Common variant in the HMGA2 gene increases susceptibility to nephropathy in patients with type 2 diabetes

AIMS/HYPOTHESIS

Type 2 diabetes is a chronic metabolic disorder associated with devastating microvascular complications. Genome-wide association studies have identified more than 60 genetic variants associated with type 2 diabetes and/or glucose and insulin traits, but their role in the progression of diabetes is not established. The aim of this study was to explore whether these variants were also associated with the development of nephropathy in patients with type 2 diabetes.

METHODS

We studied 28 genetic variants in 2,229 patients with type 2 diabetes from the local Malmö Scania Diabetes Registry (SDR) published during 2007-2010. Diabetic nephropathy (DN) was defined as micro- or macroalbuminuria and/or end-stage renal disease. Estimated glomerular filtration rate (eGFR) was assessed using the MDRD-4 formula. Replication genotyping of rs1531343 was performed in diabetic (Steno type 2 diabetes [n = 345], Genetics of Diabetes Audit and Research in Tayside Scotland [Go-DARTS] [n = 784]) and non-diabetic (Malmö Preventive Project [n = 2,523], Botnia study [n = 2,247]) cohorts.

RESULTS

In the SDR, HMGA2 single-nucleotide polymorphism rs1531343 was associated with DN (OR 1.50, 95% CI 1.20, 1.87, p = 0.00035). In the combined analysis totalling 3,358 patients with type 2 diabetes (n = 1,233 cases, n = 2,125 controls), carriers of the C-allele had a 1.45-fold increased risk of developing nephropathy (95% CI 1.20, 1.75, p = 0.00010). Furthermore, the risk C-allele was associated with lower eGFR in patients with type 2 diabetes (n = 2,499, β ± SEM, -3.7 ± 1.2 ml/min, p = 0.002) and also in non-diabetic individuals (n = 17,602, β ± SEM, -0.008 ± 0.003 ml/min (log( e )), p = 0.006).

CONCLUSIONS/INTERPRETATION

These data demonstrate that the HMGA2 variant seems to be associated with increased risk of developing nephropathy in patients with type 2 diabetes and lower eGFR in both diabetic and non-diabetic individuals and could thus be a common denominator in the pathogenesis of type 2 diabetes and kidney complications.

[Construction of let-7d expression vector and its inhibitory effect on HMGA2 and ras expression in human ovarian cancer cells in vitro]

OBJECTIVE

To elucidate the role of let-7d in regulating the biological behavior of ovarian cancer cells and their expressions of HMGA2 and ras proteins.

METHODS

The pre-let-7d sequence was synthesized and inserted into pcDNA6.2GW/EmGFPmiR and transfected into ovarian cancer IGROV1 cells to cause pre-let-7d overexpression. Real-time quantitative RT-PCR was employed to examine the expression levels of let-7d miRNA and HMGA2 mRNA, and Western blotting was performed to detect the expressions of HMGA2 and ras protein in the transfected cells. The effect of pcDNA6.2GW-let-7d transfection on IGROV1 cell proliferation was determined using MTT assay and the cell apoptosis rate was measured using flow cytometry.

RESULTS

The eukaryotic expression vector containing the target gene let-7d was successfully constructed and transfected into IGROV1 cells. The transfected cells showed a marked reduction of HMGA2 expression but a less obvious down-regulation of ras expression. Transfection with pcDNA6.2GW-let-7d to suppress the expression of HMGA2 caused alterations of the phenotype of IGROV1 cells shown by a reduced proliferative activity and increased cell apoptosis.

CONCLUSION

Let-7d plays an important role in altering the malignant cell phenotype of ovarian cancer IGROV1 cells by regulating the expression of HMGA2.

