cas Overe pression of caveolin 1 induces nuclear condensation TUNEL labeled after e posure to DNase I, whereas no cell was TUNEL labeled after vehicle treatment. We quantified www.selleckchem.com/products/lapatinib.html the proportion of apoptotic cells in ectopic caveolin 1 or EGFP e pressing cells by counting the number of cells e hibiting nuclear conden sations per 100 e ogenous caveolin 1 or EGFP e pressing cells, stained with Hoechst 33342. Significant numbers of caveolin 1 e pressing cells e hibited apoptosis after trans fection, whereas only pases plays a role in caveolin 1 induced GH3 cell apopto sis, at least in part through caspase 8 signaling. Bromocriptine sensitizes the caveolin 1 induced apoptosis in GH3 cells Bromocriptine induces activation of p38 MAP kinase in GH3 cells.

Activation of the p38 MAP kinase signal ing pathway in NIH3T3 cells causes phosphorylation of caveolin 1 on Tyr14. We e amined if there was any relationship between bromocriptine and caveolin 1 that affected GH3 cell apoptosis. GH3 cells were allowed to transiently e press caveolin 1 for 24 hours, then 30 M bromocriptine was added for another 12 hours. The pro portion of apoptotic cells was determined by estimating the number of cells containing condensed nuclear DNA. After 12 hours of bromocriptine treatment, the number of apoptotic cells was 38% of the total caveolin 1 e pressing cell population compared to 24% without bromocriptine. Only 14% and 6% of the total cell population underwent apoptosis when cells were treated with bro mocriptine or vehicle for 12 hours. The data indicate that there is an interaction between caveolin 1 and bromocriptine in the induction of GH3 apoptosis.

Bromocriptine enhances phosphorylation of caveolin 1 Tyr14 Tyrosine14 phosphorylation of caveolin 1 was found to be associated with apoptosis in the human promyelocytic leukemia cell line HL 60 after etoposide induction, indicating phosphorylation of caveolin 1 tyrosine may play a role in apoptosis. To e plore whether bromocrip tine could induce caveolin 1 phosphorylation, GH3 cells were transfected with pcDNA4 caveolin 1 for 24 hours, then e posed to bromocriptine as indicated in figure 5B. Total proteins were e tracted, separated using SDS PAGE and e amined by Western blotting using an antibody spe cific for caveolin 1 phosphorylated at Tyr14. After 12 hours of bromocriptine treatment the amount of caveolin 1 phosphorylation was 3.

75 times higher than with GSK-3 vehicle treatment. Cellular protein from H2O2 e posed NIH3T3 cells was used as a positive control for phosphorylated caveolin 1. These data demonstrated that bromocriptine enhanced phosphorylation of caveo lin 1 in GH3 cells. Discussion therefore In the present study, we demonstrated GH3 cells overe pressing caveolin 1 underwent apoptosis. Caveolin 1 has previously been reported to be associated with enhance ment of apoptotic sensitivity. For e ample, NIH3T3 cells treated with anti sense caveolin 1 were resistant to stau rosporine induced apoptosis, and T24 bladder carcinoma cells