No mutations of the Bub1 gene in human gastric carcinomas

Chromosomal instability in colorectal cancers is associated with functional loss of a mitotic check point partly due to mutations of the Bub1, one of the mitotic check point genes. However, mutation of coding sequences of human Bub1 gene has not been fully elucidated in gastric carcinomas. We performed sequencing analysis on reverse transcriptase-polymerase chain reaction (RT-PCR) product of the Bub1 cDNA (entire coding sequence) from 5 human gastric carcinomas as well as on genomic PCR products of Bub1 kinase domain from 7 gastric carcinoma tissues. Although sequencing analysis of the Bub1 cDNA revealed several point mutations in 2 gastric carcinoma cases, we could not confirm the mutations by analyzing genomic DNA. Furthermore, genomic DNA sequencing revealed no mutations in the kinase domain of the Bub1 gene in any gastric carcinoma examined. These results suggest that mutational inactivation of the Bub1 gene might not play a key role in human stomach carcinogenesis.

Genetic and epigenetic changes in stomach cancer

Genetic and epigenetic alterations of multiple cancer-related genes and molecules are implicated in the development and progression of human gastric carcinomas. Reactivation of telomerase, inactivation of p53 tumor suppressor gene, overexpression of cyclin E, and reduced expression of p27 KIP1 by disorganized degradation in proteasome are common events of both well-differentiated and poorly differentiated gastric adenocarcinomas. Inactivation of hMLH1 mismatch repair gene by CpG hypermethylation resulting in microsatellite instability, amplification of c-erbB2 oncogene, inactivation of APC tumor suppressor gene, and K-ras mutations are preferentially associated with well-differentiated gastric cancer. Conversely, reduction or loss of E-cadherin and catenins by both mutation and CpG hypermethylation and K-sam and c-met oncogene amplification are necessary for the development and progression of poorly differentiated or scirrhous gastric carcinomas. Interaction between cancer cells expressing c-met and hepatocyte growth factor from stromal cells is implicated in morphogenesis of gastric cancer.

Overexpression of retinoic acid receptor beta induces growth arrest and apoptosis in oral cancer cell lines

Expression of retinoic acid receptor beta (RARbeta) is reported to be absent or down-regulated in oral squamous cell carcinomas. Recently, we found that the growth-inhibitory effect of 9-cis-retinoic acid (9CRA) on oral squamous cell carcinoma may depend on the expression levels of endogenous RARbeta. In order to clarify the role of RARbeta in growth and differentiation, we transfected RARbeta expression vector into oral squamous carcinoma cell lines, HSC-4 and Ho-1-N-1. Both RARbeta-transfected cell lines displayed growth inhibition. Moreover, RARbeta-transfected clones underwent morphological changes, and RARbeta-transfected HSC-4 clones underwent apoptosis even in the absence of 9CRA treatment. In contrast, RARbeta-transfected Ho-1-N-1 clones exhibited cell cycle arrest without undergoing apoptosis initially; however, apoptosis was induced in these cells after 6 days of 9CRA treatment. RARalpha and RARgamma expression was reduced at both the protein and mRNA levels in RARbeta transfectants, whereas the expression of retinoid X receptor alpha (RXRalpha) was not altered. RARb transfectants exhibited alterations in the levels of cell cycle-associated proteins, histone acetyltransferase (HAT) and apoptosis-associated proteins. After 6 days of 9CRA treatment, RARbeta transfectants overexpressed Waf1 / Cip1 / Sdi1 / p21, Kip1 / p27, chk1, p300 / CBP, BAX, Bak, Apaf 1, caspase 3 and caspase 9. Conversely, E2F1, cdc25B and HDAC1 were down-regulated in these transfectants. In addition, histone H4 acetylation was induced in RARb transfectants. These findings suggest that histone acetylation mediated by histone acetyltransferase and p300 / CBP may play a role in the growth arrest and apoptosis induced by RARbeta transfection in oral squamous cell carcinoma.

