Control of mRNA half-life plays a central role in normal development and disease. Several pathological conditions, such as inflammation and cancer, tightly correlate with deregulation in mRNA ...stability of pro-inflammatory genes. Among these, pro-angiogenesis cytokines, which play a crucial role in the formation of new blood vessels, normally show rapid mRNA decay patterns. The mRNA half-life of these genes appears to be regulated by mRNA-binding proteins that interact with AU-rich elements (AREs) in the 3'-untranslated region of mRNAs. Some of these RNA-binding proteins, such as tristetraprolin (TTP), ARE RNA-binding protein 1, and KH-type splicing regulatory protein, normally promote mRNA degradation. Conversely, other proteins, such as embryonic lethal abnormal vision-like protein 1 (HuR) and polyadenylate-binding protein-interacting protein 2, act as antagonists, stabilizing the mRNA. The steady state levels of mRNA-binding proteins and their relative ratio is often perturbed in human cancers and associated with invasion and aggressiveness. Compelling evidence also suggests that underexpression of TTP and overexpression of HuR may be a useful prognostic and predictive marker in breast, colon, prostate, and brain cancers, indicating a potential therapeutic approach for these tumors. In this review, we summarize the main mechanisms involved in the regulation of mRNA decay of pro-angiogenesis cytokines in different cancers and discuss the interactions between the AU-rich-binding proteins and their mRNA targets.
Post-transcriptional regulation plays a central role in cell differentiation and proliferation. Among the regulatory factors involved in this mechanism, Tristetraprolin (ZFP36 or TTP) is the ...prototype of a family of RNA-binding proteins that bind to adenylate and uridylate (AU)-rich sequences in the 3′UTR of mRNAs, which promotes their physiological decay. Here, we investigated whether TTP correlates with tumor aggressiveness in breast cancer and is a novel prognostic factor for this neoplasia. By immunoblot analysis, we determined the amount of TTP protein in different breast cancer cell lines and found an inverse correlation between aggressiveness and metastatic potential. TTP mRNA levels were very variable among cells lines and did not correlate with protein levels. Interestingly, by sequencing the entire TTP coding region in Hs578T cells that do not express the TTP protein, we identified a synonymous polymorphism (rs3746083) that showed a statistically significant association with a lack of response to Herceptin/Trastuzumab in HER2-positive-breast cancer patients. Even though this genetic change did not modify the corresponding amino acid, we performed functional studies and showed an effect on protein translation associated with the variant allele with respect to the wild-type. These data underline the importance of synonymous variants on gene expression and the potential role of TTP genetic polymorphisms as a prognostic marker for breast cancer.
Finding genes for complex diseases has been the goal of many genetic studies. Most of these studies have been successful by searching for genes and mutations in rare familial cases, by screening ...candidate genes and by performing genome wide association studies. However, only a small fraction of the total genetic risk for these complex genetic diseases can be explained by the identified mutations and associated genetic loci. In this review we focus on Hirschsprung disease (HSCR) as an example of a complex genetic disorder. We describe the genes identified in this congenital malformation and postulate that both common ‘low penetrant’ variants in combination with rare or private ‘high penetrant’ variants determine the risk on HSCR, and likely, on other complex diseases. We also discuss how new technological advances can be used to gain further insights in the genetic background of complex diseases. Finally, we outline a few steps to develop functional assays in order to determine the involvement of these variants in disease development.
•The genetics of Hirschsprung disease resembles other complex diseases.•The risk on complex diseases is likely determined by common and rare variants.•Statistical selection with systems biology will identify potential disease variants.•Functional analyses of selected variants are needed to infer disease involvement.
The major gene for Hirschsprung disease (HSCR) encodes the receptor tyrosine kinase RET. In a study of 690 European- and 192 Chinese-descent probands and their parents or controls, we demonstrate the ...ubiquity of a >4-fold susceptibility from a C→T allele (rs2435357: p = 3.9 × 10−43 in European ancestry; p = 1.1 × 10−21 in Chinese samples) that probably arose once within the intronic RET enhancer MCS+9.7. With in vitro assays, we now show that the T variant disrupts a SOX10 binding site within MCS+9.7 that compromises RET transactivation. The T allele, with a control frequency of 20%–30%/47% and case frequency of 54%–62%/88% in European/Chinese-ancestry individuals, is involved in all forms of HSCR. It is marginally associated with proband gender (p = 0.13) and significantly so with length of aganglionosis (p = 7.6 × 10−5) and familiality (p = 6.2 × 10−4). The enhancer variant is more frequent in the common forms of male, short-segment, and simplex families whereas multiple, rare, coding mutations are the norm in the less common and more severe forms of female, long-segment, and multiplex families. The T variant also increases penetrance in patients with rare RET coding mutations. Thus, both rare and common mutations, individually and together, make contributions to the risk of HSCR. The distribution of RET variants in diverse HSCR patients suggests a “cellular-recessive” genetic model where both RET alleles' function is compromised. The RET allelic series, and its genotype-phenotype correlations, shows that success in variant identification in complex disorders may strongly depend on which patients are studied.
