Biomedical subjects

Shuho Semba

Publications and source records attributed to Shuho Semba.

At least 19 recordsLinked to original sources

PubMed2007

Epigenetic modulation of endogenous tumor suppressor expression in lung cancer xenografts suppresses tumorigenicity.

Epigenetic changes involved in cancer development, unlike genetic changes, are reversible. DNA methyltransferase and histone deacetylase inhibitors show antiproliferative effects in vitro, through tumor suppressor reactivation and induction of apoptosis. Such inhibitors have shown activity in the treatment of hematologic disorders but there is little data concerning their effectiveness in treatment of solid tumors. FHIT, WWOX and other tumor suppressor genes are frequently epigenetically inactivated in lung cancers. Lung cancer cell clones carrying conditional FHIT or WWOX transgenes showed significant suppression of xenograft tumor growth after induction of expression of the FHIT or WWOX transgene, suggesting that treatments to restore endogenous Fhit and Wwox expression in lung cancers would result in decreased tumorigenicity. H1299 lung cancer cells, lacking Fhit, Wwox, p16(INK4a) and Rassf1a expression due to epigenetic modifications, were used to assess efficacy of epigenetically targeted protocols in suppressing growth of lung tumors, by injection of 5-aza-2-deoxycytidine (AZA) and trichostatin A (TSA) in nude mice with established H1299 tumors. High doses of intraperitoneal AZA/TSA suppressed growth of small tumors but did not affect large tumors (200 mm(3)); lower AZA doses, administered intraperitoneally or intratumorally, suppressed growth of small tumors without apparent toxicity. Responding tumors showed restoration of Fhit, Wwox, p16(INKa), Rassf1a expression, low mitotic activity, high apoptotic fraction and activation of caspase 3. These preclinical studies show the therapeutic potential of restoration of tumor suppressor expression through epigenetic modulation and the promise of re-expressed tumor suppressors as markers and effectors of the responses.

Acid Anhydride Hydrolases↗

PubMed2006

Fhit modulates the DNA damage checkpoint response.

In preneoplastic lesions, the DNA damage checkpoint is induced and loss of heterozygosity at the FRA3B/FHIT common chromosome fragile region precedes or is coincident with activation of the checkpoint response in these early stages. Introduction of exogenous Fhit into cells in vitro led to modulation of expression of checkpoint proteins Hus1 and Chk1 at mid-S checkpoint, a modulation that led to induction of apoptosis in esophageal cancer cells but not in noncancerous primary cultures. Mutation of the conserved Fhit tyrosine 114 resulted in failure of this function, confirming the importance of this residue. The results suggest that the DNA damage-susceptible FRA3B/FHIT chromosome fragile region, paradoxically, encodes a protein that is necessary for protecting cells from accumulation of DNA damage through its role in modulation of checkpoint proteins, and inactivation of Fhit contributes to accumulation of abnormal checkpoint phenotypes in cancer development.

Acid Anhydride Hydrolases↗

PubMed2006

Biological functions of mammalian Nit1, the counterpart of the invertebrate NitFhit Rosetta stone protein, a possible tumor suppressor.

The "Rosetta Stone" hypothesis proposes that the existence of a fusion protein in some organisms predicts that the separate polypeptides function in the same biochemical pathway in other organisms and may physically interact. In Drosophila melanogaster and Caenorhabditis elegans, NitFhit protein is composed of two domains, a fragile histidine triad homolog and a bacterial and plant nitrilase homolog. We assessed the biological effects of mammalian Nit1 expression in comparison with Fhit and observed that: 1) Nit1 expression was observed in most normal tissues and overlapped partially with Fhit expression; 2) Nit1-deficient mouse kidney cells exhibited accelerated proliferation, resistance to DNA damage stress, and increased cyclin D1 expression; 3) cyclin D1 was up-regulated in Nit1 null mammary gland and skin; 4) Nit1 overexpression induced caspase-dependent apoptosis in vitro; and 5) Nit1 allele deficiency led to increased incidence of N-nitrosomethylbenzylamine-induced murine forestomach tumors. Thus, the biological effects of Nit1 expression are similar to Fhit effects. Adenoviruses carrying recombinant NIT1 and FHIT induced apoptosis in Fhit- and Nit1-deficient cells, respectively, suggesting that Nit1-Fhit interaction is not essential for function of either protein. The results suggest that Nit1 and Fhit share tumor suppressor signaling pathways, while localization of the NIT1 gene at a stable, rather than fragile, chromosome site explains the paucity of gene alterations and in frequent loss of expression of the NIT1 gene in human malignancies.

