TGFBR1 haplotypes and risk of non-small-cell lung cancer

Immune-cell signatures of persistent inflammation, immunosuppression, and catabolism syndrome after sepsis

BACKGROUND

Management of persistent inflammation, immunosuppression, and catabolism syndrome (PICS) after sepsis remains challenging for patients in the intensive care unit, experiencing poor quality of life and death. However, immune-cell signatures in patients with PICS after sepsis remain unclear.

METHODS

We determined immune-cell signatures of PICS after sepsis at single-cell resolution. Murine cecal ligation and puncture models of PICS were applied for validation.

FINDINGS

Immune functions of two enriched monocyte subpopulations, Mono1 and Mono4, were suppressed substantially in patients with sepsis and were partially restored in patients with PICS after sepsis and exhibited immunosuppressive and pro-apoptotic effects on B and CD8T cells. Patients with PICS and sepsis had reduced naive and memory B cells and proliferated plasma cells. Besides, naive and memory B cells in patients with PICS showed an active antigen processing and presentation gene signature compared to those with sepsis. PICS patients with better prognoses exhibited more active memory B cells and IGHA1-plasma cells. CD8TEMRA displayed signs of proliferation and immune dysfunction in the PICS-death group in contrast with the PICS-alive group. Megakaryocytes proliferation was more pronounced in patients with PICS and sepsis than in healthy controls, with notable changes in the anti-inflammatory and immunomodulatory effects observed in patients with PICS and verified in mice models.

CONCLUSIONS

Our study evaluated PICS after sepsis at the single-cell level, identifying the heterogeneity present within immune-cell subsets, facilitating the prediction of disease progression and the development of effective intervention.

FUNDING

This work was supported by the National Natural Science Foundation of China, Shanghai Municipal Health Commission "Yiyuan New Star" Youth Medical Talent Cultivating Program, and Shanghai Clinical Research Center for Anesthesiology.

Roles of matrix metalloproteinase-7 (MMP-7) in cancer

Matrix metalloproteinase-7 (MMP-7) is a small proteolytic enzyme that secretes zinc and calcium endopeptidases. It can degrade a variety of extracellular matrix substrates and other substrates and plays important regulatory roles in many human pathophysiological processes. Since its discovery, MMP-7 has been recognized as a regulatory protein in wound healing, bone growth, and remodeling. Later, MMP-7 was reported to regulate the occurrence and development of cancers and mediate the proliferation, differentiation, metastasis, and invasion of several types of cancer cells via various mechanisms. Thus, matrix metalloproteinase-7 may be a promising tumor biomarker and therapeutic target. The expression of MMP-7 correlates with the clinical characteristics of cancer patients, and its expression profile is a new diagnostic and prognostic biomarker for a variety of human diseases. Hence, manipulating the expression or function of MMP-7 may be a potential treatment strategy for different diseases including cancers. This review summarizes the role played by MMP-7 in carcinogenesis of several human cancers, underlying mechanisms, and its clinical significance of the occurrence and development of cancers.

Ski: Double roles in cancers

The Ski (Sloan-Kettering Institute) is an evolutionarily conserved protein that plays a dual role as an oncoprotein and tumor suppressor gene in the development of human cancer. The Ski oncogene was first identified as a transforming protein of the avian Sloan-Kettering retrovirus in 1986. Since its discovery, Ski has been identified as a carcinogenic regulator in a variety of malignant tumors. Later, it was reported that Ski regulates the occurrence and development of some cancers by acting as an oncogene. Ski mediates the proliferation, differentiation, metastasis, and invasion of numerous cancer cells through various mechanisms. Several studies have shown that Ski expression is correlated with the clinical characteristics of cancer patients and is a promising biomarker and therapeutic target for cancer. In this review, we summarize the mechanisms and potential clinical implications of Ski in dimorphism, cancer occurrence, and progression in various types of cancer.

miR-3607-3p suppresses non-small cell lung cancer (NSCLC) by targeting TGFBR1 and CCNE2