The control of the half-life of mRNA plays a central role in normal development and in disease progression. Several pathological conditions, such as breast cancer, correlate with deregulation of the ...half-life of mRNA encoding growth factors, oncogenes, cell cycle regulators and inflammatory cytokines that participate in cancer. Substantial stability means that a mRNA will be available for translation for a longer time, resulting in high levels of protein gene products, which may lead to prolonged responses that subsequently result in over-production of cellular mediators that participate in cancer. The stability of these mRNA is regulated at the 3'UTR level by different mechanisms involving mRNA binding proteins, micro-RNA, long non-coding RNA and alternative polyadenylation. All these events are tightly inter-connected to each other and lead to steady state levels of target mRNAs. Compelling evidence also suggests that both mRNA binding proteins and regulatory RNAs which participate to mRNA half-life regulation may be useful prognostic markers in breast cancers, pointing to a potential therapeutic approach to treatment of patients with these tumors. In this review, we summarize the main mechanisms involved in the regulation of mRNA decay and discuss the possibility of its implication in breast cancer aggressiveness and the efficacy of targeted therapy.
Most melanoma cells are characterized by the V600E mutation in B-Raf kinase. This mutation leads to increased expression of interleukin (CXCL8), which plays a key role in cell growth and ...angiogenesis. Thus CXCL8 appears to be an interesting therapeutic target. Hence, we performed vaccination of mice with GST-CXCL8, which results in a reduced incidence of syngenic B16 melanoma cell xenograft tumors. We next addressed the molecular mechanisms responsible for aberrant CXCL8 expression in melanoma. The CXCL8 mRNA contains multiples AU-rich sequences (AREs) that modulate mRNA stability through the binding of tristetraprolin (TTP). Melanoma cell lines express very low TTP levels. We therefore hypothesized that the very low endogenous levels of TTP present in different melanoma cell lines might be responsible for the relative stability of CXCL8 mRNAs. We show that TTP is actively degraded by the proteasome and that extracellular-regulated kinase inhibition results in TTP accumulation. Conditional expression of TTP in A375 melanoma cells leads to CXCL8 mRNA destabilization via its 3' untranslated regions (3'-UTR), and TTP overexpression reduces its production. In contrast, downregulation of TTP by short hairpin RNA results in upregulation of CXCL8 mRNA. Maintaining high TTP levels in melanoma cells decreases cell proliferation and autophagy and induces apoptosis. Sorafenib, a therapeutic agent targeting Raf kinases, decreases CXCL8 expression in melanoma cells through reexpression of TTP. We conclude that loss of TTP represents a key event in the establishment of melanomas through constitutive expression of CXCL8, which constitutes a potent therapeutic target.
Germline and somatic mutations play a crucial role in breast cancer (BC), driving the initiation, progression, response to therapy and outcome of the disease. Hormonal therapy is limited to patients ...with tumors expressing steroid hormone receptors, such as estrogen receptor (ER), nevertheless resistance often limits its success.The RET gene is known to be involved in neurocristopathies such as Hirschsprung disease and Multiple Endocrine Neoplasia type 2, in the presence of loss-of-function and gain-of-function mutations, respectively. More recently, RET over-expression has emerged as a new player in ER-positive (ER+) BC, and as a potential target to enhance sensitivity and avoid resistance to tamoxifen therapy.Therefore, targeting the RET pathway may lead to new therapies in ER+ BC. To this end, we have investigated the molecular mechanisms which underlie RET overexpression and its possible modulation in two BC cell lines, MCF7 and T47D, showing different RET expression levels. Moreover, we have carried out a pilot association study in 93 ER+ BC patients. Consistent with the adverse role of RET over-expression in BC, increased overall survival was observed in carriers of the variant allele of SNP rs2435357, a RET polymorphism already known to be associated with reduced RET expression.
Associated anomalies have been reported in around 20% of Hirschsprung patients but many Authors suggested a measure of underestimation. We therefore implemented a prospective observational study on ...106 consecutive HSCR patients aimed at defining the percentage of associated anomalies and implementing a personalized and up-to-date diagnostic algorithm.
