A comparison of the genetic pathways involved in the pathogenesis of three types of colorectal cancer.
Tomlinson I. Ilyas M. Johnson V. Davies A. Clark G. Talbot I. Bodmer W.
Cancer Genetics Laboratory, Imperial Cancer Research Fund, London, U.K.
Patterns of allele loss (loss of heterozygosity, LOH) have been studied in order to investigate the genetic pathways involved in the pathogenesis of three types of colorectal cancer (CRC): sporadic CRC without replication errors (RER-) (32 cases); sporadic RER+ CRC (23 cases); and ulcerative colitis-associated CRC (UCACRC) (16 cases). Each tumour was assessed for allele loss at ten microsatellite markers which map close to known or putative tumour-suppressor genes: APC (5q21-q22); DCC (18q21.1); 1p35-p36; p16 (9p21); 22q; 8p; E-cadherin (16q22.1); beta-catenin (3p22-p21.3); RB1 (13q14.1-q14.2); and HLA. Overall, high frequencies of allele loss (> 30 per cent) were found near DCC (42 per cent), p16 (38 per cent), 22q (37 per cent), 1p35-p36 (34 per cent) and APC (31 per cent), and low frequencies (< 20 per cent) near RB1 (16 per cent) and E-cadherin (13 per cent). LOH near beta-catenin, HLA, and on 8p occurred at frequencies between 20 and 30 per cent. The overall frequency of allele loss did not differ among the three tumour groups, but some variation was seen at individual loci. There was a significantly higher frequency of LOH at 1p35-36 in RER+ tumours compared to RER- tumours. Allele loss at this site was also associated with a more advanced Dukes' stage at presentation. In addition, RER- tumours showed a higher frequency of allele loss at p16 than RER+ tumours. No significant difference existed at any locus between the frequency of LOH in sporadic CRC and in UCACRC. Pairwise analysis showed a negative association between LOH at APC and DCC, and between LOH at chromosome 22p and p53 overexpression. Thus, there may be specific differences between the mutation spectra of RER+ and RER- CRCs, but there are large degrees of overlap among the underlying genetic pathways of these cancers and UCACRCs.
Expression of oestrogen receptor and oestrogen-inducible genes pS2 and ERD5 in large bowel mucosa and cancer.
Singh S. Poulsom R. Hanby AM. Rogers LA. Wright NA. Sheppard MC. Langman MJ.
Department of Medicine, Queen Elizabeth Hospital, Edgbaston, Birmingham, U.K.
Since there is a preponderance of large bowel cancer in males, both in humans and in experimental models, and hormone replacement therapy is protective, a role for sex steroid hormones in the pathogenesis of this neoplasm seems likely. Evidence of functional oestrogen receptor has been looked for in large bowel mucosa and cancer. Expression of oestrogen receptor, and of the oestrogen-inducible receptor-associated genes pS2 and ERD5, was sought. Oestrogen receptor mRNA was detected in cancers and paired normal mucosae in equal amounts. In situ hybridization identified stromal cells above the muscularis mucosae that were positive for oestrogen receptor mRNA. pS2 mRNA was also detected, with a signal intensity significantly higher in normal mucosa compared with cancers, whereas the reverse was seen with ERD5 mRNA levels. pS2 and ERD5 were expressed in epithelium, with the former in a greater amount in distal colon and rectum than proximal colon. Although oestrogen-inducible and receptor-associated genes are expressed in large bowel mucosa, their expression does not correlate with oestrogen receptor.
Clinical decision making in Barretts oesophagus can be supported by computerized immunoquantitation and morphometry of features associated with proliferation and differentiation.
Polkowski W. Baak JP. van Lanschot JJ. Meijer GA. Schuurmans LT. Ten Kate FJ. Obertop H. Offerhaus GJ.
Second Department of General Surgery, Medical Academy, Lublin, Poland.
