Circulating Insulin-Like Growth Factor 1-Related Biomarkers and Risk of Lethal Prostate Cancer

Background

Experimental and epidemiologic evidence supports the role of circulating insulin-like growth factor-1 (IGF-1) levels with the risk of prostate cancer. Most circulating IGF-1 is bound to specific binding proteins, and only about 5% circulates in a free form. We explored the relation of free IGF-1 and other components of the IGF system with lethal prostate cancer.

Methods

Using prospectively collected samples, we undertook a nested case-only analysis among 434 men with lethal prostate cancer and 524 men with indolent, nonlethal prostate cancer in the Physicians’ Health Study and the Health Professionals Follow-up Study. Prediagnostic plasma samples were assayed for free IGF-1 and total IGF-1, acid labile subunit, pregnancy-associated plasma protein A (PAPP-A), and intact and total IGF binding protein 4. We estimated odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the associations between IGF-1–related biomarkers and lethal prostate cancer using unconditional logistic regression models adjusted for age, height, and body mass index.

Results

Men in the highest quartile of PAPP-A levels had 42% higher odds of lethal prostate cancer (pooled adjusted OR = 1.42, 95% CI = 1.04 to 1.92) compared with men in the lowest 3 quartiles. There were no statistically significant differences in the other plasma analytes. The positive association between PAPP-A and lethal prostate cancer was present among men with intact PTEN but not among those with tumor PTEN loss (2-sided P_interaction = .001).

Conclusions

Our study provides suggestive evidence that among men who later develop prostate cancer, higher plasma PAPP-A levels measured prior to diagnosis are associated with increased risk of lethal compared with indolent disease.

Chimeric antigen receptor T-cell therapy for breast cancer

One of the main reasons that researchers pay enormous attention to immunotherapy is that, despite significant advances in conventional therapy approaches, breast cancer remains the leading cause of death from malignant tumors among women. Genetically modifying T cells with chimeric antigen receptors (CAR) is one of the novel methods that has exhibited encouraging activity with relative safety, further urging investigators to develop several CAR T cells to target overexpressed antigens in breast tumors. This article is aimed not only to present such CAR T cells and discuss their remarkable results but also indicates their shortcomings with the hope of achieving possible strategies for improving therapeutic response.

Dysregulation of Zinc Finger Protein 395 Contributes to the Pathogenesis of Chondrosarcoma

Introduction

The transcription factor zinc finger protein 395 (ZNF395) is involved in several cellular responses and tumorigenesis. However, the potential role and clinical significance of ZNF395 in chondrosarcoma are not well investigated. This study determines the expression profile, prognostic value and biological function of ZNF395 in human chondrosarcoma.

Methods

The mRNA and protein expressions of ZNF395 in fresh chondrosarcomas and the matched adjacent non-tumor tissues were assessed using real-time PCR and immunoblotting, respectively. The protein expression of ZNF395 in chondrosarcoma specimens was evaluated by immunohistochemistry, and the relationships among its protein level, clinicopathological parameters and prognosis were further detected. Cell viability, colony formation, migration, invasion and apoptosis assay were evaluated in chondrosarcoma cells with depletion of ZNF395.

Results

The mRNA and protein expressions of ZNF395 in chondrosarcoma tissues were significantly higher than those in the matched adjacent non-tumor tissues and benign cartilage tumors. Clinical analysis displayed that ZNF395 was expressed at higher levels in chondrosarcoma patients with higher histological grade and advanced MSTS stage. Furthermore, we demonstrated that high expression of ZNF395 correlated with a worse overall survival of chondrosarcoma patients. Multivariate Cox regression analysis indicated that ZNF395 was an independent prognostic marker in chondrosarcoma patients. Functional studies revealed that depletion of ZNF395 markedly inhibited cell viability, colony formation, migration and invasion, and promoted apoptosis in chondrosarcoma.

Conclusion

These findings suggest that dysregulation of ZNF395 contributes to chondrosarcoma development, and ZNF395 may act as a potent oncogene and serve as a independently prognostic factor, highlight the potential of ZNF395 as a novel biomarker and therapeutic target for chondrosarcoma.

