Overview: genes that predispose to cancer

Heredity and environment both operate in the origin of cancer. Dominantly heritable cancer is caused by 'cancer' genes that impart high relative risks but account for only a small part of the incidence of cancer; they are usually recessive in oncogenesis, mutation or loss of the second allele being necessary. Non-hereditary forms of cancer may involve the same genes. Other genes interact with environment in carcinogenesis; these may impart relatively small relative risks, but because their frequencies may be high, the attributable risks can be great, as probably is the case with lung cancer. The process of carcinogenesis is thought to involve 2 or more somatic genetic events in most cases. The genes whose germline mutations cause dominantly inherited cancer can also be mutated somatically to cause non-hereditary cancer. Other genes may influence the numbers of target cells, or the proliferation of once-hit stem cells, without being critical events on the path to cancer. However, such genes could greatly influence the incidence of a cancer. Other genes, such as that for Bloom's syndrome, may affect the rates at which first and second events occur. Finally, other genes may influence the occurrence of events critical for progression and metastasis, such as vascularization of a small tumor.     

Association of the FTO gene with BMI

Variants in the FTO gene have been strongly associated with obesity in a very large sample (38,759) of diabetic and control subjects. To replicate these findings, the previously reported SNP in the FTO gene (rs9939609, T/A) was genotyped in 5,607 subjects from five different Utah studies. The studies included a random sample of the Utah population, families selected for aggregation of extreme thinness, families selected for severe obesity, a series of unrelated severe obesity subjects, and families participating in a 25-year longitudinal study of cardiovascular disease and aging. Results show a strong significant increase in the rs9939609 A allele frequency with increasing BMI (P < 0.0001). In the longitudinal study, FTO genotypes were significantly associated with BMI at a baseline exam, a 2(1/2)-year follow-up exam and a 25-year follow-up exam using an additive genetic model. The mean genotype difference in BMI ranged from 1.3 to 2.1 kg/m(2) across exams. The genotype difference in BMI means was established in youth, and at-risk subjects under age 20 at baseline had a significantly larger 25-year BMI increase (10.0 for A/A; 9.7 for A/T, and 8.5 kg/m(2) for T/T, P = 0.05). We conclude that the BMI increases associated with FTO genotypes begin in youth and are maintained throughout adulthood.     

Toll-like receptor 4 polymorphisms predispose to cutaneous leishmaniasis

The clinical spectrum of cutaneous leishmaniasis (CL) is extremely variable. Studies in experimental leishmaniasis have revealed a role for TLR4 in control of infection. In the present study the associations between TLR4 mutations (Asp299Gly and Thr399Ile) with outcome of CL have been investigated. Genotyping for Asp299Gly and Thr399Ile was performed in patients with chronic (N?=?22) and acute (N?=?61) CL, asymptomatic (N?=?45) and healthy leishmanin skin test negative individuals (N?=?75). The results showed the frequency of the Asp299Gly genotype was increased in patients with chronic disease (OR 25.3, 95% CI 5.2-115.6, P?相似文献   

What aspects of autism predispose to talent?

In this paper, we explore the question, why are striking special skills so much more common in autism spectrum conditions (ASC) than in other groups? Current cognitive accounts of ASC are briefly reviewed in relation to special skills. Difficulties in ‘theory of mind’ may contribute to originality in ASC, since individuals who do not automatically ‘read other minds’ may be better able to think outside prevailing fashions and popular theories. However, originality alone does not confer talent. Executive dysfunction has been suggested as the ‘releasing’ mechanism for special skills in ASC, but other groups with executive difficulties do not show raised incidence of talents. Detail-focused processing bias (‘weak coherence’, ‘enhanced perceptual functioning’) appears to be the most promising predisposing characteristic, or ‘starting engine’, for talent development. In support of this notion, we summarize data from a population-based twin study in which parents reported on their 8-year-olds'' talents and their ASC-like traits. Across the whole sample, ASC-like traits, and specifically ‘restricted and repetitive behaviours and interests’ related to detail focus, were more pronounced in children reported to have talents outstripping older children. We suggest that detail-focused cognitive style predisposes to talent in savant domains in, and beyond, autism spectrum disorders.     

