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Biomedical subjects

J A McKay

Publications and source records attributed to J A McKay.

At least 19 recordsLinked to original sources
PubMed2002

c-erbB-2 is not a major factor in the development of colorectal cancer.

We have investigated c-erbB-2 protein expression in a large cohort of well-characterized colorectal tumours, and in a subset of lymph node metastases. We have also evaluated a Val(655)Ile single nucleotide polymorphism, which is associated with an increased risk of breast cancer, in a subset of the colorectal cancer patients and in healthy control subjects. Immunohistochemical studies revealed that while 81.8% of tumours expressed c-erbB-2, in the majority of cases equivalent levels of c-erb-B2 were seen in adjacent normal mucosa. Colon tumours were significantly more likely to express c-erbB-2 than rectal tumours (P=0.015). Only 52.4% of the metastases displayed staining patterns concordant with their primary tumour, indicating that determination of c-erbB-2 protein in colorectal tumours cannot predict the status of lymph node metastases. PCR--RFLP analysis of the Val(655)Ile single nucleotide polymorphism demonstrated that allele frequencies were identical between colorectal cancer patients and a control group of Caucasian subjects (Ile=0.80 and Val=0.20 in each case), indicating that it is not related to the risk of developing colorectal cancer in this population. Furthermore, there was no relationship between c-erbB-2 protein expression and gene polymorphism (P=0.58). In terms of prognosis, no association was seen between either c-erbB-2 protein expression or the presence of the Val allele and patient survival (P>0.05 in each case), suggesting that c-erbB-2 is not a prognostic marker in colorectal cancer.

Adenocarcinoma↗
PubMed2002

Matrix metalloproteinase 13 activity is associated with poor prognosis in colorectal cancer.

AIMS: The matrix metalloproteinases (MMPs) are a family of proteolytic enzymes collectively capable of degrading all extracellular matrix components, in particular fibrillar collagen. The importance of this group of proteins in the processes of tumour invasion and metastasis is now widely acknowledged. MMP-13 (collagenase 3) has a central role in the MMP activation cascade. The purpose of this study was to investigate the presence and activity of MMP-13 in colorectal cancer and relate these to clinicopathological features. METHODS: Immunohistochemistry for MMP-13 was performed on formalin fixed, paraffin wax embedded sections of a large series of colorectal cancers (n = 249), all of which had uniform clinical and pathological information available. Immunoreactivity to MMP-13 was detected with a monoclonal antibody to MMP-13 using a Dako TechMate 500 automated immunostaining system. The presence and cellular localisation of MMP-13 was assessed using a semiquantitative scoring system. Gelatin zymography was used to detect and measure MMP-13 activity. The zymography was performed on a subset of the cases studied by immunohistochemistry using two groups of 10 paired Dukes's C tumours and normal samples, selected by either having "good" or "poor" survival. RESULTS: Immunoreactivity to MMP-13 was identified in 91% of cases and immunoreactivity was localised to the cytoplasm of tumour cells. A high MMP-13 staining score showed a trend towards poorer survival. Tumours had significantly greater MMP-13 activity compared with normal colonic mucosa (p < 0.001). Furthermore, the tumour to normal tissue ratio was significantly higher in the poor survival group (p = 0.02). CONCLUSIONS: These results show that MMP-13 is frequently present and active in colorectal cancer and suggest that the activity of MMP-13 is associated with poorer survival in colorectal cancer.

Adult↗
PubMed2001

Colorectal cancer genomics: evidence for multiple genotypes which influence survival.