Expression analysis of MIR182 and its associated target genes in advanced ovarian carcinoma

BRCA1/BRCA2 mutations are common and the hallmarks of high-grade serous ovarian carcinoma. We found that MIR182, a negative BRCA1 regulator, is significantly overexpressed in high-grade serous ovarian carcinoma. To examine whether overexpression of MIR182 and its target genes, including BRCA1, HMGA2 (high-mobility group A2), FOXO3 and MTSS1, are associated with high-grade serous ovarian carcinoma tumor types and clinical outcome, we studied MIR182 by in situ hybridization and its target gene expression by immunohistochemistry in 117 cases of advanced ovarian cancer. We found that high-grade serous ovarian carcinoma had significantly higher MIR182 (P=0.0003) and HMGA2 (P=0.04) expression, and significantly lower BRCA1 (P<0.0001) and FOXO3 (P<0.001) expression than normal controls. MIR182 is significantly correlated with MTSS1 expression (r=0.31; P<0.001), whereas other target genes did not show a significant correlation with MIR182, indicating a complicated regulatory mechanisms of these genes in high-grade serous ovarian carcinoma. Among the examined MIR182 target genes, only HMGA2 was significantly associated with serous type carcinomas (P<0.01), ascites (P<0.01) and high death rate (P=0.02). FOXO3 expression was associated with lower-stage disease (P=0.04) and solid growth pattern (P=0.03). MIR182 expression is significantly higher in high-grade serous ovarian carcinoma than in fallopian tubes.

[Overexpression of high mobility group A2 and its correlation with microRNA let-7 family in serous ovarian cancers]

OBJECTIVE

To examine the expression of high mobility group A2 (HMGA2), P53 and let-7 family microRNA, to investigate the correlation of HMGA2 and let-7, and to compare the HMGA2 and P53 expressions in human serous ovarian cancer.

METHODS

Immunohistochemistry assay was used to examine the expressions of HMGA2 and P53 in 50 paraffin-embedded tissue specimens of human serous ovarian cancer and 4 normal fallopian tube tissues. HMGA2 mRNA and let-7 family microRNA were detected by real time fluorescent quantitative reverse transcription polymerase chain reaction in the corresponding frozen tissues.

RESULTS

HMGA2 and P53 were immuno-positive in 70% (35/50) and 78% (39/50) of the ovarian cancer tissues, respectively. HMGA2 was weakly expressed in the ciliated cells, but negative in the secretary cells of the fallopian tube. There was a tendency that the expression of HMGA2 increased with higher pathological grade of the ovarian cancer, but no correlation was observed between the HMGA2 overexpression and clinical stages. HMGA2 mRNA was detected in all the ovarian cancer samples, and its expression level was higher than that of the normal fallopian tube tissues in 72% (36/50) of the ovarian cancer samples. The expression of HMGA2 mRNA was much higher in more malignant SKOV3.ipl cells than in its corresponding SKOV3 cells. All let-7 family members were detectable in all ovarian cancer samples, and their expression were inversely correlated with HMGA2 mRNA expression (r=-0.305,P<0.05).

CONCLUSION

HMGA2 can be a biomarker complement to P53, and its high expression has an inclination of more malignancy. The downregulation of let-7 is, but not the only mechanism of HMGA2 overexpression in serous ovarian cancer.

Downregulation of HMGA2 by the pan-deacetylase inhibitor panobinostat is dependent on hsa-let-7b expression in liver cancer cell lines

Inhibitors of protein deacetylases represent a novel therapeutic option for cancer diseases due to their effects on transcriptional regulation by interfering with histones acetylation and on several other cellular pathways. Recently, their ability to modulate several transcription factors and, interestingly, also co-factors, which actively participate in formation and modulation of transcription complexes was shown. We here investigate whether HMGA2 (High Mobility Group AT-2 hook), a nuclear non-histone transcriptional co-factor with known oncogenic properties, can be influenced by the novel pan-deacetylase inhibitor panobinostat (LBH589) in human hepatocellular carcinoma models. Panobinostat strongly downregulated HMGA2 in HepG2 and Hep3B cells; this effect was mediated by transcriptional upregulation and promotion of the maturation of the tumorsuppressor miRNA hsa-let-7b, which could inhibit HMGA2 expression via RNA interference pathways. siRNA knockdown of HMGA2 or transfection of hsa-let-7b mimicking oligonucleotides confirmed the role of HMGA2 in regulating cell proliferation and apoptosis in liver cancer cell lines. Co-incubation with panobinostat showed an additive effect on inhibition of cell proliferation using an impedance-based real-time cell analyzer. Treatment of HepG2 xenografts with panobinostat also led to a downregulation of HMGA2 in vivo. These findings show that pan-deacetylase inhibitors also modulate other signaling pathways and networks than histone modifications to influence cell fate.

