Cliff Meldrum - Academia.edu (original) (raw)
Papers by Cliff Meldrum
Cancer Epidemiology Biomarkers & Prevention, 2006
Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germ-line mutations in DNA m... more Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germ-line mutations in DNA mismatch repair genes. There is considerable variation in disease expression that cannot be explained by genotype/phenotype correlation, which is likely to be the result of polymorphic modifier genes. One candidate group of modifiers is the xenobiotic clearance enzyme genes that encode CYP1A1, GSTM1, GSTT1, GSTP1, and NAT2. Alterations in these xenobiotic clearance genes can potentially influence the host response to carcinogen exposure and thereby alter cancer risk. We have investigated eight polymorphisms in xenobiotic clearance genes to assess the effect on the risk of disease in mutation positive HNPCC patients. DNA samples from 220 mutation-positive HNPCC participants (86 Australian and 134 Polish) were genotyped for single nucleotide polymorphisms (SNP) in CYP1A1, GSTM1, GSTT1, GSTP1, and NAT2. The association between the SNPs and disease characteristics, disease expression and age of diagnosis of colorectal cancer (CRC), was tested with Pearson's chi(2) and Kaplan-Meier survival analysis. The HNPCC population displays a significant difference in the genotype frequency distribution between CRC patients and unaffected mismatch repair gene mutation carriers for the CYP1A1 SNP where the CRC patients harbor more of the mutant genotype. Evidence from this study is not conclusive, but our data suggest that the CYP1A1 influences disease expression in individuals with HNPCC.
Clinical Genetics, 2006
The genetic predisposition Peutz-Jeghers Syndrome (PJS) has been shown to be associated with muta... more The genetic predisposition Peutz-Jeghers Syndrome (PJS) has been shown to be associated with mutations in the serine threonine kinase 11 (STK11) gene but only a proportion of probands have been shown to harbour changes in the gene. The remaining patients were proposed to be either associated with a second PJS gene or they harboured more cryptic mutations within the STK11 gene itself. With the introduction of the multiplex ligation probe amplification (MLPA) assay, large sequence losses or gains can be more readily identified. In this report we have screened 33 PJS patients from unrelated families, employing a combination of denaturing high-performance liquid chromatography, direct DNA sequencing and the MLPA assay to identify deleterious changes in the STK11 gene. The results revealed that 24 (73%) of patients diagnosed with PJS-harboured pathogenic mutations in the STK11 gene, including 10 (36%) with exonic or whole-gene deletions. No phenotypic differences were identified in patients harbouring large deletions in the STK11 gene compared to patients harbouring missense or nonsense mutations. Mutation analysis in PJS should include techniques such as MLPA to identify large exonic or whole-gene deletions and rearrangements. The high proportion of families with identifiable mutations in the STK11 gene using this range of techniques suggests that most, if not all PJS, is attributable to mutations in the STK11 gene, perhaps including as yet undiscovered changes in promoter or enhancer sequences or other cryptic changes.
Clinical Genetics, 2004
Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant, inherited condition ... more Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant, inherited condition that is characterized primarily by the development of early-onset colorectal cancer and a number of other epithelial malignancies. The underlying genetic basis of the disease is associated with a breakdown of DNA-mismatch repair. There are many genes involved in DNA-mismatch repair, and five of them have been implicated in HNPCC. Two of the genes (hMSH2 and hMLH1) account for the majority of HNPCC families (approximately 60%), and it is not known what the exact contributions of the remaining three genes (hPMS1, hPMS2, and hMSH6) are in relation to this condition. In addition, a sixth gene (hEXO1) has been associated with a disease phenotype that is consistent with HNPCC. Current estimates suggest that all four of these genes, combined, may account for up to 5% of families. In this report, we examine the contribution of hPMS2 and hEXO1 to a well-defined set of families that fulfill the diagnostic criteria for HNPCC. The genes, hPMS2 and hEXO1, were studied by denaturing high performance liquid chromatography (DHPLC) analysis in 21 families that have previously been determined not to have mutations in hMSH2 or hMLH1. hPMS2 accounts for a small proportion of HNPCC families, and none were deemed to be associated with hEXO1. Mutations in hPMS2 appear to account for a small proportion of families adhering to the Amsterdam II criteria, whereas hEXO1 does not appear to be associated with HNPCC.
