Genetic Risk Score Mendelian Randomization Shows that Obesity Measured as Body Mass Index, but not Waist:Hip Ratio, Is Causal for Endometrial Cancer

BACKGROUND

The strongest known risk factor for endometrial cancer is obesity. To determine whether SNPs associated with increased body mass index (BMI) or waist-hip ratio (WHR) are associated with endometrial cancer risk, independent of measured BMI, we investigated relationships between 77 BMI and 47 WHR SNPs and endometrial cancer in 6,609 cases and 37,926 country-matched controls.

METHODS

Logistic regression analysis and fixed effects meta-analysis were used to test for associations between endometrial cancer risk and (i) individual BMI or WHR SNPs, (ii) a combined weighted genetic risk score (wGRS) for BMI or WHR. Causality of BMI for endometrial cancer was assessed using Mendelian randomization, with BMIwGRS as instrumental variable.

RESULTS

The BMIwGRS was significantly associated with endometrial cancer risk (P = 3.4 × 10-17). Scaling the effect of the BMIwGRS on endometrial cancer risk by its effect on BMI, the endometrial cancer OR per 5 kg/m2 of genetically predicted BMI was 2.06 [95% confidence interval (CI), 1.89-2.21], larger than the observed effect of BMI on endometrial cancer risk (OR = 1.55; 95% CI, 1.44-1.68, per 5 kg/m2). The association attenuated but remained significant after adjusting for BMI (OR = 1.22; 95% CI, 1.10-1.39; P = 5.3 × 10-4). There was evidence of directional pleiotropy (P = 1.5 × 10-4). BMI SNP rs2075650 was associated with endometrial cancer at study-wide significance (P < 4.0 × 10-4), independent of BMI. Endometrial cancer was not significantly associated with individual WHR SNPs or the WHRwGRS.

CONCLUSIONS

BMI, but not WHR, is causally associated with endometrial cancer risk, with evidence that some BMI-associated SNPs alter endometrial cancer risk via mechanisms other than measurable BMI.

IMPACT

The causal association between BMI SNPs and endometrial cancer has possible implications for endometrial cancer risk modeling. Cancer Epidemiol Biomarkers Prev; 25(11); 1503-10. ©2016 AACR.

Repair of UVB-induced DNA damage is reduced in melanoma due to low XPC and global genome repair

UVB exposure leads to DNA damage, which when unrepaired induces C>T transitions. These mutations are found throughout the melanoma genome, particularly in non-transcribed regions. The global genome repair (GGR) branch of nucleotide excision repair (NER) is responsible for repairing UV-induced DNA damage across non-transcribed and silent regions of the genome. This study aimed to examine the relationship between UVB and GGR in melanoma. DNA repair capacity and relative expression of NER in melanocytes and melanoma cell lines before and after treatment with UVB was quantified. Transcript expression from 196 melanomas was compared to clinical parameters including solar elastosis and whole transcriptome data collected. Melanoma cell lines showed significantly reduced DNA repair when compared to melanocytes, most significantly in the S phase of the cell cycle. Expression of GGR components XPC, DDB1 and DDB2 was significantly lower in melanoma after UVB. In the melanoma tumours, XPC expression correlated with age of diagnosis and low XPC conferred significantly poorer survival. The same trend was seen in the TCGA melanoma dataset. Reduced GGR in melanoma may contribute to the UV mutation spectrum of the melanoma genome and adds further to the growing evidence of the link between UV, NER and melanoma.

Abstract 3559: The rare BCL-2 isoform BCL-2β is associated with melanoma survival and the apoptotic response to UV and cisplatin

There are two isoforms of the anti-apoptotic protein BCL-2. BCL-2α (wild-type) is well characterised and is known predominantly for its role in apoptosis, BCL-2β lacks the C-terminal transmembrane (TM) domain and its function has not yet been characterised. The aim of this study was to quantify and determine the biological role of the BCL-2β isoform in melanoma.

BCL-2α and BCL-2β isoforms were quantified at the mRNA and protein level in a cohort of 141 FFPE melanoma tumours using qPCR and multiple reaction monitoring (MRM) tandem mass spectrometry and compared to clinical parameters including age at diagnosis, gender, solar elastosis, BRAF/NRAS mutation, Breslow thickness, disease free survival and overall survival. The role of the BCL-2α and BCL-2β isoforms in apoptosis were investigated by quantifying transcript expression and apoptosis before and up to 72 hours after UVB irradiation (650J/m2) and cisplatin treatment (10ug/mL). siRNA knockdown targeted to each individual isoform transcript was used to verify the apoptotic response.