Effect of trichostatin A on cell growth and expression of cell cycle- and apoptosis-related molecules in human gastric and oral carcinoma cell lines

The effect of trichostatin A (TSA), histone deacetylase inhibitor, on cell growth and the mechanism of growth modulation was examined in 8 gastric and 3 oral carcinoma cell lines which included 9-cis-retinoic acid resistant (MKN-7 and Ho-1-N-1) and IFN-beta resistant cell lines (MKN-7, -28 and -45). TSA inhibited growth in all cell lines examined. Apoptotic cell death was confirmed by apoptotic ladder formation and induction of a cleaved form (85 kDa) of poly (ADP-ribose) polymerase (PARP) induction. TSA enhanced the protein expression of p21(WAF1), CREB-binding protein, cyclinE, cyclin A, Bak and Bax, while it reduced the expression of E2F-1, E2F-4, HDAC1, p53 and hyperphosphorylated form of Rb. Furthermore, TSA induced morphological changes, such as elongation of cytoplasm and cell-to-cell detachment, in gastric and oral carcinoma cell lines. These results suggest that TSA may inhibit cell growth and induce apoptosis of gastric and oral carcinoma cells through modulation of the expression of cell cycle regulators and apoptosis-regulating proteins.

Effect of trichostatin A on cell growth and expression of cell cycle- and apoptosis-related molecules in human gastric and oral carcinoma cell lines

The effect of trichostatin A (TSA), histone deacetylase inhibitor, on cell growth and the mechanism of growth modulation was examined in 8 gastric and 3 oral carcinoma cell lines which included 9-cis-retinoic acid resistant (MKN-7 and Ho-1-N-1) and IFN-beta resistant cell lines (MKN-7, -28 and -45). TSA inhibited growth in all cell lines examined. Apoptotic cell death was confirmed by apoptotic ladder formation and induction of a cleaved form (85 kDa) of poly (ADP-ribose) polymerase (PARP) induction. TSA enhanced the protein expression of p21(WAF1), CREB-binding protein, cyclinE, cyclin A, Bak and Bax, while it reduced the expression of E2F-1, E2F-4, HDAC1, p53 and hyperphosphorylated form of Rb. Furthermore, TSA induced morphological changes, such as elongation of cytoplasm and cell-to-cell detachment, in gastric and oral carcinoma cell lines. These results suggest that TSA may inhibit cell growth and induce apoptosis of gastric and oral carcinoma cells through modulation of the expression of cell cycle regulators and apoptosis-regulating proteins.

Molecular characteristics of eight gastric cancer cell lines established in Japan

Molecular characterization of eight gastric cancer cell lines established in Japan are summarized according to the genetic and epigenetic alterations and growth factor status. TMK-1 poorly differentiated adenocarcinoma cell line harbors mutant p53 tumor suppressor gene and rearrangement of p15MTS2. MKN-1 adenosquamous carcinoma line with mutant p53 reveals silencing of E-cadherin by promoter CpG hypermethylation. MKN-7 well-differentiated adenocarcinoma cell line has amplification of c-erbB2 oncogene and cyclin E gene. MKN-28 well-differentiated adenocarcinoma cell line reveals mutations in p53 and APC tumor suppressor genes and silencing of CD44. The MKN-45 poorly differentiated adenocarcinoma cell line with wild-type p53 is characterized by homozygous deletion of p16CDKN2/MTS1/INK4A and p15MTS2, amplification of c-met oncogene and promoter mutation of E-cadherin. MKN-74 derived from moderately differentiated tubular adenocarcinoma has wild-type p53. KATO-III signet ring cell carcinoma line has genomic deletion of p53, amplification of K-sam and c-met oncogene and mutation of E-cadherin. HSC-39 signet ring cell carcinoma cell line harboring p53 missense mutation has homozygous deletion of p16CDKN2/MTS1/INK4A and p15MTS2, amplifications of c-myc, c-met, K-sam and CD44 gene and mutation in beta-catenin gene.