Hereditary Cancer in Clinical Practice, 2005
In the analysis of genes associated with predispositions to malignancy the causative status of mu... more In the analysis of genes associated with predispositions to malignancy the causative status of mutations can be made relatively easily where it is obvious that there is a clear disruption in the coding sequence of the gene. Difficulties arise, however, if missense mutations are identified, as these are not easily categorised into genetic variants that are not associated with disease
Cancer Epidemiology, 2012
DNA repair plays a pivotal role in maintaining genomic integrity with over 130 genes involved in ... more DNA repair plays a pivotal role in maintaining genomic integrity with over 130 genes involved in various repair pathways that include base excision repair, nucleotide excision repair, double strand break repair and DNA mismatch repair. Polymorphisms within genes that are involved in these processes have been widely reported to be associated with cancer susceptibility in an extensive range of malignancies that include colorectal cancer (CRC). Lynch syndrome is caused by inherited germline mutations in DNA mismatch repair genes, predominantly in MLH1 and MSH2, that predispose to a variety of epithelial malignancies, most notably CRC. Despite being a relatively well understood hereditary cancer syndrome there remain several questions in relation to genetic influences on disease expression. Since Lynch syndrome is associated with a breakdown in DNA mismatch repair variation in other DNA repair genes may influence disease expression. In this report we have genotyped 424 Australian and Polish Lynch syndrome participants for eight common DNA repair gene polymorphisms to assess any association with the age of CRC onset. The DNA repair gene SNPs included in the study were: BRCA2 (rs11571653), MSH3 (rs26279), Lig4 (rs1805386), OGG1 (rs1052133), XRCC1 (rs25487), XRCC2 (rs3218536 and rs1799793) and XRCC3 (rs861539). Cox multi-variant regression modelling failed to provide any convincing evidence of an effect in any of the polymorphisms analysed. The data suggest that polymorphisms in DNA repair genes do not contribute to cancer risk in a population of CRC patients who are at increased risk of disease as a result in a deficiency of DNA mismatch repair.
Hereditary Cancer in Clinical Practice, 2003
Denaturing high performance liquid chromatography is a relatively new method by which heteroduple... more Denaturing high performance liquid chromatography is a relatively new method by which heteroduplex structures formed during the PCR amplification of heterozygote samples can be rapidly identified. The use of this technology for mutation detection in hereditary non-polyposis colorectal cancer (HNPCC) has the potential to appreciably shorten the time it takes to analyze genes associated with this disorder. Prior to acceptance
Scandinavian Journal of Gastroenterology, 2007
Hereditary non-polyposis colorectal cancer (HNPCC) is caused by germline mutations in DNA mismatc... more Hereditary non-polyposis colorectal cancer (HNPCC) is caused by germline mutations in DNA mismatch repair (MMR) genes and is characterized by familial aggregations of early-onset epithelial cancers. Inflammatory cells produce an attractive environment for tumour growth since reactive oxygen and nitrogen species generated by inflammatory cytokine induction can cause damage to DNA and proteins. In this study the objective was to investigate single nucleotide polymorphisms (SNPs) in cytokine genes to assess their impact on disease expression in individuals diagnosed with HNPCC. DNA samples from 220 participants diagnosed with HNPCC were genotyped for SNPs in IL-6, IL-1beta, TNF-alpha, IFN-gamma, IL-10, IL-4 and IL-1RN. The association between the polymorphisms and disease characteristics, i.e. affected or unaffected with colorectal cancer (CRC) and age of diagnosis of CRC, was tested with the Pearson chi2 test and by Kaplan-Meier survival analysis. There was no significant difference between CRC patients and unaffected MMR gene mutation carriers for any of the SNPs studied and the Kaplan-Meier survival analysis showed no significant difference between age of diagnosis of CRC and genotype. The SNPs selected for this study do not appear to modify disease expression in HNPCC. Given the complexity of the inflammatory response, the limited number of SNPs studied does not rule out the notion that other cytokine polymorphisms could act as disease modifiers of disease expression in HNPCC.
