Rare mendelian primary immunodeficiency diseases associated with impaired NF-κB signaling.

Mendelian primary immunodeficiency diseases (MPIDs) are rare disorders affecting distinct constituents of the innate and adaptive immune system. Although they are genetically heterogeneous, a substantial group of MPIDs is due to mutations in genes affecting the nuclear factor-κB (NF-κB) transcription pathway, essential for cell proliferation and cell survival and involved in innate immunity and inflammation. Many of these genes encode for crucial regulatory components of the NF-κB pathway and their mutations are associated with immunological and developmental signs somehow overlapping in patients with MPIDs. At present, nine different MPIDs listed in the online mendelian inheritance in man (OMIM) are caused by mutations in at least nine different genes strictly involved in the NF-κB pathway that result in defects in immune responses. Here we report on the distinct function of each causative gene, on the impaired NF-κB step and more in general on the molecular mechanisms underlining the pathogenesis of the disease. Overall, the MPIDs affecting the NF-κB signalosome require a careful integrated diagnosis and appropriate genetic tests to be molecularly identified. Their discovery at an ever-increasing rate will help establish a common therapeutic strategy for a subclass of immunodeficient patients.

Serum osteoprotegerin correlates with age and bone mass in postmenopausal, but not in fertile age women.

PURPOSE OF INVESTIGATION: Osteoprotegerin (OPG) and receptor activator of nuclear factor kappaB ligand (RANKL) are bone turnover modulators expressed by osteoblasts. The aim of this study was to assess the relationship between the circulating OPG/RANKL system, age and bone mass, in fertile age and postmenopausal women. METHODS: In this cross-sectional observational study on 48 patients (fertile age, n = 22; postmenopause, n = 26), we investigated the correlation between serum OPG and RANKL, age and bone mineral density (BMD). Serum concentrations of OPG and RANKL were determined by enzyme-linked immunosorbent assay (ELISA); estimate BMD evaluation was performed with heel quantitative ultrasonometry (QUS). RESULTS: Serum OPG significantly increased (p = 0.003) and serum RANKL significantly decreased (p = 0.002), in the postmenopausal group compared to fertile age women. A significant correlation of serum OPG with age (r(s) = 0.39, p = 0.047) and BMD (r(s) = 0.45, p = 0.023) in postmenopausal women, and between RANKL and BMD (r(s) = 0.48, p = 0.024) in fertile age was found. CONCLUSION: These data demonstrate in vivo that the OPG/RANKL system is significantly associated with menopausal status and could play a role in postmenopausal osteoporosis.

c-FLIPL enhances anti-apoptotic Akt functions by modulation of Gsk3ß activity.

This corrects the article DOI: 10.1038/cdd.2010.65.

miR-340 inhibits tumor cell proliferation and induces apoptosis by targeting multiple negative regulators of p27 in non-small cell lung cancer.

MicroRNAs (miRNAs) control cell cycle progression by targeting the transcripts encoding for cyclins, CDKs and CDK inhibitors, such as p27(KIP1) (p27). p27 expression is controlled by multiple transcriptional and posttranscriptional mechanisms, including translational inhibition by miR-221/222 and posttranslational regulation by the SCF(SKP2) complex. The oncosuppressor activity of miR-340 has been recently characterized in breast, colorectal and osteosarcoma tumor cells. However, the mechanisms underlying miR-340-induced cell growth arrest have not been elucidated. Here, we describe miR-340 as a novel tumor suppressor in non-small cell lung cancer (NSCLC). Starting from the observation that the growth-inhibitory and proapoptotic effects of miR-340 correlate with the accumulation of p27 in lung adenocarcinoma and glioblastoma cells, we have analyzed the functional relationship between miR-340 and p27 expression. miR-340 targets three key negative regulators of p27. The miR-340-mediated inhibition of both Pumilio family RNA-binding proteins (PUM1 and PUM2), required for the miR-221/222 interaction with the p27 3'-UTR, antagonizes the miRNA-dependent downregulation of p27. At the same time, miR-340 induces the stabilization of p27 by targeting SKP2, the key posttranslational regulator of p27. Therefore, miR-340 controls p27 at both translational and posttranslational levels. Accordingly, the inhibition of either PUM1 or SKP2 partially recapitulates the miR-340 effect on cell proliferation and apoptosis. In addition to the effect on tumor cell proliferation, miR-340 also inhibits intercellular adhesion and motility in lung cancer cells. These changes correlate with the miR-340-mediated inhibition of previously validated (MET and ROCK1) and potentially novel (RHOA and CDH1) miR-340 target transcripts. Finally, we show that in a small cohort of NSCLC patients (n=23), representative of all four stages of lung cancer, miR-340 expression inversely correlates with clinical staging, thus suggesting that miR-340 downregulation contributes to the disease progression.

