Prostate cancer (CaP) often develops androgen independence (AI) and proliferates uninhibited despite anti-androgen therapy. Src kinase is a non-receptor tyrosine kinase that mediates a variety of cellular functions. Previous studies have demonstrated that neuropeptide and IL-8 can activate Src kinase and stimulate AI growth in CaP cells. However, a role for Src in prostate cancer is not yet defined. We evaluated Src activation in the most commonly used CaP cell lines and the effect of a Src kinase inhibitor on proliferation and migration. Src activation and basal Src expression levels were profiled in CaP cell lines CWR22Rv1, LNCaP, PC3, DU145, and LAPC-4 in serum-free (SF), charcoal-stripped serum with minimal androgen and small molecules (CS), and regular serum (RS) conditions. CaP cell lines were treated with 62.5nM to 12μM of AZD0530, a novel Src kinase inhibitor in RS and its effects on cell growth were examined. PC3 and DU145 cell migration were assayed in Boyden Chamber in the presence of 5μM AZD0530 with laminin (LMN) and fibronectin (FN) as chemoattractants. Src expression level was found to be about the same in the CaP cell lines examined. In SF media, CWR22Rv1 has the highest relative amount activated Src, followed by DU145 and PC3. Under CS conditions, Src was activated in LNCaP, DU145, and CWR22Rv1. In RS, activated Src was observed in PC3, DU145, and LNCaP. All CaP cells treated with AZD0530 demonstrated dose-dependent inhibition of cell growth in MTT proliferation assays. IC50s for growth in LNCaP, CWR22Rv1, DU145, and PC3 were 3 to 6μM, 6 to 9μM, 3 to 6μM, and 0.5 to 3μM, respectively. Cytostatic or cytostatic growth curves were observed in LNCaP treated with greater than 9μM of AZD0530. Treatment with FN and LMN increased PC3 cell migration to 246 and 225% respectively over basal levels and the addition of AZD0530 to FN and LMN decreased cell migration to 68 and 64% respectively. FN treatment increased cell migration in DU145 to 402% while adding AZD0530 to FN treatment decreased cell migration to 66%. We therefore conclude that Src may be important mediator of cell growth and migration in CaP. Rationale exists for the inhibition of Src in the treatment of androgen-independent CaP.

[Proc Amer Assoc Cancer Res, Volume 47, 2006]