European Journal of Human Genetics, 2009
Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is characterized by inactiva... more Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is characterized by inactivating germline mutations in DNA mismatch repair genes resulting in an increased risk of developing an epithelial malignancy. There is considerable variability in disease expression observed in this syndrome, which is thought to be due to a combination of genetic and environmental factors. Alterations in the kinetics of methylene
International Journal of Cancer, 2007
Disease expression in hereditary nonpolyposis colorectal cancer (HNPCC) cannot be readily explain... more Disease expression in hereditary nonpolyposis colorectal cancer (HNPCC) cannot be readily explained by mutation site in the respective DNA mismatch repair genes associated with this disorder. One explanation is the role of modifying genes that can either promote or prevent disease development on a background of increased risk. Two single nucleotide polymorphisms in MDM2 and TP53 have been shown to be associated with younger ages of disease onset in HNPCC (TP53) and Li-Fraumeni syndrome (MDM2). In this study 220 HNPCC patients were examined, from Australia and Poland, all characterized at the molecular level to determine the frequency of the MDM2 SNP309 T>G and to assess its influence on disease expression. The results were then pooled with the results of a previous study to assess the combined influence of the MDM2 SNP309 T>G and TP53 SNP R72P. A significant difference was observed between CRC patients and unaffected MMR gene mutation carriers over the age of 45 years (p = 0.01). The unaffected MMR gene mutation carriers over the age of 45 years who carry the G allele have a reduced risk of developing CRC. The results indicate that the MDM2 SNP309, alone or in combination with TP53 R72P, does not influence age of diagnosis of CRC in individuals with HNPCC. In conclusion, the data indicates the G allele of MDM2 SNP309 might have a protective effect on disease development in HNPCC patients and that age of diagnosis of CRC is not associated with MDM2 SNP309 or TP53 R72P either as single SNPs or combined.
Hereditary Cancer in Clinical Practice, 2004
Familial adenomatous polyposis (FAP) is characterized by the presence of hundreds to thousands of... more Familial adenomatous polyposis (FAP) is characterized by the presence of hundreds to thousands of adenomas that carpet the entire colon and rectum. Nonsense and frameshift mutations in the adenomatous polyposis coli (APC) gene account for the majority of mutations identified to date and predispose primarily to the typical disease phenotype. Some APC mutations are associated with a milder form of
Hereditary Cancer in Clinical Practice, 2006
H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct t... more H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct ti ic ce e 2006; 4(2)
Hereditary Cancer in Clinical Practice, 2005
H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct t... more H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct ti ic ce e 2005; 3(2)
Gut, 2001
Familial adenomatous polyposis (FAP) is characterised by the presence of profuse colonic carpetin... more Familial adenomatous polyposis (FAP) is characterised by the presence of profuse colonic carpeting of adenomas throughout the entire colon and rectum. The genetic basis of FAP has been shown to be primarily associated with germline mutations in theAPC gene. Notwithstanding, several reports have been published indicating that there is genetic heterogeneity in FAP and that the most likely explanation is
Oncogene, 2002
Blockade of the mitogen-activated protein (MAP) kinase pathway suppresses growth of colon cancer ... more Blockade of the mitogen-activated protein (MAP) kinase pathway suppresses growth of colon cancer in vivo. Here we demonstrate a direct link between the extracellular signal-regulated kinase ERK2 and the growth-promoting cell adhesion molecule, integrin avb6, in colon cancer cells. Down-regulation of b6 integrin subunit expression inhibits tumour growth in vivo and MAP kinase activity in response to serum stimulation. In avb6-expressing cells ERK2 is bound only to the b6 subunit. The increase in cytosolic MAP kinase activity upon epidermal growth factor stimulation is all accounted for by b6-bound ERK. Deletion of the ERK2 binding site on the b6 cytoplasmic domain inhibits tumour growth and leads to an association between ERK and the b5 subunit. The physical interaction between integrin avb6 and ERK2 de®nes a novel paradigm of integrin-mediated signalling and provides a therapeutic target for cancer treatment.