Expression of the BCL-2β isoform in tumours was significantly associated with increased overall survival (686.4 weeks, 95% CI 462.5-910.3). BCL-2α response to UVB and cisplatin (i.e. downregulation prior to apoptosis) was the same in melanocyte and melanoma cell lines. However, BCL-2β response was varied across the melanoma cell lines, but was similar to that of BCL-2α in melanocytes. siRNA knock-down of BCL-2α resulted in increased apoptosis and cell death in melanoma cell lines, but knock-down of BCL-2β delayed onset of apoptosis, suggesting the BCL-2β is pro-apoptotic.

Our current understanding of the role of BCL-2β is based on the concept that it lack the C-terminal transmembrane domain, and is incapable of localising to target organelles. It is currently thought that the isoform is of null function. However, these observations are based on studies of non-representative synthetic versions of BCL-2β. This is the first time the naturally transcribed version of the rare isoform has been studied. We have demonstrated herein that BCL-2β performs an apoptotic role, and that its regulation in melanoma may be a biomarker of better overall survival.

Citation Format: Chloe Warren, Ricardo E. Vilain, Katie A. Ashton, Juhura G. Almazi, Stephen Braye, Pablo Moscato, Nikola A. Bowden. The rare BCL-2 isoform BCL-2β is associated with melanoma survival and the apoptotic response to UV and cisplatin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3559.

Abstract 4811: Global demethylation with decitabine increases DNA repair and sensitizes melanoma to carboplatin

Global genome repair (GGR) is critical for recognizing DNA damage by the chemotherapy agent carboplatin, and triggering apoptotic signalling. XPC is a critical gene in the GGR pathway but in melanoma XPC is not induced in response to carboplatin resulting in extreme resistance. Despite low global methylation levels across the melanoma genome, there is evidence methylation plays a role in suppression of XPC. 5-aza-2’-deoxycytidine (decitabine), is a DNA methyltransferases inhibitor used as a chemotherapy agent that results in global loss of methylation and re-expression of silenced genes. We hypothesised that restoring expression of XPC in melanoma using decitabine could overcome resistance to carboplatin. To confirm low XPC in melanoma tumour tissue, transcript and protein expression from 196 advanced primary and metastatic melanomas was quantified and compared to normal tissue and other cancer types. Melanoma cell lines with low baseline XPC were treated with pharmacological doses of decitabine or carboplatin alone, or in sequential combination. XPC transcript, apoptosis, proliferation, senescence, global and CpG island shore demethylation was quantified. XPC transcript and protein was low in a proportion of melanoma tumours and expression correlated with overall survival. Treatment of melanoma cells with carboplatin alone did not significantly induce XPC expression or increase apoptosis in the majority of melanoma cell lines. Decitabine decreased global methylation (average 44.67% decrease) and increased XPC expression (0.9-3.0 fold increase). Hotspots of demethylation after decitabine treatment in the XPC CpG island shore were detected and could be responsible for the increase in XPC expression. When carboplatin was administered following decitabine, a greater XPC induction (1.5-7.6 fold increase) occurred with significantly increased levels of apoptosis (1.6-2.2 fold increase). This was coupled with a decreased proliferation and the presence of markers of senescence. Knocking down XPC expression with siRNA significantly reduced the effects of combination treatment. The outcomes of this study are evidence that silencing of XPC by methylation is a mechanism of carboplatin resistance in melanoma and sequential combination of decitabine followed by carboplatin may be used to restore GGR function and overcome resistance.

Citation Format: Timothy Budden, Ryan J. Davey, Ricardo E. Vilain, Katie A. Ashton, Stephen Braye, Andre van der Westhuizen, Nikola A. Bowden. Global demethylation with decitabine increases DNA repair and sensitizes melanoma to carboplatin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4811.

Renin-angiotensin system gene polymorphisms and endometrial cancer

Endometrial cancer (EC) is the most common gynaecological malignancy and its incidence is increasing. Dysregulation of the endometrial renin-angiotensin system (RAS) could predispose to EC; therefore, we studied the prevalence of RAS single nucleotide polymorphisms (SNPs) in Australian women with EC. SNPs assessed were AGT M235T (rs699); AGTR1 A1166C (rs5186); ACE A240T and T93C (rs4291, rs4292) and ATP6AP2 (rs2968915). They were identified using TaqMan SNP Genotyping Assays. The C allele of the AGTR1 SNP (rs5186) was more prevalent in women with EC (odds ratio (OR) 1.7, 95% confidence interval (CI) (1.2-2.3), P=0.002). The CC genotype of this SNP is associated with upregulation of the angiotensin II type 1 receptor (AGTR1). The G allele of AGT rs699, which is associated with higher angiotensinogen (AGT) levels, was less prevalent in women with EC (OR 0.54, 95% CI (0.39-0.74), P<0.001) compared with controls. AGT and AGT formed by removal of angiotensin I (des(Ang I)AGT) are both anti-angiogenic. In women with EC who had had hormone replacement therapy (HRT), the prevalence of the AGTR1 SNP (rs5186) and the ACE SNPs (rs4291 and rs4292) was greater than in women who had no record of HRT; SNP rs4291 is associated with increased plasma ACE activity. These data suggest there is an interaction between genotype, oestrogen replacement therapy and EC. In conclusion, the prevalence of two SNPs that enhance RAS activity was different in women with EC compared with healthy controls. These genetic factors may interact with obesity and hyperoestrogenism, predisposing ageing, obese women to EC.

