isozymes. Prolonged bryostatin 1 treatment abrogated PKCα expression without altering expression levels of the other PKC isozymes. Pharmacologic PKCα “knockdown” abrogated TPA-induced Erk1/2 activation without affecting the EGF/EGFR-induced response, indicating that PKCα was required for EGFR transactivation but dispensable for signaling of ligand-activated EGFR to Erk1/2 activation. We corroborated this by showing that Gö6976, which is a PKCα-selective inhibitor in PC-3 cells, likewise abolished TPA-induced Erk1/2 activation and did not inhibit EGF/EGFR-induced Erk1/2 activation. Gö6976 had similar effects in DU145 cells, providing evidence for a common PKCα-dependent Erk1/2 activation mechanism in androgen-independent human prostate cancer cells of distinct genetic origin. These results constitute a rational basis for selective PKCα inhibition as a modality of prostate cancer therapy.

[1]  Z. Hall.  Cancer , 1906, The Hospital.

[2]  S. Aaronson,et al.  Novel source of 1,2-diacylglycerol elevated in cells transformed by Ha-ras oncogene , 1987, Nature.

[3]  T. Bradshaw,et al.  Comparison of effects of bryostatins 1 and 2 and 12-O-tetradecanoylphorbol-13-acetate on protein kinase C activity in A549 human lung carcinoma cells. , 1989, Cancer research.

[4]  A. Deblasio,et al.  Prolonged induction of p21Cip1/WAF1/CDK2/PCNA complex by epidermal growth factor receptor activation mediates ligand-induced A431 cell growth inhibition , 1995, The Journal of cell biology.

[5]  C. Cordon-Cardo,et al.  Changing pattern of expression of the epidermal growth factor receptor and transforming growth factor alpha in the progression of prostatic neoplasms. , 1995, Clinical cancer research : an official journal of the American Association for Cancer Research.

[6]  M. Gschwendt,et al.  Inhibition of protein kinase C mu by various inhibitors. Differentiation from protein kinase c isoenzymes. , 1996, FEBS letters.

[7]  M. Gschwendt,et al.  Inhibition of protein kinase C μ by various inhibitors. Inhibition from protein kinase c isoenzymes , 1996 .

[8]  Xin-Yuan Fu,et al.  Cell Growth Arrest and Induction of Cyclin-Dependent Kinase Inhibitor p21WAF1/CIP1 Mediated by STAT1 , 1996, Science.

[9]  E. Rozengurt,et al.  Bombesin, Vasopressin, Endothelin, Bradykinin, and Platelet-derived Growth Factor Rapidly Activate Protein Kinase D through a Protein Kinase C-dependent Signal Transduction Pathway* , 1997, The Journal of Biological Chemistry.

[10]  Johann Hofmann,et al.  The potential for isoenzyme‐selective modulation of protein kinase C , 1997, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[11]  A. Gomez-Muñoz,et al.  Increased concentrations of phosphatidate, diacylglycerol and ceramide in ras- and tyrosine kinase (fps)-transformed fibroblasts , 1997, Oncogene.

[12]  Catherine Magill,et al.  Neutral endopeptidase 24.11 loss in metastatic human prostate cancer contributes to androgen-independent progression , 1998, Nature Medicine.

[13]  J. Neoptolemos,et al.  Protein kinase C isoenzyme patterns characteristically modulated in early prostate cancer. , 1999, The American journal of pathology.

[14]  A. Ullrich,et al.  EGF receptor transactivation by G-protein-coupled receptors requires metalloproteinase cleavage of proHB-EGF , 1999, Nature.

[15]  B. Fraile,et al.  IMMUNOHISTOCHEMICAL COMPARATIVE ANALYSIS OF TRANSFORMING GROWTH FACTOR α, EPIDERMAL GROWTH FACTOR, AND EPIDERMAL GROWTH FACTOR RECEPTOR IN NORMAL, HYPERPLASTIC AND NEOPLASTIC HUMAN PROSTATES , 1999 .

[16]  S. Yeh,et al.  From HER2/Neu signal cascade to androgen receptor and its coactivators: a novel pathway by induction of androgen target genes through MAP kinase in prostate cancer cells. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[17]  G Bartsch,et al.  Epidermal growth factor (EGF) receptor blockade inhibits the action of EGF, insulin-like growth factor I, and a protein kinase A activator on the mitogen-activated protein kinase pathway in prostate cancer cell lines. , 1999, Cancer research.

[18]  Weiya Ma,et al.  Transactivation of the Epidermal Growth Factor Receptor Is Involved in 12-O-Tetradecanoylphorbol-13-acetate-induced Signal Transduction* , 2001, The Journal of Biological Chemistry.

