Transcription Factor T-bet Attenuates the Development of Elastase-induced Emphysema in Mice.

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterized by peripheral airways inflammation and emphysema. Emerging evidence indicates a contribution of both innate and adaptive immune cells to the development of COPD. Transcription factor T-bet modulates the function of immune cells and therefore might be involved in the pathogenesis of COPD. To elucidate the role for T-bet in elastase-induced emphysema, pathological phenotypes were compared between wild-type and T-bet-/- mice. T-bet-/- mice demonstrated enhanced emphysema development on histological analyses, with higher values of mean linear intercept and dynamic compliance relative to wild-type mice. The number of neutrophils in BAL fluids, lung IL-6 and IL-17 expression, and the proportion of CD4+ T cells positive for IL-17 or retinoic acid receptor-related orphan receptor-γt were higher in T-bet-/- mice than in wild-type mice. Although T-bet downregulates cytokine expression in bone marrow-derived macrophages and MH-S cells, a murine alveolar cell line, depending on the surrounding environment, IL-6 expression in alveolar macrophages isolated from elastase-treated mice was not dependent on T-bet. Coculture of bone marrow-derived macrophages and CD4+ T cells revealed that T-bet regulation of IL-17 expression was dependent on CD4+ T cells. Neutralizing antibodies against IL-6R or IL-17 ameliorated the development of emphysema in T-bet-/- mice. In conclusion, we demonstrate that T-bet ameliorates elastase-induced emphysema formation by modulating the host immune response in the lungs.

Retinoic acid receptor-related receptor alpha (RORalpha) is a prognostic marker for hepatocellular carcinoma.

Retinoic acid receptor-related receptor alpha (RORalpha) has been proven to play a tumor suppressive role in certain types of solid tumors. However, the clinical characteristic of RORalpha has not been reported by far. This study investigated the expression of RORalpha in hepatocellular carcinoma (HCC) and evaluated its relationship with clinical parameters and prognosis in HCC patients. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot analyses were performed to detect RORalpha expression levels in 20 paired HCC and corresponding adjacent non-cancerous tissues. Immunohistochemistry was performed on 100 archived paraffin-embedded HCC samples. Statistical analyses evaluated the correlations between RORalpha expression and clinicopathological features. qRT-PCR showed that RORalpha mRNA expression was significantly down-regulated in tumors compared to the adjacent non-cancerous tissues, and Western blots found that RORalpha protein expression was also reduced in tumor tissues. Immunohistochemical assays revealed that decreased RORalpha expression was present in 65 % of HCC patients. Correlation analyses showed that RORalpha expression was significantly correlated with serum alpha fetoprotein (AFP, p = 0.005), pathology grade (p < 0.001), tumor recurrence (p = 0.008), and vascular invasion (p < 0.001). Kaplan-Meier analysis revealed that patients with low RORalpha expression levels had a shorter overall and disease-free survival than patients with high expression (p < 0.001 and p = 0.002, respectively). Multivariate regression analysis indicated that RORalpha was an independent predictor for overall survival and disease-free survival. In conclusion, the results of our study showed that down-regulated RORalpha expression was associated with poorer prognosis in HCC patients. RORalpha may be a new potential prognostic marker for HCC patients.

Analysis of the daily changes of melatonin receptors in the rat liver.

Melatonin membrane (MT1 and MT2) and nuclear (RORα) receptors have been identified in several mammalian tissues, including the liver. The mechanisms regulating hepatic melatonin receptors are yet unknown. This study investigated whether these receptors exhibit daily changes and the effects of melatonin on their levels. Our results show that mRNAs for MT1/MT2 receptors exhibit circadian rhythms that were followed by rhythms in their respective protein levels; the acrophases for the two rhythms were reached at 04:00 and 05:00 hr, respectively. Pinealectomy blunted the rhythms in both mRNAs and protein levels. In contrast, mRNA and protein levels of nuclear receptor RORα increased significantly after pinealectomy. The cycles of the latter receptor also exhibited circadian rhythms which peaked at 03:00 and 03:45 hr, respectively. Melatonin administration (10-200 mg/kg) increased in a dose-dependent manner the protein content of MT1/MT2 receptors, with no effects on RORα. Lunzindole treatment, however, did not affect melatonin receptor expression or content of either the membrane or nuclear receptors. Together with previously published findings which demonstrated the intracellular distribution of melatonin in rat liver, the current results support the conclusion that the circadian rhythms of MT1/MT2 and RORα receptors are under the control of the serum and intracellular melatonin levels. Moreover, the induction of MT1/MT2 receptors after the administration of high doses of melatonin further suggests that the therapeutic value of melatonin may not be restricted to only low doses of the indoleamine.

RORα suppresses breast tumor invasion by inducing SEMA3F expression.

Inactivation of tumor suppressors and inhibitory microenvironmental factors is necessary for breast cancer invasion; therefore, identifying those suppressors and factors is crucial not only to advancing our knowledge of breast cancer, but also to discovering potential therapeutic targets. By analyzing gene expression profiles of polarized and disorganized human mammary epithelial cells in a physiologically relevant three-dimensional (3D) culture system, we identified retinoid orphan nuclear receptor alpha (RORα) as a transcription regulator of semaphorin 3F (SEMA3F), a suppressive microenvironmental factor. We showed that expression of RORα was downregulated in human breast cancer tissue and cell lines, and that reduced mRNA levels of RORα and SEMA3F correlated with poor prognosis. Restoring RORα expression reprogrammed breast cancer cells to form noninvasiveness structures in 3D culture and inhibited tumor growth in nude mice, accompanied by enhanced SEMA3F expression. Inactivation of RORα in nonmalignant human mammary epithelial cells inhibited SEMA3F transcription and impaired polarized acinar morphogenesis. Using chromatin immunoprecipitation and luciferase reporter assays, we showed that transcription of SEMA3F is directly regulated by RORα. Knockdown of SEMA3F in RORα-expressing cancer cells rescued the aggressive 3D phenotypes and tumor invasion. These findings indicate that RORα is a potential tumor suppressor and inhibits tumor invasion by inducing suppressive cell microenvironment.

Altered expression of NFY-C and RORA in colorectal adenocarcinomas.

NFY-C, a subunit of the transcription factor NFY, binds to the promoters of several eukaryotic genes, including cell cycle-related genes. RORA is a steroid hormone receptor implicated in a range of important cellular processes. We evaluated the expression of NFY-C and RORA in colorectal adenocarcinomas and normal colonic tissue. NFY-C expression was elevated in adenocarcinomas. Moreover, NFY-C mRNA levels correlated with time to disease progression, while NFY-C protein expression was significantly higher in metastatic disease. RORA expression was downregulated in CRC adenocarcinomas compared to normal controls and correlated with time to disease progression. The role of NFY-C and RORA in CRC merits further investigation.