Selective Nonmethylated CpG DNA Recognition Mechanism of Cysteine Clamp Domains

Methylation of DNA at CpG sites is a major mark for epigenetic regulation, but how transcription factors are influenced by CpG methylation is not well understood. Here, we report the molecular mechanisms of how the TCF (T-cell factor) and GEF (glucose transporter 4 enhancer factor) families of proteins selectively target unmethylated DNA sequences with a C-clamp type zinc finger domain. The structure of the C-clamp domain from human GEF family protein HDBP1 (C-clamp^HDBP1) in complex with DNA was determined using NMR spectroscopy, which adopts a unique zinc finger fold and selectively binds RCCGG (R = A/G) DNA sequences with an "Arg···Trp-Lys-Lys" DNA recognition motif inserted in the major groove. The CpG base pairs are central to the binding due to multiple hydrogen bonds formed with the backbone carbonyl groups of Trp378 and Lys379, as well as the side chain ε-amino groups of Lys379 and Lys380 from C-clamp^HDBP1. Consequently, methylation of the CpG dinucleotide almost abolishes the binding. Homology modeling reveals that the C-clamp domain from human TCF1E (C-clamp^TCF1E) binds DNA through essentially the same mechanism, with a similar "Arg···Arg-Lys-Lys" DNA recognition motif. The substitution of tryptophan by arginine makes C-clamp^HDBP1 prefer RCCGC DNA sequences. The two signature DNA recognition motifs are invariant in the GEF and TCF families of proteins, respectively, from fly to human. The recognition of the CpG dinucleotide through two consecutive backbone carbonyl groups is the same as that of the CXXC type unmethylated CpG DNA binding domains, suggesting a common mechanism shared by unmethylated CpG binding proteins.

Engineered IL-7 Receptor Enhances the Therapeutic Effect of AXL-CAR-T Cells on Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a very aggressive malignant type of tumor that currently lacks effective targeted therapies. In hematological malignancies, chimeric antigen receptor T (CAR-T) cells have shown very significant antitumor ability; however, in solid tumors, the efficacy is poor. In order to apply CAR-T cells in the treatment of TNBC, in this study, constitutively activated IL-7 receptor (C7R) that has been reported is used to enhance the antitumor function of constructed CAR-T cells by ourselves. Using in vitro coincubation experiments with target cells and in vivo antitumor experiments in mice, we found that the coexpressed C7R can significantly improve the activation, cell proliferation, and cytotoxicity of CAR-T cells. In addition, the in vivo experiments suggested that the enhanced CAR-T cells displayed significant antitumor activity in a TNBC subcutaneous xenograft model, in which in vivo, the survival time of CAR-T cells was prolonged. Together, these results indicated that CAR-T cells that coexpress C7R may be a novel therapeutic strategy for TNBC.

Identification of Copy Number Variation in Domestic Chicken Using Whole-Genome Sequencing Reveals Evidence of Selection in the Genome

Simple Summary

Chickens have been bred for meat and egg production as a source of animal protein. With the increase of productivity as the main purpose of domestication, factors such as metabolism and immunity were boosted, which are detectable signs of selection on the genome. This study focused on copy number variation (CNV) to find evidence of domestication on the genome. CNV was detected from whole-genome sequencing of 65 chickens including Red Jungle Fowl, broilers, and layers. After that, CNV region, the overlapping region of CNV between individuals, was made to identify which genomic regions showed copy number differentiation. The 663 domesticated-specific CNV regions were associated with various functions such as metabolism and organ development. Also, by performing population differentiation analyses such as clustering analysis and ANOVA test, we found that there are a lot of genomic regions with different copy number patterns between broilers and layers. This result indicates that different genetic variations can be found, depending on the purpose of artificial selection and provides considerations for future animal breeding.