Journal of Stroke and Cerebrovascular Diseases, 2007
To investigate whether the 4G/5G polymorphism of plasminogen activator inhibitor type 1 (PAI-1) a... more To investigate whether the 4G/5G polymorphism of plasminogen activator inhibitor type 1 (PAI-1) and the Ϫ7351 C/T polymorphism of tissue-type plasminogen activator (t-PA) are associated with ischemic stroke, we conducted a case-control study of 190 hospital cases of first-ever ischemic stroke and 185 community-based controls. Our findings do not indicate any association between the PAI-1 or t-PA polymorphisms and risk of stroke. Adding our PAI-1 results to previous studies in a meta-analysis indicated a strong association between this polymorphism and ischemic stroke (P ϭ .0002), with no publication bias but with extreme heterogeneity. There was evidence of stroke association with the PAI-1 4G/5G locus. Strong heterogeneity indicates the need to address other issues, including association with particular stroke subtypes or linkage disequilibrium (LD) with another causative allele. The results also sound a cautionary note that varying LD structure across populations may obscure the relationship with a causative locus, and that future meta-analyses need to look beyond a simple pooled estimate. Key Words: Strokecerebrovascular accident-genetic polymorphisms-tissue-type plasminogen activator-plasminogen activator inhibitor type 1-genetic association study.
Journal of Cancer Research and Clinical Oncology, 2002
Purpose: Identification of germline mutations in mismatch repair genes is increasingly being used... more Purpose: Identification of germline mutations in mismatch repair genes is increasingly being used to guide clinical practice in hereditary non-polyposis colon cancer. The aim of this study was to retrospectively assess the clinical utility of immunostaining and microsatellite instability testing in a group of individuals in whom germline testing of hMSH2 and hMLH1 had already been performed. Methods: Individuals were identified from the records of family cancer clinics. A total of thirty-eight tumour blocks were retrieved from 28 kindreds. DNA was extracted and PCR amplification of six microsatellite markers was performed. Immunostaining was used to examine the expression of hMSH2 and hMLH1 protein. Results: Of the 32 assessable tumours, 24 (75%) showed microsatellite instability. Most of the MSI-H cancers (92%) failed to express either hMLH1 or hMSH2. Deleterious germline mutations were identified in the proband in 12 of 28 families. Missense mutations were identified in 11 cases and no mutations in six probands. Conclusions: The use of germline genetic testing is indicated for a highly selected group of individuals. MSI testing and immunostaining are extremely useful tools which significantly improve the clinical interpretation of germline results. Ambiguity regarding the significance of missense mutations in hereditary bowel cancer suggests that these findings should be interpreted with caution.
International Journal of Cancer, 2005
The MYH gene has recently been shown to be associated with a recessive form of colorectal adenoma... more The MYH gene has recently been shown to be associated with a recessive form of colorectal adenomatous polyposis. Two common mutations in the MYH gene have been identified that lend themselves to rapid screening. We have examined a series of 302 individuals comprising 120 control subjects, 120 patients diagnosed with adenomatous polyposis but without germline mutations in the APC gene and 62 patients diagnosed with familial adenomatous polyposis all harbouring confirmed causative APC germline mutations. The results reveal that MYH accounts for 16 percent of polyposis patients without germline mutations in the APC gene and that it does not appear to be a modifier gene in FAP patients diagnosed with APC germline mutations. ' 2005 Wiley-Liss, Inc.