Colorectal cancer (CRC) is a leading cause of cancer death and the mechanism for variable outcome in this disease is not yet fully understood. It is hypothesized that differences in the genetic make-up of tumours may be partially responsible for the differences observed in survival among same staged individuals for this disease. In this study the tumour genomes of 29 consecutive patients undergoing surgery for Dukes' C CRC were assessed by comparative genomic hybridization (CGH). In addition, the CGH profiles from the tumours were compared with those from eight colorectal cell lines. Great variation in genetic grade (all detectable aberrations i.e., loss + gain) was observed in 29 Dukes' C colorectal tumours by CGH (median four aberrations per tumour, range 0-20). Gain was found in 76% and loss in 41% of tumours. The most frequently observed regions of gain were 13q (27.6%), 20q (27.6%), 7p (24.1%), 8q (24.1%), and 1q (20.7%) and loss were 18q (31%), 4q (20.7%), 17p (20.7%), 18p (20.7%), and 15q (20.1%). None of these specific genomic aberrations were associated with patient survival. However, patients with more than two aberrations had a better survival than patients with fewer regions of loss and gain (P = 0.02). CRC cell lines had similar regions of loss or gain as the tumours. However, the frequency of genomic aberrations was much greater in the CRC cell lines. Although genomic change in CRC is relevant to the survival of patients with Dukes' C CRC, careful analysis is required to identify cell lines which are representative models of CRC genomics.

Aged↗
PubMed2001

Polymorphism in the thymidylate synthase promoter enhancer region in colorectal cancer.

Thymidylate synthase (TS) is an important target for chemotherapy drugs such as 5-fluorouracil and raltitrexed. Over-expression of TS has been linked to chemotherapy resistance. A polymorphic tandem repeat sequence in the 5' untranslated region (5'UTR) of the human TS gene (TSER) has been shown to influence TS expression. The presence of a triple tandem repeat (TSER*3) increases in vitro TS expression compared to a double tandem repeat (TSER*2) and is associated with higher in vivo tumor TS activity. The polymorphism of this promoter enhancer region has not been extensively studied in patients with cancer and may represent a possible mechanism of intrinsic resistance to TS inhibitors. In this study, PCR analysis of genomic DNA from 121 patients with colorectal cancer demonstrated 29% of patients were homozygous for TSER*3, 16% were homozygous for TSER*2 and 55% were heterozygous. In 44/45 microdissected tumors the TS enhancer genotype was identical between paired samples of colorectal tumor and normal tissue. In 24 patients receiving a bolus/infusion 5-fluorouracil (5FU) regimen for metastatic colorectal cancer, 22% of non-responders to chemotherapy were homozygous for TSER*2 compared with 40% of responders. Median survival dropped from 16 months for homozygous TSER*2 to 12 months for homozygous TSER*3. This is consistent with previous studies where higher TS expression was associated with poor response to TS inhibitors. Prospective analysis of the influence of the TS polymorphism on patient outcome is warranted.

Colorectal Neoplasms↗
PubMed2000

Cyclin D1 protein expression and gene polymorphism in colorectal cancer. Aberdeen Colorectal Initiative.

Cyclin D1 is a key cell cycle regulatory protein, the expression and subcellular localization of which is often altered in human tumor cells. A common A/G single nucleotide polymorphism (A870G) in exon 4 of the cyclin D1 gene, CCND1, is associated with the presence of 2 distinct mRNA transcripts for this G1/S regulatory protein, and CCND1 genotype has been related to prognosis in lung cancer and head and neck carcinoma. We have investigated both the expression of cyclin D1 protein and the CCND1 A870G polymorphism in 100 colorectal cancer patients. Immunohistochemistry demonstrated cyclin D1 protein expression in 55% of tumors, and while the absence of cyclin D1 protein was not associated with outcome (p=0.81), high levels of protein expression (>50% of tumor cells expressing cyclin D1) correlated with significantly shortened overall survival (p=0.01). Using polymerase chain reaction restriction fragment length polymorphism analysis, we determined the frequency of each genotype and found that CCND1 genotype was not related to overall survival (p>0.05). In addition, genotype was unrelated to the level of expression and localization of cyclin D1 protein, as well as other key G1/S checkpoint proteins (p21, p27, p53, retinoblastoma) and tumor proliferation markers (proliferating cell nuclear antigen). However, higher levels of p27, and to a lesser extent p21, were associated with reduced cytoplasmic cyclin D1 protein (p=0.029 and p=0.054, respectively). In conclusion, we have demonstrated that high levels of cyclin D1 protein expression are related to outcome in colorectal cancer; however, the CCND1 A870G polymorphism is unrelated to either cyclin D1 protein expression or patient survival.

