Structural basis of SUFU-GLI interaction in human Hedgehog signalling regulation.

Hedgehog signalling plays a fundamental role in the control of metazoan development, cell proliferation and differentiation, as highlighted by the fact that its deregulation is associated with the development of many human tumours. SUFU is an essential intracellular negative regulator of mammalian Hedgehog signalling and acts by binding and modulating the activity of GLI transcription factors. Despite its central importance, little is known about SUFU regulation and the nature of SUFU-GLI interaction. Here, the crystal and small-angle X-ray scattering structures of full-length human SUFU and its complex with the key SYGHL motif conserved in all GLIs are reported. It is demonstrated that GLI binding is associated with major conformational changes in SUFU, including an intrinsically disordered loop that is also crucial for pathway activation. These findings reveal the structure of the SUFU-GLI interface and suggest a mechanism for an essential regulatory step in Hedgehog signalling, offering possibilities for the development of novel pathway modulators and therapeutics.

Parental occupation and preterm births: a nationwide epidemiological study in Sweden.

The hypothesis was that some occupations could lead to preterm birth (PTB) because of potential exposures to various agents. The objective in this nationwide follow-up study was to analyse the association between PTB and parental occupational groups, controlling for potential confounders. Data from the Swedish Medical Birth Register, in which all children born in Sweden from 1990 onward are registered with their parents, were linked to census data. Inclusion criteria for the study population were employment (both women and men) and age >20 years (women). There were 816,743 first singleton live births from 1990 to 2004, of whom 43,956 were PTBs. A total of 7659 of the 43,956 PTBs were very PTBs. Odds ratios (ORs) with 95% confidence intervals were calculated separately for mothers and fathers to estimate the odds of PTB and very PTB in 51 occupational groups (reference groups: mothers or fathers who were 'Technical, science research-related workers and physicians') and by family income level. Women and men with low family incomes had increased ORs of PTB and very PTB. Significantly increased ORs of PTB (including very PTB) were found in four maternal and nine paternal occupational groups after accounting for family income, geographic region of residence, civil status, smoking habits, maternal age at infant's birth and period of birth. Further studies should examine specific agents in those parental occupations that were associated with increased odds of PTB and very PTB.

Vascular endothelial growth factor polymorphisms in relation to breast cancer development and prognosis.

PURPOSE: Angiogenesis is a necessary step in tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is a major mediator of breast cancer angiogenesis. Therefore, we investigated the association of polymorphisms in the VEGF gene with breast cancer risk and prognostic characteristics of the tumors in a large case-control study. EXPERIMENTAL DESIGN: We examined three polymorphisms in the VEGF gene (-2578C/A, -1154G/A, and +936C/T) in 571 familial breast cancer cases from Poland and Germany and -2578C/A, -634G/C, and +936C/T polymorphisms in 974 unselected breast cancer cases from Sweden together with ethnically and geographically selected controls. RESULTS: None of the polymorphisms or any haplotype was significantly associated with either familial or unselected breast cancers. Our study suggests that the +936C/T polymorphism is unlikely to be associated with breast cancer. We also analyzed the unselected cases for genotypes or haplotypes that associated with tumor characteristics. The -634CC genotype and the -2578/-634 CC haplotype were significantly associated with high tumor aggressiveness (large tumor size and high histologic grade, P < 0.01) and the -2578AA genotype and the -2578/-634 AG haplotype with low histologic grade tumors (P = 0.04). The genotypes and haplotypes were not related with other tumor characteristics such as regional or distant metastasis, stage at diagnosis, or estrogen or progesterone receptor status. CONCLUSIONS: Although none of the polymorphisms studied in the VEGF gene was found to influence susceptibility to breast cancer significantly, some of the VEGF genotypes and haplotypes may influence tumor growth through an altered expression of VEGF and tumor angiogenesis.

DYRK1B-dependent autocrine-to-paracrine shift of Hedgehog signaling by mutant RAS.

Synergism between the RAS and Hedgehog (HH) pathways has been suggested for carcinogenesis in the pancreas, lung and colon. We investigated the molecular cross-talk between RAS and HH signaling and found that, although mutant RAS induces or enhances SHH expression and favors paracrine HH signaling, it antagonizes autocrine HH signal transduction. Activated RAS can be found in primary cilia, the central organelle of HH signal transduction, but functions in a cilium-independent manner and interferes with Gli2 function and Gli3 processing. In addition, the cell-autonomous negative regulation of HH signal transduction involves the RAS effector molecule dual specificity tyrosine phosphorylated and regulated kinase 1B (DYRK1B). In line with a redirection of autocrine toward paracrine HH signaling by a KRAS-DYRK1B network, we find high levels of GLI1 expression restricted to the stromal compartment and not to SHH-expressing tumor cells in human pancreatic adenocarcinoma.

Polymorphisms in the KDR and POSTN genes: association with breast cancer susceptibility and prognosis.

