Expression of prohibitin 3' untranslated region suppressor RNA alters morphology and inhibits motility of breast cancer cells

Antiosteoporotic Effects of Huangqi Sanxian Decoction in Cultured Rat Osteoblasts by Proteomic Characterization of the Target and Mechanism

Huangqi Sanxian decoction (HQSXD) is routinely used for the treatment of osteoporosis in the Chinese traditional healthcare system. However, the targets and mechanism underlying the effect of HQSXD on osteoporosis have not been documented. In the present study, seropharmacology and proteomic approaches (two-dimensional gel electrophoresis combined with mass spectrometry) were used to investigate the effects and possible target proteins of HQSXD on osteoblast. We found that HQSXD-treated rat serum significantly enhanced osteoblast proliferation, differentiation, and mineralization. In HQSXD-S-treated osteoblasts, there were increases in the expression of N-formyl peptide receptor 2 and heparan sulfate (glucosamine) 3-O-sulfotransferase 3A1 and reduction in the expression of alpha-spectrin, prohibitin, and transcription elongation factor B (SIII), polypeptide 1. The identified proteins are associated with cell proliferation, differentiation, signal transcription, and cell growth. These findings might provide valuable insights into the mechanism of antiosteoporotic effect affected by HQSXD treatment in osteoblasts.

Prohibitin expression deregulation in gastric cancer is associated with the 3' untranslated region 1630 C>T polymorphism and copy number variation

PHB is a reported oncogene and tumor suppressor in gastric cancer. Here, we evaluated whether the PHB copy number and the rs6917 polymorphism affect its expression in gastric cancer. Down-regulation and up-regulation of PHB were observed in the evaluated tumors. Reduced expression was associated with tumor dedifferentiation and cancer initiation. The T allele of the rs6917 polymorphism was associated with reduced PHB mRNA levels. Moreover, the up-regulation of PHB appeared to be regulated by the gain of additional gene copies. Thus, PHB copy number variation and differential expression of the rs6917 polymorphism may play a role in PHB transcriptional regulation.

Gonadotropin-releasing hormone-regulated prohibitin mediates apoptosis of the gonadotrope cells

GnRH regulates circulating levels of the gonadotropins but has also been implicated in establishing the gonadotrope cell population. Consistent with this, GnRH induces proliferation of partially differentiated gonadotropes, while reducing the numbers of fully differentiated cells. We have previously reported that the proapoptotic protein, prohibitin (PHB) is expressed more abundantly in gonadotrope-derived LβT2 cells than in partially differentiated αT3-1 gonadotrope precursor cells, suggesting a possible role for PHB in GnRH-induced apoptosis. We show here that PHB is required for GnRH-induced apoptosis in mature gonadotropes. PHB expression and activity are regulated by GnRH: its transcription is via c-Jun NH2-terminal kinase, whereas its nuclear export follows activation of ERK. Moreover, PHB levels are down-regulated by microRNA27, which is expressed at lower levels in mature gonadotropes, possibly explaining the switch to an apoptotic response with development. PHB is required for mitochondrial import of the proapoptotic BAX, whose expression is also induced by GnRH-activated c-Jun NH2-terminal kinase, as is expression of the BH3-only protein, HRK, and this too plays a role in GnRH-induced apoptosis. Finally, we show that gonadotrope-specific PHB-knockout mice display reproductive abnormalities, including a larger gonadotrope population, increased LH levels, reduced fertility, and altered gonad development. We thus demonstrate a role for PHB in GnRH-induced cell death in mature gonadotropes, which is crucial for the normal development and function of the reproductive axis.

3' untranslated region 1630 C>T polymorphism of prohibitin increases risk of breast cancer

Background:

Prohibitin 3′ untranslated region 1630 C>T (rs6917) polymorphism creates a variant T allele that lacks the antiproliferative activity of the more common functional C allele. Previous studies indicate that women carrying the prohibitin T allele have an increased susceptibility to breast cancer. However, the role of 1630 C>T polymorphism in mRNA expression of prohibitin and its contribution to carcinogenesis in the breast remains controversial.