Abstract

Copy number variation (CNV) has great significance both functionally and evolutionally. Various CNV studies are in progress to find the cause of human disease and to understand the population structure of livestock. Recent advances in next-generation sequencing (NGS) technology have made CNV detection more reliable and accurate at whole-genome level. However, there is a lack of CNV studies on chickens using NGS. Therefore, we obtained whole-genome sequencing data of 65 chickens including Red Jungle Fowl, Cornish (broiler), Rhode Island Red (hybrid), and White Leghorn (layer) from the public databases for CNV region (CNVR) detection. Using CNVnator, a read-depth based software, a total of 663 domesticated-specific CNVRs were identified across autosomes. Gene ontology analysis of genes annotated in CNVRs showed that mainly enriched terms involved in organ development, metabolism, and immune regulation. Population analysis revealed that CN and RIR are closer to each other than WL, and many genes (LOC772271, OR52R1, RD3, ADH6, TLR2B, PRSS2, TPK1, POPDC3, etc.) with different copy numbers between breeds found. In conclusion, this study has helped to understand the genetic characteristics of domestic chickens at CNV level, which may provide useful information for the development of breeding systems in chickens.

Identification of novel human leukocyte antigen-A*11:01-restricted cytotoxic T-lymphocyte epitopes derived from osteosarcoma antigen papillomavirus binding factor

Osteosarcoma is the most common malignancy of bone that affects young people. Neoadjuvant chemotherapy and surgery have significantly improved the prognosis. However, the prognosis of non-responders to chemotherapy is still poor. To develop peptide-based immunotherapy for osteosarcoma, we previously identified CTL epitopes derived from papillomavirus binding factor (PBF) in the context of human leukocyte antigen (HLA)-A2, HLA-A24 and HLA-B55. In the present study, we identified two novel CTL epitopes, QVT (QVTVWLLEQK) and LSA (LSALPPPLHK), in the context of HLA-A11 using a sequence of screenings based on the predicted affinity of peptides, in vitro folding ability of peptide/HLA-A11 complex, reactivity of peptide/HLA-A11 tetramer and interferon (IFN)-γ production of T cells that was induced by mixed lymphocyte peptide culture under a limiting dilution condition. CTL clones directed to QVT and LSA peptides showed specific cytotoxicity against HLA-A11+ PBF+ osteosarcoma (HOS-A11) cells. In contrast, another epitope, ASV (ASVLSRRLGK), could highly induce cognate tetramer-positive CTL. This might be because the ASV peptide mimics the peptide ASV (R6Q) (ASVLSQRLGK) derived from bacterial polypeptides, ROK family proteins. However, ASV-induced CTL did not show cytokine production against the cognate peptide. In conclusion, the CTL epitopes QVT and LSA peptides might be useful for the development of immunotherapy targeting PBF for patients with osteosarcoma.

A novel AXL chimeric antigen receptor endows T cells with anti-tumor effects against triple negative breast cancers

Identifying targets for chimeric antigen receptor-modulated T lymphocyte (CAR-T) therapy against solid tumors is an urgent problem to solve. In this study, we showed for the first time that the receptor tyrosine kinase, AXL, is overexpressed in various tumor cell lines and patient tumor tissues including triple negative breast cancer (TNBC) cell lines and patient samples, making AXL a potent novel target for cancer therapy, specifically for TNBC treatment. We also engineered T cells with a CAR consisting of a novel single-chain variable fragment against AXL and revealed its antigen-specific cytotoxicity and ability to release cytokines in a TNBC cell line and other AXL-positive tumors in vitro. Furthermore, AXL-CAR-T cells displayed a significant anti-tumor effect and in vivo persistence in a TNBC xenograft model. Taken together, our findings indicate that AXL-CAR-T cells can represent a promising therapeutic strategy against TNBC.

Overexpression of RASD1 inhibits glioma cell migration/invasion and inactivates the AKT/mTOR signaling pathway

The RAS signaling pathway is hyperactive in malignant glioma due to overexpression and/or increased activity. A previous study identified that RASD1, a member of the RAS superfamily of small G-proteins, is a significantly dysregulated gene in oligodendroglial tumors that responded to chemotherapy. However, the role and mechanism of RASD1 in the progression of human glioma remain largely unknown. In the present study, by analyzing a public genomics database, we found that high levels of RASD1 predicted good survival of astrocytoma patients. We thus established lentivirus-mediated RASD1-overexpressing glioma cells and found that overexpressing RASD1 had no significant effects on glioma cell proliferation. However, the overexpression of RASD1 inhibited glioma cell migration and invasion. In the intracranial glioma xenograft model, the overexpression of RASD1 significantly reduced the number of tumor cells invading into the surrounding tissues without affecting the tumor size. An intracellular signaling array revealed that the phosphorylation of both AKT and the S6 ribosomal protein significantly decreased with RASD1 overexpression in glioma cells. Interestingly, RASD1 protein levels were significantly higher in grade II and grade III astrocytoma tissues than in nontumorous brain tissues. These findings suggest that the upregulation of RASD1 in glioma tissues may play an inhibitory role in tumor expansion, possibly through inactivating the AKT/mTOR signaling pathway.