Adenocarcinoma↗
PubMed2000

Therapeutic opportunities from tumour biology in metastatic colon cancer.

Tumour metastasis is the major cause of morbidity and mortality from colorectal cancer. While improvements in quality of life and patient survival have been made over the past 10 years, the majority of patients with metastatic colorectal cancer will die from their disease. As knowledge of the biology of colon cancer and its invasion/metastasis programme evolve, this presents new therapeutic opportunities for pharmacological and genetic intervention. This review discusses the current approaches to metastatic colorectal cancer therapy, details genomic and biological variance between primary and metastatic tumours, and highlights approaches for harnessing these differences to improve therapy.

Antineoplastic Agents↗
PubMed2000

Laser capture microscopy.

Human tissues are composed of complex admixtures of different cell types and their biologically meaningful analysis necessitates the procurement of pure samples of the cells of interest. Many approaches have been used in attempts to overcome this difficulty, including a variety of microdissection methods. This review concerns a recent advance in microdissection techniques, namely laser capture microdissection (LCM). The principle underlying this technique is outlined, and practical issues pertaining to LCM are considered. In addition, the literature relating to LCM is reviewed, with examples of research applications of this technique being outlined.

Cell Separation↗
PubMed2000

Application of the enrichment approach to identify putative markers of response to 5-fluorouracil therapy in advanced colorectal carcinomas.

A wide range of tumor response is seen amongst patients with the same stage of colorectal cancer, even with the use of uniform chemotherapy. The significant economic and personal impact of chemotherapy provides the impetus for the identification of markers of response for use in guiding patient treatment. However, practical constraints prevent evaluation of all putative markers in a definitive manner. In this study, the enrichment approach was evaluated by examining the expression of a panel of putative response markers in selected patient populations with advanced colorectal cancer (i.e., those demonstrating the best and the poorest clinical response to a standardized 5-fluorouracil/folinic acid chemotherapy regimen). Patients showing a good response had a significantly increased survival when compared with poor responders (P=0.0013). Markers were then ranked for clinical importance based on differences in expression between the two groups. This allows for the relatively rapid and inexpensive investigation of multiple markers, using defined patient groups. Bcl-2 overexpression in primary colorectal tumor specimens was found to correlate with clinical response of metastatic deposits to chemotherapy (P=0.044), as did the site of the primary tumor (P=0.011). However, no clear association was observed between response status and the other examined factors (p53, PCNA, TP, MMPs 1, 2 or 9, TIMPs 1 or 2, TS, Dukes' stage at initial diagnosis, histological grade, sex or age). This approach has allowed prioritization of markers of clinical response on which larger, statistically definitive studies will be performed.

Adult↗
PubMed2000

Expression of cell cycle control proteins in primary colorectal tumors does not always predict expression in lymph node metastases.

Analysis of tumor markers focuses on expression in primary tumors with the assumption that this is representative of metastatic tumor, against which treatment is targeted. Few studies have compared the expression of such markers in primary and secondary tumors. In this study, several key genes involved in cell cycle regulation were investigated in colorectal tumors and corresponding lymph node metastases. The cell cycle regulators p53, cyclin D1, p21, p27, retinoblastoma protein (Rb), and proliferating cell nuclear antigen (PCNA) were examined in a series of 42 paired samples of primary colorectal and secondary lymph node tumors by immunohistochemistry. Expression of p53, p27, and Rb was similar in virtually all paired samples (p53, 38 of 42; p27, 39 of 42; Rb, 40 of 42), indicating that the pattern of these proteins in colorectal tumors may be used to predict that in lymph node tumors. It also suggests a lack of direct involvement in the metastatic process. A lower concordance for p21 and cyclin D1 staining was observed between primary and secondary tumors (p21, 19 of 42; cyclin D1, 22 of 42). p21 expression was more often observed in primary colorectal cancers, whereas cyclin D1 expression was more frequently seen in lymph node metastases, in keeping with the contrasting roles of these proteins as a cell cycle inhibitor (p21) and activator (cyclin D1). The PCNA-labeling index was found to vary considerably in a number of cases, thus limiting the ability to predict expression of this protein in lymph node metastases from the primary tumor. In addition, PCNA-labeling indices between paired samples were neither consistently higher nor lower, suggesting that the proliferative capacity of tumor cells is not directly related to their ability to metastasize.