Acid Anhydride Hydrolases↗

PubMed2006

A role for the WWOX gene in prostate cancer.

Expression of the WWOX gene, encompassing the common chromosome fragile site FRA16D, is altered in a large fraction of cancers of various types, including prostate cancer. We have examined expression and biological functions of WWOX in prostate cancer. WWOX mRNA and protein expression were significantly reduced in prostate cancer-derived cells (LNCaP, DU145, and PC-3) compared with noncancer prostate cells (PWR-1E), and WWOX expression was reduced in 84% of prostate cancers, as assessed by immunohistochemical staining. Down-modulation of WWOX expression in the prostate cancer-derived cells is due to DNA hypermethylation in the WWOX regulatory region. Treatment with 5-aza-2'-deoxycytidine (AZA), a DNA methyltransferase inhibitor, and trichostatin A, a histone deacetylase inhibitor, led to increased WWOX mRNA and protein expression in prostate cancer-derived cells, most strikingly in DU145 cells. Transfection-mediated WWOX overexpression in DU145 cells suppressed colony growth (P = 0.0012), and WWOX overexpression by infection with Ad-WWOX virus induced apoptosis through a caspase-dependent mechanism and suppressed cell growth. Lastly, ectopic expression of WWOX by Ad-WWOX infection suppressed tumorigenicity of xenografts in nude mice, and intratumoral AZA treatment halted tumor growth. The data are consistent with a role for WWOX as a prostate cancer tumor suppressor and suggest that WWOX signal pathways should be further investigated in normal and cancerous prostate cells and tissues.

Adenoviridae↗

PubMed2006

Expression of the enhancer of zeste homolog 2 is correlated with poor prognosis in human gastric cancer.

Overexpression of the enhancer of zeste homolog 2 (EZH2) protein, a known repressor of gene transcription, has been reported to be associated with biological malignancy of prostate cancer and several other cancers. The purpose of this study was to examine the expression of EZH2 and analyze its relationship with the clinicopathological features of human gastric cancers. Expression levels of EZH2 mRNA and protein were examined in 13 gastric cancer cell lines and in 83 surgically removed human gastric cancer tissues. Immunohistochemical analysis of the 83 tissue samples and corresponding non-cancerous gastric mucosa showed that EZH2 was more highly expressed in the cancerous than in the non-cancerous tissues, and the expression levels of EZH2 were highly correlated with tumor size, depth of invasion, vessel invasion, lymph node metastasis and clinical stages. Univariate analysis of survival rate calculated by the Kaplan-Meier method revealed that gastric cancer patients with high-level EZH2 expression had poorer prognosis than those expressing no or low levels of EZH2 (P = 0.0271). These findings suggest that overexpression of EZH2 may contribute to the progression and oncogenesis of human gastric cancers, and thus immunohistochemical study of EZH2 expression may serve as a new biomarker for predicting the prognosis of gastric cancers.

Aged↗

PubMed2006

Protein expression profiling identifies cyclophilin A as a molecular target in Fhit-mediated tumor suppression.