Distribution of germline BAT-40 poly-adenine tract microsatellite variants in the Japanese

Distribution of allelic variants of a poly-adenine tract microsatellite named BAT-40, locating at intron 2 of 3-beta-hydroxysteroid dehydrogenase gene, were investigated in 412 Japanese individuals free from mismatch repair gene defect. Out of them, 60 (14.6%) were heterozygotes for BAT-40, which is significantly lower than that reported in Europeans. Observed allelic variants in the Japanese ranged from 17- to 46-adenine repeats with different distribution pattern from those reported in the Americans or Europeans. These data will provide significant background knowledge for the evaluation of microsatellite instability in cancer DNA from the Japanese population.

Genetic and epigenetic alterations in multistep carcinogenesis of the stomach

An accumulation of multiple genetic and epigenetic alterations of oncogenes, tumor suppressor genes, DNA repair genes, cell cycle regulators, cell adhesion molecules, and the growth factor/receptor system is involved in the course of multistep conversion of normal epithelial cells to clinical gastric cancer. Some of them differ depending on the histological type, well-differentiated (intestinal) and poorly differentiated (diffuse) types, suggesting the presence of two distinct genetic pathways. Genetic instability, chromosomal instability (telomere reduction), and immortality (activation of telomerase and expression of telomerase reverse transcriptase: TERT) participate in the initial step of stomach carcinogenesis. Because TERT protein expression precedes the telomerase activities in precancerous lesions, TERT expression may be a prerequisite for telomerase activation. The cyclin E gene is amplified in 15%-20% of gastric cancer. Reduced expression of a cyclin-dependent kinase (CDK) inhibitor, p27Kip1, is frequently found in gastric cancer associated with high grade malignancy. E2F-1, an important downstream target of cyclins/CDKs, is overexpressed in about 40% of gastric carcinomas, whereas gene amplification of E2F-1 rarely occurs. Loss of heterozygosity (LOH) of p73, the p53-related new tumor suppressor gene, preferentially occurs in well-differentiated adenocarcinomas of foveolar type expressing pS2, a gastric-specific trefoil factor, indicating the importance of p73 LOH in the genesis.

[Carcinogenesis through abnormalities of DNA repair genes]

Mechanisms of carcinogenesis through abnormalities of DNA repair genes are overviewed. Inactivation of DNA mismatch repair(MMR) gene(s) observed in tumors of hereditary non-polyposis colorectal cancer induces frameshift mutator mutation in MMR genes themselves, growth inhibitory genes and apoptosis inhibitory genes providing favorable genetic background for a malignant clone to be expanded. Deficiency of nucleotide excision repair that is usually employed for the removal of pyrimidine dimer formed by ultraviolet-irradiation in xeroderma pigmentosum (XP) causes hypersensitivity of the skin to sunlight as well as increased risk of skin cancer. Strand specificity and absence of hot spots for p53 tumor suppressor gene mutations was reported in ultraviolet induced skin cancers of XP model mice.