The problem of late ovarian metastases from primary cervical adenocarcinoma

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Ovarian metastases can occur after hysterectomy for cervical adenocarcinoma.

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Cervical adenocarcinoma and ovarian metastases showed common genetic profiles.

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Most likely mechanism is trans-tubal spread of neoplastic cells via ovarian stroma.

Regulators of global genome repair do not respond to DNA damaging therapy but correlate with survival in melanoma

Nucleotide excision repair (NER) orchestrates the repair of helix distorting DNA damage, induced by both ultraviolet radiation (UVR) and cisplatin. There is evidence that the global genome repair (GGR) arm of NER is dysfunctional in melanoma and it is known to have limited induction in melanoma cell lines after cisplatin treatment. The aims of this study were to examine mRNA transcript levels of regulators of GGR and to investigate the downstream effect on global transcript expression in melanoma cell lines after cisplatin treatment and in melanoma tumours. The GGR regulators, BRCA1 and PCNA, were induced in melanocytes after cisplatin, but not in melanoma cell lines. Transcripts associated with BRCA1, BRCA2, ATM and CHEK2 showed altered expression in melanoma cell lines after cisplatin treatment. In melanoma tumour tissue BRCA1 transcript expression correlated with poor survival and XPB expression correlated with solar elastosis levels. Taken together, these findings provide evidence of the mechanisms underlying NER deficiency in melanoma.

Combined analysis of three Lynch syndrome cohorts confirms the modifying effects of 8q23.3 and 11q23.1 in MLH1 mutation carriers

Two colorectal cancer (CRC) susceptibility loci have been found to be significantly associated with an increased risk of CRC in Dutch Lynch syndrome (LS) patients. Recently, in a combined study of Australian and Polish LS patients, only MLH1 mutation carriers were found to be at increased risk of disease. A combined analysis of the three data-sets was performed to better define this association. This cohort-study includes three sample populations combined totaling 1,352 individuals from 424 families with a molecular diagnosis of LS. Seven SNPs, from six different CRC susceptibility loci, were genotyped by both research groups and the data analyzed collectively. We identified associations at two of the six CRC susceptibility loci in MLH1 mutation carriers from the combined LS cohort: 11q23.1 (rs3802842, HR = 2.68, p ≤ 0.0001) increasing risk of CRC, and rs3802842 in a pair-wise combination with 8q23.3 (rs16892766) affecting age of diagnosis of CRC (log-rank test; p ≤ 0.0001). A significant difference in the age of diagnosis of CRC of 28 years was observed in individuals carrying three risk alleles compared to those with 0 risk alleles for the pair-wise SNP combination. A trend (due to significance threshold of p ≤ 0.0010) was observed in MLH1 mutation carriers towards an increased risk of CRC for the pair-wise combination (p = 0.002). This study confirms the role of modifier loci in LS. We consider that LS patients with MLH1 mutations would greatly benefit from additional genotyping of SNPs rs3802842 and rs16892766 for personalized risk assessment and a tailored surveillance program.

P53 in human melanoma fails to regulate target genes associated with apoptosis and the cell cycle and may contribute to proliferation

Background

Metastatic melanoma represents a major clinical problem. Its incidence continues to rise in western countries and there are currently no curative treatments. While mutation of the P53 tumour suppressor gene is a common feature of many types of cancer, mutational inactivation of P53 in melanoma is uncommon; however, its function often appears abnormal.

Methods

In this study whole genome bead arrays were used to examine the transcript expression of P53 target genes in extracts from 82 melanoma metastases and 6 melanoma cell lines, to provide a global assessment of aberrant P53 function. The expression of these genes was also examined in extracts derived from diploid human melanocytes and fibroblasts.

Results

The results indicated that P53 target transcripts involved in apoptosis were under-expressed in melanoma metastases and melanoma cell lines, while those involved in the cell cycle were over-expressed in melanoma cell lines. There was little difference in the transcript expression of P53 target genes between cell lines with null/mutant P53 compared to those with wild-type P53, suggesting that altered expression in melanoma was not related to P53 status. Similarly, down-regulation of P53 by short-hairpin RNA (shRNA) had limited effect on P53 target gene expression in melanoma cells, whereas there were a large number of P53 target genes whose mRNA expression was significantly altered by P53 inhibition in melanocytes. Analysis of whole genome gene expression profiles indicated that the ability of P53 to regulate genes involved in the cell cycle was significantly reduced in melanoma cells. Moreover, inhibition of P53 in melanocytes induced changes in gene expression profiles that were characteristic of melanoma cells and resulted in increased proliferation. Conversely, knockdown of P53 in melanoma cells resulted in decreased proliferation.