After Institutional Ethical Committee approval, 106 consecutive Hirschsprung patients admitted to our Institution between January 2010 and December 2012 were included. All families were asked to sign a specific Informed Consent form and in case of acceptance each patient underwent an advanced diagnostic algorithm, including renal ultrasound scan (US), cardiologic assessment with cardiac US, cerebral US, audiometry, ENT and ophthalmologic assessments plus further specialist evaluations based on specific clinical features.
Male to female ratio of our series of patients was 3,4:1. Aganglionosis was confined to the rectosigmoid colon (classic forms) in 74,5% of cases. We detected 112 associated anomalies in 61 (57,5%) patients. The percentage did not significantly differ according to gender or length of aganglionosis. Overall, 43,4% of patients complained ophthalmologic issues (mostly refraction anomalies), 9,4% visual impairment, 20,7% congenital anomalies of the kidney and urinary tract, 4,7% congenital heart disease, 4,7% hearing impairment or deafness, 2,3% central nervous system anomalies, 8,5% chromosomal abnormalities or syndromes and 12,3% other associated anomalies.
Our study confirmed the underestimation of certain associated anomalies in Hirschsprung patients, such as hearing impairment and congenital anomalies of the kidney and urinary tract. Subsequently, based on our results we strongly suggest performing renal US and audiometry in all patients. Conversely, ophthalmologic assessment and cerebral and heart US can be performed according to guidelines applied to the general population or in case of patients with suspected clinical features or chromosomal abnormalities. This updated diagnostic algorithm aims at improving overall outcome thanks to better prognostic expectations, prevention strategies and early rehabilitation modalities. The investigation of genetic background of patients with associated anomalies might be the next step to explore this intriguing multifactorial congenital disease.
Hirschsprung disease (HSCR) is a rare congenital anomaly characterized by the absence of enteric ganglia in the distal intestinal tract. While classified as a multigenic disorder, the altered ...function of the RET tyrosine kinase receptor is responsible for the majority of the pathogenesis of HSCR. Recent evidence demonstrate a strong association between RET and the homeostasis of immune system. Here, we utilize a unique cohort of fifty HSCR patients to fully characterize the expression of RET receptor on both innate (monocytes and Natural Killer lymphocytes) and adaptive (B and T lymphocytes) human peripheral blood mononuclear cells (PBMCs) and to explore the role of RET signaling in the immune system. We show that the increased expression of RET receptor on immune cell subsets from HSCR individuals correlates with the presence of loss-of-function RET mutations. Moreover, we demonstrate that the engagement of RET on PBMCs induces the modulation of several inflammatory genes. In particular, RET stimulation with glial-cell line derived neurotrophic factor family (GDNF) and glycosyl-phosphatidylinositol membrane anchored co-receptor α1 (GFRα1) trigger the up-modulation of genes encoding either for chemokines (CCL20, CCL2, CCL3, CCL4, CCL7, CXCL1) and cytokines (IL-1β, IL-6 and IL-8) and the down-regulation of chemokine/cytokine receptors (CCR2 and IL8-Rα). Although at different levels, the modulation of these "RET-dependent genes" occurs in both healthy donors and HSCR patients. We also describe another set of genes that, independently from RET stimulation, are differently regulated in healthy donors versus HSCR patients. Among these "RET-independent genes", there are CSF-1R, IL1-R1, IL1-R2 and TGFβ-1, whose levels of transcripts were lower in HSCR patients compared to healthy donors, thus suggesting aberrancies of inflammatory responses at mucosal level. Overall our results demonstrate that immune system actively participates in the physiopathology of HSCR disease by modulating inflammatory programs that are either dependent or independent from RET signaling.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Marta Rusmini: Laboratory of Molecular Genetics, IRCCS, Giannina Gaslini Istitute, Genoa, Italy, Unit of Clinical and Experimental Immunology, Humanitas Clinical and Research Center, Rozzano, Milan, ...Italy Ivana Matera: Laboratory of Molecular Genetics, IRCCS, Giannina Gaslini Istitute, Genoa, Italy, Unit of Clinical and Experimental Immunology, Humanitas Clinical and Research Center, Rozzano, Milan, Italy Roberto Ravazzolo: Laboratory of Molecular Genetics, IRCCS, Giannina Gaslini Istitute, Genoa, Italy, DINOGMI Department, University of Genova, Genova, Italy Citation: Rusmini M, Griseri P, Lantieri F, Matera I, Hudspeth KL, Roberto A, et al. (2013) Correction: Induction of RET Dependent and Independent Pro-Inflammatory Programs in Human Peripheral Blood Mononuclear Cells from Hirschsprung Patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