Angiogenesis is an important step in the development of cancer. Vascular endothelial growth factor is a major regulator of breast cancer angiogenesis, the effects of which are transmitted through the kinase domain receptor (KDR). Up-regulation of KDR by periostin (POSTN) induces angiogenesis. We screened the KDR and the POSTN genes for published single nucleotide polymorphisms (SNPs) and chose two SNPs in each gene for further analyses. We carried out a case-control study consisting of 412 familial and 912 unselected breast cancer cases together with ethnically and geographically selected controls. Genotype, haplotype and genotype combination analyses were carried out to evaluate their effect on susceptibility to and prognosis of breast cancer. A haplotype in the POSTN gene was associated with an increased risk even after correction for multiple comparisons. Nominal associations between the SNPs and prognostic indicators were also observed. Tumors of the KDR 472His allele carriers were less often progesterone receptor negative according to both genotype and haplotype analyses (OR 0.61, 95%CI 0.40-0.92 and OR 0.60, 95%CI 0.40-0.91, respectively). The POSTN -33G allele carriers had more often high grade and estrogen receptor negative tumors (OR 1.75, 95%CI 1.02-3.01 and OR 1.70, 95%CI 1.04-2.78, respectively). The overall and cancer specific survival after 15 years of follow-up was more than 75%, and it did not depend on the genotype. Although a major effect of the SNPs in the KDR and the POSTN genes on breast cancer susceptibility and prognosis was excluded, the effect of the POSTN C-33G SNP on prognosis needs further characterization.

Polymorphisms and haplotype structures in genes for transforming growth factor beta1 and its receptors in familial and unselected breast cancers.

Alterations in TGF-beta signaling appear to be associated with an altered risk of developing cancer, including breast cancer. We carried out a case-control study on 8 polymorphisms, including 5 in the TGF-beta1 gene (G-800A, C-509T, Leu10-->Pro, Arg25-->Pro and Thr263-->Ile), a polyalanine polymorphism (9A-->6A) in the TGF-betaRI gene and 2 (G-875A and A-364G) in the TGF-betaRII gene, using samples from 2 different populations, Polish familial and Finnish unselected breast cancer cases, together with ethnically and geographically matched controls. Additionally, familial breast cancer cases with respective controls from Sweden and Germany were studied in the Leu10-->Pro polymorphism, making the total number of familial cases 659. Allele, genotype and haplotype analysis on the TGF-beta1 gene as well as an analysis of the combinations of genotypes of the TGF-beta1 and its receptor genes in each individual were performed. Population differences in the allele and genotype distributions were found from 5 of the polymorphisms and 3 common haplotypes from the TGF-beta1 gene between the Finnish and other populations. However, no statistically significant difference between the breast cancer and healthy control groups was found for any of the 8 polymorphisms nor did the haplotype or genotype combination analysis reach statistical significance. Thus, none of the studied polymorphisms from the TGF-beta1 and its receptor genes was found to influence significantly susceptibility to breast cancer. The possible contribution of 6A/6A homozygosity in the TGF-betaRI gene to breast cancer needs to be confirmed in an independent study.

Sex hormone-binding globulin polymorphisms in familial and sporadic breast cancer.

Ovarian steroids are one of the strongest risk factors for breast cancer. Sex hormone-binding globulin (SHBG) binds and transports sex steroids in the blood, regulating their bioavailable fraction and access to target cells. It can also inhibit the estradiol-induced proliferation of breast cancer cells through its membrane receptor. Three coding-region polymorphisms, which lead to an amino acid change, have been reported. We studied the influence of these three polymorphisms on breast cancer risk in three different populations: Polish familial breast cancer cases, 27% of them carrying a BRCA1/BRCA2 mutation, Nordic familial and sporadic breast cancer cases. The reported G to A polymorphism in exon 1 was not found in the 423 analyzed samples. Instead, we found a C to T transition causing an arg to cys amino acid change within the same codon in one Polish breast cancer patient and her daughter. Both of them were heterozygotes for the exon 8 G to A polymorphism as well. They were diagnosed for bilateral breast cancer and carried a BRCA1 mutation (5382insC). Analysis of the tumor samples showed that they had lost the wild-type allele both at exons 1 and 8 of the SHBG gene. Analysis of the other Polish samples showed no correlation of the exon 8 polymorphism to breast cancer, bilateral breast cancer, BRCA1/BRCA2 mutations or age at diagnosis. No association of the exon 8 polymorphism with breast cancer in the Nordic familial or sporadic cases was found. The C to T polymorphism located in exon 4 was rare in all the studied populations (overall allele frequency 0.011). However, in each of the study populations there was a trend for a lower variant allele frequency in cancer cases than in controls. Variant allele frequency in all the breast cancer cases was significantly lower than in all the controls (chi(2) = 5.27, P-value 0.02; odds ratio = 0.23, 95% confidence interval 0.05-0.84).