Four loci explain 83% of size variation in the horse

Horse body size varies greatly due to intense selection within each breed. American Miniatures are less than one meter tall at the withers while Shires and Percherons can exceed two meters. The genetic basis for this variation is not known. We hypothesize that the breed population structure of the horse should simplify efforts to identify genes controlling size. In support of this, here we show with genome-wide association scans (GWAS) that genetic variation at just four loci can explain the great majority of horse size variation. Unlike humans, which are naturally reproducing and possess many genetic variants with weak effects on size, we show that horses, like other domestic mammals, carry just a small number of size loci with alleles of large effect. Furthermore, three of our horse size loci contain the LCORL, HMGA2 and ZFAT genes that have previously been found to control human height. The LCORL/NCAPG locus is also implicated in cattle growth and HMGA2 is associated with dog size. Extreme size diversification is a hallmark of domestication. Our results in the horse, complemented by the prior work in cattle and dog, serve to pinpoint those very few genes that have played major roles in the rapid evolution of size during domestication.

Altered microRNA expression profile in human pituitary GH adenomas: down-regulation of miRNA targeting HMGA1, HMGA2, and E2F1

CONTEXT

MicroRNA (miRNA) are an important class of regulators of gene expression. Altered miRNA expression has been constantly found in human neoplasias and plays an important role in the process of carcinogenesis.

OBJECTIVE

The aim of this study was to identify specific miRNA whose expression is altered in GH-secreting pituitary adenomas.

DESIGN

Using a miRNACHIP microarray, we have analyzed the miRNA expression profile of human GH adenomas vs. normal pituitary gland.

RESULTS

We report the identification of a set of miRNA, including miR-34b, miR-326, miR-432, miR-548c-3p, miR-570, and miR-603, drastically and constantly down-regulated in GH adenomas. We demonstrate that these miRNA target genes such as high-mobility group A1 (HMGA1), HMGA2, and E2F1, whose overexpression and/or activation plays a critical role in pituitary tumorigenesis. We also show that the enforced expression of the down-regulated miRNA has a negative role on the growth regulation of pituitary adenoma cells. Finally, an inverse correlation is found between the expression of these miRNA and HMGA1 and HMGA2 protein levels in GH adenomas.

CONCLUSION

Our study identifies a specific subset of miRNA, whose down-regulation might contribute to pituitary tumorigenesis.

[The effects of lentivirus-mediated RNA interference silencing HMGA2 on proliferation and expressions of cyclin B2 and cyclin A2 in HL-60 cells]

OBJECTIVE

To explore the effects of lentivirus-mediated RNA interference silencing HMGA2 on proliferation and expressions of cyclin B2 and cyclin A2 in HL-60 cell line.

METHODS

The protein and mRNA expressions of HMGA2 in HL-60 cells transduced by recombinant lentivirus producing HMGA2 gene short hairpin (shRNA) were examined by Western-blot and reverse transcription-polymerase chain reaction (RT-PCR) analysis; The effects of the lentivirus on cell proliferation inhibiting rate, the ability of cell proliferation and cell cycle were analyzed by soft agar colony formation assay and FCM, respectively; The protein and mRNA expressions of cyclin B2 and cyclin A2 were also examined by Western-blot and RT-PCR.