Loss of fragile histidine triad (Fhit) expression is often associated with human malignancies, and Fhit functions as a tumor suppressor in controlling cell growth and apoptosis, although specific signal pathways are still undefined. We have used a proteomic approach to define proteins in the Fhit-mediated tumor suppression pathway. Because substitution of Tyr(114) (Y114) with phenylalanine (Y114F) diminishes Fhit functions, we did protein expression profiling to identify proteins differentially expressed in Fhit-negative H1299 lung cancer cells infected with wild-type (Ad-FHIT-wt) and Y114 mutant FHIT-expressing (Ad-FHIT-Y114F) adenoviruses. Among 12 distinct proteins that exhibited 4-fold differences in expression on comparison of the two infected cell lysates, cyclophilin A, the intracellular reporter of the immunosuppressive drug cyclosporine A, showed a remarkably decreased protein level in cells infected with Ad-FHIT-wt versus Ad-FHIT-Y114F. Conversely, loss of Fhit expression resulted in increased cyclophilin A expression in mouse tissues and cell lines. Restoration of Fhit expression led to down-regulated cyclophilin A protein expression and subsequently prevented cyclophilin A-induced up-regulation of cyclin D1, Cdk4, and resultant cell cycle progression (G(1)-S transition), which was independent of Ca(2+)/calmodulin-dependent kinase inhibitor, KN-93. Interestingly, Fhit down-modulation of phosphatase activity of calcineurin, which controls cyclin D1/Cdk4 activation, was reversed by cyclophilin A treatment in a concentration-dependent manner, a reversal that was inhibited by additional cyclosporine A treatment. Thus, cyclophilin A is a downstream target in Fhit-mediated cessation of cell cycle progression at late G(1) phase. Elucidation of the protein effectors of Fhit signaling may lead to identification of targets for lung cancer therapy.

Acid Anhydride Hydrolases↗

PubMed2006

Significance of Akt phosphorylation on tumor growth and vascular endothelial growth factor expression in human gastric carcinoma.

OBJECTIVE: Hypoxia is known to be a prevalent stress stimulus and increases the transcription of vascular endothelial growth factor (VEGF) mediated by hypoxia inducible factor-1alpha (HIF-1alpha). We investigated the role of phosphatidyl inositol-3 OH kinase (PI3K)-Akt signaling in the regulation of HIF-1alpha and VEGF expression in human gastric adenocarcinoma. METHODS: The growth-inhibitory and apoptosis-inducing effects of the LY294002 PI3K inhibitor were analyzed in four gastric cancer cell lines and in vivo. The regulatory mechanism of VEGF and HIF-1alpha expression under hypoxic conditions was examined in the cell cultures. In 88 gastric cancer tissue samples, phosphorylated Akt and VEGF expression were analyzed immunohistochemically. RESULTS: LY294002 suppressed cell proliferation but induced apoptosis with decreased levels of phosphorylated Akt. HIF-1alpha expression and VEGF secretion were induced under hypoxic conditions and VEGF protein secretion was significantly decreased by treatment with LY294002. In tumor samples, phosphorylated Akt expression was detected in 57% of the tumors, which was correlated with high VEGF expression, angiogenesis, clinicopathological parameters as well as a poor outcome. CONCLUSIONS: These findings suggest that phosphorylated Akt (Ser473) reflects the grade of malignancy in human gastric adenocarcinomas, not only in terms of tumor growth but also with respect to tumor angiogenesis.

Adenocarcinoma↗

PubMed2005

BRAF mutation associated with dysregulation of apoptosis in human colorectal neoplasms.

To understand the role of BRAF dysfunction in the carcinogenesis and progression/development of colorectal tumors, the authors investigated genetic alterations in the BRAF gene in human colorectal neoplasms as well as the effects of an RAS inhibitor in BRAF-mutant cells. Seven colon cancer cell lines and 116 colorectal tumors (34 adenomas and 82 adenocarcinomas) were analyzed. Genetic alterations in the BRAF and K-ras genes were examined using polymerase chain reaction-single strand conformation polymorphism and direct sequencing analyses. The growth-inhibitory and apoptosis-inducing effects of the FTI-277 RAS inhibitor in colon cancer cell lines were analyzed as well. An immunohistochemical study was also performed to investigate the correlations between the clinicopathologic parameters involved in the Ki-67 labeling index and the number of apoptotic bodies in tumor cells. FTI-277 did not suppress the proliferation of BRAF-mutant cells (WiDr and TCO), but remarkably inhibited the growth of K-ras mutant cells (LoVo). Interestingly, LoVo cells underwent apoptosis by FTI-277 in a dose-dependent manner, whereas WiDr cells were resistant to this agent. In tumor samples, BRAF mutations were found in 1 (3.0%) of 33 adenomas and 6 (7.2%) of 83 adenocarcinomas. No tumor exhibited mutations in both the BRAF and K-ras genes. Neither BRAF nor K-ras mutations correlated with the Ki-67 labeling index immunohistochemically. However, the number of apoptotic bodies was significantly decreased in the BRAF-mutant tumors. Mutation in the BRAF gene may contribute to colorectal carcinogenesis by upregulating the antiapoptotic role of the RAS/RAF/MEK/ERK pathway.