Effect of 9-cis-retinoic acid on oral squamous cell carcinoma cell lines

Retinoic acid (RA) has been shown to be effective in suppressing premalignant lesions and preventing second primary malignancies in patients cured of squamous cell carcinoma of the head and neck. However, the precise mechanisms of these effects are still uncertain. In the present study, we examined the effect of 9-cis-RA on the growth of six oral cancer cell lines (HSC-2, HSC-3, HSC-4, Ca9-22, Ho-1-N-1 and Ho-1-u-1). In addition, the relationship among growth and differentiation of tumor cells, RA responsiveness and the expression of nuclear retinoic acid receptors were also investigated. Among the six cell lines examined, five (HSC-2, HSC-3, HSC-4, Ca9-22 and Ho-1-u-1) displayed growth inhibition after treatment with 1x10(-6) M 9-cis-RA, while Ho-1-N-1 cells were resistant to 9-cis-RA. The expression level of RARbeta in 9-cis-RA resistant Ho-1-N-1 cells was very low in comparison with the sensitive cell lines. On the other hand, all of the six the cell lines expressed RARalpha, RARgamma, and RXRalpha at various levels. 9-cis-RA induced accumulation of cell population in G1 phase in HSC-3 cells on the 6th day of the treatment, followed by a marked reduction in the levels of hyperphosphorylated pRB, whereas p53 level was not altered. Interestingly, 9-cis-RA induced transiently the expression of p21(Waf1/Cip1), p27(Kip1), p300, CBP, BAX, Bak and bcl-2 proteins, respectively. This effect was associated with reduction of cyclin D1, cdk4 and CDK-activating kinase (cyclin H and cdk7) protein in HSC-3 cells. These results suggest that the growth inhibitory effect of 9-cis-RA on oral squamous cell carcinoma may depend on the expression levels of RARs, especially RARbeta proteins and RXRalpha proteins, and that 9-cis-RA may provide a powerful therapeutic agent for head and neck cancers.

Helicobacter pylori infection and carcinogenesis of the stomach

INTRODUCTION

Human stomach carcinogenesis occurs after a multi-step process of genetic and epigenetic alterations in oncogenes, tumor-suppressor genes, cell-adhesion molecules, telomere and telomerase activity as well as genetic instability at several microsatellite loci.

RESULTS AND DISCUSSION

These sequential alterations found in gastric cancer differ between the two histological types, indicating that different genetic pathways exist for well-differentiated or intestinal-type and poorly differentiated or diffuse-type gastric cancers, even though both types of gastric cancer may arise from epithelial "stem cells", which express human telomerase reverse transcriptase (hTERT) protein and telomerase activity. Infection with Helicobacter pylori, which evidently causes the release of reactive oxygen species (ROMs) and reactive nitrogen species (NO), may be a strong trigger for "stem cell" hyperplasia in intestinal metaplasia, followed by telomere reduction and increased telomerase activity as well as hTERT overexpression. They may precede DNA replication error, DNA hypermethylation, CD44 abnormal transcript, and p53 mutations, all of which occur in at least 30% of intestinal metaplasias as early events of multi-step pathogenesis of well-differentiated type gastric cancer. Here, we propose a new concept for gastric preneoplasic lesion, "metaplastic dysplasia", based on our molecular observations.

DNA hypermethylation at the pS2 promoter region is associated with early stage of stomach carcinogenesis

pS2, a member of the trefoil peptide family, has been suggested to be a gastric-specific tumor suppressor. We examined the expression of pS2 in gastric carcinomas, adenomas and non-neoplastic mucosa and analyzed the DNA methylation in the pS2 promoter. Reduced expression of pS2 was frequently associated with well-differentiated adenocarcinomas. The CpG sites within the promoter region of the pS2 gene were methylated in pS2-negative gastric carcinoma cell lines whereas it was not in pS2-positive cell line. The promoter methylation was detected in gastric carcinoma tissues and intestinal metaplasia with reduced pS2 expression whereas none of the carcinomas with preserved pS2 expression showed the promoter methylation. These findings suggest that reduced expression of pS2 due to the promoter methylation may participate in an early stage of stomach carcinogenesis, especially of well differentiated type.

Chromophobe renal cell carcinoma with osseous metaplasia: a case report

A 60-year-old Japanese male with a chromophobe cell carcinoma of his left kidney is reported. The tumor, 18 x 27 mm in size, was incidentally found by abdominal ultrasonography. Computed tomography and magnetic resonance imaging demonstrated a well-demarcated solid tumor arising from the lower pole of the left kidney. Histopathological examination of the surgically removed tumor revealed that it was composed of solid sheets of cancer cells having abundant and slightly eosinophilic reticular cytoplasm with accentuated cell membranes making up a plant cell-like appearance. Electron microscopic examination demonstrated numerous intracytoplasmic microvesicles. Although the tumor cells were positive for cytokeratin and epithelial membrane antigen, they did not show vimentin immunoreactivity. The unique histological finding of this tumor from other reported renal chromophobe carcinomas was that it had a peripheral fibrotic area with a focus of metaplastic ossification.

