Ali, Bushra

Mitochondrial function declines with age but increases with caloric restriction (CR). Mitochondria and muscle fibers were prepared from young (8–11mo) and old (22–24mo) AL‐fed and old CR mice. State 3 respiration was lower in OAL vs. YAL, but preserved in OCR (). Normalizing to protein content eliminated the age‐effect in AL mice but amplified the effect of CR, indicating that CR enhances the intrinsic mito function. ROS production in isolated fibers increased with age in AL but not CR mice (). Coupling was reduced in OAL but not OCR. These results indicate that mito capacity declines with age in situ and in vitro, apparently driven largely by decreased mitochondrial protein content. CR increases mito capacity and efficiency independently of mito protein content. YAL OAL OCR Fibers (pmol/s/m g tiss) CI 54.0±4.1 38.9±1.6 50.8±3.0 CII 44.4±3.4 36.9±1.4 45.0±2.3 CI+II 63.4±5.5 51.8±2.5 67.0±3.4 Mito (pmol/s/m g tiss) CI 38.9±1.8 21.5±2.6 30.7±2.0 CII 30.6±0.9 19.6±1.2 24.7±1.4 CI+II 59.0±1.6 34.0±1.9 46.7±2.7 Mito (pmol/s/m g prot) CI 8350±635 7071±1082 10422±863 CII 6536±414 6309±506 8408±676 CI+II 12601±762 11063±1156 15949±1381 H 2 O 2 (pM/s/mg tiss) CI 10.0±1.8 30.8±3.7 15.0±2.0 CI+II 141.4±20.9 187.2±53.8 101.1±13.6 P:O State IV to III 2.94±0.03 2.71±0.02 2.92±0.05 Means±SEM. P<0.05 OAL vs YAL, P<0.05 OCR vs OAL, P<0.05 OCR vs. OAL & YAL.

Abstract Purpose: In humans, several distinctive cancers result from mutations that aberrantly activate hedgehog (HH) signal transduction. Here, we investigate the role of HH signaling in ovarian cancer. Experimental Design: We assessed the expression of different components of hedghehog pathway in primary tumor samples and cell lines. We used specific hedghehog pathway blocker to study the effect on clonal growth and proliferation of ovarian cancer cell both in vitro and in vivo. Results: We show that the up-regulation of several HH pathway components is a common feature of primary ovarian tumors and cell lines. However, expression of PATCHED1 (PTCH1), a direct transcriptional target of the HH pathway, is down-regulated in ovarian cancer in direct contrast to the expression observed in other adult solid tumors. Cyclopamine, a specific HH pathway inhibitor, inhibits the proliferation and clonal growth of ovarian tumor cells in vitro and arrests ovarian tumor growth in vivo. Expression of BMI-1, a polycomb gene, is down-regulated in ovarian cancer cells following cyclopamine treatment. Overexpression of PTCH1 phenocopied the effects of cyclopamine; it down-regulated BMI-1 and reduced clonal growth in ovarian cancer cell lines. Furthermore, knocking down BMI-1 using small interfering RNA also inhibited the clonal growth of all the ovarian cancer cell lines tested. Conclusions: In brief, the constitutive low-level expression of PTCH1 contributes to proliferation and clonal growth of ovarian cancer cells by an aberrant HH signal. Because the HH pathway can be inhibited by specific inhibitors, these findings point toward possible new treatments to inhibit ovarian cancer growth.