International Journal of Cancer, 2006
Cancer Epidemiology Biomarkers & Prevention, 2006
Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germ-line mutations in DNA m... more Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germ-line mutations in DNA mismatch repair genes. There is considerable variation in disease expression that cannot be explained by genotype/phenotype correlation, which is likely to be the result of polymorphic modifier genes. One candidate group of modifiers is the xenobiotic clearance enzyme genes that encode CYP1A1, GSTM1, GSTT1, GSTP1, and NAT2. Alterations in these xenobiotic clearance genes can potentially influence the host response to carcinogen exposure and thereby alter cancer risk. We have investigated eight polymorphisms in xenobiotic clearance genes to assess the effect on the risk of disease in mutation positive HNPCC patients. DNA samples from 220 mutation-positive HNPCC participants (86 Australian and 134 Polish) were genotyped for single nucleotide polymorphisms (SNP) in CYP1A1, GSTM1, GSTT1, GSTP1, and NAT2. The association between the SNPs and disease characteristics, disease expression and age of diagnosis of colorectal cancer (CRC), was tested with Pearson's chi(2) and Kaplan-Meier survival analysis. The HNPCC population displays a significant difference in the genotype frequency distribution between CRC patients and unaffected mismatch repair gene mutation carriers for the CYP1A1 SNP where the CRC patients harbor more of the mutant genotype. Evidence from this study is not conclusive, but our data suggest that the CYP1A1 influences disease expression in individuals with HNPCC.
Clinical Genetics, 2006
The genetic predisposition Peutz-Jeghers Syndrome (PJS) has been shown to be associated with muta... more The genetic predisposition Peutz-Jeghers Syndrome (PJS) has been shown to be associated with mutations in the serine threonine kinase 11 (STK11) gene but only a proportion of probands have been shown to harbour changes in the gene. The remaining patients were proposed to be either associated with a second PJS gene or they harboured more cryptic mutations within the STK11 gene itself. With the introduction of the multiplex ligation probe amplification (MLPA) assay, large sequence losses or gains can be more readily identified. In this report we have screened 33 PJS patients from unrelated families, employing a combination of denaturing high-performance liquid chromatography, direct DNA sequencing and the MLPA assay to identify deleterious changes in the STK11 gene. The results revealed that 24 (73%) of patients diagnosed with PJS-harboured pathogenic mutations in the STK11 gene, including 10 (36%) with exonic or whole-gene deletions. No phenotypic differences were identified in patients harbouring large deletions in the STK11 gene compared to patients harbouring missense or nonsense mutations. Mutation analysis in PJS should include techniques such as MLPA to identify large exonic or whole-gene deletions and rearrangements. The high proportion of families with identifiable mutations in the STK11 gene using this range of techniques suggests that most, if not all PJS, is attributable to mutations in the STK11 gene, perhaps including as yet undiscovered changes in promoter or enhancer sequences or other cryptic changes.
Clinical Genetics, 2004
Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant, inherited condition ... more Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant, inherited condition that is characterized primarily by the development of early-onset colorectal cancer and a number of other epithelial malignancies. The underlying genetic basis of the disease is associated with a breakdown of DNA-mismatch repair. There are many genes involved in DNA-mismatch repair, and five of them have been implicated in HNPCC. Two of the genes (hMSH2 and hMLH1) account for the majority of HNPCC families (approximately 60%), and it is not known what the exact contributions of the remaining three genes (hPMS1, hPMS2, and hMSH6) are in relation to this condition. In addition, a sixth gene (hEXO1) has been associated with a disease phenotype that is consistent with HNPCC. Current estimates suggest that all four of these genes, combined, may account for up to 5% of families. In this report, we examine the contribution of hPMS2 and hEXO1 to a well-defined set of families that fulfill the diagnostic criteria for HNPCC. The genes, hPMS2 and hEXO1, were studied by denaturing high performance liquid chromatography (DHPLC) analysis in 21 families that have previously been determined not to have mutations in hMSH2 or hMLH1. hPMS2 accounts for a small proportion of HNPCC families, and none were deemed to be associated with hEXO1. Mutations in hPMS2 appear to account for a small proportion of families adhering to the Amsterdam II criteria, whereas hEXO1 does not appear to be associated with HNPCC.