Pappalysin-1 T cell receptor transgenic allo-restricted T cells kill Ewing sarcoma in vitro and in vivo

Pregnancy-associated plasma protein-A (PAPPA), also known as pappalysin, is a member of the insulin-like growth factor (IGF) family. PAPPA acts as a protease, cleaving IGF inhibitors, i.e., IGF binding proteins (IGFBPs), thereby setting free IGFs. The insulin/IGF-axis is involved in cancer in general and in Ewing sarcoma (ES) in particular. ES is a highly malignant bone tumor characterized by early metastatic spread. PAPPA is associated with various cancers. It is overexpressed and required for proliferation in ES. PAPPA also stimulates normal bone growth. We isolated HLA-A*02:01⁺/peptide-restricted T cells from A*02:01⁻ healthy donors directed against PAPPA, generated by priming with A*02:01⁺ PAPPA peptide loaded dendritic cells. After TCR identification, retrovirally TCR transduced CD8⁺ T cells were assessed for their in vitro specificity and in vivo efficacy in human ES bearing Rag2^−/−γc^−/− mice. Engraftment in mice and tumor infiltration of TCR transgenic T cells in the mice was evaluated. The TCR transgenic T cell clone PAPPA-2G6 demonstrated specific reactivity toward HLA-A*02:01⁺/PAPPA⁺ ES cell lines. We furthermore detected circulating TCR transgenic T cells in the blood in Rag2^−/−γc^−/− mice and in vivo engraftment in bone marrow. Tumor growth in mice with xenografted ES was significantly reduced after treatment with PAPPA-2G6 TCR transgenic T cells in contrast to controls. Tumors of treated mice revealed tumor-infiltrating PAPPA-2G6 TCR transgenic T cells. In summary, we demonstrate that PAPPA is a first-rate target for TCR-based immunotherapy of ES.

Identification of activated enhancers and linked transcription factors in breast, prostate, and kidney tumors by tracing enhancer networks using epigenetic traits

Background

Although technological advances now allow increased tumor profiling, a detailed understanding of the mechanisms leading to the development of different cancers remains elusive. Our approach toward understanding the molecular events that lead to cancer is to characterize changes in transcriptional regulatory networks between normal and tumor tissue. Because enhancer activity is thought to be critical in regulating cell fate decisions, we have focused our studies on distal regulatory elements and transcription factors that bind to these elements.

Results

Using DNA methylation data, we identified more than 25,000 enhancers that are differentially activated in breast, prostate, and kidney tumor tissues, as compared to normal tissues. We then developed an analytical approach called Tracing Enhancer Networks using Epigenetic Traits that correlates DNA methylation levels at enhancers with gene expression to identify more than 800,000 genome-wide links from enhancers to genes and from genes to enhancers. We found more than 1200 transcription factors to be involved in these tumor-specific enhancer networks. We further characterized several transcription factors linked to a large number of enhancers in each tumor type, including GATA3 in non-basal breast tumors, HOXC6 and DLX1 in prostate tumors, and ZNF395 in kidney tumors. We showed that HOXC6 and DLX1 are associated with different clusters of prostate tumor-specific enhancers and confer distinct transcriptomic changes upon knockdown in C42B prostate cancer cells. We also discovered de novo motifs enriched in enhancers linked to ZNF395 in kidney tumors.

Conclusions

Our studies characterized tumor-specific enhancers and revealed key transcription factors involved in enhancer networks for specific tumor types and subgroups. Our findings, which include a large set of identified enhancers and transcription factors linked to those enhancers in breast, prostate, and kidney cancers, will facilitate understanding of enhancer networks and mechanisms leading to the development of these cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13072-016-0102-4) contains supplementary material, which is available to authorized users.

