Caveolin-1 can also acts as a pro-apoptotic protein. This was originally observed in Rat-1 fibroblasts, where overexpression of caveolin 1 sensitizes the cells to both g-irradiation and ceramide-induced cell death . Elevated sensitivity to apoptotic stimuli was also reported in caveolin-1-transfected OVCAR-3 ovarian carcinoma cells  and T24 bladder cancer cells , and in mouse embryo fibroblasts that transgenically overexpress caveolin-1 . Activation of caspase-3 was reported to occur in three OVCA ovarian cancer cell lines upon expression of caveolin-1 . Supporting these data, caveolin-1 antisense-suppressed NIH-3T3 cells were reported to be more resistant to staurosporine-induced apoptosis . Similarly, ret-roviral disruption of the caveolin-1 gene in L929 murine fibrosarcoma cells caused resistance to tumor necrosis factor-a (TNF-a)-, hydrogen peroxide- and staurospor-ine-induced apoptosis, whereas forced caveolin-1 expression sensitized HepG2 human hepatocellular carcinoma cells to TNF-a . Caveolin-1 expression also sensitizes HeLa human cervical carcinoma cells to sodium arsenite and hydrogen peroxide toxicity . In addition, adenoviral overexpression of caveolin-1 was found to inhibit platelet-derived growth factor (PDGF)-induced proliferation of primary vascular smooth muscle cells (VSMCs), leading to apoptosis . Collectively, the results of these studies indicate that the growth-inhibitory actions of caveolin-1 may sometimes be accompanied by a pro-apoptotic activity.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.