RESULTS

Recombinant lentivirus producing HMGA2 shRNA was successfully constructed, which was identified by PCR and sequencing; Stable HMGA2-deficient HL-60 cell line was established by puromycin, its mRNA and protein expression inhibition rates were (80.66 ± 7.98)% and (76.35 ± 12.72)%, respectively. Silencing of endogenous HMGA2 resulted in efficient inhibition of the cellular proliferative activity, low and flat of the cell growth curve and the lack of typical character of exponential growth. FCM revealed significant more cell cycle G(2)/M arrest \[(30.00 ± 5.78)%\] in HL-60 cell line transfected specific shRNA than control group \[(13.90 ± 4.07)%\] (P < 0.05). The cyclin B2 mRNA and protein expression inhibition rates in stable HMGA2-deficient HL-60 cell line were (67.55 ± 7.69)% and (51.77 ± 4.81)%, respectively, while the expression of cyclin A2 had no significant change compared with control group.

CONCLUSION

RNAi silencing of HMGA2 down-regulated cyclinB2, significantly inhibited the proliferation of HL-60 cells and induced the accumulation of HL-60 cells in the G(2)/M phase. Thus, HMGA2 may be an important target for anti-leukemia therapy.

Expression profiling of uterine leiomyomata cytogenetic subgroups reveals distinct signatures in matched myometrium: transcriptional profilingof the t(12;14) and evidence in support of predisposing genetic heterogeneity

Uterine leiomyomata (UL), the most common neoplasm in reproductive-age women, are classified into distinct genetic subgroups based on recurrent chromosome abnormalities. To develop a molecular signature of UL with t(12;14)(q14-q15;q23-q24), we took advantage of the multiple UL arising as independent clonal lesions within a single uterus. We compared genome-wide expression levels of t(12;14) UL to non-t(12;14) UL from each of nine women in a paired analysis, with each sample weighted for the percentage of t(12;14) cells to adjust for mosaicism with normal cells. This resulted in a transcriptional profile that confirmed HMGA2, known to be overexpressed in t(12;14) UL, as the most significantly altered gene. Pathway analysis of the differentially expressed genes showed significant association with cell proliferation, particularly G1/S checkpoint regulation. This is consistent with the known larger size of t(12;14) UL relative to karyotypically normal UL or to UL in the deletion 7q22 subgroup. Unsupervised hierarchical clustering demonstrated that patient variability is relatively dominant to the distinction of t(12;14) UL compared with non-t(12;14) UL or of t(12;14) UL compared with del(7q) UL. The paired design we employed is therefore important to produce an accurate t(12;14) UL-specific gene list by removing the confounding effects of genotype and environment. Interestingly, myometrium not only clustered away from the tumors, but generally separated based on associated t(12;14) versus del(7q) status. Nine genes were identified whose expression can distinguish the myometrium origin. This suggests an underlying constitutional genetic predisposition to these somatic changes which could potentially lead to improved personalized management and treatment.

Rearrangement of HMGA2 in a case of infantile lipoblastoma without Plag1 alteration

Lipoblastoma is a rare benign adipocytic tumor that occurs usually in children. It can be difficult to distinguish a lipoblastoma from other lipogenic tumors. In such cases, the detection of a rearrangement of the PLAG1 gene by fluorescence in situ hybridization analysis is useful for characterizing a lipoblastoma. We present here a novel case of morphological infantile lipoblastoma showing a rearrangement of HMGA2 instead of the classical PLAG1 alteration. HMGA2 is the main target of clonal aberrations encountered in lipomas. This result supports the hypothesis that benign lipomatous tumors harboring PLAG1 or HMGA2 rearrangement could constitute a unique pathogenetic entity.

The expression of HMGA2 varies strongly among colon carcinomas

BACKGROUND

The expression of high mobility group protein AT-hook2 (HMGA2) indicates a worse prognosis in many epithelial malignancies, such as colon cancer. The present study addresses methodological aspects, as well as the genetic background, of the HMGA2 expression in colon cancer.