Microsatellite instability in squamous cell carcinomas and dysplasias of the esophagus

Microsatellite instability (MSI) caused by the defective functions of mismatch repair genes plays an important role in the carcinogenesis of gastrointestinal tumors. However, little is known about the role of MSI in esophageal carcinogenesis. In the present study, we conducted microsatellite assays on 41 esophageal carcinomas and also on 44 dysplasias of the esophagus with 7 separate microsatellite loci. MSI was detected in 17 cases (42%) among 41 esophageal carcinomas. MSI negative cases revealed greater lymph node metastasis, metastasis at a more advanced stage, a higher recurrence level and a poorer prognosis (statistically not significant). In the analysis of dysplasias, MSI was detected in 26 lesions (59%) among 44 lesions. Interestingly, MSI was detected in 21 lesions (78%) from the mutator phenotype dysplasias, but detected in only 5 lesions (29%) from the non-mutator phenotype cases. Although the significance of MSI in esophageal carcinoma was not clear, these results indicate that MSI occurs in the early stage of esophageal carcinogenesis.

Cloning of a human hepatocyte growth factor/scatter factor transcription variant from a gastric cancer cell line HSC-39

A new transcription variant of hepatocyte growth factor/scatter factor (HGF/SF) was cloned from human gastric cancer cell line HSC-39. Northern blot analysis of eight human gastric cancer cell lines (TMK-1, MKN-1, MKN-7, MKN-28, MKN-45, MKN-74, KATO-III and HSC-39) demonstrated that HSC-39 cells expressed a 1.3 kb abnormal HGF/SF transcript. Screening of 1 x 10(6) colonies of cDNA library from HSC-39 constructed in pAP3neo mammalian expression vector selected four positive clones containing HGF/SF transcript. Among them, two contained a 1.3 kbp insert detecting the identical transcript to that obtained with HGF/SF probe by Northern blotting. Deoxynucleotide sequencing of the 1.3 kbp insert revealed that it was composed of a part of HGF/SF cDNA from exon 14 to exon 18, corresponding to the whole sequence of HGF/SF light chain, with 5' 75 nucleotides unrelated to any sequence involved in HGF/SF.

Idiopathic granulomatous meningoencephalitis presenting as an intracranial tumor

A 2-year-old girl presented with a single episode of generalized seizure. Magnetic resonance imaging examination showed an intracranial mass with a diameter of 2.5 cm in the right parieto-occipital region of the cerebrum. These clinicoradiological findings were suggestive of intracranial tumor. Histologically, fibroblastic proliferation of storiform pattern was noted, associated with epithelioid granulomas. The etiological pathogens for the granulomas could not be detected even though investigation of special histochemical staining, immunohistochemical study and DNA analysis of Mycobacterium tuberculosis by polymerase chain reaction technique was performed. On electron microscopic examination, the area appearing as a storiform pattern consisted of fibroblasts showing much dilated rough endoplasmic reticulum and slender tappering cytoplasmic processes without cellular junctional complex. No organisms were identified in the granulomatous area of the lesion. From those findings the diagnosis as idiopathic granulomatous meningoencephalitis was made.