Zinc finger proteins in cancer progression

Zinc finger proteins are the largest transcription factor family in human genome. The diverse combinations and functions of zinc finger motifs make zinc finger proteins versatile in biological processes, including development, differentiation, metabolism and autophagy. Over the last few decades, increasing evidence reveals the potential roles of zinc finger proteins in cancer progression. However, the underlying mechanisms of zinc finger proteins in cancer progression vary in different cancer types and even in the same cancer type under different types of stress. Here, we discuss general mechanisms of zinc finger proteins in transcription regulation and summarize recent studies on zinc finger proteins in cancer progression. In this review, we also emphasize the importance of further investigations in elucidating the underlying mechanisms of zinc finger proteins in cancer progression.

The role of PAPP-A in the IGF system: location, location, location

Although discovered as a placental protein present abundantly in the circulation of pregnant women, pregnancy-associated plasma protein-A (PAPP-A) is widely expressed in multiple tissues. PAPP-A is a highly specific metalloproteinase binding tightly to glycosaminoglycans present on the surface of cells. By cleaving a subset of insulin-like growth factor binding proteins (IGFBPs), PAPP-A thus functions within tissues as a growth-promoting enzyme, releasing bioactive IGF in close proximity to the IGF receptor. IGFBP-4 is believed to be the principal PAPP-A substrate, and the focus in this review is on PAPP-A enzymatic activity and its role in the PAPP-A-IGFBP-4-IGF axis, which is subject to regulation at several different levels. These include e.g., transcriptional control, competing reactions potentially sequestering IGF from IGFBP-4 and hence antagonizing PAPP-A-mediated IGF activation, and proteolytic inhibition of PAPP-A. The latter may involve the protein stanniocalcin-2 (STC2), recently found to potently inhibit PAPP-A activity by forming a covalent complex with PAPP-A. PAPP-A or complex-bound variants may escape from pathological tissues into the circulation. It is emphasized that the potential use of PAPP-A as a diagnostic or predictive biomarker in nonpregnant individuals requires precise knowledge of analyte identity and assay specificity in addition to an appropriate material for standardization. Finally, PAPP-A may serve as a therapeutic target to indirectly inhibit IGF signaling in tissues where this is driven by increased PAPP-A activity. By taking advantage of the intricate interaction between PAPP-A and IGFBP-4, highly specific and selective inhibition of PAPP-A is possible.

DNA methylation profiling reveals novel diagnostic biomarkers in renal cell carcinoma

BACKGROUND

Renal cell carcinoma (RCC) is the tenth most commonly diagnosed cancer in the United States. While it is usually lethal when metastatic, RCC is successfully treated with surgery when tumors are confined to the kidney and have low tumor volume. Because most early stage renal tumors do not result in symptoms, there is a strong need for biomarkers that can be used to detect the presence of the cancer as well as to monitor patients during and after therapy.

METHODS

We examined genome-wide DNA methylation alterations in renal cell carcinomas of diverse histologies and benign adjacent kidney tissues from 96 patients.

RESULTS

We observed widespread methylation differences between tumors and benign adjacent tissues, particularly in immune-, G-protein coupled receptor-, and metabolism-related genes. Additionally, we identified a single panel of DNA methylation biomarkers that reliably distinguishes tumor from benign adjacent tissue in all of the most common kidney cancer histologic subtypes, and a second panel does the same specifically for clear cell renal cell carcinoma tumors. This set of biomarkers were validated independently with excellent performance characteristics in more than 1,000 tissues in The Cancer Genome Atlas clear cell, papillary, and chromophobe renal cell carcinoma datasets.

CONCLUSIONS

These DNA methylation profiles provide insights into the etiology of renal cell carcinoma and, most importantly, demonstrate clinically applicable biomarkers for use in early detection of kidney cancer.