Conclusions

These results indicate that P53 target genes involved in apoptosis and cell cycle regulation are aberrantly expressed in melanoma and that this aberrant functional activity of P53 may contribute to the proliferation of melanoma.

Colorectal cancer susceptibility loci on chromosome 8q23.3 and 11q23.1 as modifiers for disease expression in Lynch syndrome

OBJECTIVE

Recently, six colorectal cancer (CRC) susceptibility loci have been identified, and two single-nucleotide polymorphisms (SNPs)--rs16892766 (8q23.3) and rs3802842 (11q23.1)--from two of these regions have been found to be significantly associated with an increased CRC risk in patients with Lynch syndrome. The objective of this study was to genotype nine SNPs within these six loci to confirm previous findings and investigate whether they act as modifiers of disease risk in patients with Lynch syndrome.

DESIGN

The patient cohort consisted of 684 mutation-positive patients with Lynch syndrome from 298 Australian and Polish families. Nine SNPs were genotyped: rs16892766 (8q23.3), rs7014346 and rs6983267 (8q24.21), rs10795668 (10p14), rs3802842 (11q23.1), rs10318 and rs4779584 (15q13.3), and rs4939827 and rs4464148 (18q21.1). The data were analysed to investigate possible associations between the presence of variant alleles and the risk of developing disease.

RESULTS

An association between SNP rs3802842 on chromosome 11q23.1 and rs16892766 on chromosome 8q23.3 and the risk of developing CRC and age of diagnosis was found in MLH1 mutation carriers. Female MLH1 mutation carriers harbouring the homozygous variant genotype for SNP rs3802842 have the highest risk of developing CRC. When the number of risk alleles for the two SNPs combined was analysed, a difference of 24 years was detected between individuals carrying three risk alleles and those carrying no risk alleles.

CONCLUSION

The authors were able to replicate the association between the CRC susceptibility loci on chromosomes 8q23.3 and 11q23 and the risk of developing CRC in patients with Lynch syndrome, but the association could only be detected in MLH1 mutation carriers in this study.

Nucleotide excision repair gene expression after Cisplatin treatment in melanoma

Two of the hallmark features of melanoma are its development as a result of chronic UV radiation exposure and the limited efficacy of cisplatin in the disease treatment. Both of these DNA-damaging agents result in large helix-distorting DNA damage that is recognized and repaired by nucleotide excision repair (NER). The aim of this study was to examine the expression of NER gene transcripts, p53, and p21 in melanoma cell lines treated with cisplatin compared with melanocytes. Basal expression of all genes was greater in the melanoma cell lines compared with melanocytes. Global genome repair (GGR) transcripts showed significantly decreased relative expression (RE) in melanoma cell lines 24 hours after cisplatin treatment. The basal RE of p53 was significantly higher in the melanoma cell lines compared with the melanocytes. However, induction of p53 was only significant in the melanocytes at 6 and 24 hours after cisplatin treatment. Inhibition of p53 expression significantly decreased the expression of all the GGR transcripts in melanocytes at 6 and 24 hours after cisplatin treatment. Although the RE levels were lower with p53 inhibition, the induction of the GGR genes was very similar to that in the control melanocytes and increased significantly across the time points. The findings from this study revealed reduced GGR transcript levels in melanoma cells 24 hours after cisplatin treatment. Our findings suggest a possible mechanistic explanation for the limited efficacy of cisplatin treatment and the possible role of UV light in melanoma.

Toll-like receptor (TLR) and nucleosome-binding oligomerization domain (NOD) gene polymorphisms and endometrial cancer risk

Background

Endometrial cancer is the most common gynaecological malignancy in women of developed countries. Many risk factors implicated in endometrial cancer trigger inflammatory events; therefore, alterations in immune response may predispose an individual to disease. Toll-like receptors (TLRs) and nucleosome-binding oligomerization domain (NOD) genes are integral to the recognition of pathogens and are highly polymorphic. For these reasons, the aim of the study was to assess the frequency of polymorphic variants in TLR and NOD genes in an Australian endometrial cancer population.

Methods

Ten polymorphisms were genotyped in 191 endometrial cancer cases and 291 controls using real-time PCR: NOD1 (rs2075822, rs2907749, rs2907748), NOD2 (rs5743260, rs2066844, rs2066845), TLR2 (rs5743708), TLR4 (rs4986790) and TLR9 (rs5743836, rs187084).

