Anthony K. House

Concordance between p53 protein overexpression and gene mutation in a large series of common human carcinomas

Immunohistochemical (IHC) detection of p53 protein was compared with the presence of p53 gene mutation in many colorectal (n = 100), breast (n = 92), endometrial (n = 122), and gastric (n = 116) carcinomas. Two commercially available antibodies, DO7 and CM1, were used for IHC analysis of paraffin-embedded tissue sections. Screening for gene mutations in frozen and paraffin-embedded tumor samples was carried out using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP). The frequency of nuclear staining with DO7 or CM1 for each tumor type, respectively, was colorectal (36%, 23%); breast (15%, 19%); endometrial (21%, 33%); and gastric (23%,-). Overall correlation between the two antibodies for nuclear staining was 90% for the 314 tumors analyzed. Cytoplasmic staining was observed with DO7 in 7% of breast and 5% of gastric carcinomas and with CM1 in 17% of breast and 54% of endometrial carcinomas. p53 gene mutation was found in 39% of colorectal, 28% of breast, 13% of endometrial, and 25% of gastric cancers. The concordance between p53 nuclear overexpression and gene mutation (both positive or both negative) was 68% for colorectal, 79% for breast, 76% for endometrial, and 73% for gastric carcinomas. This study provides further evidence that IHC detection of p53 protein accumulation does not always indicate the presence of a gene mutation and vice versa. Discordant results were observed in approximately 20% to 30% of the tumors studied, highlighting the need for careful characterization of both p53 gene and protein alterations when assessing the relationship between p53 status and tumor behavior.

Mutation of the transforming growth factor-β type II receptor gene in right-sided colorectal cancer : Relationship to clinicopathological features and genetic alterations

The presence of inactivating mutations in the transforming growth factor‐β (TGF‐β) type II receptor (RII) gene in colon cancer suggests that it may behave like a tumour suppressor gene. RII is mutated in the majority of colon tumours exhibiting widespread microsatellite instability, a characteristic generally referred to as the replication error phenotype (RER+). We investigated the association between RII mutations and various clinicopathological variables and genetic alterations in a large series of sporadic adenocarcinomas arising in the proximal colon. RII mutations were found in 17 per cent (36/210) of right‐sided tumours and in 86 per cent (32/37) of those displaying RER+. They were associated with the absence of lymph node invasion (P=0·04), poor histological differentiation (P=0·006), and with a trend for improved patient survival. Tumours with an RII mutation also showed non‐significant trends for a lower incidence of p53 protein overexpression and of p53, K‐ras, and APC gene mutation compared with tumours with normal RII. These results indicate that right‐sided colorectal tumours containing RII mutations resemble those with the RER+ phenotype in terms of their clinicopathological features and genetic alterations.

Gastric carcinomas with microsatellite instability: clinical features and mutations to the TGF‐β type II receptor, IGFII receptor, and BAX genes

The replication error phenotype (RER+) represents an important new form of genetic alteration characterized by widespread instability in repetitive nucleotide sequences. The aim of this study was to compare the features of RER+ gastric tumours with those of RER+ colonic tumours. RER status was determined by analysis of size alterations in the BAT‐26 mononucleotide repeat microsatellite. Twelve of 121 (10 per cent) gastric carcinomas from a low‐incidence region were found to be RER+. BAT‐26 instability was associated with tumours showing an absence of nodal invasion (p = 0·009) and with a trend for improved prognosis. These tumours were more frequent in older, female patients. Frameshift mutations in mononucleotide repeat sequences within the transforming growth factor‐β receptor II (RII), insulin‐like growth factor II receptor (IGFIIR), and BAX genes were observed in 83, 33, and 25 per cent, respectively, of RER+ tumours. Only 1/12 (8 per cent) RER+ tumours contained a p53 gene mutation compared with 29/109 (27 per cent) RER− tumours. RER+ gastric carcinomas therefore share several important features with RER+ colonic tumours, including less frequent nodal invasion, improved prognosis, a similar frequency of mutation in growth control genes containing repetitive nucleotide sequences, and a low frequency of mutation of the p53 tumour suppressor gene. Copyright

p53 accumulation and mutation are prognostic indicators of poor survival in human gastric carcinoma

The aim of our study was to examine the prognostic significance of p53 protein accumulation and gene mutation in a series of 116 gastric carcinomas from a low incidence population. Formalin‐fixed, paraffin‐embedded tumour sections were used to investigate p53 protein accumulation by immunostaining with monoclonal antibody (MAb) DO‐7 and p53 gene mutation by single‐strand conformation polymorphism analysis of exons 5‐8. Nuclear p53 accumulation was detected in 23% of tumours and mutation in 28%. Concordance between the 2 alterations was observed in 73% of cases. p53 protein accumulation was more frequent in tumours with lymph node metastasis, while p53 mutations were more frequent in tumours from older patients. The histopathological parameters of depth of invasion, grade and histological type showed no significant associations with either p53 alteration. In univariate analysis, both alterations were associated with significantly shortened patient survival. The 5‐year survival rate for patients with a p53 mutation was 9% compared to 42% for those without a mutation. In multivariate analysis adjusted for the other histopathological parameters, p53 gene mutation but not immunohistochemically‐detected p53 protein accumulation was an independent prognostic indicator of poor survival in gastric carcinoma.