Hereditary Cancer in Clinical Practice, 2005
In the analysis of genes associated with predispositions to malignancy the causative status of mu... more In the analysis of genes associated with predispositions to malignancy the causative status of mutations can be made relatively easily where it is obvious that there is a clear disruption in the coding sequence of the gene. Difficulties arise, however, if missense mutations are identified, as these are not easily categorised into genetic variants that are not associated with disease
Cancer Epidemiology, 2012
DNA repair plays a pivotal role in maintaining genomic integrity with over 130 genes involved in ... more DNA repair plays a pivotal role in maintaining genomic integrity with over 130 genes involved in various repair pathways that include base excision repair, nucleotide excision repair, double strand break repair and DNA mismatch repair. Polymorphisms within genes that are involved in these processes have been widely reported to be associated with cancer susceptibility in an extensive range of malignancies that include colorectal cancer (CRC). Lynch syndrome is caused by inherited germline mutations in DNA mismatch repair genes, predominantly in MLH1 and MSH2, that predispose to a variety of epithelial malignancies, most notably CRC. Despite being a relatively well understood hereditary cancer syndrome there remain several questions in relation to genetic influences on disease expression. Since Lynch syndrome is associated with a breakdown in DNA mismatch repair variation in other DNA repair genes may influence disease expression. In this report we have genotyped 424 Australian and Polish Lynch syndrome participants for eight common DNA repair gene polymorphisms to assess any association with the age of CRC onset. The DNA repair gene SNPs included in the study were: BRCA2 (rs11571653), MSH3 (rs26279), Lig4 (rs1805386), OGG1 (rs1052133), XRCC1 (rs25487), XRCC2 (rs3218536 and rs1799793) and XRCC3 (rs861539). Cox multi-variant regression modelling failed to provide any convincing evidence of an effect in any of the polymorphisms analysed. The data suggest that polymorphisms in DNA repair genes do not contribute to cancer risk in a population of CRC patients who are at increased risk of disease as a result in a deficiency of DNA mismatch repair.
Hereditary Cancer in Clinical Practice, 2003
Denaturing high performance liquid chromatography is a relatively new method by which heteroduple... more Denaturing high performance liquid chromatography is a relatively new method by which heteroduplex structures formed during the PCR amplification of heterozygote samples can be rapidly identified. The use of this technology for mutation detection in hereditary non-polyposis colorectal cancer (HNPCC) has the potential to appreciably shorten the time it takes to analyze genes associated with this disorder. Prior to acceptance
Scandinavian Journal of Gastroenterology, 2007
Hereditary non-polyposis colorectal cancer (HNPCC) is caused by germline mutations in DNA mismatc... more Hereditary non-polyposis colorectal cancer (HNPCC) is caused by germline mutations in DNA mismatch repair (MMR) genes and is characterized by familial aggregations of early-onset epithelial cancers. Inflammatory cells produce an attractive environment for tumour growth since reactive oxygen and nitrogen species generated by inflammatory cytokine induction can cause damage to DNA and proteins. In this study the objective was to investigate single nucleotide polymorphisms (SNPs) in cytokine genes to assess their impact on disease expression in individuals diagnosed with HNPCC. DNA samples from 220 participants diagnosed with HNPCC were genotyped for SNPs in IL-6, IL-1beta, TNF-alpha, IFN-gamma, IL-10, IL-4 and IL-1RN. The association between the polymorphisms and disease characteristics, i.e. affected or unaffected with colorectal cancer (CRC) and age of diagnosis of CRC, was tested with the Pearson chi2 test and by Kaplan-Meier survival analysis. There was no significant difference between CRC patients and unaffected MMR gene mutation carriers for any of the SNPs studied and the Kaplan-Meier survival analysis showed no significant difference between age of diagnosis of CRC and genotype. The SNPs selected for this study do not appear to modify disease expression in HNPCC. Given the complexity of the inflammatory response, the limited number of SNPs studied does not rule out the notion that other cytokine polymorphisms could act as disease modifiers of disease expression in HNPCC.