Germline BRCA1 mutations predispose to pancreatic adenocarcinoma

Although the association of germline BRCA2 mutations with pancreatic adenocarcinoma is well established, the role of BRCA1 mutations is less clear. We hypothesized that the loss of heterozygosity at the BRCA1 locus occurs in pancreatic cancers of germline BRCA1 mutation carriers, acting as a “second-hit” event contributing to pancreatic tumorigenesis. Seven germline BRCA1 mutation carriers with pancreatic adenocarcinoma and nine patients with sporadic pancreatic cancer were identified from clinic- and population-based registries. DNA was extracted from paraffin-embedded tumor and nontumor samples. Three polymorphic microsatellite markers for the BRCA1 gene, and an internal control marker on chromosome 16p, were selected to test for the loss of heterozygosity. Tumor DNA demonstrating loss of heterozygosity in BRCA1 mutation carriers was sequenced to identify the retained allele. The loss of heterozygosity rate for the control marker was 20%, an expected baseline frequency. Loss of heterozygosity at the BRCA1 locus was 5/7 (71%) in BRCA1 mutation carriers; tumor DNA was available for sequencing in 4/5 cases, and three demonstrated loss of the wild-type allele. Only 1/9 (11%) sporadic cases demonstrated loss of heterozygosity at the BRCA1 locus. Loss of heterozygosity occurs frequently in pancreatic cancers of germline BRCA1 mutation carriers, with loss of the wild-type allele, and infrequently in sporadic cancer cases. Therefore, BRCA1 germline mutations likely predispose to the development of pancreatic cancer, and individuals with these mutations may be considered for pancreatic cancer-screening programs.     

Genetic variation at KIT locus may predispose to melanoma

As loss of KIT frequently occurs in melanoma progression, we hypothesized that KIT is implicated in predisposition to melanoma (MM). Thus, we sequenced the KIT coding region in 112 familial MM cases and 143 matched controls and genotyped tag single‐nucleotide polymorphisms (SNPs) in two cohorts of melanoma patients and matched controls. Five rare KIT substitutions, all predicted possibly or probably deleterious, were identified in five patients, but none in controls [RR = 2.26 (1.26–2.26)]. Expressed in melanocyte lines, three substitutions inhibited KIT signaling. Comparison with exomes database (7020 alleles) confirmed a significant excess of rare deleterious KIT substitutions in patients. Additionally, a common SNP, rs2237028, was associated with MM risk, and 6 KIT variants were associated with nevus count. Our data strongly suggest that rare KIT substitutions predispose to melanoma and that common variants at KIT locus may also impact nevus count and melanoma risk.     

Comparative analysis of plasma metabolomics response to metabolic challenge tests in healthy subjects and influence of the FTO obesity risk allele

The measurement of metabolites during intravenous or nutritional challenges may improve the identification of novel metabolic signatures which are not detectable in the fasting state. Here, we comprehensively characterized the plasma metabolomics response to five defined challenge tests and explored their use to identify interactions with the FTO rs9939609 obesity risk genotype. Fifty-six non-diabetic male participants of the KORA S4/F4 cohort, including 25 homozygous carriers of the FTO risk allele (AA genotype) and 31 carriers of the TT genotype were recruited. Challenges comprised an oral glucose tolerance test, a standardized high-fat high-carbohydrate meal and a lipid tolerance test, as well as an intravenous glucose tolerance test and a euglycemic hyperinsulinemic clamp. Blood was sampled for biochemical and metabolomics measurement before and during the challenges. Plasma samples were analyzed using a mass spectrometry-based metabolomics approach targeting 163 metabolites. Linear mixed-effects models and cluster analysis were performed. In both genotype groups, we observed significant challenge-induced changes for all major metabolite classes (amino acids, hexose, acylcarnitines, phosphatidylcholines, lysophosphatidylcholines and sphingomyelins, with corrected p-values ranging from 0.05 to 6.7E?37), which clustered in five distinct metabolic response profiles. Our data contribute to the understanding of plasma metabolomics response to diverse metabolic challenges, including previously unreported metabolite changes in response to intravenous challenges. The FTO genotype had only minor effects on the metabolite fluxes after standardized metabolic challenges.     