Results

Haplotype analysis revealed that the combination of the variant alleles of the two TLR9 polymorphisms, rs5743836 and rs187084, were protective for endometrial cancer risk: OR 0.11, 95% CI (0.03-0.44), p = 0.002. This result remained highly significant after adjustment for endometrial cancer risk factors and Bonferroni correction for multiple testing. There were no other associations observed for the other polymorphisms in TLR2, TLR4, NOD1 and NOD2.

Conclusions

The variant 'C' allele of rs5743836 causes greater TLR9 transcriptional activity compared to the 'T' allele, therefore, higher TLR9 activity may be related to efficient removal of microbial pathogens within the endometrium. Clearly, the association of these TLR9 polymorphisms and endometrial cancer risk must be further examined in an independent population. The results point towards the importance of examining immune response in endometrial tumourigenesis to understand new pathways that may be implicated in disease.

Abstract 3938: Altered nucleotide excision repair gene expression after cisplatin treatment in melanoma

Melanoma incidence rates in Australia are the highest in the world. Two of the hallmark features of melanoma are the development of disease as a result of chronic repeated ultraviolet (UV) radiation exposure and the limited efficacy of cisplatin in treatment. These features have one commonality; both result in large helix distorting DNA damage that is recognised and repaired by the DNA repair system, nucleotide excision repair (NER). The aim of this study was to examine the expression of NER gene transcripts in melanoma cell lines treated with cisplatin.

One melanocyte, three primary melanoma (MM200, IgR3, Me4405) and two metastatic melanoma (Mel-RM and Sk-Mel-28) cell lines were used for this study. The cells were treated with cisplatin (10μg/mL) and RNA was harvested at 0, 6 and 24 hours after treatment. Thirteen NER gene transcripts were measured by semi-quantitative real-time PCR. The relative expression of each gene was calculated and t-tests were used to identify significantly altered expression in melanoma compared to melanocytes and between timepoints.

The genes involved in the global genome repair (GGR) DNA damage recognition pathway; XPC, DDB1 and DDB2 (XPE) showed significantly decreased relative expression (RE) in the melanomas compared to the melanocytes, 24 hours after cisplatin treatment. In contrast, the genes involved in the transcription coupled repair (TCR) DNA damage recognition pathway, ERCC8 (CSA) and ERCC6 (CSB) showed low RE in all cell lines at all time points. Furthermore, the genes involved in the convergent NER pathway revealed no significant change in RE 24 hours after cisplatin treatment in the melanomas, however, an increase in RE was seen in the melanocytes. Overall, the basal expression levels of all genes investigated were greater in the melanoma cell lines compared to the melanocytes.

The GGR DNA damage recognition arm of the NER pathway is essential to maintain genomic stability through the identification of helix distorting DNA adducts arising from UV radiation and genotoxic chemicals. The findings from this study revealed reduced GGR transcript levels 24 hours after cisplatin treatment. This finding may be the first step towards identifying the biological mechanisms underlying the limited efficacy of cisplatin in melanoma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3938.

Abstract 3944: Base excision repair and gene expression profiling in malignant melanoma

Melanoma is a potentially deadly skin tumour and its incidence continues to increase worldwide. Despite the many efforts to elucidate the molecular mechanisms involved in melanoma development, these pathways still remain relatively unknown. For this reason, new methods are required to identify new biological targets implicated in melanoma. Our pilot study examined whole genome gene expression (Illumina Ref8 V2) in 82 melanoma samples and 8 control melanocyte cell lines. Gene transcripts with significantly altered expression (p&lt;0.05) and greater than 2-fold change were identified for the melanomas compared to the melanocytes (GeneSpring GX V10), revealing a number of new targets not previously described in melanoma. Interestingly, a number of genes involved in the DNA repair, immune response and cell cycle arrest pathways were differentially expressed in the melanomas. With respect to the DNA repair pathways, we identified that key components of the base excision repair (BER) pathway were significantly altered in melanoma. Sequencing analysis confirmed several alterations in genes involved in the BER pathway and the frequency of these variants were further confirmed in an independent cohort of 105 formalin-fixed paraffin embedded (FFPE) melanoma patients. Hierarchical cluster analysis showed that melanoma patients with sequence variants in the BER pathway had altered gene expression profiles compared to those melanoma patients with no known variants in this pathway. Taken together, these results suggest that the BER pathway may be implicated in the development of melanoma, which may lead to the introduction of mutation screening and gene expression profiling for the management of melanoma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3944.

Estrogen receptor polymorphisms and the risk of endometrial cancer

OBJECTIVE

There is evidence that estrogens and some of their metabolites are involved in endometrial cancer pathogenesis. As estrogens mediate their effects via the estrogen receptors, ESR1 and ESR2, the objective of this investigation was to determine whether six single nucleotide polymorphisms (SNPs) in these two genes were over-represented in a population of endometrial cancer patients compared with a healthy matched control population, thereby associating differences in these genes with endometrial cancer.