MATERIALS AND METHODS

Samples of 38 colon carcinomas were studied for the expression of HMGA2 by quantitative Real-Time PCR (qRT-PCR). In selected cases, immunohistochemistry (IHC) was also performed.

RESULTS

The overexpression of HMGA2, compared to adjacent mucosa, is not consistent among colon carcinomas: Only a minority of carcinomas strongly overexpressed HMGA2, but in no more than 50% of the tumors did the expression exceed the average value in mucosa samples. qRT-PCR clearly reveals a continuum between cases with high and low expression.

CONCLUSION

For HMGA2-based risk assessment, continuous rather than discontinuous models seem to be most appropriate. However, in daily practice, IHC seems to be a suitable method to stratify for high-risk patients.

PIT1 upregulation by HMGA proteins has a role in pituitary tumorigenesis

We have previously demonstrated that HMGA1B and HMGA2 overexpression in mice induces the development of GH and prolactin (PRL) pituitary adenomas mainly by increasing E2F1 transcriptional activity. Interestingly, these adenomas showed very high expression levels of PIT1, a transcriptional factor that regulates the gene expression of Gh, Prl, Ghrhr and Pit1 itself, playing a key role in pituitary gland development and physiology. Therefore, the aim of our study was to identify the role of Pit1 overexpression in pituitary tumour development induced by HMGA1B and HMGA2. First, we demonstrated that HMGA1B and HMGA2 directly interact with both PIT1 and its gene promoter in vivo, and that these proteins positively regulate Pit1 promoter activity, also co-operating with PIT1 itself. Subsequently, we showed, by colony-forming assays on two different pituitary adenoma cell lines, GH3 and αT3, that Pit1 overexpression increases pituitary cell proliferation. Finally, the expression analysis of HMGA1, HMGA2 and PIT1 in human pituitary adenomas of different histological types revealed a direct correlation between PIT1 and HMGA expression levels. Taken together, our data indicate a role of Pit1 upregulation by HMGA proteins in pituitary tumours.

Three-gene molecular diagnostic model for thyroid cancer

BACKGROUND

The preoperative diagnosis of thyroid nodules primarily depends upon fine needle aspiration (FNA) cytology. However, up to 25% of FNA samples have associated "suspicious or indeterminate", but not diagnostic cytologic reports, resulting in difficulty deciding appropriate clinical management for these patients. We hypothesize that the use of molecular markers as an adjunct to FNA cytology can improve the distinction of benign from malignant nodules that have associated suspicious or indeterminate cytology.

METHODS

Using microarray analysis, we previously identified and reported on 75 genes useful in the distinction of benign versus malignant thyroid nodules. In the present study, we have further validated the expression of 14 of these markers in a large number of thyroid samples by immunohistochemistry (IHC) analysis of 154 thyroid tumors and quantitative real-time RT-PCR (QRT-PCR) analysis of 95 FNA samples. Of the 154 tumors analyzed by IHC, 44 samples (29%) had associated suspicious or indeterminate FNA cytology.

RESULTS

Receiver operating characteristic using three-gene model, (HMGA2, MRC2, and SFN) analysis for the detection of malignant nodules resulted in areas under the curve (AUCs) of≥0.95 (80% sensitivity; 100% specificity) and≥0.84 (71% sensitivity; 84% specificity) for the IHC data in tumors, and QRT-PCR data in FNA samples, respectively.

CONCLUSIONS

Our results suggest that a three-gene model for the cytological diagnosis of indeterminate thyroid nodules is both feasible and promising. Implementation of this as an adjunct to thyroid cytology may significantly impact the clinical management of patients with suspicious or indeterminate thyroid FNA nodules.