Accumulating evidence indicates that miRNAs can be promising diagnostic and/or prognostic markers for various cancers. In this study, we identified a novel miRNA, miR-3607-3p, and its targets in non-small cell lung cancer (NSCLC). The expression of miR-3607-3p was measured and its correlation with patient prognosis was determined. Ectopic expression in NSCLC cells, xenografts, and metastasis models was used to evaluate the effects of miR-3607-3p on proliferation and migration of NSCLC. Luciferase assay and western blotting were performed to validate the potential targets of miR-3607-3p after preliminary screening by microarray analysis and computer-aided algorithms. We demonstrated that miR-3607-3p was downregulated in NSCLC tissues and that miR-3607-3p might act as an independent predictor for overall survival in NSCLC. Moreover, serum miR-3607-3p may be a novel and stable marker for NSCLC. We found that overexpression of miR-3607-3p inhibited cell proliferation, colony formation, migration and invasion, and hampered the cell cycle of NSCLC cell lines in vitro. Our results suggested that miR-3607-3p directly targets TGFBR1 and CCNE2. In accordance with in vitro studies, we confirmed that miR-3607-3p functions as a potent suppressor miRNA of NSCLC. We showed that miR-3607-3p agomir could reduce tumor growth and inhibit TGFBR1 and CCNE2 protein expression. Taken together, our findings indicate that miR-3607-3p can inhibit NSCLC cell growth and metastasis by targeting TGFBR1 and CCNE2 protein expression, and provide new evidence of miR-3607-3p as a potential non-invasive biomarker and therapeutic target for NSCLC.

REHUNT: a reliable and open source package for restriction enzyme hunting

Background

Restriction enzymes are used frequently in biotechnology. However, manual mining of restriction enzymes is challenging. Furthermore, integrating available restriction enzymes into different bioinformatics systems is necessary for many biotechnological applications, such as polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Thus, in the present study, we developed the package REHUNT (Restriction Enzymes HUNTing), which mines restriction enzymes from the public database REBASE using a series of search operations.

Results

REHUNT is a reliable and open source package implemented in JAVA. It provides useful methods and manipulations for biological sequence analysis centered around restriction enzymes contained in REBASE. All available restriction enzymes for the imported biological sequences can be identified by REHUNT. Different genotypes can be identified using PCR-RFLP based on REHUNT for single nucleotide polymorphism (SNP), mutations, and the other variations. REHUNT robustly recognizes multiple inputs with different formats, e.g. regular DNA sequences, variation-in-sequence indicated by IUPAC code, as well as variation-in-sequence indicated by dNTPs format. Variations including di-, tri-, and tetra-allelic types and indel formats are also acceptable. Furthermore, REHUNT provides classified restriction enzymes output, including IUPAC and general sequence types, as well as commercial and non-commercial availabilities. REHUNT also enables analysis for high throughput screening (HTS) technologies.

Conclusions

REHUNT is open source software with GPL v3 license and can be run on all platforms. Its features include: 1) Quick restriction enzymes search throughout a sequence based on the Boyer-Moore algorithm; 2) all available restriction enzymes provided and regularly updated from REBASE; 3) an open source API available of integrating all types of bioinformatics systems and applications; 4) SNP genotyping available for plant and animal marker-assisted breeding, and for human genetics; and 5) high throughput analysis available for Next Generation Sequencing (NGS). REHUNT not only to effectively looks for restriction enzymes in a sequence, but also available for SNP genotyping. Furthermore, it can be integrated into other biological and medical applications. REHUNT offers a convenient and flexible package for powerful restriction enzymes analyses in association studies, and supports high throughput analysis. The source codes and complete API documents are available at SourceForge: https://sourceforge.net/projects/rehunt/, GitHub: https://github.com/yuhuei/rehunt, and at: https://sites.google.com/site/yhcheng1981/rehunt.

Genome-wide haplotype association study identifies risk genes for non-small cell lung cancer

Lung cancer is the leading cause of cancer-related death worldwide. Most lung cancer is non-small cell lung cancer (NSCLC), in which malignant cells form in the lung epithelium. Mutations in multiple genes and environmental factors both contribute to NSCLC, and although some NSCLC susceptibility genes have been characterized, the pathogenesis of this disease remains unclear. To identify genes conferring NSCLC risk and determine their associated pathological mechanism, we combined genome-wide haplotype associated analysis with gene prioritization using 224,677 SNPs in 37 NSCLC cell lines and 116 unrelated European individuals. Five candidate genes were identified: ESR1, TGFBR1, INSR, CDH3, and MAP3K5. All of these have previously been implicated in NSCLC, with the exception of CDH3, which can therefore be considered a novel indicator of NSCLC risk. Functional annotation confirmed the relationship between these five genes and NSCLC. Our findings are indicative of the underlying pathological mechanisms of NSCLC and provide information to support future directions in diagnosing and treating NSCLC.