Methods:

Using mRNA expression data from the HapMap online database, we sought an association between prohibitin 1630 C>T polymorphism and its mRNA expression, then conducted a meta-analysis of prohibitin 1630 C>T polymorphism and risk of breast cancer.

Results:

Although no significant association was found between prohibitin 1630 C>T polymorphism and mRNA expression in lymphoblastoid cell lines from the HapMap database (P_trend = 0.543), the present meta-analysis involving 5072 cases and 4796 controls demonstrated that prohibitin 1630 C>T polymorphism was significantly correlated with breast cancer risk in allele contrast model T versus C (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.01–1.18), the homozygote codominant model TT versus CC (OR 1.47, 95% CI 1.12–1.92), and the recessive model TT versus CC/CT (OR 1.45, 95% CI 1.10–1.89).

Conclusion:

Our study indicates that minor allele T of prohibitin 1630 C>T polymorphism is associated with increased susceptibility to breast cancer.

Association of PHB 1630 C>T and MTHFR 677 C>T polymorphisms with breast and ovarian cancer risk in BRCA1/2 mutation carriers: results from a multicenter study

BACKGROUND

The variable penetrance of breast cancer in BRCA1/2 mutation carriers suggests that other genetic or environmental factors modify breast cancer risk. Two genes of special interest are prohibitin (PHB) and methylene-tetrahydrofolate reductase (MTHFR), both of which are important either directly or indirectly in maintaining genomic integrity.

METHODS

To evaluate the potential role of genetic variants within PHB and MTHFR in breast and ovarian cancer risk, 4102 BRCA1 and 2093 BRCA2 mutation carriers, and 6211 BRCA1 and 2902 BRCA2 carriers from the Consortium of Investigators of Modifiers of BRCA1 and BRCA2 (CIMBA) were genotyped for the PHB 1630 C>T (rs6917) polymorphism and the MTHFR 677 C>T (rs1801133) polymorphism, respectively.

RESULTS

There was no evidence of association between the PHB 1630 C>T and MTHFR 677 C>T polymorphisms with either disease for BRCA1 or BRCA2 mutation carriers when breast and ovarian cancer associations were evaluated separately. Analysis that evaluated associations for breast and ovarian cancer simultaneously showed some evidence that BRCA1 mutation carriers who had the rare homozygote genotype (TT) of the PHB 1630 C>T polymorphism were at increased risk of both breast and ovarian cancer (HR 1.50, 95%CI 1.10-2.04 and HR 2.16, 95%CI 1.24-3.76, respectively). However, there was no evidence of association under a multiplicative model for the effect of each minor allele.

CONCLUSION

The PHB 1630TT genotype may modify breast and ovarian cancer risks in BRCA1 mutation carriers. This association need to be evaluated in larger series of BRCA1 mutation carriers.

The role and therapeutic potential of prohibitin in disease

Prohibitin 1 (PHB1), a pleiotropic protein in the cell, has been implicated in the regulation of proliferation, apoptosis, transcription, mitochondrial protein folding, and as a cell-surface receptor. This diverse array of functions of PHB1 is attributed to the cell type studied and its subcellular localization. This review discusses recent data that indicate a diverse role of PHB1 in disease pathogenesis and suggest that targeting PHB1 may be a potential therapeutic option for treatment of diseases including cancer, inflammatory bowel disease, insulin resistance/type 2 diabetes, and obesity. These diseases are associated with increased oxidative stress and mitochondrial dysfunction and therefore, the role of PHB1 in both responses will also be discussed.

Ovarian cancer risk in Polish BRCA1 mutation carriers is not associated with the prohibitin 3' untranslated region polymorphism

BACKGROUND

The variable penetrance of ovarian cancer in BRCA1 mutation carriers suggests that other genetic or environmental factors modify disease risk. The C to T transition in the 3' untranslated region of the prohibitin (PHB) gene alters mRNA function and has recently been shown to be associated with hereditary breast cancer risk in Polish women harbouring BRCA1 mutations.