DESIGN

The study is a case-control investigation large enough to detect a two-fold increased risk, assuming a dominant genetic model, with P = 0.05 and 80% power.

SETTING

The study and control populations were all from the Hunter-New England region of New South Wales, Australia collected between the years 1992 and 2005.

POPULATION

The study consisted of 191 endometrial cancer patients and 291 healthy controls matched for gender and age.

METHODS

Two SNPs in ESR1 and four SNPs in ESR2 were genotyped using PCR-based restriction fragment length polymorphism analysis and real-time PCR. Odds ratios were calculated using unconditional logistic regression and SIMHAP was used for haplotype analysis, adjusting for potential endometrial cancer risk factors. Kaplan-Meier survival analysis, Cox regression and t tests were used to examine the patient's age of diagnosis of endometrial cancer and genotype.

MAIN OUTCOME MEASURES

Over-representation of ESR1 and ESR2 polymorphisms in the endometrial cancer population compared with the control population indicates an involvement in the development and/or progression of disease.

RESULTS

Two ESR1 (rs2234693 and rs9340799) and two ESR2 (rs1255998 and rs944050) polymorphisms were associated with an increased risk of endometrial cancer. Following adjustment for risk factors, the association with the ESR1 and ESR2 polymorphisms (rs2234693, rs1255998 and rs944050) remained highly significant. Haplotype analysis revealed that carriers of the ESR1 haplotype (variant alleles; rs2234693 and rs9340799) and the ESR2 haplotype (variant allele; rs1255998 and wild-type alleles; rs944050, rs4986938 and rs1256049) were at an increased risk (OR 1.862, P = 0.013 and OR 1.918, P = 0.046 respectively). This risk was even greater in women carrying both risk haplotypes (OR 5.041, P = 0.007).

CONCLUSIONS

Our data suggest that the ESR1 (rs2234693 and rs9340799) and the ESR2 (rs1255998 and rs944050) polymorphisms may be associated with an increased risk of developing endometrial cancer.

Polymorphisms in TP53 and MDM2 combined are associated with high grade endometrial cancer

OBJECTIVES

Determinants of endometrial cancer grade have not been precisely defined, however, cell cycle control is considered to be integrally involved in endometrial cancer development. TP53 and MDM2 are essential components for cell cycle arrest and apoptosis. Polymorphisms in these genes cause TP53 inactivation and MDM2 over-expression, leading to accumulation of genetic errors.

METHODS

One polymorphism in MDM2, rs2279744 (SNP309) and three polymorphisms in TP53 rs1042522 (R72P), rs17878362 and rs1625895 were genotyped in 191 endometrial cancer cases and 291 controls using PCR-based fragment analysis, RFLP analysis and real-time PCR.

RESULTS

The results showed no associations of the three TP53 polymorphisms and MDM2 SNP309 alone or in combination with endometrial cancer risk. However, the combination of MDM2 SNP309 and the three TP53 polymorphisms was significantly associated with a higher grade of endometrial cancer (wild-type genotypes versus variant genotypes: OR 4.15, 95% CI 1.82-9.46, p=0.0003). Analysis of family history of breast cancer revealed that the variant genotypes of the three TP53 polymorphisms were significantly related to a higher frequency of family members with breast cancer in comparison to endometrial cancer cases without a family history of breast cancer (wild-type genotypes versus variant genotypes: OR 2.78, 95% CI 1.36-5.67, p=0.004).

CONCLUSIONS

The combination of the MDM2 SNP309 and the three TP53 polymorphisms appear to be related to a higher grade of endometrial cancer. The association of the endometrial cancer cases with family history of breast cancer and the three TP53 polymorphisms suggests that this constellation of malignancies may represent a low-risk familial cancer grouping.

Genetic variants in MUTYH are not associated with endometrial cancer risk

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is an autosomal dominant inherited predisposition to a number of epithelial cancers, most notably colorectal and endometrial cancer. Outside of the context of Lynch syndrome there is little evidence for an autosomal dominant or recessive condition that predisposes to endometrial cancer. Recently, genetic variants in MUTYH have been associated with a recessive form of colorectal cancer, known as MUTYH associated polyposis or MAP. MUTYH is involved in base excision repair of DNA lesions and as such a breakdown in the fidelity of this process would necessarily not be predicted to result in a specific disease. At present there is little information about the role of MUTYH in other types of cancer and only one report indicating a possible relationship with endometrial cancer.

Similar to a previous study, we investigated a series of endometrial cancer patients to determine if MUTYH variants were over-represented compared to a series of healthy control subjects and to assess whether or not endometrial cancer risk could be explained by an autosomal recessive model of inheritance.

