Increased resistance to trail-induced apoptosis in prostate cancer cells selected in the presence of bicalutamide.

Following prolonged treatment with the non-steroidal anti-androgen bicalutamide (Casodex), LNCaP cells have become resistant to this drug. Previously, we found that the bicalutamide-refractory subline LNCaP-Bic acquires a growth advantage and does not respond to androgenic stimulation. In the present study, we have asked whether changes in response to the tumor-selective apoptosis inducer TNF-related apoptosis-inducing ligand (TRAIL) occur in LNCaP-Bic cells. LNCaP and LNCaP-Bic cells were incubated with increasing concentrations of TRAIL and apoptosis rate was analyzed using FACS. Expression of death receptors (DR), adaptor protein Fas-associated death domain (FADD), members of the Bcl-2 family, and caspases were investigated by Western blot. The percentage of cells undergoing apoptosis was lower in LNCaP-Bic in comparison to LNCaP cells. There were no major differences in death receptor expression between control LNCaP and bicalutamide-selected cells. Surprisingly, treatment with TRAIL increased the levels of Bcl-2 by 50% in LNCaP-Bic cells. The ratio cleaved caspase/procaspase-8 was substantially lower in LNCaP-Bic cells. Reduced sensitivity to TRAIL-induced apoptosis is a novel mechanism relevant to resistance to bicalutamide in prostate cancer. Inability of TRAIL to cause programmed cell death might be caused by multiple perturbations in the TRAIL-signaling pathway.

Mitterberger M ，Neuwirt H ，Cavarretta IT ，Hobisch A ，Culig Z ... -  《PROSTATE》

The androgen receptor pathway is by-passed in prostate cancer cells generated after prolonged treatment with bicalutamide.

Experimental work in various prostate cancer models revealed that the androgen receptor is frequently upregulated and implicated in tumor progression. However, little attention has been paid to the androgen receptor-signaling pathway in the development of therapy resistance in patients who receive chronic treatment with a non-steroidal anti-androgen. We have generated a novel subline, LNCaP-Bic, after prolonged treatment with androgen and bicalutamide in vitro. Proliferation of LNCaP-Bic cells in the absence or presence of androgen, tocopherol succinate, and/or bicalutamide was assessed by cell counting. Androgen receptor expression was determined by Western blot. Luciferase activity was measured in cells transfected with an androgen-responsive reporter. In basal conditions, proliferation of LNCaP-Bic cells increased more than threefold over that of control LNCaP cells. Neither synthetic androgen R1881 nor bicalutamide showed any effect on LNCaP-Bic growth in vitro. Androgen receptor expression did not differ between the cell subline generated in the presence of bicalutamide and parental LNCaP cells. The ability of R1881 to induce reporter gene activity in LNCaP-Bic cells was reduced by 56%. Tocopherol succinate caused inhibition of proliferation only in the parental cell line although the androgen receptor and prostate-specific antigen were down regulated by the vitamin E derivative in both parental LNCaP and LNCaP-Bic cells. Androgen receptor-mediated signal transaction is not enhanced in cells selected in the presence of bicalutamide. Our data may suggest that a more differentiated approach in targeting the androgen receptor is needed in prostate cancers that become resistant to classic endocrine treatment.

Hobisch A ，Fritzer A ，Comuzzi B ，Fiechtl M ，Malinowska K ，Steiner H ，Bartsch G ，Culig Z ... -  《PROSTATE》

Antagonistic interaction between bicalutamide (Casodex) and radiation in androgen-positive prostate cancer LNCaP cells.

Bicalutamide (Casodex) reportedly improves high-risk prostate cancer survival as an adjuvant treatment following radiotherapy. However, biological data for the interaction between bicalutamide and ionizing radiation in concomitant association are lacking. To explore this issue, androgen-dependent (LNCaP) and -independent (DU145) human prostate cancer cells were exposed for 48 hr to 20, 40, or 80 microM bicalutamide introduced before (neoadjuvant), during (concomitant), or following (adjuvant) radiation. Growth inhibition and cytotoxicity, cell cycle distribution and expression of the prostate serum antigen (PSA) and androgen receptor (AR), were measured as endpoints. Bicalutamide-induced cytotoxic and cytostatic effects were found to be correlated with a marked G1 phase arrest and S phase depression. The drug down-regulated PSA and AR proteins and psa mRNA in LNCaP cells. However, transient up-regulation of the expression of ar mRNA was observed in the presence of 40 microM drug. DU145 cells did not express PSA and proved to be comparatively resistant to the drug from both cytostatic and cytotoxic effects. Bicalutamide dose-dependently induced a significant decrease of radiation susceptibility among drug survivors in LNCaP cells, whilst the interaction appeared to be additive in DU145 cells. The antagonistic radiation-drug interaction observed in LNCaP cells is of significance in relation to combined radiotherapy-bicalutamide treatments directed against tumors expressing the AR. The results suggest that bicalutamide is amenable to combined schedule with radiotherapy provided the drug and radiation are not given in close temporal proximity.

Quéro L ，Giocanti N ，Hennequin C ，Favaudon V ... -  《-》

Imatinib enhances human melanoma cell susceptibility to TRAIL-induced cell death: Relationship to Bcl-2 family and caspase activation.

Hamaï A ，Richon C ，Meslin F ，Faure F ，Kauffmann A ，Lecluse Y ，Jalil A ，Larue L ，Avril MF ，Chouaib S ，Mehrpour M ... -  《ONCOGENE》

Androgen sensitivity related proteins in hormone-sensitive and hormone-insensitive prostate cancer cell lines treated by androgen antagonist bicalutamide.

Madarová J ，Lukesová M ，Hlobilková A ，Riháková P ，Murray PG ，Student V ，Vojtsek B ，Kolár Z ... -  《NEOPLASMA》