Aberrant promoter methylation of hOGG1 may be associated with increased risk of non-small cell lung cancer

DNA methylation may epigenetically inactivate tumor suppressor genes in NSCLC. As the human 8-oxoguanine DNA glycosylase (hOGG1) gene promoter is frequently methylated in NSCLC, we evaluated whether genetic or epigenetic alterations of hOGG1 are associated with increased risk of non-small cell lung cancer. Three hOGG1 haplotype-tagging SNPs (htSNP) were genotyped in PCR-restriction fragment length polymorphism assays, and one htSNP was genotyped in a PCR-single-strand conformation polymorphism assay in case-control studies of 217 NSCLC patients and 226 healthy controls. The methylation profiles of peripheral blood mononuclear cell specimens from 121 NSCLC patients and 121 controls were determined through methylation-specific PCR of hOGG1. No differences in allele or genotype frequencies between NSCLC patients and controls were observed at any of the four polymorphic sites (rs159153, rs125701, rs1052133, and rs293795). However, hOGG1 methylation-positive carriers had a 2.25-fold greater risk of developing NSCLC (adjusted odds ratio: 2.247; 95% confidence interval: 1.067-4.734; P = 0.03) than methylation-free subjects. Furthermore, the demethylating agent 5-aza-2'-deoxycytidine restored hOGG1 expression in NSCLC cell lines. These data provide strong evidence of an association between peripheral blood mononuclear cell hOGG1 methylation and the risk of NSCLC in a Chinese population.

AKIP1 promoted epithelial-mesenchymal transition of non-small-cell lung cancer via transactivating ZEB1

Non-small-cell lung cancer (NSCLC) is one of the leading death-related malignancies worldwide with elusive molecular mechanisms. A-kinase interacting protein 1 (AKIP1) is an important regulator controlling metastasis, lymphangiogenesis and angiogenesis. However, the role of AKIP1 in NSCLC progression is still little known. Here, we found that AKIP1 was overexpressed in NSCLC specimens as well as cell lines. Overexpression of AKIP1 in NSLCC tissues was positively correlated with TNM stage, lymph node metastasis and poor prognosis. Knockdown of AKIP1 inhibited NSCLC cell migration, invasion and epithelial-mesenchymal transition (EMT), as indicated by the up-regulation of mesenchymal markers (fibronectin and vimentin) and down-regulation of epithelial marker E-cadherin, whereas overexpression of AKIP1 showed the opposite effects. Moreover, AKIP1 transactivated Zinc Finger E-Box Binding Homeobox 1 (ZEB1) expression via directly binding to ZEB1 promoter, thereby leading to E-cadherin transcriptional repression. Additionally, we observed that the binding efficiency of AKIP1 within ZEB1 promotor was determined by the interaction between AKIP1 and SP1. In conclusion, AKIP1 promoted EMT of NSCLC via transactivating ZEB1, suggesting AKIP1 as a potential therapeutic target.

The role of microRNA in metastatic processes of non-small cell lung carcinoma

BACKGROUND

MicroRNAs are small non-coding one-stranded RNA molecules that play an important role in the post-transcriptional regulation of genes. Bioinformatic predictions indicate that each miRNA can regulate hundreds of target genes. MicroRNA expression can be associated with various cellular processes leading to the metastasis of malignant tumours including non-small cell lung carcinoma. This review summarizes current knowledge on the role of microRNAs in NSCLC metastasis to the brain and lymph nodes.

METHODS

A search of the NCBI/PubMed database for publications on expression levels and the mechanisms of microRNA action in NSCLC metastasis.

RESULTS AND CONCLUSION

Dysregulation of microRNAs in NSCLC can be associated with brain and lymph node metastasis. There are differences in microRNA expression profiling between NSCLC with and without metastases but it is currently not possible to reliably predict the site of metastasis in NSCLC. Based on data from RNAmicroarrays, bioinformatics analysis is able to predict the target genes of highlighted microRNAs, providing us with complex information about cancer cell features such as enhanced proliferation, migration and invasion. Such microRNAs may then be knocked-down using siRNAs or substituted with miRNA mimics. RNA microarray profiling may thus be a useful tool to select up- or down-regulated microRNAs. A number of authors suggest that microRNAs could serve as biomarkers and therapeutic targets in the treatment of NSCLC metastasis.