Adenocarcinoma↗

PubMed2005

Analysis of gene expression induced by diethylstilbestrol (DES) in human primitive Mullerian duct cells using microarray.

The Mullerian ducts are strongly influenced by natural estrogen, estradiol (E2) and diethylstilbestrol (DES) in their development. We screened E2 and DES responsive genes using a microarray analysis in human primitive Mullerian duct cell line, EMTOKA cells expressed estrogen receptor (ER) beta. c-myc oncogene and other target genes expression was detected in cells treated by high-dose DES, but ER antagonist ICI 182,780 could not prevent c-myc induction above. Results of our present study suggested the presence of ER independent pathway in oncogenes induction process by high-dose DES treatment in a human primitive Mullerian duct cell line.

Antineoplastic Agents, Hormonal↗

PubMed2005

Molecular pathological subclassification of mucinous adenocarcinoma of the colorectum.

The purpose of the present report was to examine the possibility of molecular pathological subtyping of mucinous adenocarcinomas (MAC) of the colorectum. Thirty-five formalin-fixed and paraffin-embedded MAC specimens of the colorectum were analyzed. Genetic alterations of p53 gene and microsatellite instability (MSI) as well as immunohistochemical analysis of mucin subtypes (human gastric mucin (HGM), anti-mucin monoclonal antibody recognizing gastric gland mucous cells-1, MUC2, CD10) and expression levels of human mutL homolog 1 (hMLH1), p53 and Ki-67 were performed. According to MSI and p53 status, these tumors were subclassified into three groups: mutator-type tumors with a high frequency of MSI (20%), suppressor/p53-type tumors with p53 mutation, p53 overexpression or loss of heterozygosity of D17S250 (an adjacent locus to p53; 40%) and the unclassified tumors (40%). The suppressor/p53-type tumors had a significant association with distal colon location (P = 0.019), venous invasion (P = 0.002), extent of lymph node metastasis (P = 0.007) and higher tumor stage (P = 0.018). In contrast, mutator-type tumors had frequent expression of HGM (P = 0.005) and prominent lymphocytic infiltration at the advancing front of the tumor (P = 0.005). These results indicate that MAC of the colorectum could be subclassified according to molecular pathological background, reflecting distinct clinicopathological and phenotypic characteristics.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Biological similarities and differences between pancreatic intraepithelial neoplasias and intraductal papillary mucinous neoplasms.