METHODS

To investigate whether the PHB 3'UTR polymorphism also modifies hereditary ovarian cancer risk, we performed a case-control study among Polish women carrying one of the three common founder mutations (5382insC, 300 T > G, 4154delA) including 127 ovarian cases and 127 unaffected controls who had both breasts and ovaries intact. Controls were matched to cases by year of birth and BRCA1 mutation. Genotyping analysis was performed using PCR-based restriction fragment length polymorphism analysis. Odds ratios (OR) were calculated using conditional and penalized univariable and multivariable logistic regression.

RESULTS

A comparison of the genotype frequencies between cases and controls revealed no association of the PHB 3'UTR _CT+TT genotypes with ovarian cancer risk (ORadj 1.34; 95% CI, 0.59-3.11).

CONCLUSION

Our data suggest that the PHB 3'UTR polymorphism does not modify ovarian cancer risk in women carrying one of the three Polish BRCA1 founder mutations.

Prohibitin protects against oxidative stress in intestinal epithelial cells

Prohibitin (PHB) is an evolutionarily conserved and ubiquitously expressed protein whose expression or function in intestinal diseases is not known. In this study, we examined the expression and role of PHB in oxidative stress associated with inflammatory bowel disease. Our results show that PHB primarily localizes to the mitochondria in intestinal epithelial cells. Its expression is down-regulated during active human Crohn's disease, experimental colitis in vivo, and oxidative stress in vitro. PHB overexpression increases the expression of glutathione-S-transferase pi and protects from oxidant-induced depletion of glutathione. Finally, PHB overexpression decreases accumulation of reactive oxygen metabolites, as well as increased permeability induced by oxidative stress in intestinal epithelial cells. Together, these results suggest that PHB constitutes a previously unrecognized cellular defense against oxidant injury. Thus, strategies to modulate PHB levels may constitute a novel therapeutic approach for intestinal inflammatory diseases, wherein oxidative stress plays a critical role in tissue injury and inflammation.

Transcriptome analysis of a cnidarian-dinoflagellate mutualism reveals complex modulation of host gene expression

BACKGROUND

Cnidarian-dinoflagellate intracellular symbioses are one of the most important mutualisms in the marine environment. They form the trophic and structural foundation of coral reef ecosystems, and have played a key role in the evolutionary radiation and biodiversity of cnidarian species. Despite the prevalence of these symbioses, we still know very little about the molecular modulators that initiate, regulate, and maintain the interaction between these two different biological entities. In this study, we conducted a comparative host anemone transcriptome analysis using a cDNA microarray platform to identify genes involved in cnidarian-algal symbiosis.

RESULTS

We detected statistically significant differences in host gene expression profiles between sea anemones (Anthopleura elegantissima) in a symbiotic and non-symbiotic state. The group of genes, whose expression is altered, is diverse, suggesting that the molecular regulation of the symbiosis is governed by changes in multiple cellular processes. In the context of cnidarian-dinoflagellate symbioses, we discuss pivotal host gene expression changes involved in lipid metabolism, cell adhesion, cell proliferation, apoptosis, and oxidative stress.

CONCLUSION

Our data do not support the existence of symbiosis-specific genes involved in controlling and regulating the symbiosis. Instead, it appears that the symbiosis is maintained by altering expression of existing genes involved in vital cellular processes. Specifically, the finding of key genes involved in cell cycle progression and apoptosis have led us to hypothesize that a suppression of apoptosis, together with a deregulation of the host cell cycle, create a platform that might be necessary for symbiont and/or symbiont-containing host cell survival. This first comprehensive molecular examination of the cnidarian-dinoflagellate associations provides critical insights into the maintenance and regulation of the symbiosis.