The tyrosine phosphatase Shp-2 mediates intracellular signaling initiated by Ret mutants.

The Src homology 2-containing tyrosine phosphatase, Shp-2, is a crucial enzyme that mediates intracellular signaling and is implicated in cell proliferation and differentiation. Here we investigated the involvement of the Shp-2 tyrosine phosphatase in determining the downstream signaling pathways initiated by the Ret oncogene, carrying either the cysteine 634 to tyrosine or the methionine 918 to threonine substitutions. These mutations convert the receptor tyrosine kinase, Ret, into a dominant transforming protein and induce constitutive activation of its intrinsic tyrosine kinase activity leading to congenital and sporadic cancers in neuroendocrine organs. Using the PC12, rat pheochromocytoma cell line, as model system, we show that Shp-2 mediates immediate-early gene expression if induced by either of the mutant alleles. Furthermore, we show that Shp-2 activity is required for RetM918T-induced Akt activation. The results indicate that Shp-2 is a downstream mediator of the mutated receptors RetC634Y and RetM918T, thus suggesting that it may act as a limiting factor in Ret-associated endocrine tumors, in the neoplastic syndromes multiple endocrine neoplasia types 2A and 2B.

miR-221/222 overexpession in human glioblastoma increases invasiveness by targeting the protein phosphate PTPµ.

Glioblastoma is the most frequent brain tumor in adults and is the most lethal form of human cancer. Despite the improvements in treatments, survival of patients remains poor. In order to identify microRNAs (miRs) involved in glioma tumorigenesis, we evaluated, by a miRarray, differential expression of miRs in the tumorigenic glioma LN-18, LN-229 and U87MG cells compared with the non-tumorigenic T98G cells. Among different miRs we focused our attention on miR-221 and -222. We demonstrated the presence of a binding site for these two miRs in the 3' untranslated region of the protein tyrosine phosphatase µ (PTPµ). Previous studies indicated that PTPµ suppresses cell migration and is downregulated in glioblastoma. Significantly, we found that miR-221 and -222 overexpression induced a downregulation of PTPµ as analyzed by both western blot and real-time PCR. Furthermore, miR-222 and -221 induced an increase in cell migration and growth in soft agar in glioma cells. Interestingly, the re-expression of PTPµ gene was able to revert the miR-222 and -221 effects on cell migration. Furthermore, we found an inverse correlation between miR-221 and -222 and PTPµ in human glioma cancer samples. In conclusion, our results suggest that miR-221 and -222 regulate glioma tumorigenesis at least in part through the control of PTPµ protein expression.

c-FLIPL enhances anti-apoptotic Akt functions by modulation of Gsk3ß activity.

Akt is a serine-threonine kinase that has an important role in transducing survival signals. Akt also regulates a number of proteins involved in the apoptotic process. To find new Akt interactors, we performed a two-hybrid screening in yeast using full-length Akt cDNA as bait and a human cDNA heart library as prey. Among 200 clones obtained, two of them were identified as coding for the c-FLIP(L) protein. c-FLIP(L) is an endogenous inhibitor of death receptor-induced apoptosis through the caspase-8 pathway. Using co-immunoprecipitation experiments of either transfected or endogenous proteins, we confirmed the interaction between Akt and c-FLIP(L). Furthermore, we observed that c-FLIP(L) overexpression interferes with Gsk3-ß phosphorylation levels. Moreover, through its effects on Gsk3ß, c-FLIP(L) overexpression in cancer cells induced resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). This effect was mediated by the regulation of p27(Kip1) and caspase-3 expression. These results indicate the existence of a new mechanism of resistance to TRAIL in cancer cells, and unexpected functions of c-FLIP(L).