[Selection and anti-cancer effects of siRNAs targeting HMGA2 gene]

High mobility group A2 protein (HMGA2), an architectural factor, is highly expressed in various cancer types including lung cancers. It is a candidate target for cancer therapy. RNAi is an effective gene silencing method with low cost and less time-consuming. It is possible to exploit this technology in therapy. Here, 5 siRNAs targeting Hmga2 gene (HMGA2 siRNA1-5) were designed and synthesized. MTT assay, colony formation assay, transwell assay and flow cytometry were used to evaluate the effects of these siRNAs on lung cancer cell lines (NCI-H446 and A549). Results from cell proliferation, clone formation, migration and apoptosis showed that HMGA2 siRNA1, 3, 5 could affect these aspects for both lung cancer cell lines. Among the five siRNAs, HMGA2 siRNA5 showed the greatest inhibition effects. The inhibition effects of HMGA2 siRNA5 are sequence specific and are not due to the induction of interferon response. Taken together, siRNAs targeting Hmga2 gene are potential candidates for lung cancer gene therapy.

Isolated GH deficiency: mutation screening and copy number analysis of HMGA2 and CDK6 genes

OBJECTIVE

In most patients, the genetic cause of isolated GH deficiency (IGHD) is unknown. By identifying several genes associated with height variability within the normal population, three separate genome-wide association studies provided new candidate genes for human growth disorders. We selected two of them for genetic screening of our IGHD population.

AIM

We aimed to determine whether high-mobility group A2 (HMGA2) and cyclin-dependent protein kinase 6 (CDK6) are involved in the pathogenicity of IGHD.

METHODS

We directly sequenced coding regions and exon-intron boundaries of the genes HMGA2 and CDK6 in 105 Caucasian IGHD patients from the Dutch HYPOPIT study. In addition, we developed a new probe set of multiplex ligation-dependent probe amplification for both genes in order to detect copy number variations.

RESULTS

In one patient with classical IGHD phenotype, we identified a new heterozygous 20 bp deletion in the intronic region of HMGA2 (c.250-29_-9del), which was absent in the databases and healthy controls. Together, with recently published data concerning the 12q14 microdeletion syndrome, where patients with an HMGA2 haploinsufficiency had proportionate short stature, this study provides further support of the important role for HMGA2 in growth. In CDK6, we found only known polymorphisms.

CONCLUSIONS

This study provides the first report of a deletion in the HMGA2 gene that might be related to IGHD. We suggest that this gene is investigated as a second screening in patients with a classical IGHD phenotype in which mutations in classical candidate genes have been excluded.

Genome-wide association study identifies four loci associated with eruption of permanent teeth

The sequence and timing of permanent tooth eruption is thought to be highly heritable and can have important implications for the risk of malocclusion, crowding, and periodontal disease. We conducted a genome-wide association study of number of permanent teeth erupted between age 6 and 14 years, analyzed as age-adjusted standard deviation score averaged over multiple time points, based on childhood records for 5,104 women from the Danish National Birth Cohort. Four loci showed association at P<5×10(-8) and were replicated in four independent study groups from the United States and Denmark with a total of 3,762 individuals; all combined P-values were below 10(-11). Two loci agreed with previous findings in primary tooth eruption and were also known to influence height and breast cancer, respectively. The two other loci pointed to genomic regions without any previous significant genome-wide association study results. The intronic SNP rs7924176 in ADK could be linked to gene expression in monocytes. The combined effect of the four genetic variants was most pronounced between age 10 and 12 years, where children with 6 to 8 delayed tooth eruption alleles had on average 3.5 (95% confidence interval: 2.9-4.1) fewer permanent teeth than children with 0 or 1 of these alleles.