Grading of dysplasia in Barrett's oesophagus has a therapeutic impact, but subjective grading is associated with substantial observer variation. Quantitative pathological methods could help to achieve a more accurate and reproducible diagnosis. In the present study, the immunoquantitation of p53 and Ki67 and the morphometric analysis of features associated with proliferation and differentiation were evaluated for this purpose. In slides of 35 oesophagectomy specimens, 73 areas that displayed either no dysplasia (ND), low-grade dysplasia (LGD), high-grade dysplasia (HGD), or intramucosal carcinoma (ImCa) were initially considered. Agreement on double blind examination by two experienced pathologists was reached in 58 areas, which were used as the 'learning set'. The 15 areas of disagreement were used as a second set. In the univariate analysis, the most significant differences in the learning set were found for Ki67, p53, stratification index (SI), mean nuclear area, and volume. Further multivariate analysis showed that for discrimination between ND and LGD, the combination of Ki67 and SI resulted in 94 per cent correctly classified areas. Likewise, for the discrimination between LGD and HGD, Ki67 and SI were the most powerful combination (again, 94 per cent of areas classified correctly). The discrimination between HGD and ImCa with any combination of the quantitative parameters never exceeded 80 per cent correct classification. The addition of p53 was of no value in improving the discrimination of ND vs. LGD, or of LGD vs. HGD. In the 15 original disagreement areas of the initial set of 73, three of the five ND/LGD areas could be uniquely classified as either ND or LGD by Ki67 and SI. Moreover, three of the four LGD/HGD disagreement areas could be uniquely classified with the combination of Ki67 and SI as either LGD or HGD. We conclude that the quantitative assessment of cytometric and morphometric features associated with proliferation and differentiation (especially Ki67 and SI) can be a valuable adjunct tool for clinical decision making in Barrett's oesophagus.
Cytokeratins and cell differentiation in the pancreas.
Experimental Pathology Department, Vrije Universiteit Brussel, Laarbeeklaan, Belgium.
Keratins, or cytokeratins, represent a family of more than 20 different polypeptides which are important markers of epithelial cell differentiation. This review deals with the use of keratin immunohistochemistry in the study of pancreatic cell differentiation. Exocrine acinar cells and endocrine islet cells are well-differentiated cells which express the keratin combination 8 and 18, whereas the less-differentiated cells of the ductal tree are characterized by the additional expression of keratin 7, keratin 19, and, in the rat, keratin 20. Keratin expression is stable and can be used for cell identification after isolation and culture, and in clinical or experimental injury. The intercalated ductal cells and centroacinar cells are inconspicuous unless specific immunohistochemical markers, such as keratins, are used. In conditions where there is morphogenetic differentiation such as in fetal life, or where transdifferentiation is occurring, keratins have been used to trace the origin and fate of pancreatic cells.
Expression of HNF-1 alpha and HNF-1 beta in various histological differentiations of hepatocellular carcinoma.
Wang W. Hayashi Y. Ninomiya T. Ohta K. Nakabayashi H. Tamaoki T. Itoh H.
First Division of Pathology, Kobe University School of Medicine, Japan.
Hepatic nuclear factor 1 (HNF-1) regulates genes in a hepatocyte-specific manner. It has been previously reported that the ratio of HNF-1 alpha and HNF-1 beta mRNA is related to histological differentiation hepatocellular carcinoma (HCC). In this study, the expression levels of the HNF-1 alpha and HNF-1 beta proteins were analysed relatively and quantitatively in various histologically differentiated HCC and surrounding non-cancerous tissues, and HNF-1 alpha binding activity for the AT element of the B domain of the human alpha-fetoprotein enhancer was examined. Western blot analysis demonstrated that HNF-1 alpha protein was expressed at a higher level in well-differentiated HCC tissues than in the surrounding non-HCC tissues; on the other hand, the HNF-1 alpha protein was expressed at lower levels in moderately and poorly differentiated HCCs than in the surrounding non-HCC tissues. The levels of HNF-1 beta expression in well-differentiated and poorly differentiated HCCs were similar to and higher than those found in the respective surrounding non-cancerous portions. In binding assays, HNF-1 binding activity was high in well-differentiated HCC and lower in moderately and poorly differentiated HCCs. Most well-differentiated HCC cases showed immunohistochemical expression of HNF-1 alpha. These findings show that poor histological differentiation of HCC correlates with decreases in the level and activity of HNF-1 alpha proteins.
Hyaluronate binding assay study of transfected CD44 V4-V7 isoforms into the human gastric carcinoma cell line SC-M1.
Harn HJ. Shen KL. Liu CA. Ho LI. Yang LS. Yueh KC.
Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.
The potential human metastasis molecule CD44 and its isoforms V5 and V6 are overexpressed in human gastric carcinoma. Among the numerous extracellular matrix components, hyaluronate, a CD44 ligand, is of increasing interest in relation to its role in cancer cell development and invasion. By using the dynabead separation method, the SC-M1 cell line was separated into V5 and V6 isoform-positive and -negative populations. The V5 and V6 isoform-negative populations exhibited significantly higher hyaluronate binding activity than the corresponding positive cells. The hyaluronate binding activity of V5 and V6-positive cells could be restored by pretreatment with anti-CD44 V5 and V6 monoclonal antibodies (MAbs). In addition, transfection of aVV5 and V6-negative cells decreased their hyaluronate binding activity to the levels of CD44 V5 and V6-positive cells. Cells transfected with V5 and V6 recovered their hyaluronate binding activity after pretreatment with MAbs against V5 and V6. These data suggest that cell adhesion involving hyaluronate can be regulated by multiple mechanisms, one of which involves alternative splicing of CD44 isoforms.