Climate interacts with anthropogenic drivers to determine extirpation dynamics

Theoretical studies suggest that the dynamics of a species’ range during a period of climate change depends upon the existence and interplay of various ecological and evolutionary processes. Here we tested how anthropogenic pressures contribute to climate‐mediated extirpation patterns of 32 freshwater fish species over the last 20 yr. We contrasted two extreme cases to determine whether extirpations were governed by patterns of climate exposure, assuming full adaptation of species to local climate, or instead by the interplay between climate exposure and the distance from the centroid of species’ climatic niches, assuming a fixed niche, and asked whether anthropogenic disturbances interact with these climatic drivers. We found strong support for the fixed niche hypothesis, but showed that species‐specific local adaptation to climate may also be important in determining extirpation dynamics. We also demonstrated that anthropogenic disturbance acted in concert with climate, ultimately determining population changes. Our results add novel evidence that unravelling the direct links between range dynamics and climate requires a multifaceted treatment, and that accounting for the cumulative effects of anthropogenic pressures deserves special attention in the context of climate change.     

HUWE1 interacts with PCNA to alleviate replication stress

Defects in DNA replication, DNA damage response, and DNA repair compromise genomic stability and promote cancer development. In particular, unrepaired DNA lesions can arrest the progression of the DNA replication machinery during S‐phase, causing replication stress, mutations, and DNA breaks. HUWE1 is a HECT‐type ubiquitin ligase that targets proteins involved in cell fate, survival, and differentiation. Here, we report that HUWE1 is essential for genomic stability, by promoting replication of damaged DNA. We show that HUWE1‐knockout cells are unable to mitigate replication stress, resulting in replication defects and DNA breakage. Importantly, we find that this novel role of HUWE1 requires its interaction with the replication factor PCNA, a master regulator of replication fork restart, at stalled replication forks. Finally, we provide evidence that HUWE1 mono‐ubiquitinates H2AX to promote signaling at stalled forks. Altogether, our work identifies HUWE1 as a novel regulator of the replication stress response.     

Lactoferrin interacts with nucleotides

Lactoferrin (LF) is an iron-binding glycoprotein found predominantly in milk and in granulocytes. LF is extremely polyfunctional protein some biological functions of which are determined by its capacity to bind iron, but many other functions are iron-independent. In this article we show for the first time that LF interacts with a number of various mononucleotides.     

Does the failure to acquire helminthic parasites predispose to Crohn's disease?

Two polarized patterns (Th1 and Th2) of cytokines regulate inflammatory responses. Each cytokine pattern inhibits production of the opposing pattern. Lymphocytes from inflamed intestine due to Crohn's disease secrete a Th1 pattern of cytokines. Crohn's disease is most prevalent in highly industrialized countries with temperate climates. It occurs rarely in tropical third world countries with poor sanitation. We propose that exposure to an environmental agent predisposes individuals to Crohn's disease. Parasitic worms (helminths) are common in tropical climates and in populations subject to crowding and poor sanitation. Children are most subject to helminthic colonization. Many helminths live within or migrate through the human gut where they interact with the mucosal immune system. The host mounts a mucosal response that includes Th2 cytokine production limiting helminthic colonization. Helminths and their eggs probably are the most potent stimulators of mucosal Th2 responses. The Th2 response provoked by parasitic worms can modulate immune reactions to unrelated parasitic, bacterial, and viral infections. Many people in developed countries now live in increasingly hygienic environments, avoiding exposure to helminths. Perhaps failure to acquire these parasites and experience mucosal Th2 conditioning predisposes to Crohn's disease, which is an overly active Th1 inflammation.     