Repression of TIF1γ by SOX2 promotes TGF-β-induced epithelial-mesenchymal transition in non-small-cell lung cancer

TIF1γ is a novel regulator of transforming growth factor (TGF)-β/Smad signaling. Our previous studies show that dysregulated expression of transcriptional intermediary factor 1 γ (TIF1γ) and abnormal TGF-β/Smad signaling are implicated in non-small-cell lung cancer (NSCLC) separately. However, how TIF1γ contributes to NSCLC by controlling TGF-β/Smad signaling is poorly understood. Here, we investigated the mechanistic role of TIF1γ in TGF-β-induced epithelial-mesenchymal transition (EMT), as well as a link between TIF1γ and SOX2 in NSCLC. We show that TIF1γ is a downstream target of SOX2 in NSCLC cells. SOX2 overexpression negatively regulated TIF1γ promoter activity and thereby attenuated TIF1γ mRNA and protein expression levels; SOX2 knockdown significantly enhanced TIF1γ promoter activity and augmented TIF1γ expression. Moreover, TIF1γ mRNA expression was downregulated in human NSCLC tissues and negatively correlated with SOX2 protein, which was upregulated in NSCLC tissues. Importantly, knockdown of TIF1γ or SOX2 overexpression augmented SMAD4 (human Mad (mothers against decapentaplegic)-related homologous protein 4)-dependent transcriptional responses, and enhanced TGF-β-induced EMT and human NSCLC cell invasion; knockdown of SOX2 impaired TGF-β-induced EMT and NSCLC cell invasion. In an in vivo model of metastasis, knockdown of TIF1γ promotes NSCLC cell metastasis. In addition, our data suggested that TIF1γ inhibited TGF-β-induced EMT through competing with SMAD4 in NSCLC cells. Taken together, our findings reveal a new mechanism by which SOX2-mediated transcription repression of TIF1γ promotes TGF-β-induced EMT in NSCLC.

TGF-β-activated SMAD3/4 complex transcriptionally upregulates N-cadherin expression in non-small cell lung cancer

OBJECTIVES

Epithelial-mesenchymal transition (EMT) is a key process in early stage of cancer metastasis. TGF-β-mediated EMT is characterized by repression of E-cadherin and induction of N-cadherin (CDH2) in various cancers. Although many investigations have focused on the regulation of E-cadherin expression, the transcription-mediated events that directly induce N-cadherin expression in TGF-β-induced EMT are not fully clear. Here, we mainly focus on non-small cell lung cancer (NSCLC) cells, in which expression of CDH2 can be activated upon TGF-β stimulation, to investigate the underlying mechanisms of CDH2 expression regulation.

MATERIALS AND METHODS

Western blot analysis, real-time quantitative reverse transcriptase PCR, luciferase reporter gene assays, RNA interference and in vivo chromatin immunoprecipitation (ChIP) assay were performed on human NSCLC cell lines A549 and SPC-A1. Twenty-six paired NSCLC tissues and adjacent noncancerous lung tissues were collected.

RESULTS

Luciferase reporter assay revealed that a functional TGF-β-response element was located at position -1078 to -891 in the CDH2 promoter region. Furthermore, in vivo ChIP experiment indicated that TGF-β-activated SMAD3/4 complex was directly recruited to CDH2 promoter region (-1078 to -891). Upon TGF-β1 stimulation, knockdown of SMAD3 or/and SMAD4 led to a significant reduction in CDH2 promoter activity, and silencing of SMAD3 or SMAD4 significantly inhibited CDH2 mRNA and protein expression in A549 and SPC-A1 cells. In human NSCLC tissues, SMAD3 or SMAD4 mRNA level was positively correlated with CDH2 mRNA level, respectively.

CONCLUSIONS

We found that TGF-β-activated SMAD3/4 complex may upregulate CDH2 expression by directly interacting with a specific SMAD-binding element in CDH2 promoter. Our findings provide insights into mechanisms underlying the transcriptional regulation of CDH2 expression in TGF-β-induced EMT and SMADs-based therapeutic strategies for NSCLCs.

