Rab25 increases cellular ATP and glycogen stores protecting cancer cells from bioenergetic stress

Cancer cells are metabolically stressed during tumour progression due to limited tumour vascularity and resultant nutrient, growth factor and oxygen deficiency that can induce cell death and inhibit tumour growth. We demonstrate that Rab25, a small GTPase involved in endosomal recycling, that is genomically amplified in multiple tumour lineages, is a key regulator of cellular bioenergetics and autophagy. RAB25 enhanced survival during nutrient stress by preventing apoptosis and autophagy via binding and activating AKT leading to increased glucose uptake and improved cellular bioenergetics. Unexpectedly, Rab25 induced the accumulation of glycogen in epithelial cancer cells, a process not previously identified. Strikingly, an increase in basal ATP levels combined with AKT-dependent increases in glucose uptake and glycogen storage allowed maintenance of ATP levels during bioenergetic stress. The clinical relevance of these findings was validated by the ability of a Rab25-dependent expression profile enriched for bioenergetics targets to identify patients with a poor prognosis. Thus, Rab25 is an unexpected regulator of cellular bioenergetics implicated as a useful biomarker and potential therapeutic target

Atypical PKCiota Contributes to Poor Prognosis Through Loss of Apical-basal Polarity and Cyclin E Overexpression in Ovarian Cancer

We show that atypical PKCι, which plays a critical role in the establishment and maintenance of epithelial cell polarity, is genomically amplified and overexpressed in serous epithelial ovarian cancers. Furthermore, PKCι protein is markedly increased or mislocalized in all serous ovarian cancers. An increased PKCι DNA copy number is associated with decreased progression-free survival in serous epithelial ovarian cancers. In a Drosophila in vivo epithelial tissue model, overexpression of persistently active atypical PKC results in defects in apical-basal polarity, increased Cyclin E protein expression, and increased proliferation. Similar to the Drosophila model, increased PKCι proteins levels are associated with increased Cyclin E protein expression and proliferation in ovarian cancers. In nonserous ovarian cancers, increased PKCι protein levels, particularly in the presence of Cyclin E, are associated with markedly decreased overall survival. These results implicate PKCι as a potential oncogene in ovarian cancer regulating epithelial cell polarity and proliferation and suggest that PKCι is a novel target for therapy

Transcription regulation of human gonadotropin-releasing hormone receptor gene expression

Human placental GnRHR cDNA isolated from human choriocarcinoma JEG-3 cells, immortalized human extravillous trophoblasts (IEVT) and primary culture of cytotrophoblasts was identical to the pituitary counterpart. In addition, placental GnRHR wasshown coupling to both the protein kinase C (PKC) and protein kinase A (PKA) signaling transduction pathways. Interestingly, homologous down-regulation of GnRHR mRNA level was not observed in placental cells as in pituitary cells, suggesting that a different regulatory mechanism may exist in controlling the expression of this gene in these two tissues. UsingJEG-3 and IEVT cells as models, an upstream promoter was shown to confer the placental cell-specific expression of hGnRHR gene both in vitro and in vivo. Four putative transcription factor binding sites, namely hGR-Oct-1, hGR-CRE, hGR-GATA and hGR-AP-1, were located and confirmed to be essential for the placental expression of this gene. Importantly, hGR-CRE and hGR-GATA motifs were subsequently found to be placenta specific. A differential regulation of human GnRHR promoter activity by progesterone (P) in the pituitary and placenta was observed. P treatment decreased the promoter activity at the level of pituitary. In contrast, P stimulated the expression of this gene in the placenta. A progesterone response element, namely hGR-PRE, mediated the P-action. Interestingly, human progesterone receptor (PR)-B exhibits a cell-dependent transcriptional activity, such that it functions as a transcription activator in the placenta but a transcription repressor in the pituitary. In contrast, human PR-A acts as a transcription repressor in both tissues. The increase in hGnRHR promoter activity after cAMP/PKA pathway activation by either pharmacological agents or by PACAP and hCG in the pituitary and placenta, respectively, implies that any hormones, which activate cAMP/PKA pathway, may increase the hGnRHR gene transcription. Two elements, namely hGR-AP/CRE-1 and -2, were subsequently demonstrated to be responsible for mediating this stimulatory effect. The comparison studies on the transcriptional regulation of hGnRHR gene by P and cAMP/PKA pathway at the level of the pituitary and placenta implicate that the regulation of hGnRHR gene transcription is constantly under fine-tuning by a complex regulatory mechanism through the availability of different transcription factors and the activation of multiple signal transduction pathways.Medicine, Faculty ofObstetrics and Gynaecology, Department ofGraduat