Let-7a is a direct EWS-FLI-1 target implicated in Ewing's sarcoma development

Ewing's sarcoma family tumors (ESFT) are the second most common bone malignancy in children and young adults, characterized by unique chromosomal translocations that in 85% of cases lead to expression of the EWS-FLI-1 fusion protein. EWS-FLI-1 functions as an aberrant transcription factor that can both induce and suppress members of its target gene repertoire. We have recently demonstrated that EWS-FLI-1 can alter microRNA (miRNA) expression and that miRNA145 is a direct EWS-FLI-1 target whose suppression is implicated in ESFT development. Here, we use miRNA arrays to compare the global miRNA expression profile of human mesenchymal stem cells (MSC) and ESFT cell lines, and show that ESFT display a distinct miRNA signature that includes induction of the oncogenic miRNA 17–92 cluster and repression of the tumor suppressor let-7 family. We demonstrate that direct repression of let-7a by EWS-FLI-1 participates in the tumorigenic potential of ESFT cells in vivo. The mechanism whereby let-7a expression regulates ESFT growth is shown to be mediated by its target gene HMGA2, as let-7a overexpression and HMGA2 repression both block ESFT cell tumorigenicity. Consistent with these observations, systemic delivery of synthetic let-7a into ESFT-bearing mice restored its expression in tumor cells, decreased HMGA2 expression levels and resulted in ESFT growth inhibition in vivo. Our observations provide evidence that deregulation of let-7a target gene expression participates in ESFT development and identify let-7a as promising new therapeutic target for one of the most aggressive pediatric malignancies.

Type 2 diabetes risk allele near CENTD2 is associated with decreased glucose-stimulated insulin release

AIMS/HYPOTHESIS

By combining multiple genome-wide association (GWA) studies and comprehensive replication efforts, 12 novel type 2 diabetes associated loci have recently been discovered. Here we evaluate the effect of lead variants of these loci on estimates of insulin release and insulin resistance derived from an oral glucose tolerance test.

METHODS

We examined 12 lead variants in or near HMGA2, CENTD2 (also known as ARAP1), KLF14, PRC1, TP53INP1, ZBED3, ZFAND6, CHCHD9, DUSP9, KCNQ1, BCL11A and HNF1A in 5,722 middle-aged people from the population-based Inter99 sample.

RESULTS

Carriers of the major diabetogenic allele of rs1552224 in CENTD2 had increased 30-min plasma glucose values (2.0%, p = 2 × 10(-5)) as well as 4.2% reduced insulin release 30 min after an oral glucose load (p = 0.001). Risk allele carriers also had decreased BIGTT-acute insulin release (AIR), which is a surrogate measure of insulin release where sex, BMI, plasma glucose and serum insulin are integrated (5.3%, p = 8 × 10(-7)). In addition, a decreased corrected insulin response (CIR; 9.9%, p = 3 × 10(-8)) was observed. For rs5945326 near DUSP9 on the X-chromosome we stratified according to sex. Male carriers of the risk allele showed nominally decreased BIGTT-AIR (2.6%, p = 0.01). No associations with intermediate metabolic traits were found in women. For the remaining ten lead variants no consistent associations were demonstrated.

CONCLUSIONS/INTERPRETATION

Of the lead variants from 12 novel type 2 diabetes associated loci, CENTD2 significantly associated with increased plasma glucose values and decreased glucose-stimulated insulin release, suggesting that the diabetogenic effect of this locus is mediated through an impaired pancreatic beta cell function.

HMGA2 overexpression-induced ovarian surface epithelial transformation is mediated through regulation of EMT genes

The AT-hook transcription factor HMGA2 is an oncogene involved in the tumorigenesis of many malignant neoplasms. HMGA2 overexpression is common in both early and late-stage high-grade ovarian serous papillary carcinoma. To test whether HMGA2 participates in the initiation of ovarian cancer and promotion of aggressive tumor growth, we examined the oncogenic properties of HMGA2 in ovarian surface epithelial (OSE) cell lines. We found that introduction of HMGA2 overexpression was sufficient to induce OSE transformation in vitro. HMGA2-mediated OSE transformation resulted in tumor formation in the xenografts of nude mice. By silencing HMGA2 in HMGA2-overexpressing OSE and ovarian cancer cell lines, the aggressiveness of tumor cell growth behaviors was partially suppressed. Global gene profiling analyses revealed that HMGA2-mediated tumorigenesis was associated with expression changes of target genes and microRNAs that are involved in epithelial-to-mesenchymal transition (EMT). Lumican, a tumor suppressor that inhibits EMT, was found to be transcriptionally repressed by HMGA2 and was frequently lost in human high-grade serous papillary carcinoma. Our findings show that HMGA2 overexpression confers a powerful oncogenic signal in ovarian cancers through the modulation of EMT genes.