MiR-142-3p represses TGF-β-induced growth inhibition through repression of TGFβR1 in non-small cell lung cancer

TGFβR1 plays an important role in TGF-β signaling transduction and serves as a tumor suppressor. Our previous studies show that reduced expression of TGFβR1 is common in non-small cell lung cancer (NSCLC) and TGFβR1 variants confer risk of NSCLC. However, the epigenetic mechanisms underlying the role of TGFβR1 in NSCLC carcinogenesis are still elusive. We investigated the function and regulation of TGF-β signaling-based miRNAs in NSCLC. Computational algorithms predicted that the 3'-untranslated region (3'-UTR) of TGFβR1 is a target of miR-142-3p. Here a luciferase reporter assay confirmed that miR-142-3p can directly bind to 3'-UTR of TGFβR1. Overexpression of miR-142-3p in NSCLC A549 cells suppressed expression of TGFβR1 mRNA and protein, while knockdown of endogenous miR-142-3p led to increased expression of TGFβR1. On TGF-β1 stimulation, stable overexpression of miR-142-3p attenuated phosphorylation of SMAD3, an indispensable downstream effector in canonical TGF-β/Smad signaling, via repression of TGFβR1 in A549 cells. Furthermore, miR-142-3p-mediated down-regulation of TGFβR1 weakened TGF-β-induced growth inhibition effect, and this effect was reversed by stable knockdown of endogenous miR-142-3p in A549 cells. In NSCLC tissues, miR-142-3p expression was increased and inversely correlated with TGFβR1 expression. These data demonstrate that miR-142-3p influences the proliferation of NSCLC cells through repression of TGFβR1.

Genetic variations in stem cell-related genes and colorectal cancer prognosis

BACKGROUND

Many properties of cancer cells are reminiscent of those in normal stem cells. Genes important to stem cell development have been significantly implicated in the etiology and clinical outcome of colorectal cancer (CRC). However, the associations of genetic variations in these genes with CRC prognosis have not yet been elucidated.

METHODS

We analyzed the effects of eight potentially functional single nucleotide polymorphisms (SNPs) in six stem cell-related genes on the prognosis of a well-characterized population of 380 Chinese CRC patients diagnosed from February 2006 to January 2010.

RESULTS

The most significant finding was related to rs879882, a variant in the 5' region of POU5F1 gene which encodes a protein essential for embryonic stem cell self-renewal and pluripotency, and induced pluripotent stem cell reprogramming. The variant-containing genotypes of rs879882 were associated with an increased risk of recurrence (hazard ratio [HR] = 2.10, 95% confidence interval [CI] 1.17-3.76, P = 0.01). In chemotherapy-stratified analysis, the association remained borderline significant in patients receiving chemotherapy (HR = 1.97, 95% CI 0.89-4.34, P = 0.09). In addition, a nonsynonymous SNP of APC gene was also significantly associated with recurrence risk in chemotherapy-treated patients (HR = 2.63, 95% CI 1.14-6.06 P = 0.02). Further analyses showed a combined effect of the two SNPs in predicting CRC recurrence in patients receiving chemotherapy (P = 0.04) but not in those without chemotherapy (P = 0.43). Moreover, an exploratory multivariate assessment model indicated that these two variants enhanced the power to predict recurrence after chemotherapy.

CONCLUSION

We presented one of the first epidemiologic studies showing that stem cell-related genetic variants may impact CRC clinical outcomes, especially in chemotherapy-treated patients.

A two-SNP IL-6 promoter haplotype is associated with increased lung cancer risk

BACKGROUND

Aberrant expression of interleukin-6 (IL-6) may play an important role in lung carcinogenesis. Whether IL-6 promoter haplotypes are associated with lung cancer risk and their functions have not yet been studied. We tested the hypothesis that single-nucleotide polymorphism (SNP) and/or haplotypes of IL-6 promoter are associated with risk of lung cancer.

METHODS

Two functional IL-6 promoter SNPs (-6331T>C and -572C>G) were genotyped in the discovery group including 622 patients and 614 controls, and the results were replicated in an independent validation group including 615 patients and 638 controls. Luciferase reporter gene assays were conducted to examine the function of IL-6 promoter haplotypes.