European Journal of Human Genetics, 2009
Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is characterized by inactiva... more Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is characterized by inactivating germline mutations in DNA mismatch repair genes resulting in an increased risk of developing an epithelial malignancy. There is considerable variability in disease expression observed in this syndrome, which is thought to be due to a combination of genetic and environmental factors. Alterations in the kinetics of methylene
International Journal of Cancer, 2007
Disease expression in hereditary nonpolyposis colorectal cancer (HNPCC) cannot be readily explain... more Disease expression in hereditary nonpolyposis colorectal cancer (HNPCC) cannot be readily explained by mutation site in the respective DNA mismatch repair genes associated with this disorder. One explanation is the role of modifying genes that can either promote or prevent disease development on a background of increased risk. Two single nucleotide polymorphisms in MDM2 and TP53 have been shown to be associated with younger ages of disease onset in HNPCC (TP53) and Li-Fraumeni syndrome (MDM2). In this study 220 HNPCC patients were examined, from Australia and Poland, all characterized at the molecular level to determine the frequency of the MDM2 SNP309 T>G and to assess its influence on disease expression. The results were then pooled with the results of a previous study to assess the combined influence of the MDM2 SNP309 T>G and TP53 SNP R72P. A significant difference was observed between CRC patients and unaffected MMR gene mutation carriers over the age of 45 years (p = 0.01). The unaffected MMR gene mutation carriers over the age of 45 years who carry the G allele have a reduced risk of developing CRC. The results indicate that the MDM2 SNP309, alone or in combination with TP53 R72P, does not influence age of diagnosis of CRC in individuals with HNPCC. In conclusion, the data indicates the G allele of MDM2 SNP309 might have a protective effect on disease development in HNPCC patients and that age of diagnosis of CRC is not associated with MDM2 SNP309 or TP53 R72P either as single SNPs or combined.
Hereditary Cancer in Clinical Practice, 2004
Familial adenomatous polyposis (FAP) is characterized by the presence of hundreds to thousands of... more Familial adenomatous polyposis (FAP) is characterized by the presence of hundreds to thousands of adenomas that carpet the entire colon and rectum. Nonsense and frameshift mutations in the adenomatous polyposis coli (APC) gene account for the majority of mutations identified to date and predispose primarily to the typical disease phenotype. Some APC mutations are associated with a milder form of
Hereditary Cancer in Clinical Practice, 2006
H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct t... more H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct ti ic ce e 2006; 4(2)
Hereditary Cancer in Clinical Practice, 2005
H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct t... more H He er re ed di it ta ar ry y C Ca an nc ce er r i in n C Cl li in ni ic ca al l P Pr ra ac ct ti ic ce e 2005; 3(2)
Gut, 2001
Familial adenomatous polyposis (FAP) is characterised by the presence of profuse colonic carpetin... more Familial adenomatous polyposis (FAP) is characterised by the presence of profuse colonic carpeting of adenomas throughout the entire colon and rectum. The genetic basis of FAP has been shown to be primarily associated with germline mutations in theAPC gene. Notwithstanding, several reports have been published indicating that there is genetic heterogeneity in FAP and that the most likely explanation is
Oncogene, 2002
Blockade of the mitogen-activated protein (MAP) kinase pathway suppresses growth of colon cancer ... more Blockade of the mitogen-activated protein (MAP) kinase pathway suppresses growth of colon cancer in vivo. Here we demonstrate a direct link between the extracellular signal-regulated kinase ERK2 and the growth-promoting cell adhesion molecule, integrin avb6, in colon cancer cells. Down-regulation of b6 integrin subunit expression inhibits tumour growth in vivo and MAP kinase activity in response to serum stimulation. In avb6-expressing cells ERK2 is bound only to the b6 subunit. The increase in cytosolic MAP kinase activity upon epidermal growth factor stimulation is all accounted for by b6-bound ERK. Deletion of the ERK2 binding site on the b6 cytoplasmic domain inhibits tumour growth and leads to an association between ERK and the b5 subunit. The physical interaction between integrin avb6 and ERK2 de®nes a novel paradigm of integrin-mediated signalling and provides a therapeutic target for cancer treatment.