BACKGROUND: Ever since the classification of pancreatic intraepithelial neoplasia (PanIN) was published, studies on the precursor lesions of pancreatic cancer have been advancing along a new directions, using standardized terminology. There are few studies that have examined the biological differences between PanIN and intraductal papillary mucinous neoplasm (IPMN) in detail. AIMS: PanIN and IPMN, which are similar in morphology, were compared using various indicators, with the aim of identifying the similarities and differences between the two. METHODOLOGY: A total of 46 PanINs and 37 ducts with IPMN were identified in 19 patients with invasive ductal carcinoma and 18 patients with IPMN. These PanINs and IPMNs were examined immunohistologically with respect to the expression patterns of HER2/neu, DPC4/Smad4, Akt/PKB, p53, cyclin A, Ki67, MUC1, and MUC2. RESULTS: Significant differences in the expression of MUC1 and MUC2 were observed between IPMNadenoma and PanIN-2 and between CIS and PanIN-3 (MUC1: p = 0.001 and p = 0.005, respectively; MUC2: p = 0.002 and p < 0.001, respectively). A significant difference in the p53 expression level was also observed between CIS and PanIN-3 (p = 0.015). CONCLUSIONS: In both IPMN and PanIN, the grade of atypism increased with increasing expression of HER2/neu, DPC4/Smad4, and Akt/PKB, along with progression in the process of multistage carcinogenesis. Although the expression levels of these factors reflected the grade of atypism, they did not reflect any differences in the grade of biological malignancy between IPMN and PanIN. On the other hand, MUC1 and MUC2 may serve as indicators of the direction of differentiation, i.e., either progression to IDAC or IPMN. Positivity for MUC1 was believed to suggest differentiation into IDAC, and positivity for MUC2 appeared to be indicative of differentiation into IPMN. Such indication of the direction of differentiation seemed to appear in PanIN1-2, even before abnormalities of HER2/neu, Akt/PKB, DPC4/Smad4, p53, and cyclin A expression began to be detected.

Aged↗

PubMed2004

High expression of PRL-3 promotes cancer cell motility and liver metastasis in human colorectal cancer: a predictive molecular marker of metachronous liver and lung metastases.

PURPOSE: Overexpression of PRL-3 has been implicated in colorectal cancer metastases. We investigated the significance of PRL-3 expression in the progression and development of colorectal cancer. EXPERIMENTAL DESIGN: We transfected PRL-3-specific small interfering RNA into human colon cancer DLD-1 cells and analyzed its effect on proliferation, motility, and hepatic colonization. Using an in situ hybridization method, we examined the levels of PRL-3 expression in both primary (177 cases) and metastatic (92 cases) human colorectal cancers and elucidated the relationships with clinicopathological parameters including the incidence of metachronous liver and/or lung metastasis after curative surgery for primary tumor. RESULTS: Transient down-regulation of PRL-3 expression in DLD-1 cells abrogated motility (in vitro) and hepatic colonization (in vivo), but no effect on the proliferation of these cells was observed. In human primary colorectal cancers, the frequency of up-regulated PRL-3 expression in cases with liver (84.4%) or lung (88.9%) metastasis was statistically higher than that in cases without either type of metastasis (liver, 35.9%; lung, 42.3%). In metastatic colorectal cancer lesions, high expression of PRL-3 was frequently detected (liver, 91.3%; lung, 100%). Interestingly, metachronous metastasis was observed more frequently in the cases with high PRL-3 expression (P < 0.0001). CONCLUSIONS: These results indicate that PRL-3 expression in colorectal cancers may contribute to the establishment of liver metastasis, particularly at the step in which cancer cells leave the circulation to extravasate into the liver tissue. In addition, PRL-3 is expected to be a promising biomarker for identifying colorectal cancer patients at high risk for distant metastases.

Aged↗

PubMed2004

BRAF/K-ras mutation, microsatellite instability, and promoter hypermethylation of hMLH1/MGMT in human gastric carcinomas.

BACKGROUND: The BRAF and K-ras genes are the most frequently mutated oncogenes in various human malignancies. We examined BRAF and K-ras mutations in human gastric cancer, and investigated their relationship with microsatellite instability (MSI) and the hypermethylation of promoter regions in hMLH1 and O6-methylguanine DNA methyltransferase (MGMT). METHODS: Sixteen gastric cancer cell lines and 62 gastric cancer tissue samples were screened for BRAF and K-ras mutations by direct sequencing. We also performed a microsatellite assay and investigated methylation status in the promoter regions of hMLH1 and MGMT. RESULTS: mutation was not found in any of the cancer cell lines examined. One (1.6%) cancer tissue sample showed a point mutation in the BRAF gene (GTG --> GAG; V599E). K-ras mutation (GGT --> GAT, G12D) was detected in five (31%) gastric cancer cell lines and in 1 (1.6%) gastric cancer tissue sample. In the gastric cancer tissue samples examined, MSI was detected in 23 (37%) samples. Hypermethylated promoter regions in hMLH1 and MGMT, respectively, were detected in 6 (10%) and 13 (21%) gastric cancer tissue samples. Microsatellite stable (MSS) tumors showed frequent lymphatic invasion (P = 0.050). CONCLUSION: Although BRAF mutation has been reported in a variety of other human cancers, it is a rare event in the carcinogenesis and progression/development of gastric cancer.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Expression of PRL-3 phosphatase in human gastric carcinomas: close correlation with invasion and metastasis.