Genomic Analysis as the First Step toward Personalized Treatment in Renal Cell Carcinoma

Drug resistance mechanisms in renal cell carcinoma (RCC) still remain elusive. Although most patients initially respond to targeted therapy, acquired resistance can still develop eventually. Most of the patients suffer from intrinsic (genetic) resistance as well, suggesting that there is substantial need to broaden our knowledge in the field of RCC genetics. As molecular abnormalities occur for various reasons, ranging from single nucleotide polymorphisms to large chromosomal defects, conducting whole-genome association studies using high-throughput techniques seems inevitable. In principle, data obtained via genome-wide research should be continued and performed on a large scale for the purposes of drug development and identification of biological pathways underlying cancerogenesis. Genetic alterations are mostly unique for each histological RCC subtype. According to recently published data, RCC is a highly heterogeneous tumor. In this paper, the authors discuss the following: (1) current state-of-the-art knowledge on the potential biomarkers of RCC subtypes; (2) significant obstacles encountered in the translational research on RCC; and (3) recent molecular findings that may have a crucial impact on future therapeutic approaches.

The hypoxia-inducible transcription factor ZNF395 is controlled by IĸB kinase-signaling and activates genes involved in the innate immune response and cancer

Activation of the hypoxia inducible transcription factor HIF and the NF-ĸB pathway promotes inflammation-mediated tumor progression. The cellular transcription factor ZNF395 has repeatedly been found overexpressed in various human cancers, particularly in response to hypoxia, implying a functional relevance. To understand the biological activity of ZNF395, we identified target genes of ZNF395 through a genome-wide expression screen. Induced ZNF395 expression led to the upregulation of genes known to play a role in cancer as well as a subset of interferon (IFN)-stimulated genes (ISG) involved in antiviral responses such as IFIT1/ISG56, IFI44 and IFI16. In cells that lack ZNF395, the IFN-α-mediated stimulation of these factors was impaired, demonstrating that ZNF395 is required for the full induction of these antiviral genes. Transient transfections revealed that ZNF395-mediated activation of the IFIT1/ISG56 promoter depends on the two IFN-stimulated response elements within the promoter and on the DNA-binding domain of ZNF395, a so-called C-clamp. We also show that IĸBα kinase (IKK)-signaling is necessary to allow ZNF395 to activate transcription and simultaneously enhances its proteolytic degradation. Thus, ZNF395 becomes activated at the level of protein modification by IKK. Moreover, we confirm that the expression of ZNF395 is induced by hypoxia. Our results characterize ZNF395 as a novel factor that contributes to the maximal stimulation of a subset of ISGs. This transcriptional activity depends on IKK signaling further supporting a role of ZNF395 in the innate immune response. Given these results it is possible that under hypoxic conditions, elevated levels of ZNF395 may support inflammation and cancer progression by activating the target genes involved in the innate immune response and cancer.

Germline genetic variations at 11q13 and 12p11 locus modulate age at onset for renal cell carcinoma

PURPOSE

Few risk factors have been identified for renal cell carcinoma. We performed a validation study in a population with a European background to identify the most significant variants previously identified in association with renal cell carcinoma risk.

MATERIALS AND METHODS

We performed a case-control validation study after recruiting 463 controls and 463 patients with a histologically confirmed diagnosis of clear cell renal cell carcinoma. For each patient and matched control we genotyped 8 single nucleotide polymorphisms selected from previous studies to evaluate the association between candidate single nucleotide polymorphisms and renal cell carcinoma susceptibility.

RESULTS

After adjusting for patient age, gender, smoking status and body mass index the AG + AA genotypes from rs7105934 (11q13) were associated with a decreased risk of renal cell carcinoma (OR 0.50, 95% CI 0.33-0.75, p = 0.001) and the AC + CC genotypes from rs1049380 (ITPR2) were associated with an increased risk (OR 1.66, 95% CI 1.28-2.16, p <0.001). Kidney cancer developed at an older age in patients carrying the dominant risk allele A for rs7105934 (mean age at diagnosis 73.1 vs 68.9 years, p = 0.002) and at a younger age in those carrying the dominant allele C for rs1049380 (mean 68.1 vs 70.8 years, p = 0.005).

CONCLUSIONS

In what is to our knowledge the first validation study of the main 8 single nucleotide polymorphism variants associated with renal cell carcinoma susceptibility we confirmed the association of 2 single nucleotide polymorphisms with the risk of renal cell carcinoma. Each variant influenced patient age at disease diagnosis.