Microsatellite instability and hMSH2 gene mutation in a triple cancer (colon cancer, endometrial cancer, ovarian cancer) patient in hereditary non-polyposis colorectal cancer (HNPCC) kindred

A patient who had triple cancer (colon cancer, endometrial cancer, and ovarian cancer) in HNPCC kindred is reported. Her family history revealed the occurrence of colon cancer in her paternal aunt and in two cousins, fulfilling the minimum HNPCC criteria. Microsatellite instability analysis revealed replication error (RER)+ in all cancer lesions at 2 microsatellite loci (D1S191, BAT 40). SSCP analysis suggested germline mutation in exon 2 of the hMSH2 gene. This case showed the importance of complete family-history investigations to identify HNPCC patients. In the near future, definitive diagnosis of HNPCC will be possible on the basis of DNA studies.

Alterations of p73 preferentially occur in gastric adenocarcinomas with foveolar epithelial phenotype

To establish the possible involvement of p73, a newly discovered p53-related candidate as a tumor-suppressor gene in human stomach carcinogenesis, the allelic status, allele-specific expression and mutations of the gene were investigated using PCR-restriction fragment length polymorphism (PCR-RFLP) analysis, RT-PCR SSCP analysis and direct DNA sequencing in 95 gastric adenocarcinomas. Of these, 32 exhibited the heterozygous p73 allele for the StyI restriction site in exon 2. Among these, the cancer DNA of 12 revealed loss of heterozygosity (LOH) of p73. All of the cancers with p73 LOH exhibited phenotypes of foveolar epithelium of the stomach. RT-PCR SSCP analysis of p73 heterozygous cases demonstrated not only bi-allelic expression of the gene but also relatively reduced expression of the affected allele in 6 of 8 tumors with p73 LOH. No gene mutation was detected in the remaining allele of LOH-positive cancers. Our results suggest that alterations of p73, including LOH and abnormal expression, may play roles in the genesis of foveolar-type gastric adenocarcinomas, though this is not in line with a classical Knudson's "2-hit" model.

Alterations of p73 preferentially occur in gastric adenocarcinomas with foveolar epithelial phenotype

To establish the possible involvement of p73, a newly discovered p53-related candidate as a tumor-suppressor gene in human stomach carcinogenesis, the allelic status, allele-specific expression and mutations of the gene were investigated using PCR-restriction fragment length polymorphism (PCR-RFLP) analysis, RT-PCR SSCP analysis and direct DNA sequencing in 95 gastric adenocarcinomas. Of these, 32 exhibited the heterozygous p73 allele for the StyI restriction site in exon 2. Among these, the cancer DNA of 12 revealed loss of heterozygosity (LOH) of p73. All of the cancers with p73 LOH exhibited phenotypes of foveolar epithelium of the stomach. RT-PCR SSCP analysis of p73 heterozygous cases demonstrated not only bi-allelic expression of the gene but also relatively reduced expression of the affected allele in 6 of 8 tumors with p73 LOH. No gene mutation was detected in the remaining allele of LOH-positive cancers. Our results suggest that alterations of p73, including LOH and abnormal expression, may play roles in the genesis of foveolar-type gastric adenocarcinomas, though this is not in line with a classical Knudson's "2-hit" model.

Transfection of interleukin-8 increases angiogenesis and tumorigenesis of human gastric carcinoma cells in nude mice

The growth and spread of tumour cells depends on adequate vasculature. We have previously reported that the expression of interleukin-8 (IL-8) directly correlates with the vascularity of human gastric carcinomas. To provide evidence for a causal role of IL-8 in angiogenesis and tumorigenicity of human gastric cancer, we used the lipofectin method to stably transfect the human TMK-1 gastric carcinoma cells (low endogenous IL-8) with an IL-8 expression vector or control vector. Transfection with IL-8 did not affect the proliferation of cultured cells, yet the culture supernatants of the transfected (but not control) cells stimulated proliferation of human umbilical vein endothelial cells. The IL-8-transfected and control cells were injected into the gastric wall of nude mice. IL-8-transfected cells produced rapidly growing, highly vascular neoplasms as compared to control cells. These results provide direct evidence for the role of IL-8 in the angiogenesis and tumorigenicity of human gastric carcinomas.