Two MUTYH mutations, Y165C and G382D, and three common MUTYH polymorphisms, V22M, Q324H and S501F, were genotyped in 213 endometrial cancer patients and 226 controls from Australia using real time PCR. Differences in genotype frequencies were compared using Chi-squared analysis and by calculating odds ratios and 95% confidence intervals.

Three endometrial cancer patients were identified with heterozygous MUTYH mutations (two G382D and one Y165C). No bi-allelic mutation carriers were identified. Two of the three patients' clinical characteristics were similar to those commonly identified in HNPCC and lend support to the notion that MUTYH mutations increase the risk of developing HNPCC related diseases. There was no difference in the five genotype frequencies of the endometrial cancer patients compared to the controls. The results of our study suggest that MUTYH is unlikely to be involved in the genetic basis of endometrial cancer but a possible association of MUTYH variants with HNPCC related diseases cannot be excluded.

The influence of the Cyclin D1 870 G>A polymorphism as an endometrial cancer risk factor

Background

Cyclin D1 is integral for the G1 to S phase of the cell cycle as it regulates cellular proliferation. A polymorphism in cyclin D1, 870 G>A, causes overexpression and supports uncontrollable cellular growth. This polymorphism has been associated with an increased risk of developing many cancers, including endometrial cancer.

Methods

The 870 G>A polymorphisms (rs605965) in the cyclin D1 gene was genotyped in an Australian endometrial cancer case-control population including 191 cases and 291 controls using real-time PCR analysis. Genotype analysis was performed using chi-squared (χ²) statistics and odds ratios were calculated using unconditional logistic regression, adjusting for potential endometrial cancer risk factors.

Results

Women homozygous for the variant cyclin D1 870 AA genotype showed a trend for an increased risk of developing endometrial cancer compared to those with the wild-type GG genotype, however this result was not statistically significant (OR 1.692 95% CI (0.939–3.049), p = 0.080). Moreover, the 870 G>A polymorphism was significantly associated with family history of colorectal cancer. Endometrial cancer patients with the homozygous variant AA genotype had a higher frequency of family members with colorectal cancer in comparison to endometrial cancer patients with the GG and combination of GG and GA genotypes (GG versus AA; OR 2.951, 95% CI (1.026–8.491), p = 0.045, and GG+GA versus AA; OR 2.265, 95% CI (1.048–4.894), p = 0.038, respectively).

Conclusion

These results suggest that the cyclin D1 870 G>A polymorphism is possibly involved in the development of endometrial cancer. A more complex relationship was observed between this polymorphism and familial colorectal cancer.

Aurora-A and Cyclin D1 polymorphisms and the age of onset of colorectal cancer in hereditary nonpolyposis colorectal cancer

Polymorphisms in the 2 cell-cycle control genes Aurora A and Cyclin D1 have previously been associated with changes in the age of onset of colorectal cancer in persons harboring germline mutations in DNA mismatch repair genes associated with hereditary nonpolyposis colorectal cancer (HNPCC). In this report, we have genotyped 312 individuals, who all harbored confirmed causative mutations in either hMSH2 or hMLH1, for 2 polymorphisms, one in Aurora A (T91A) and the other in Cyclin D1 (G870A). The results reveal that the previous association with the Aurora A polymorphism could not be confirmed in our larger group of HNPCC patients. The Cyclin D1 polymorphism, however, was associated with a significant difference in the age of disease onset on patients harboring hMSH2 mutations, which was not observed in hMLH1 mutation carriers. A combined analysis of the Aurora A and Cyclin D1 polymorphisms did not reveal any obvious association. In conclusion, it appears that the polymorphic variant of Aurora A does not appear to be associated with variation in colorectal cancer risk in HNPCC, whereas there is a more complex relationship between the Cyclin D1 polymorphism and disease risk in HNPCC.

The Association of the COMT V158M Polymorphism with Endometrial/Ovarian Cancer in HNPCC Families Adhering to the Amsterdam Criteria

Catechol-O-methyltransferase (COMT) is vital for the conjugation of catechol estrogens that are produced during oestrogen metabolism. The efficiency of this process varies due to a polymorphism in COMT, which changes valine to methionine (V158M). The Met genotypes slow the metabolism of catechol oestrogens, which are agents that are capable of causing DNA damage through the formation of DNA adducts and reactive oxygen species (ROS) production. The slower metabolism of catechol oestrogens results in there being a higher circulating concentration of these oeastrogens and consequently greater probability of DNA damage. To determine whether metabolic inefficiencies of oeastrogen metabolism are associated with the development of malignancy in hereditary non-polyposis colorectal cancer (HNPCC), we studied the V158M polymorphism in COMT in a large cohort of 498 HNPCC patients from Australia and Poland that were either mutation positive (n = 331) or negative (n = 167) for mismatch repair (MMR) gene mutations (hMLH1 or hMSH2). HNPCC is a familial predisposition to colorectal cancer (CRC) and extracolonic cancers that include endometrial cancer.