Polymorphisms of the BRAF gene predispose males to malignant melanoma

The incidence of malignant melanoma has rapidly increased in recent years. Evidence points to the role of inheritance in melanoma development, but specific genetic risk factors are not well understood. Recent reports indicate a high prevalence of somatic mutations of the BRAF gene in melanomas and melanocytic nevi. Here we report that germ-line single nucleotide polymorphisms (SNPs) in BRAF are significantly associated with melanoma in German males, but not females. At-risk haplotypes of BRAF are shown. Based upon their frequencies, we estimate that BRAF could account for a proportion attributable risk of developing melanoma of 4% in the German population. The causal variant has yet to be determined. The burden of disease associated with this variant is greater than that associated with the major melanoma susceptibility locus CDKN2A, which has an estimated attributable risk of less than 1%.     

Can colonic bacterial metabolites predispose to cholesterol gall stones?

The cholesterol content of biliary lipids increased significantly when 16 healthy volunteers ingested deoxycholic acid (DC) for two weeks in a daily dose of 100-150 mg. Serum cholesterol also fell significantly to 88% of the baseline levels. Since DC is formed in the colon we suggest that populations in whom there is a high colonic absorption of bacterially metabolized cholate--that is, DC--have an increased predisposition to cholesterol gall stones.     

Reduced estrogen in menopause may predispose women to takotsubo cardiomyopathy

Background: Takotsubo cardiomyopathy (apical ballooning syndrome) has been reported with increased frequency, most commonly in postmenopausal women. Despite the gender disparity, no clear link between estrogen and its possible cardioprotective effects has been shown.Objectives: We present a case series of takotsubo cardiomyopathy in women and examine the prevalence of estrogen replacement therapy (ERT), in addition to conducting a systematic literature review on this topic.Methods: Consecutive cases of takotsubo cardiomyopathy were identified at our institution, Cleveland Clinic Florida, from January 2006 to December 2008, and patient-level data were extracted for analysis. For the literature review, we searched the MEDLINE database from January 1990 to March 2008 for English-language publications, using the terms apical ballooning syndrome, takotsubo, and stress cardiomyopathy, and identified case reports and series of takotsubo cardiomyopathy. Articles describing female patients and their medication use at time of presentation were included in the study.Results: Eighteen cases of takotsubo cardiomyopathy were identified at our institution, all in postmenopausal women except for 2 who were still menstruating. Of the 16 postmenopausal cases, none were taking ERT at time of presentation. From the literature review, >400 publications were queried, of which 296 were recognized as case reports or series, with 7 articles meeting all of our inclusion criteria. From these reports, 13 women were identified, none of whom were taking ERT at time of presentation.Conclusions: Lack of estrogen replacement in the postmenopausal state may predispose women to takotsubo cardiomyopathy. Further studies are needed to establish the link more firmly.     

Cdc42 interacts with the exocyst complex to promote phagocytosis

The process of phagocytosis in multicellular organisms is required for homeostasis, clearance of foreign particles, and establishment of long-term immunity, yet the molecular determinants of uptake are not well characterized. Cdc42, a Rho guanosine triphosphatase, is thought to orchestrate critical actin remodeling events needed for internalization. In this paper, we show that Cdc42 controls exocytic events during phagosome formation. Cdc42 inactivation led to a selective defect in large particle phagocytosis as well as a general decrease in the rate of membrane flow to the cell surface. Supporting the connection between Cdc42 and exocytic function, we found that the overproduction of a regulator of exocytosis, Rab11, rescued the large particle uptake defect in the absence of Cdc42. Additionally, we demonstrated a temporal interaction between Cdc42 and the exocyst complex during large particle uptake. Furthermore, disruption of exocyst function through Exo70 depletion led to a defect in large particle internalization, thereby establishing a functional role for the exocyst complex during phagocytosis.