Adult↗
PubMed1998

Matrix metalloproteinase-1 is associated with poor prognosis in oesophageal cancer.

The matrix metalloproteinases (MMPs) are a family of closely related proteolytic enzymes which are involved in the degradation of different components of the extracellular matrix. There is increasing evidence to indicate that individual MMPs have an important role in tumour invasion and tumour spread. Monoclonal antibodies specific for MMP-1, MMP-2, or MMP-9 have been produced, using as immunogens peptides selected from the amino acid sequences of individual MMPs. The presence of MMP-1, MMP-2, and MMP-9 in oesophageal cancer was investigated by immunohistochemistry on formalin-fixed, wax-embedded sections of oesophageal cancers. The relationship of individual MMPs to prognosis and survival was determined. MMP-1 was present in 24 per cent of oesophageal cancers, while MMP-2 and MMP-9 were present in 78 and 70 per cent of tumours, respectively. The presence of MMP-1 was associated with a particularly poor prognosis (log rank test 8.46, P < 0.004) and was an independent prognostic factor (P = 0.02). The identification of individual MMPs in oesophageal cancer provides a rational basis for use in the treatment of oesophageal cancer of MMP inhibitors which are currently undergoing clinical trial.

Adenocarcinoma↗
PubMed1997

Tumor-specific expression of cytochrome P450 CYP1B1.

Cytochrome P450 CYP1B1 is a recently cloned dioxin-inducible form of the cytochrome P450 family of xenobiotic metabolizing enzymes. An antibody raised against a peptide specific for CYP1B1 was found to recognize CYP1B1 expressed in human lymphoblastoid cells but not to recognize other forms of cytochrome P450, particularly CYP1A1 and CYP1A2. Using this antibody, the cellular distribution and localization of CYP1B1 were investigated by immunohistochemistry in a range of malignant tumors and corresponding normal tissues. CYP1B1 was found to be expressed at a high frequency in a wide range of human cancers of different histogenetic types, including cancers of the breast, colon, lung, esophagus, skin, lymph node, brain, and testis. There was no detectable immunostaining for CYP1B1 in normal tissues. These results provide the basis for the development of novel methods of cancer diagnosis based on the identification of CYP1B1 in tumor cells and the development of anticancer drugs that are selectively activated in tumors by CYP1B1.

Amino Acid Sequence↗
PubMed1997

Amplification of fluorescent in situ hybridisation signals in formalin fixed paraffin wax embedded sections of colon tumour using biotinylated tyramide.

Fluorescent in situ hybridisation (FISH) is a powerful tool for the evaluation of chromosomal alterations in formalin fixed paraffin wax embedded sections of colorectal cancer. However, initial experiments using a two-step detection system for digoxigenin labelled chromosome specific centromeric probes resulted in a complete lack of hybridisation signal from a number of colorectal tumour sections. This was due to high levels of background autofluorescence observed in this tissue, which masked any relatively weak hybridisations present. To overcome this problem, a biotinylated tyramide mediated amplification system was incorporated into the FISH detection protocol. This involves the use of horseradish peroxidase to activate the biotinylated tyramide, resulting in the deposition of a large number of biotin molecules at the site of bound peroxidase, which corresponds directly to the location of hybridised probe. Final detection was by means of a streptavidin-FITC conjugate. Using this technique, a panel of 11 colorectal tumour samples studied to date have shown strong, specific hybridisation signals to the nucleus of tumour cells. Amplification of FISH signals by biotinylated tyramide has the potential to improve weak hybridisation signals in cells from numerous sources, using a variety of probe types, including single copy gene probes as well as centromere specific probes.