Journal of Stroke and Cerebrovascular Diseases, 2007
To investigate whether the 4G/5G polymorphism of plasminogen activator inhibitor type 1 (PAI-1) a... more To investigate whether the 4G/5G polymorphism of plasminogen activator inhibitor type 1 (PAI-1) and the Ϫ7351 C/T polymorphism of tissue-type plasminogen activator (t-PA) are associated with ischemic stroke, we conducted a case-control study of 190 hospital cases of first-ever ischemic stroke and 185 community-based controls. Our findings do not indicate any association between the PAI-1 or t-PA polymorphisms and risk of stroke. Adding our PAI-1 results to previous studies in a meta-analysis indicated a strong association between this polymorphism and ischemic stroke (P ϭ .0002), with no publication bias but with extreme heterogeneity. There was evidence of stroke association with the PAI-1 4G/5G locus. Strong heterogeneity indicates the need to address other issues, including association with particular stroke subtypes or linkage disequilibrium (LD) with another causative allele. The results also sound a cautionary note that varying LD structure across populations may obscure the relationship with a causative locus, and that future meta-analyses need to look beyond a simple pooled estimate. Key Words: Strokecerebrovascular accident-genetic polymorphisms-tissue-type plasminogen activator-plasminogen activator inhibitor type 1-genetic association study.
Journal of Cancer Research and Clinical Oncology, 2002
Purpose: Identification of germline mutations in mismatch repair genes is increasingly being used... more Purpose: Identification of germline mutations in mismatch repair genes is increasingly being used to guide clinical practice in hereditary non-polyposis colon cancer. The aim of this study was to retrospectively assess the clinical utility of immunostaining and microsatellite instability testing in a group of individuals in whom germline testing of hMSH2 and hMLH1 had already been performed. Methods: Individuals were identified from the records of family cancer clinics. A total of thirty-eight tumour blocks were retrieved from 28 kindreds. DNA was extracted and PCR amplification of six microsatellite markers was performed. Immunostaining was used to examine the expression of hMSH2 and hMLH1 protein. Results: Of the 32 assessable tumours, 24 (75%) showed microsatellite instability. Most of the MSI-H cancers (92%) failed to express either hMLH1 or hMSH2. Deleterious germline mutations were identified in the proband in 12 of 28 families. Missense mutations were identified in 11 cases and no mutations in six probands. Conclusions: The use of germline genetic testing is indicated for a highly selected group of individuals. MSI testing and immunostaining are extremely useful tools which significantly improve the clinical interpretation of germline results. Ambiguity regarding the significance of missense mutations in hereditary bowel cancer suggests that these findings should be interpreted with caution.
International Journal of Cancer, 2005
The MYH gene has recently been shown to be associated with a recessive form of colorectal adenoma... more The MYH gene has recently been shown to be associated with a recessive form of colorectal adenomatous polyposis. Two common mutations in the MYH gene have been identified that lend themselves to rapid screening. We have examined a series of 302 individuals comprising 120 control subjects, 120 patients diagnosed with adenomatous polyposis but without germline mutations in the APC gene and 62 patients diagnosed with familial adenomatous polyposis all harbouring confirmed causative APC germline mutations. The results reveal that MYH accounts for 16 percent of polyposis patients without germline mutations in the APC gene and that it does not appear to be a modifier gene in FAP patients diagnosed with APC germline mutations. ' 2005 Wiley-Liss, Inc.
International Journal of Cancer, 2006