Monocyte chemoattractant protein-1 gene expression in injured pig artery coincides with early appearance of infiltrating monocyte/macrophages

Monocyte chemoattractant protein‐1 (MCP‐1) and interleukin‐8 (IL‐8) are potent chemokines which attract circulating monocytes and neutrophils respectively to inflamed tissues. JE/MCP‐1 gene expression has been previously studied in rabbit aortae after endothelial denudation and the rapid appearance of this transcript was thought to precede emigration of phagocytes. We now report MCP‐1 gene expression following de‐endothelialization of iliac arteries in the pig, a species which can develop spontaneous atherosclerosis. Using Northern blot analysis, we demonstrated that MCP‐1 mRNA was rapidly induced in pig arteries at 2 h and continued to increase to reach a maximum at 8 h before returning to low levels at 16–24 h after injury. The increase seen for MCP‐1 mRNA at 8 h was also observed for IL‐8 mRNA but was not apparent for growth‐related gene expressions, urokinase‐type plasminogen activator (u‐PA), and plasminogen activator inhibitor‐1 (PAI‐1). Since smooth muscle cells, endothelial cells, and phagocytes are all capable of expressing MCP‐1, we examined pig arteries for immunostaining using a monoclonal antibody to human MCP‐1 (5D3‐F7). At 8 h after injury, the predominant cell type staining positive for MCP‐1 was the monocyte/macrophage. Staining was also observed in occasional scattered neutrophils, but MCP‐1 protein could not be detected in smooth muscle cells or on extracellular matrix within the sensitivity constraints posed by our methodology. Our results are consistent with invading monocyte/macrophages having a major input into the production of this chemokine in the arterial wall following injury. The fact that MCP‐1 expression accompanied monocyte/macrophage presence in damaged artery, rather than preceding it, is suggestive that continued MCP‐1 expression is required for functions other than chemoattraction.

Asymptomatic carotid artery stenosis associated with peripheral vascular disease: a prospective study

This study aimed to determine the prevalence of symptomless internal carotid artery stenosis in consecutive patients presenting with peripheral vascular disease. Duplex ultrasound screening of the carotid arteries was used to determine the degree of stenosis. Co-morbidities were recorded together with age, sex and tobacco use. Internal carotid artery stenosis of > 50% was found in 35% of patients. Among these there was > or = 70% stenosis in 18% of patients and of this group 5% had an occluded carotid vessel at first presentation. Males presented with peripheral vascular disease and associated carotid stenoses at a younger age than females. Male smokers had a higher prevalence of stenosis (P = 0.036) but all smokers had developed stenoses 3-5 years before non-smokers. Females with abdominal aortic aneurysms had a greater prevalence of carotid stenosis (P = 0.037), and male aneurysmal disease diminished stenosis prevalence (P = 0.023). Men with an elevated serum creatinine were more likely to have a stenosis (P = 0.019), but not women. The other co-morbidities were not specifically associated with carotid artery stenosis.

Costs of accessing surgical specialists by rural and remote residents

Introduction: Access to surgical specialist services by rural and remote residents in Australia is limited. Little information is available on the cost to rural residents of accessing specialist treatment. The aim of the present study was to define the personal costs incurred by country patients in Western Australia when accessing specialist surgical services in a rural or metropolitan setting.

Clonal Analysis of Colorectal Tumors using K-ras and P53 Gene Mutations as Markers

Mutations to the K-ras oncogene and p53 tumor suppressor gene are two of the most common genetic lesions in human cancers. In the present study we examined the clonality of colorectal tumors with respect to each of these genetic alterations. Screening for mutations was carried out using the polymerase chain reaction—based technique of single-strand conformation polymorphism. Eleven primary colorectal adenocarcinomas and two secondary adenocarcinomas were analyzed at four different sites within the tumor. Involved pericolic lymph nodes were collected from nine of these cases, a metastatic deposit in the liver was obtained in one case, and adjacent adenomatous lesions were collected in two cases. Seven tumors contained mutations in either the K-ras or p53 genes. In all cases, DNA derived from multiple sites within an individual tumor or metastatic deposits arising from that tumor showed the same pattern of gene mutation. Immunohistochemical staining for p53 protein over-expression also showed similar patterns of reactivity within individual tumors and their metastatic deposits. These results suggest that the major clonal expansion of colorectal carcinomas occurs after the acquisition of mutations in these genes. Our results also indicate that sampling errors are unlikely to occur in molecular studies aimed at defining the role of these genes in colorectal cancer progression.

Chylous ascites caused by portal vein thrombosis treated with octreotide.

Abstract  Chylous ascites is an uncommon entity with variable causes and rarely arises from portal vein thrombosis. This is a case report of chylous ascites caused by idiopathic portal vein thrombosis that was refractory to medical therapy and shunt surgery, which showed an impressive response to treatment with subcutaneous octreotide. We review the literature on chylous ascites with particular reference to the role of somatostatin analogs in the management of this rare condition.

Loss of heterozygosity of tumour suppressor gene loci in human colorectal carcinoma

We used Southern blot analysis and polymerase chain reaction-based techniques to examine deletions of tumour suppressor gene loci in 91 primary colorectal tumours. The tumour suppressor genes studied were MCC and APC on chromosome 5q, p53 on chromosome 17p, DCC on chromosome 18q, and the putative suppressor gene nm23-H1 on chromosome 17q. The most frequent allelic loss observed was in chromosome 17p with 76% (68/89) of informative tumours showing loss of heterozygosity at this locus, followed by 34% (19/55) for DCC, 31% (12/39) for MCC, 17% (9/53) for APC and 16% (3/19) for nm23. No significant differences in the frequency of these suppressor gene allelic losses were observed between Dukes B and C stage adenocarcinomas.