Activation of extracellular signal-regulated kinase (ERK) and induction of mitogen-activated protein kinase phosphatase 1 (MKP-1) by perifused thyrotropin-releasing hormone (TRH) stimulation in rat pituitary GH3 cells.

We investigated the pattern of extracellular signal-regulated kinase (ERK) phosphorylation and the induction of mitogen-activated protein kinase phosphatase 1 (MKP-1) by thyrotropin-releasing hormone (TRH) under various stimulation conditions in pituitary GH3 cells. In static culture, ERK activation by continuous TRH was maximal at 10 min and persisted for up to 60 min, with a return to the basal level by 2h. Stimulation with continuous TRH in perifused cells resulted in a similar level of ERK phosphorylation. MKP-1 was expressed 60 min following either static or perifused, continuous TRH stimulation. When cells were stimulated with pulsatile TRH every 30 min, ERK activation was maximal at 10 min and returned to its baseline level by 30 min. ERK was phosphorylated again with each subsequent pulse. Pulsatile TRH did not induce MKP-1. Prolactin promoter activity following continuous, static TRH stimulation was higher than that following perifused TRH stimulation. TRH at a frequency of one pulse every 30 min increased prolactin promoter activity similar to that of perifused, continuous TRH stimulation. Additionally, changes in pulse frequency resulted in alterations in the level of prolactin promoter. Following static stimulation, a 10 min exposure to TRH was sufficient to obtain full activation of the prolactin promoter. Additionally, a 5-10 min exposure of TRH was sufficient to maintain ERK activation. A single 5-min pulse of TRH stimulation resulted in low activation of the prolactin promoter. ERK activation was necessary for prolactin gene transcription; however, prolactin gene transcription is not entirely determined by the strength or duration of TRH-induced ERK activation.

Expression of the bric-a-brac tramtrack broad complex protein NAC-1 in cervical carcinomas seems to correlate with poorer prognosis.

PURPOSE: Recent studies have suggested a novel oncogenic role of a bric-a-brac tramtrack broad complex (also known as POZ) domain gene, NAC-1, in ovarian carcinomas. The aim of this study was to clarify the functional role of NAC-1 in human cervical carcinomas. EXPERIMENTAL DESIGN: NAC-1 expression in cervical cancer was assessed by immunohistochemistry, and data on clinical variables were collected by retrospective chart review. NAC-1 gene knockdown using small interfering RNA and a NAC-1 gene transfection system were used to asses NAC-1 function in cervical cancer in vivo. RESULTS: Immunohistochemical and gene expression analysis revealed that NAC-1 is significantly overexpressed in cervical adenocarcinomas and adenosquamous carcinomas compared with squamous cell carcinomas. Patients with squamous cell carcinomas positive for NAC-1 expression who received radiotherapy had significantly shorter overall survival than peers whose tumors did not express NAC-1, and multivariate analysis showed that NAC-1 expression was an independent prognostic factor for overall survival after radiotherapy. Overexpressions of the NAC-1 gene stimulated cell proliferation in cervical carcinoma cells of the TCS, CaSki, and HeLa P3 lines, which do not have endogenous NAC-1 expression. NAC-1 gene knockdown inhibited cell growth and induced apoptosis in HeLa, HeLa TG, and ME180 cells, all of which overexpressed NAC-1. CONCLUSIONS: Our findings suggest that NAC-1 may play an important role in cervical carcinomas; moreover, these findings provide a rationale for future development of NAC-1-based therapy for cervical carcinomas that overexpress this candidate oncogene.

Genetic classification of ovarian carcinoma based on microsatellite analysis: relationship to clinicopathological features and patient survival.

Ovarian carcinomas can progress through two pathways of genomic instability: chromosomal instability (CIN) and microsatellite instability (MSI). However, it is unknown whether these two mechanisms could be distinguished from each other in the molecular characteristics in ovarian carcinomas. We hypothesized that these two pathways are not always independent in ovarian carcinomas. We classified 51 ovarian carcinomas based on their MSI and CIN status using microsatellite analysis and assessed whether these carcinogenic pathways affect the clinicopathological features and patient survival. Of the 51 cases, 77.4% of the tumors were microsatellite stable (MSS), 5.9% were MSI-Low (MSI-L) whilst, 16.7% were MSI-High (MSI-H). Overall, 56.8% of the tumors had at least one loss of heterozygosity (LOH) event, i.e., 56.8% CIN. Notably, we identified a significant degree of overlap between the MSI and CIN pathways. Of the 34 tumors with LOH events (CIN), 5 (14.7%) were MSI-H. In addition, of the 7 tumors that were MSI-H, 5 (71.4%) had one or more LOH events (CIN). We also identified a group of 29.4% of all tumors that did not demonstrate any evidence of either of the two pathways of genomic instability as they were MSS/MSI-L with no evidence of LOH events (CIN negative). Furthermore, patients with CIN with MSS/MSI-L have a significantly shorter overall survival compared to those in other genetic categories (P=0.019). Cox regression analysis revealed that tumors with CIN with MSS/MSI-L exhibit a poor prognostic outcome after adjustment for FIGO stage and grade. These findings suggest that some ovarian carcinomas have a significant degree of overlap between the two pathways of genomic instability and that the genetic classification using microsatellite markers may represent a potential new biomarker of risk prediction in ovarian carcinoma.