Purpose-A recent landmark study demonstrated that Dichloroacetate (DCA) treatment promoted apoptosis in lung, breast, and glioblastoma cancer cell lines by shifting metabolism from aerobic glycolysis to glucose oxidation coupled with NFAT-Kv1.5 axis remodeling. The objective of this study was to determine whether DCA induces apoptosis in endometrial cancer cells and to assess apoptotic mechanism.Methods-A panel of endometrial cancer cell lines with varying degrees of differentiation was treated with DCA and analyzed for apoptosis via flow cytometry. Biological correlates such as gene expression, intracellular Ca 2+ , and mitochondrial membrane potential were examined to assess apoptotic mechanism.Results-Initiation of apoptosis was observed in five low to moderately invasive cancer cell lines including Ishikawa, RL95-2, KLE, AN3CA, and SKUT1B while treatment had no effect on noncancerous 293T cells. Two highly invasive endometrial adenocarcinoma cell lines, HEC1A and HEC1B, were found to be resistant to DCA induced apoptosis. Apoptotic responding cell lines had a significant increase in early and late apoptotis, a decrease in mitochondrial membrane potential, and decreased Survivin transcript abundance, which are consistent with a mitochondrial-regulated mechanism. DCA treatment decreased intracellular calcium levels in most apoptotic responding cell lines which suggests a contribution from the NFAT-Kv1.5-mediated pathway. DCA treatment increased p53 upregulated modulator of apoptosis (PUMA) transcripts in cell lines with an apoptotic response, suggesting involvement of a p53-PUMA-mediated mechanism. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Conflict of Interest Statement:The authors declare there are no conflicts of interest. NIH Public Access

Rac1 is an intracellular signal transducer regulating a variety of cell functions. Previous studies by overexpression of dominant-negative or constitutively active mutants of Rac1 in clonal cell lines have established that Rac1 plays a key role in actin lamellipodia induction, cell-matrix adhesion, and cell anoikis. In the present studies, we have examined the cellular behaviors of Rac1 gene-targeted primary mouse embryonic fibroblasts (MEFs) after Cre recombinase-mediated deletion of Rac1 gene. Rac1-null MEFs became contracted and elongated in morphology and were defective in lamellipodia formation, cell spreading, cell-fibronectin adhesion, and focal contact formation in response to platelet-derived growth factor or serum. Unexpectedly, deletion of Rac1 also abolished actin stress fibers in the cells without detectable alteration of endogenous RhoA activity. Although the expression and/or activation status of focal adhesion complex components such as Src, FAK, and vinculin were not affected by Rac1 deletion, the number and size of adhesion plaques were significantly reduced, and the molecular complex between Src, FAK, and vinculin was dissembled in Rac1-null cells. Overexpression of an active RhoA mutant or ROK failed to rescue the stress fiber and adhesion plaque defects of the Rac1-null cells. Although Rac1 deletion caused a significant reduction in phospho-PAK1, -AKT, and -ERK under serum stimulation, reconstitution of active PAK1, but not AKT or MEK1, was able to rescue the actin cytoskeleton and adhesion phenotypes of the Rac1-deficient cells. Furthermore, Rac1 deletion led to a marked increase in spontaneous apoptosis that could be rescued by active PAK1, AKT, or MEK1 expression. Our results obtained from gene-targeted primary MEFs indicate that Rac1 is essential not only for lamellipodia induction but also for the RhoA-regulated actin stress fiber and focal adhesion complex formation and that Rac1 is involved in cell survival regulation through anoikis-dependent as well as -independent mechanisms.

Cdc42 is a member of the Rho GTPase family known to regulate cell actin cytoskeleton organization, polarity, and growth, but its function in mammalian organismal physiology remains unclear. We found that natural aging of WT mice is marked with increased Cdc42 activity in various tissues. Among the negative regulators of Cdc42, gene targeting of Cdc42 GTPase-activating protein (Cdc42GAP) results in constitutively elevated Cdc42-GTP level in diverse tissues of adult mice; significantly shortened life span of the animals; and multiple premature aging-like phenotypes, including a reduction in body mass, a loss of subdermal adipose tissue, severe lordokyphosis, muscle atrophy, osteoporosis, and reduction of reepithelialization ability in wound-healing. Cdc42GAP ؊/؊ mouse embryonic fibroblasts and/or tissues display reduced population doubling, significantly dampened DNA damage repair activity after DNA-damaging agent treatment, accumulated genomic abnormalities, and induction of p53, p16 Ink4a , p21 Cip1 , and senescence-associated ␤-galactosidase expressions. Furthermore, Cdc42 activation is sufficient to promote a premature cellular senescence phenotype that depends on p53. These results suggest a role of Cdc42 activity in regulating mammalian genomic stability and aging-related physiology.cell senescence ͉ DNA damage repair ͉ genomic stability ͉ Rho GTPases