Molecular studies of proopiomelanocortin in goldfish brain

published_or_final_versionZoologyMasterMaster of Philosoph

Functional mapping of a placenta-specific upstream promoter for human gonadotropin-releasing hormone receptor gene

GnRH has been showed to regulate hCG expression and secretion from the placenta through a GnRH receptor (GnRHR)-mediated process. Recently, we have reported the isolation of human GnRHR full-length complementary DNA from the human placental cells including choriocarcinoma JEG-3 cells, immortalized extravillous trophoblasts, and primary cultures of trophoblasts. Despite these observations, the molecular mechanism that controls the transcription regulation of the GnRHR gene expression in the placenta remains unknown. Here we described the identification of an upstream placenta-specific promoter located between nucleotide (nt) -1737 and -1346 (relative to the translation start site) for the human GnRHR gene. Using transient transfection studies, this upstream promoter has been shown to determine the placental cell-specific expression of this gene. Primer extension studies further confirmed the utilization of this promoter in JEG-3 cells in vivo. By mutagenesis coupled to functional studies, we have identified four putative transcription factor-binding sites, namely human glucocorticoid receptor (hGR)-Oct-1 (nt -1718 to -1710), hGR-cAMP response element (CRE; nt -1649 to -1641), hGR-GATA (nt -1602 to -1597), and hGR-activating protein-1 (nt -1518 to -1511), that are essential to the expression of this gene. Mutations of these cis-acting motifs reduced the promoter activity. The CRE and GATA motifs were subsequently shown to be placenta specific, as mutations of these motifs caused a dramatic loss in promoter activities in the placental JEG-3 cells, but not in the ovarian carcinoma OVCAR-3, monkey kidney COS-1, and human embryonic kidney 293 cells. Gel mobility assays confirmed the binding of nuclear proteins Oct-1, CRE-binding protein, GATA-2, GATA-3, c-Fos, and c-Jun from JEG-3 cells to these four elements.link_to_subscribed_fulltex

Simultaneous submission of seven CTSA proposals: UM1, K12, R25, T32-predoctoral, T32-postdoctoral, and RC2: strategies, evaluation, and lessons learned

Translation is the process of turning observations in the research laboratory, clinic, and community into interventions that improve people’s health. The Clinical and Translational Science Awards (CTSA) program is a National Center for Advancing Translational Sciences (NCATS) initiative to advance translational science and research. Currently, 64 “CTSA hubs” exist across the nation. Since 2006, the Houston-based Center for Clinical Translational Sciences (CCTS) has assembled a well-integrated, high-impact hub in Texas that includes six partner institutions within the state, encompassing ∼23,000 sq. miles and over 16 million residents. To achieve the NCATS goal of “more treatments for all people more quickly,” the CCTS promotes diversity and inclusion by integrating underrepresented populations into clinical studies, workforce training, and career development. In May 2023, we submitted the UM1 application and six “companion” proposals: K12, R25, T32-Predoctoral, T32-Postdoctoral, and RC2 (two applications). In October 2023, we received priority scores for the UM1 (22), K12 (25), T32-Predoctoral (20), and T32-Postdoctoral (23), which historically fall within the NCATS funding range. This report describes the grant preparation and submission approach, coupled with data from an internal survey designed to assimilate feedback from principal investigators, writers, reviewers, and administrative specialists. Herein, we share the challenges faced, the approaches developed, and the lessons learned