PHLDA3 is a novel tumor suppressor of pancreatic neuroendocrine tumors.

The molecular mechanisms underlying the development of pancreatic neuroendocrine tumors (PanNETs) have not been well defined. We report here that the genomic region of the PHLDA3 gene undergoes loss of heterozygosity (LOH) at a remarkably high frequency in human PanNETs, and this genetic change is correlated with disease progression and poor prognosis. We also show that the PHLDA3 locus undergoes methylation in addition to LOH, suggesting that a two-hit inactivation of the PHLDA3 gene is required for PanNET development. We demonstrate that PHLDA3 represses Akt activity and Akt-regulated biological processes in pancreatic endocrine tissues, and that PHLDA3-deficient mice develop islet hyperplasia. In addition, we show that the tumor-suppressing pathway mediated by MEN1, a well-known tumor suppressor of PanNETs, is dependent on the pathway mediated by PHLDA3, and inactivation of PHLDA3 and MEN1 cooperatively contribute to PanNET development. Collectively, these results indicate the existence of a novel PHLDA3-mediated pathway of tumor suppression that is important in the development of PanNETs.

Sarcoidosis and NOD1 variation with impaired recognition of intracellular Propionibacterium acnes.

Sarcoidosis is a systemic granulomatous disease of unknown etiology. NOD2 mutations have been shown to predispose to granulomatous diseases, including Crohn's disease, Blau syndrome, and early-onset sarcoidosis, but not to adult sarcoidosis. We found that intracellular Propionibacterium acnes, a possible causative agent of sarcoidosis, activated NF-kappaB in both NOD1- and NOD2-dependent manners. Systematic search for NOD1 gene polymorphisms in Japanese sarcoidosis patients identified two alleles, 796G-haplotype (156C, 483C, 796G, 1722G) and 796A-haplotype (156G, 483T, 796A, 1722A). Allelic discrimination of 73 sarcoidosis patients and 215 healthy individuals showed that the frequency of 796A-type allele was significantly higher in sarcoidosis patients and the ORs were significantly elevated in NOD1-796G/A and 796A/A genotypes (OR [95% CI]=2.250 [1.084, 4.670] and 3.243 [1.402, 7.502], respectively) as compared to G/G genotype, showing an increasing trend across the 3 genotypes (P=0.006 for trend). A similar association was found when 52 interstitial pneumonia patients were used as disease controls. Functional studies showed that the NOD1 796A-allele was associated with reduced expression leading to diminished NF-kappaB activation in response to intracellular P. acnes. The results indicate that impaired recognition of intracellular P. acnes through NOD1 affects the susceptibility to sarcoidosis in the Japanese population.

Using a customized DNA microarray for expression profiling of the estrogen-responsive genes to evaluate estrogen activity among natural estrogens and industrial chemicals.

We developed a DNA microarray to evaluate the estrogen activity of natural estrogens and industrial chemicals. Using MCF-7 cells, we conducted a comprehensive analysis of estrogen-responsive genes among approximately 20,000 human genes. On the basis of reproducible and reliable responses of the genes to estrogen, we selected 172 genes to be used for developing a customized DNA microarray. Using this DNA microarray, we examined estrogen activity among natural estrogens (17beta-estradiol, estriol, estrone, genistein), industrial chemicals (diethylstilbestrol, bisphenol A, nonylphenol, methoxychlor), and dioxin. We obtained results identical to those for other bioassays that are used for detecting estrogen activity. On the basis of statistical correlations analysis, these bioassays have shown more sensitivity for dioxin and methoxychlor.