RESULTS

None of the functional IL-6 promoter SNPs were associated with lung cancer risk in either study. However, a two-SNP CC (-6331C and -572C) IL-6 promoter haplotype was significantly more common among cases than among controls in both groups (P = 0.031 and P = 0.035, respectively), indicating that this haplotype is associated with increased lung cancer risk {adjusted odds ratio [OR], 1.56 [95 % confidence interval (95 % CI), 1.04-2.34] and 1.51 [95 % CI, 1.03-2.22], respectively}. Combined analysis of both studies showed a strong association of this two-SNP haplotype with increased lung cancer risk (adjusted OR, 1.53; 95 % CI, 1.16-2.03; P = 0.003). Comparably, luciferase reporter assays of A549 lung cancer cell lines transfected with the CC haplotype revealed that the two-SNP haplotype had significantly higher IL-6 transcriptional activity compared with cells transfected with the common haplotype.

CONCLUSIONS

This is the first evidence of identifying an IL-6 promoter haplotype (CC) associated with increased risk of lung cancer.

A Single Nucleotide Polymorphism in the Phospholipase D1 Gene is Associated with Risk of Non-Small Cell Lung Cancer

Phospholipase D (PLD) has an important role in various biological functions including vesicular transport, endocytosis, exocytosis, cell migration, and mitosis. These cellular biological processes are deregulated in the development of various human tumors. In order to explore the relationship between the PLD1 gene and risk of non-small cell lung cancer (NSCLC), single nucleotide polymorphisms (SNP) in the PLD1 exon region were surveyed in 211 NSCLC patients and 205 normal controls. In this study, we identified six SNPs at exon 23 in the PLD1 gene. Among the six SNPs, the most notable was a heterozygous A to C transition at nucleotide 2698 (A2698C, p<0.001). In addition, the genotype frequencies of A2744C (AC+CC) and A2756C (AC+CC) were associated with gender (female, A2744C and A2756C: p=0.071) in NSCLC patients. Interestingly, although the SNP A2698C did not cause change in amino acid, correlation between odd ratio of NSCLC patients and the SNP A2698C was observed to be statistically significant.

A Bayesian hierarchical model for detecting haplotype-haplotype and haplotype-environment interactions in genetic association studies

OBJECTIVE

Genetic association studies based on haplotypes are powerful in the discovery and characterization of the genetic basis of complex human diseases. However, statistical methods for detecting haplotype-haplotype and haplotype-environment interactions have not yet been fully developed owing to the difficulties encountered: large numbers of potential haplotypes and unknown haplotype pairs. Furthermore, methods for detecting the association between rare haplotypes and disease have not kept pace with their counterpart of common haplotypes.

METHODS/RESULTS

We herein propose an efficient and robust method to tackle these problems based on a Bayesian hierarchical generalized linear model. Our model simultaneously fits environmental effects, main effects of numerous common and rare haplotypes, and haplotype-haplotype and haplotype-environment interactions. The key to the approach is the use of a continuous prior distribution on coefficients that favors sparseness in the fitted model and facilitates computation. We develop a fast expectation-maximization algorithm to fit models by estimating posterior modes of coefficients. We incorporate our algorithm into the iteratively weighted least squares for classical generalized linear models as implemented in the R package glm. We evaluate the proposed method and compare its performance to existing methods on extensive simulated data.

CONCLUSION

The results show that the proposed method performs well under all situations and is more powerful than existing approaches.

TGFBR1 signaling and breast cancer

Over the past decade mutations discovered in genes such as BRCA1, BRCA2, TP53 and PTEN, have emerged as high-penetrance susceptibility genes and are clinically relevant for determination of breast cancer risk. Genetic counseling and subsequent screening for mutations and gene rearrangement has improved patient outcome through early detection and prophylactic interventions in patients with familial breast cancer syndromes. However, these high-penetrance genes only account for a small fraction of the hereditary linked breast cancers. It is currently believed that low-penetrance susceptibility alleles and/or environmental factors may play an important role in the remaining cases. TGFBR1*6A (*6A) is a common hypomorphic variant of the type I TGF-β receptor gene (TGFBR1) that has been associated with risk for several forms of cancer, in particular breast cancer. Several epidemiological studies have suggested that patients who carry the *6A allele have an increased risk of breast cancer. Furthermore, functional analysis suggests that this mutation alters TGF-β signaling and promotes tumorigenesis. Although a decade of research has provided basic information in regards to the prevalence of this mutation in several cancer types and populations the molecular underpinning of its functional effects are poorly understood. A better understanding of the molecular mechanism of TGFBR1 signaling in breast cancer may have an impact on breast cancer risk assessment and breast cancer prevention.