Expression of p27Kip1, cyclin E and E2F-1 in primary and metastatic tumors of gastric carcinoma

The cell cycle is controlled by positive and negative regulators. Gene abnormalities and aberrant expressions of various cyclins/CDKs and CDK inhibitors may play a pivotal role in stomach carcinogenesis. To clarify the role of cyclin E, CDK inhibitor p27Kip1 and their target molecule, E2F-1 in tumor metastasis, we examined immunohistochemically the expression of cyclin E, p27Kip1 and E2F-1 in 23 gastric carcinomas and metastatic tumors of the lymph node. Most of gastric carcinomas with lymph node metastasis showed reduced p27Kip1 expression. p27Kip1 was negative in 39% (9/23) of primary tumors, while it was so in 52% (12/23) of lymph node metastases. By comparison of p27Kip1 expression in primary and metastatic tumors in individual cases, metastatic tumor cells in the lymph nodes were expressed at weaker levels than in those in primary tumors in 43% (10/23) of the cases. On the other hand, over 70% (17/23) and 50% (12/23) of the cases expressed cyclin E and E2F-1 at nearly the same levels in both primary tumor and lymph node metastasis, respectively. These results suggest that tumor cells with reduced p27Kip1 expression may selectively metastasize to lymph node or distant organs.

Molecular-pathological diagnosis of gastrointestinal tissues and its contribution to cancer histopathology

Multiple genetic and epigenetic alterations of cancer-related genes and molecules are involved in the course of the development and progression of gastrointestinal cancers. These include telomerase activation, genetic instability, and abnormalities of oncogenes, tumor suppressor genes, cell cycle regulators, cell adhesion molecules and DNA repair genes. By analyzing these alterations in pathology specimens, we can improve differential diagnosis of cancer, obtain information of grade of malignancy, and identify patients at high risk for developing multiple primary cancers. Since 1993, a system of molecular-pathological diagnosis was established, and has been performed as a routine service in collaboration with Hiroshima City Medical Association Clinical Laboratory. More than 10 000 cases of gastrointestinal biopsy and surgery have been analyzed, and additional information of differential diagnosis, biological malignancy and tumor multiplicity could be obtained. Molecular-pathological diagnosis may provide a new approach to cancer diagnosis and novel therapeutics for the 21st century. Furthermore, the analysis of the genetic and epigenetic abnormalities in clinical materials may clarify the molecular mechanism of carcinogenesis and comparative morphological changes. From the analyses of p27KIP1 and telomerase in gastrointestinal adenomas, we have learned that morphological abnormality of the nucleus is an indicator for cells with immortality and malignant potential that must participate in super-early diagnosis (detection of true precancerous lesions) of gastrointestinal cancer. Molecular-pathological diagnosis thus contributes to detailed understanding of cancer histopathology and improves the histopathological diagnosis.

Expression of cell-cycle-regulating transcription factor E2F-1 in colorectal carcinomas

The expression of E2F-1 in human colorectal carcinomas was examined immunohistochemically, and the correlation of E2F-1 expression with clinicopathological findings and with the expression of p27(Kip1) was analyzed to elucidate the role of E2F-1 in the development and progression of colorectal carcinomas. In nonneoplastic mucosa, a small number of epithelial cells in the proliferative zone were weakly positive for E2F-1. Weak expression of E2F-1 was detected in many adenoma cells. Most of the colorectal carcinomas expressed E2F-1 at various levels, and strong expression of E2F-1 was detected in 56% (49/88) of the cases. There was no correlation between the expression of E2F-1 and any clinicopathological parameters such as tumor stage, depth of tumor invasion and lymph node metastasis. Reduced expression of p27(Kip1) was confirmed to be significantly correlated with deep tumor invasion and presence of metastasis. No correlation was evident between overexpression of E2F-1 and reduced p27(Kip1) expression.