Biotin↗
PubMed1995

Expression of cytochrome P450 CYP1B1 in breast cancer.

The expression of CYP1B1 has been identified in breast cancer using the reverse transcriptase-polymerase chain reaction and immunoblotting. CYP1B1 mRNA was expressed in the majority of breast tumours and immunoblotting of breast tumours identified a single protein band of molecular weight 60 kDa corresponding to the predicted molecular weight of human CYP1B1. This is the first study to identify CYP1B1 expression in a tumour where it may represent a previously unknown pathway for the metabolism of oestradiol and chemotherapeutic drugs.

Adult↗
PubMed1995

The immunohistochemical localization of drug-metabolizing enzymes in prostate cancer.

The major groups of enzymes involved in activating and detoxifying therapeutic drugs, not least several anti-cancer drugs, include the cytochromes P450 (P450s), epoxide hydrolase, and glutathione S-transferases (GSTs). The expression of these enzymes in malignant tumours is one possible mechanism of anti-cancer drug resistance. This study has investigated the presence, cellular localization, and distribution of drug-metabolizing enzymes in prostate cancer. The P450 subfamilies CYP1A, CYP2C, and CYP3A were present in 63, 25, and 61 per cent of tumours, respectively. Epoxide hydrolase was identified in 96 per cent of tumours. GST-alpha and GST-mu were expressed in 29 and 41 per cent of tumours, respectively, while there was no immunoreactivity for the pi form of GST. The absence of GST-pi in prostate cancer contrasts with the frequent expression of GST-pi observed in other types of malignant tumour. In non-neoplastic prostatic epithelium, there was expression of CYP1A, CYP2C, epoxide hydrolase, and the different forms of GST, while there was no apparent immunoreactivity for CYP3A.

Aged↗
PubMed1995

Localization of microsomal epoxide hydrolase in normal and neoplastic human kidney.

Microsomal epoxide hydrolase is a xenobiotic metabolizing enzyme that catalyzes the conversion of toxic and carcinogenic epoxides to less toxic dihydrodiols. The cellular localization and distribution of microsomal epoxide hydrolase were investigated for the first time in normal and neoplastic human kidney. Light microscopic immunohistochemical studies using an alkaline phosphatase-anti-alkaline phosphatase technique showed that in normal kidney there was a wide distribution of epoxide hydrolase immunoreactivity. The main localization of epoxide hydrolase immunoreactivity was to the proximal and distal tubule epithelial cells. Strong epoxide hydrolase immunoreactivity was also identified in epithelium of the collecting ducts. In addition, epoxide hydrolase immunoreactivity was present in vascular endothelial cells, including endothelial cells lining glomerular capillaries. Epoxide hydrolase immunoreactivity was identified in all the renal tumors, and in each tumor immunoreactivity for epoxide hydrolase was localized to tumor cells. Immunoblotting of both normal kidney and tumor microsomes confirmed the presence of a single protein band of molecular weight 49 KD corresponding to the molecular weight of human hepatic microsomal epoxide hydrolase.

Adult↗
PubMed1995

Expression of xenobiotic metabolizing enzymes in tumours of the urinary bladder.

The cytochromes P450, epoxide hydrolase and glutathione S-transferases are several of the major groups of enzymes involved in the metabolism of xenobiotics and these enzymes may have a role in influencing the response of tumours to anti-cancer drugs. In this study the cell specific expression of individual xenobiotic metabolizing enzymes has been investigated using immunohistochemistry in primary transitional cell tumours of the urinary bladder. The cytochromes P450 CYP1A, CYP2C and CYP3A, were present in 68, 28 and 68% of tumours respectively and the expression of CYP1A correlated with bladder tumour grade (P = 0.03). Epoxide hydrolase was identified in 84% of tumours while the alpha, mu and pi forms of glutathione S-transferase were expressed in 56, 72 and 52% of tumours respectively. In normal bladder epoxide hydrolase and glutathione S-transferase pi were the main enzymes expressed while there was no expression of CYP2C.

Adult↗