Genetic variations in the transforming growth factor-beta pathway as predictors of survival in advanced non-small cell lung cancer

The magnitude of benefit is variable for advanced non-small cell lung cancer (NSCLC) patients receiving platinum-based chemotherapy. The purpose of this study is to determine whether genetic variations in the transforming growth factor-beta (TGF-β) pathway are associated with clinical outcomes in NSCLC patients receiving first-line platinum-based chemotherapy. Five hundred and ninety-eight advanced-stage NSCLC patients who received first-line platinum-based chemotherapy with or without radiotherapy were recruited at the MD Anderson Cancer Center between 1995 and 2007. DNA from blood was genotyped for 227 single nucleotide polymorphisms (SNPs) in 23 TGF-β pathway-related genes to evaluate their associations with overall survival. In individual SNP analysis, 22 variants were significantly associated with overall survival, of which the strongest associations were found for BMP2:rs235756 [hazard ratio (HR) = 1.45; 95% confidence interval (CI), 1.11-1.90] and SMAD3:rs4776342 (HR = 1.25; 95% CI, 1.06-1.47). Fifteen and 18 genetic loci displayed treatment-specific associations for chemotherapy and chemoradiation, respectively, identifying a majority of the cases who would be predicted to respond favorably to a specific treatment regimen. BMP2:rs235753 and a haplotype in SMAD3 were associated with overall survival for both treatment modalities. Cumulative effect analysis showed that multiple risk genotypes had a significant dose-dependent effect on overall survival (P(trend) = 2.44 x 10(-15)). Survival tree analysis identified subgroups of patients with dramatically different median survival times of 45.39 versus 13.55 months and 18.02 versus 5.89 months for high- and low- risk populations when treated with chemoradiation and chemotherapy, respectively. These results suggest that genetic variations in the TGF-β pathway are potential predictors of overall survival in NSCLC patients treated with platinum-based chemotherapy with or without radiation.

Candidate gene association studies: successes and failures

Epidemiologic studies of twins indicate that 20-40% of common tumors such as breast, colorectal, and prostate cancers are inherited. However, the effect of high penetrance tumor susceptibility genes such as APC, BRCA1, BRAC2, MSH1, MLH2 and MSH6 only accounts for a small fraction of these cancers. Low to moderate penetrance tumor susceptibility genes likely account for the large remaining proportion of familial cancer risk. Candidate tumor susceptibility genes have been identified based on the discovery of tumor-specific mutations, in vitro experiments, as well as animal models of cancer. Translational studies based on in vitro and in vivo discoveries have led to the identification of novel phenotypes and genotypes associated with cancer in humans. Case-control studies followed by validation studies and meta-analyses have unveiled several novel tumor susceptibility genes, several of which belong to genes encoding metabolizing enzymes and genes from the TGF-beta signaling pathway. Together with genome-wide association studies, candidate gene approaches are likely to fill a large gap in our knowledge of the genetic basis of cancer within the next decade.

Tgfbr1 haploinsufficiency inhibits the development of murine mutant Kras-induced pancreatic precancer

To dissect the role of constitutively altered Tgfbr1 signaling in pancreatic cancer development, we crossed Elastase-Kras(G12D) (EL-Kras) mice with Tgfbr1 haploinsufficient mice to generate EL-Kras/Tgfbr1(+/-) mice. Mice were euthanized at 6 to 9 months to compare the incidence, frequency, and size of precancerous lesions in the pancreas. Only 50% of all EL-Kras/Tgfbr1(+/-) mice developed preinvasive lesions compared with 100% of EL-Kras (wild-type Tgfbr1) mice. The frequency of precancerous lesions was 4-fold lower in haploinsufficient than in control mice. Paradoxically, the precancerous lesions of EL-Kras/Tgfbr1(+/-) mice were considerably larger than those in EL-Kras mice. Yet, the mitotic index of precancerous cells and the observable levels of fibrosis, lipoatrophy, and lymphocytic infiltration were reduced in EL-Kras/Tgfbr1(+/-) mice. We conclude that Tgfbr1 signaling promotes the development of precancerous lesions in mice. These findings suggest that individuals with constitutively decreased TGFBR1 expression may have a decreased risk of pancreatic cancer.