Using Real Time PCR, the COMT V158M polymorphism was examined and its association with disease expression, age of diagnosis of cancer, mutation status and mutation type was assessed in the HNPCC MMR mutation positive and negative groups. This study showed that the V158M polymorphism had no association with disease risk in the HNPCC MMR mutation positive population. However, the polymorphism was significantly associated with endometrial/ovarian cancer risk in HNPCC MMR mutation negative patients (p = 0.002). The heterozygous (Val/Met) genotype was associated with an increased risk of developing endometrial/ovarian cancer whereas the homozygous mutant (Met/Met) showed a decreased risk. The results suggest heterosis, where there is an apparent greater effect of the heterozygous state in this dichotomous trait. In conclusion, this study shows that the COMT V158M polymorphism alters the risk of developing endometrial/ovarian cancer in patients that adhere to the Amsterdam HNPCC criteria but do not have a DNA mismatch repair gene mutation.

Frequency of the Common MYH Mutations (G382D and Y165C) in MMR Mutation Positive and Negative HNPCC Patients

Recently mutations in the MYH gene have been associated with a milder form of adenomatous polyposis which is characterized by a variable level of colonic polyps ranging from a few to several hundred. In the context of HNPCC it is not unusual to identify patients with a smattering of polyps. The MYH gene product is involved in DNA repair and indeed the hMSH2/hMSH6 complex (both genes being essential elements of the DNA mismatch repair pathway) is required to stimulate MYH activity. We reasoned that because of the clinical similarity of a subset of HNPCC patients to those described with MYH mutations and the role of the hMSH2/hMSH6 complex in the activation of MYH protein that MYH mutations may account for a small proportion of HNPCC patients. In a study of 442 HNPCC patients we identified MYH mutations at the same frequency as that expected in the general population. Nevertheless, two HNPCC families were identified harbouring biallelic changes in MYH.

Familial breast and bowel cancer: does it exist?

There is much debate in the literature about familial predispositions to breast and bowel cancers yet little evidence is forthcoming to suggest that there are susceptibility genes that can account for such kindreds. Within the context of known susceptibility genes the most controversial syndrome is hereditary non-polyposis colorectal cancer (HNPCC). In HNPCC, breast cancers do occur yet their incidence overall is no different to that of the general population yet when studied at the molecular level these tumours often display DNA microsatellite instability suggesting that they do indeed belong to this genetic entity. In this review we examine the relationship between breast and bowel cancer and suggest a possible explanation for the diverse points of view described in the literature.

Isolated right ventricular outflow tract mass presenting as hemoptysis

Infective endocarditis presenting as an isolated right ventricular outflow tract mass is rare. We report a 34-year-old man with no history of congenital heart defect or intravenous drug abuse who presented with hemoptysis and fevers. Diagnostic workup revealed isolated right ventricular outflow tract vegetation. Despite aggressive antibiotic treatment for endocarditis, he developed septic emboli and acute respiratory distress. He was taken to the operating room for successful resection of the ventricular mass.

Indwelling catheter-induced right ventricular rupture

We describe a case of a 68-year-old man who, because of postoperative mediastinitis, underwent a multiple muscle flap closure of the mediastinum. A chronic indwelling catheter led to erosion and rupture of the anterior wall of the right ventricle. The near exsanguinating hemorrhage was corrected under circulatory arrest. A pericardial patch repair was performed with good results.

Basal and meal-stimulated colonic absorption

PURPOSE

Few quantitative experiments evaluating colonic absorption of water and electrolytes have been performed using an awake, conscious animal model. The purpose of these experiments was to develop this type of model and evaluate both basal and meal-stimulated colonic absorption of water and electrolytes.

METHODS

Canine Thiry-Vella fistulas were created using a 20 cm segment of distal colon under general anesthesia. Colonic absorption studies were performed using infusion of the Thirty-Vella fistulas with a buffer solution containing [14C]polyethylene glycol. Electrolyte analysis and concentration of radioactivity in the effluent were obtained and used to calculate the net flux of water, sodium, and chloride. Each study consisted of an one-hour basal period and a three-hour experimental period divided into two groups. Group 1 received no meal. Group 2 orally ingested a mixed meal at the completion of the basal hour.

RESULTS

In the basal state, water and electrolytes are absorbed from the distal colon at a steady and constant rate. An orally ingested meal produces a statistically significant increase in the rate of absorption, independent of direct colonic luminal contact with the nutrients of the meal given.

CONCLUSIONS

These studies demonstrate an in vivo quantitative and qualitative measure of mammalian colonic water and electrolyte absorption. An increase in absorption rate occurs in response to a meal that is probably the result of an unidentified neural or humoral signal.