Regulation of the G-protein regulatory-Gαi signaling complex by nonreceptor guanine nucleotide exchange factors

Group II activators of G-protein signaling (AGS) serve as binding partners for Gα(i/o/t) via one or more G-protein regulatory (GPR) motifs. GPR-Gα signaling modules may be differentially regulated by cell surface receptors or by different nonreceptor guanine nucleotide exchange factors. We determined the effect of the nonreceptor guanine nucleotide exchange factors AGS1, GIV/Girdin, and Ric-8A on the interaction of two distinct GPR proteins, AGS3 and AGS4, with Gα(il) in the intact cell by bioluminescence resonance energy transfer (BRET) in human embryonic kidney 293 cells. AGS3-Rluc-Gα(i1)-YFP and AGS4-Rluc-Gα(i1)-YFP BRET were regulated by Ric-8A but not by Gα-interacting vesicle-associated protein (GIV) or AGS1. The Ric-8A regulation was biphasic and dependent upon the amount of Ric-8A and Gα(i1)-YFP. The inhibitory regulation of GPR-Gα(i1) BRET by Ric-8A was blocked by pertussis toxin. The enhancement of GPR-Gα(i1) BRET observed with Ric-8A was further augmented by pertussis toxin treatment. The regulation of GPR-Gα(i) interaction by Ric-8A was not altered by RGS4. AGS3-Rluc-Gα(i1)-YFP and AGS4-Rluc-G-Gα(i1)-YFP BRET were observed in both pellet and supernatant subcellular fractions and were regulated by Ric-8A in both fractions. The regulation of the GPR-Gα(i1) complex by Ric-8A, as well as the ability of Ric-8A to restore Gα expression in Ric8A(-/-) mouse embryonic stem cells, involved two helical domains at the carboxyl terminus of Ric-8A. These data indicate a dynamic interaction between GPR proteins, Gα(i1) and Ric-8A, in the cell that influences subcellular localization of the three proteins and regulates complex formation.

Group II activators of G-protein signalling and proteins containing a G-protein regulatory motif

Beyond the core triad of receptor, Gαβγ and effector, there are multiple accessory proteins that provide alternative modes of signal input and regulatory adaptability to G-protein signalling systems. Such accessory proteins may segregate a signalling complex to microdomains of the cell, regulate the basal activity, efficiency and specificity of signal propagation and/or serve as alternative binding partners for Gα or Gβγ independent of the classical heterotrimeric Gαβγ complex. The latter concept led to the postulate that Gα and Gβγ regulate intracellular events distinct from their role as transducers for cell surface seven-transmembrane span receptors. One general class of such accessory proteins is defined by AGS proteins or activators of G-protein signalling that refer to mammalian cDNAs identified in a specific yeast-based functional screen. The discovery of AGS proteins and related entities revealed a number of unexpected mechanisms for regulation of G-protein signalling systems and expanded functional roles for this important signalling system.

A genome-wide association study identifies a novel susceptibility locus for renal cell carcinoma on 12p11.23

Renal cell carcinoma (RCC) is the most lethal urologic cancer. Only two common susceptibility loci for RCC have been confirmed to date. To identify additional RCC common susceptibility loci, we conducted an independent genome-wide association study (GWAS). We analyzed 533 191 single nucleotide polymorphisms (SNPs) for association with RCC in 894 cases and 1516 controls of European descent recruited from MD Anderson Cancer Center in the primary scan, and validated the top 500 SNPs in silico in 3772 cases and 8505 controls of European descent involved in the only published GWAS of RCC. We identified two common variants in linkage disequilibrium, rs718314 and rs1049380 (r(2) = 0.64, D ' = 0.84), in the inositol 1,4,5-triphosphate receptor, type 2 (ITPR2) gene on 12p11.23 as novel susceptibility loci for RCC (P = 8.89 × 10(-10) and P = 6.07 × 10(-9), respectively, in meta-analysis) with an allelic odds ratio of 1.19 [95% confidence interval (CI): 1.13-1.26] for rs718314 and 1.18 (95% CI: 1.12-1.25) for rs1049380. It has been recently identified that rs718314 in ITPR2 is associated with waist-hip ratio (WHR) phenotype. To our knowledge, this is the first genetic locus associated with both cancer risk and WHR.