Artemisinin, a naturally occurring component of Artemisia annua, or sweet wormwood, is a potent anti-malaria compound that has recently been shown to have anti-proliferative effects on a number of human cancer cell types, although little is know about the molecular mechanisms of this response. We have observed that artemisinin treatment triggers a stringent G1 cell cycle arrest of LNCaP (lymph node carcinoma of the prostate) human prostate cancer cells that is accompanied by a rapid down-regulation of CDK2 and CDK4 protein and transcript levels.
LEDGF/p75 interacts with DNA/protein to regulate gene expression and function. Despite the recognized diversity of function of LEDGF/p75, knowledge of its transregulation is in its infancy. Here we report that LEDGF/p75 gene is TATA-less, contains GC-rich cis elements and is transcriptionally regulated by Sp1 involving small ubiquitin-like modifier (Sumo1). Using different cell lines, we showed that Sp1 overexpression increased the level of LEDGF/p75 protein and mRNA expression in a concentration-dependent fashion.
We previously established a bioassay method to screen for compounds that activate the promoter activity of p21(WAF1/CIP1), a potent inhibitor of cyclin-dependent kinases, in a p53-independent manner. As an activator of p21(WAF1/CIP1) promoter activity, we isolated cryptolepine (CLP: 5-methyl indolo (2,3b)-quiniine), an indoloquinoline alkaloid, from the traditional Ayurvedic medicinal plant Sida cordifolia. We show here that CLP induces the expression of p21(WAF1/CIP1) with growth arrest in p53-mutated human osteosarcoma MG63 cells.
Huntington's disease (HD) is an inherited neurodegenerative disease caused by expansion of a polyglutamine tract in the huntingtin protein. Transcriptional dysregulation has been implicated in HD pathogenesis. Here, we report that huntingtin interacts with the transcriptional activator Sp1 and coactivator TAFII130. Coexpression of Sp1 and TAFII130 in cultured striatal cells from wild-type and HD transgenic mice reverses the transcriptional inhibition of the dopamine D2 receptor gene caused by mutant huntingtin, as well as protects neurons from huntingtin-induced cellular toxicity.
The Journal of Neuroscience: The Official Journal of the Society for Neuroscience
The precise cause of neuronal death in Huntington's disease (HD) is unknown. Although no single specific protein-protein interaction of mutant huntingtin has emerged as the pathologic trigger, transcriptional dysfunction may contribute to the neurodegeneration observed in HD. Pharmacological treatment using the histone deacetylase inhibitor sodium butyrate to modulate transcription significantly extended survival in a dose-dependent manner, improved body weight and motor performance, and delayed the neuropathological sequelae in the R6/2 transgenic mouse model of HD.
Increased expression of vascular endothelial growth factor (VEGF) contributes to the growth of many tumors by increasing angiogenesis. Although hypoxia is a potent inducer of VEGF, we previously showed that epidermal growth factor receptor amplification and loss of PTEN, both of which can increase phosphatidylinositol-3-kinase (PI3K) activity, increase VEGF expression.
Human differentially expressed in chondrocytes (DEC), mouse stimulated with retinoic acid and rat split and hairy related proteins constitute a structurally distinct class of the basic helix-loop-helix proteins. DEC1 is abundantly expressed in tumors and protects against apoptosis induced by serum starvation. In this study, we report that DEC1 antiapoptosis is achieved by inducing survivin, an antiapoptotic protein. In paired tumor-normal tissues, survivin and DEC1 exhibited a paralleled expression pattern.
Interactions between mutant huntingtin (Htt) and a variety of transcription factors including specificity proteins (Sp) have been suggested as a central mechanism in Huntington disease (HD). However, the transcriptional activity induced by Htt in neurons that triggers neuronal death has yet to be fully elucidated. In the current study, we characterized the relationship of Sp1 to Htt protein aggregation and neuronal cell death. We found increased levels of Sp1 in neuronal-like PC12 cells expressing mutant Htt, primary striatal neurons, and brain tissue of HD transgenic mice.
MicroRNA-27a (miR-27a) is expressed in MCF-7 breast cancer cells, and antisense miR-27a (as-miR-27a) induces ZBTB10, a specificity protein (Sp) repressor. Both as-miR-27a and overexpression of ZBTB10 decreased Sp1, Sp3, and Sp4 mRNA and protein expression in MCF-7 cells, and this was also accompanied by decreased levels of estrogen receptor alpha (ERalpha) mRNA and protein. RNA interference studies confirmed that basal expression of ERalpha was dependent on Sp1 but not Sp3 or Sp4 in MCF-7 cells.
Exposure of mice to UV radiation results in suppression of the contact hypersensitivity (CHS) response. Here, we report that the UV-induced suppression of CHS is associated with increases in the levels of cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and PGE2 receptors in the exposed skin. UV radiation-induced suppression of CHS was inhibited by topical treatment of the skin with celecoxib or indomethacin (inhibitors of COX-2) or AH6809 (an EP2 antagonist). Moreover, mice deficient in COX-2 were found to be resistant to UV-induced suppression of CHS.