HMGA2: A pituitary tumour subtype-specific oncogene?

The high mobility group AT-hook (HMGA) proteins, a family of DNA architectural factors, are highly expressed during embryogenesis and play a crucial role in several different biological processes, as well as in tumorigenesis of a wide range of tissues, including pituitary. Indeed, HMGA2 has been found rearranged and amplified in human prolactinomas, and transgenic mice overexpressing either Hmga1 or Hmga2 develop pituitary adenomas secreting prolactin and growth hormone. Here, we overview HMGA proteins in human tumours, focusing on pituitary adenomas and the mechanisms by which the HMGA proteins are involved in their onset and development. Different HMGA-dependent potential drives of pituitary oncogenesis are discussed as future research directions in the field.

Polymorphisms of LIG4, BTBD2, HMGA2, and RTEL1 genes involved in the double-strand break repair pathway predict glioblastoma survival

PURPOSE

Glioblastoma (GBM) is the most common and aggressive type of glioma and has the poorest survival. However, a small percentage of patients with GBM survive well beyond the established median. Therefore, identifying the genetic variants that influence this small number of unusually long-term survivors may provide important insight into tumor biology and treatment.

PATIENTS AND METHODS

Among 590 patients with primary GBM, we evaluated associations of survival with the 100 top-ranking glioma susceptibility single nucleotide polymorphisms from our previous genome-wide association study using Cox regression models. We also compared differences in genetic variation between short-term survivors (STS; <or= 12 months) and long-term survivors (LTS; >or= 36 months), and explored classification and regression tree analysis for survival data. We tested results using two independent series totaling 543 GBMs.

RESULTS

We identified LIG4 rs7325927 and BTBD2 rs11670188 as predictors of STS in GBM and CCDC26 rs10464870 and rs891835, HMGA2 rs1563834, and RTEL1 rs2297440 as predictors of LTS. Further survival tree analysis revealed that patients >or= 50 years old with LIG4 rs7325927 (V) had the worst survival (median survival time, 1.2 years) and exhibited the highest risk of death (hazard ratio, 17.53; 95% CI, 4.27 to 71.97) compared with younger patients with combined RTEL1 rs2297440 (V) and HMGA2 rs1563834 (V) genotypes (median survival time, 7.8 years).

CONCLUSION

Polymorphisms in the LIG4, BTBD2, HMGA2, and RTEL1 genes, which are involved in the double-strand break repair pathway, are associated with GBM survival.

HMGA2: a biomarker significantly overexpressed in high-grade ovarian serous carcinoma

Ovarian carcinoma consists of a group of histologically heterogeneous diseases involving distinct tumorigenic pathways. High-grade papillary serous carcinoma of the ovary is commonly associated with p53 mutations. HMGA2, an oncofetal protein, is found to be overexpressed in ovarian cancer. To study the function of HMGA2 in ovarian cancer, it is important to know which subtypes of ovarian cancer are associated with HMGA2 overexpression. In this study, we collected six different types of ovarian cancer and examined HMGA2 expression by immunohistochemistry, along with HMGA1, p53 and Ki-67. We found that HMGA2 overexpression was significantly higher in high-grade papillary serous carcinoma (64%) and carcinosarcoma (60%) than in other types of ovarian cancers (7-23%). HMGA2 overexpression was moderately associated with dominant p53 mutations (R=0.51). In addition, the microRNA in situ analysis revealed that let-7b, the HMGA2-negative regulators, were significantly lost in high-grade serous carcinoma. Our findings suggest that HMGA2 is an important molecular change significantly related to high-grade papillary serous carcinoma and is less common in other histological types of ovarian cancer.