[19]  Jayoung Kim,et al.  Heparin-binding epidermal growth factor-like growth factor stimulates androgen-independent prostate tumor growth and antagonizes androgen receptor function. , 2002, Endocrinology.

[20]  Z. Werb,et al.  The metalloprotease Kuzbanian (ADAM10) mediates the transactivation of EGF receptor by G protein–coupled receptors , 2002, The Journal of cell biology.

[21]  R. Autorino,et al.  Expression of epidermal growth factor receptor (EGFR) correlates with disease relapse and progression to androgen-indepedence in human prostate cancer , 2002 .

[22]  H. Scher,et al.  Studies with CWR22 xenografts in nude mice suggest that ZD1839 may have a role in the treatment of both androgen-dependent and androgen-independent human prostate cancer. , 2002, Clinical cancer research : an official journal of the American Association for Cancer Research.

[23]  C. Basbaum,et al.  Platelet-activating factor receptor and ADAM10 mediate responses to Staphylococcus aureus in epithelial cells , 2002, Nature Medicine.

[24]  F. Bethencourt,et al.  Regulation of proliferation/apoptosis equilibrium by mitogen-activated protein kinases in normal, hyperplastic, and carcinomatous human prostate. , 2002, Human pathology.

[25]  Stefania Staibano,et al.  Expression of epidermal growth factor receptor correlates with disease relapse and progression to androgen-independence in human prostate cancer. , 2002, Clinical cancer research : an official journal of the American Association for Cancer Research.

[26]  Nils Brose,et al.  Move over protein kinase C, you've got company: alternative cellular effectors of diacylglycerol and phorbol esters , 2002, Journal of Cell Science.

[27]  A. Scott,et al.  Antitumor efficacy of cytotoxic drugs and the monoclonal antibody 806 is enhanced by the EGF receptor inhibitor AG1478 , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[28]  X. Qu,et al.  Activation of extracellular signal-regulated kinase mediates bombesin-induced mitogenic responses in prostate cancer cells. , 2003, Cellular signalling.

[29]  C. Logothetis.  Foundation for the integration of biologically based therapy in the management of prostate cancer , 2003, The Prostate.

[30]  Teruhiko Fujii,et al.  Protein Kinase C Promotes Apoptosis in LNCaP Prostate Cancer Cells through Activation of p38 MAPK and Inhibition of the Akt Survival Pathway* , 2003, Journal of Biological Chemistry.

[31]  N. Matsuura,et al.  Transactivation of epidermal growth factor receptor after heparin‐binding epidermal growth factor‐like growth factor shedding in the migration of prostate cancer cells promoted by bombesin , 2003, The Prostate.

[32]  D. Tindall,et al.  Mechanisms of androgen-refractory prostate cancer. , 2004, The New England journal of medicine.

[33]  F. S. French,et al.  Epidermal Growth Factor Increases Coactivation of the Androgen Receptor in Recurrent Prostate Cancer* , 2004, Journal of Biological Chemistry.

[34]  M. Lahn,et al.  The Role of Protein Kinase C-alpha (PKC-α) in Cancer and its Modulation by the Novel PKC-α-Specific Inhibitor Aprinocarsen , 2004 .

[35]  D. Nanus,et al.  Chemosensitization of Androgen-Independent Prostate Cancer with Neutral Endopeptidase , 2004, Clinical Cancer Research.

[36]  Koichiro Yoshino,et al.  ADAM Binding Protein Eve-1 Is Required for Ectodomain Shedding of Epidermal Growth Factor Receptor Ligands* , 2004, Journal of Biological Chemistry.

[37]  Vincenzo Valentini,et al.  Targeted inhibition of the epidermal growth factor receptor‐tyrosine kinase by ZD1839 (‘Iressa’) induces cell‐cycle arrest and inhibits proliferation in prostate cancer cells , 2004, Journal of cellular physiology.

[38]  G. Tortora,et al.  Combined Targeting of Epidermal Growth Factor Receptor and MDM2 by Gefitinib and Antisense MDM2 Cooperatively Inhibit Hormone-Independent Prostate Cancer , 2004, Clinical Cancer Research.

[39]  C. O'Brian,et al.  Resveratrol Antagonizes EGFR-Dependent Erk1/2 Activation in Human Androgen-Independent Prostate Cancer Cells with Associated Isozyme-Selective PKCα Inhibition , 2004, Investigational New Drugs.

[40]  L. Yin,et al.  Phorbol Ester-induced Apoptosis of C4-2 Cells Requires Both a Unique and a Redundant Protein Kinase C Signaling Pathway* , 2005, Journal of Biological Chemistry.