SUMMARY Chromatin diminution is the programmed elimination of specific DNA sequences during development. It occurs in diverse species, but the function(s) of diminution and the specificity of sequence loss remain largely unknown. Diminution in the nematode Ascaris suum occurs during early embryonic cleavages and leads to the loss of germline genome sequences and the formation of a distinct genome in somatic cells. We found that ~43 Mb (~13%) of genome sequence is eliminated in A. suum somatic cells, including ~12.7 Mb of unique sequence. The eliminated sequences and location of the DNA breaks are the same in all somatic lineages from a single individual, and between different individuals. At least 685 genes are eliminated. These genes are preferentially expressed in the germline and during early embryogenesis. We propose that diminution is a mechanism of germline gene regulation that specifically removes a large number of genes involved in gametogenesis and early embryogenesis.
The administration of GTCs with caffeine is associated with statistically significant reductions in BMI, body weight, and WC; however, the clinical significance of these reductions is modest at best. Current data do not suggest that GTCs alone positively alter anthropometric measurements.
Endometrial cancer is the most common invasive gynecologic malignancy, yet molecular mechanisms and signaling pathways underlying its etiology and pathophysiology remain poorly characterized. We sought to define a functional role for the protein kinase C (PKC) isoform, PKCa, in an established cell model of endometrial adenocarcinoma. Ishikawa cells depleted of PKCa protein grew slower, formed fewer colonies in anchorage-independent growth assays and exhibited impaired xenograft tumor formation in nude mice. Consistent with impaired growth, PKCa knockdown increased levels of the cyclin-dependent kinase (CDK) inhibitors p21 Cip1/WAF1 (p21) and p27 Kip1 (p27). Despite the absence of functional phosphatase and tensin homolog (PTEN) protein in Ishikawa cells, PKCa knockdown reduced Akt phosphorylation at serine 473 and concomitantly inhibited phosphorylation of the Akt target, glycogen synthase kinase-3b (GSK-3b). PKCa knockdown also resulted in decreased basal ERK phosphorylation and attenuated ERK activation following EGF stimulation. p21 and p27 expression was not increased by treatment of Ishikawa cells with ERK and Akt inhibitors, suggesting that PKCa regulates CDK expression independently of Akt and ERK. Immunohistochemical analysis of Grade 1 endometrioid adenocarcinoma revealed aberrant PKCa expression, with foci of elevated PKCa staining, not observed in normal endometrium. These studies demonstrate a critical role for PKCa signaling in endometrial tumorigenesis by regulating expression of CDK inhibitors p21 and p27 and activation of Akt and ERK-dependent proliferative pathways. Thus, targeting PKCa may provide novel therapeutic options in endometrial tumors. ' 2009 UICC
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Endometrial cancer is the most common invasive gynecologic malignancy in developed countries. The most prevalent endometrioid tumors are linked to excessive estrogen exposure and hyperplasia. However, molecular mechanisms and signaling pathways underlying their etiology and pathophysiology remain poorly understood. We have shown that protein kinase Cα (PKCα) is aberrantly expressed in endometrioid tumors and is an important mediator of endometrial cancer cell survival, proliferation, and invasion. In this study, we demonstrate that expression of active, myristoylated PKCα conferred ligand-independent activation of estrogen-receptor- (ER-) dependent promoters and enhanced responses to estrogen. Conversely, knockdown of PKCα reduced ER-dependent gene expression and inhibited estrogen-induced proliferation of endometrial cancer cells. The ability of PKCα to potentiate estrogen activation of ER-dependent transcription was attenuated by inhibitors of phosphoinositide 3-kinase (PI3K) and Akt. Evidence suggests that PKCα and estrogen signal transduction pathways functionally interact, to modulate ER-dependent growth and transcription. Thus, PKCα signaling, via PI3K/Akt, may be a critical element of the hyperestrogenic environment and activation of ER that is thought to underlie the development of estrogen-dependent endometrial hyperplasia and malignancy. PKCα-dependent pathways may provide much needed prognostic markers of aggressive disease and novel therapeutic targets in ER positive tumors.
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