Lack of inducible nitric oxide synthase in bronchial epithelium: a possible mechanism of susceptibility to infection in cystic fibrosis.
Meng QH. Springall DR. Bishop AE. Morgan K. Evans TJ. Habib S. Gruenert DC. Gyi KM. Hodson ME. Yacoub MH. Polak JM.
Department of Histochemistry, Royal Postgraduate Medical School, London, U.K.
Cystic fibrosis (CF) is an inherited disorder associated with severe inflammation and repeated bacterial infection and colonization in the lung. Airway epithelium is involved in defence against bacteria, but this system may be defective in CF. Pro-inflammatory cytokines can stimulate the expression of inducible nitric oxide synthase (iNOS), an enzyme generating nitric oxide, which functions as an important mediator in host defence mechanisms. To understand better the poor resistance to infections in the CF lung, the expression of the iNOS gene was investigated in explanted lungs from patients with cystic fibrosis (n = 13), bronchiectasis (n = 3), emphysema (n = 14), and in normal lungs (n = 8). In addition, bronchial epithelial cell lines were examined to study iNOS gene expression in vitro. Strong immunoreactivity for iNOS was seen in inflammatory cells and bronchial epithelium in all the diseased lungs, except for bronchial epithelium in CF. Quantitative analysis showed a significant reduction in the area of epithelium immunostained in CF [CF 6.8 +/- 1.6 (% +/- SEM); emphysema 18.2 +/- 2.8; normal 9.6 +/- 0.8, P < 0.01], regardless of steroid treatment. These results were supported by in situ hybridization of iNOS mRNA, which showed a pattern of gene expression in CF, emphysema, and normal lung which paralleled that of protein immunoreactivity. Stimulation with cytokines (IL-1 beta, TNF-alpha, and IFN-gamma) increased the expression of iNOS mRNA detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in cultures of normal (16HBE14o-), but not CF (CFBE41o-, with delta F508 CFTR mutation) epithelial cells. Expression of iNOS in inflammatory cells suggests that the gene is normal in CF. Absence of iNOS from bronchial epithelium may be due to low expression of the gene resulting from abnormalities in the signalling system that normally causes induction, such as cytokine receptors, second messengers or transcription factors. The resulting deficiency of the nitric oxide defence system may be relevant to the susceptibility of CF patients to pulmonary bacterial colonization.
Predicting the risk of metachronous colorectal cancer in patients with rectosigmoid adenoma using quantitative pathological features. A case-control study.
Meijer GA. Baak JP. Talbot IC. Atkin WS. Meuwissen SG.
Department of Pathology, Free University Hospital, Amsterdam, The Netherlands.
The prognostic value of quantitative pathological features in rectosigmoid adenomas was investigated, in search of more precise identifiers of adenoma-bearing patients at high risk of metachronous colorectal cancer. In a "nested case-control study" design, 21 cases with metachronous colon cancer during an average follow-up time of 16 years (range 3-30 years) after polypectomy and 67 controls were selected from a cohort of 1618 patients. The most advanced adenoma of each patient was analysed. Cases were matched with up to three controls simultaneously for size, grade of dysplasia, histological type, and number of adenomas, as well as for duration of follow-up. The patients did not undergo any post-polypectomy surveillance. Geometric characteristics of tumour nuclei, the arrangement of nuclei in the epithelium, and glandular changes were measured, and mitoses were counted. Several quantitative features measuring nuclear polymorphism and crowding showed significant prognostic value, while those measuring glandular changes and mitotic activity did not. A multivariate combination of the average distance between nuclei and the standard deviation of nuclear area discriminated an unfavourable group (n = 44) with 17 metachronous cancers from a favourable group (n = 44) with four metachronous cancers (P = 0*001, RR = 6*3). With the optimum cut-off, 28 patients without any metachronous cancer were discriminated from a group of 60 patients with 21 metachronous cancers. In conclusion, in the present study, quantitative pathological features assessed in rectosigmoid adenomas showed prognostic value additional to traditional measures. These features may therefore be useful in guiding post-polypectomy surveillance.