OBJECTIVE: High expression of PRL-3, a protein tyrosine phosphatase, has been reported to be associated with metastasis of colorectal carcinoma. The aim of this study is to investigate the significance of PRL-3 expression in tumor progression and metastasis of gastric carcinoma. METHODS: The levels of PRL-3 mRNA expression in 8 gastric cancer cell lines were examined by RT-PCR. Ninety-four human gastric carcinomas and 54 matched lymph node metastases were employed in this study. The expression of PRL-3 was detected by immunohistochemistry and the relationship with clinicopathological parameters was analyzed. RESULTS: The expression of PRL-3 mRNA was clearly detected in 7 of 8 gastric cancer cell lines (87.5%) by RT-PCR. In tumor samples, PRL-3 expression was detected in 68% of primary gastric carcinoma (with nodal metastasis 81.5%, without nodal metastasis 50%; p = 0.004). The incidence of PRL-3 expression in lymph node metastasis was significantly higher than that in primary gastric cancers (p < 0.001). Moreover, PRL-3 expression was closely associated with lymphatic invasion (p = 0.002), extent of lymph node metastasis (p = 0.002) and tumor stage (p = 0.045). CONCLUSIONS: These results strongly suggest that PRL-3 expression may play a significant role in invasion and metastasis of gastric carcinoma. PRL-3 might be a novel molecular marker for aggressive gastric cancer.

Adenocarcinoma↗

PubMed2004

Molecular pathological analysis of mucinous adenocarcinomas of the stomach.

OBJECTIVE: Mucinous adenocarcinomas (MACs) of the stomach usually show an invasive expansive growth and a poor prognosis. We examined the possibility of molecular pathological subtyping of MACs of the stomach. METHODS: Forty-one formalin-fixed and paraffin-embedded MAC specimens of the stomach were analyzed. Mucin subtypes (MUC2, CD10, HGM, M-GGMC-1) and expression levels of hMLH1, p53 and Ki-67 were analyzed by immunohistochemistry as well as genetic alterations in the p53 gene and microsatellite instability (MSI). RESULTS: According to both MSI and p53 status, these tumors were subclassified into three groups: the mutator-type tumors, the suppressor/p53-type tumors and the unclassified tumors. The mutator-type tumors demonstrated lower p53 expression and had lower proliferative activity than the suppressor/p53-type tumors, whereas most of the suppressor/p53-type tumors expressed CD10. However, there was no significant difference between the mutator- and suppressor/p53-type tumors in clinicopathological parameters including the patients' outcome. CONCLUSION: Our results indicate that MACs of the stomach are composed of at least three subtypes according to the molecular pathological background for their carcinogenesis. Further study of carcinomas with detailed morphological and biological phenotyping of each subtype may provide useful information for better clinical management.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Phosphorylated Akt/PKB controls cell growth and apoptosis in intraductal papillary-mucinous tumor and invasive ductal adenocarcinoma of the pancreas.

INTRODUCTION: Akt/PKB promotes cell proliferation and rescues cells from apoptosis. AIM: To evaluate the role of Akt/PKB, a key molecule in phosphatidylinositol 3-OH kinase (PI3K) signaling, during the development of pancreatic duct neoplasias such as intraductal papillary-mucinous tumor (IPMT) and invasive ductal adenocarcinoma (IDAC) of the pancreas. METHODOLOGY AND RESULTS: In PK-45H pancreatic cancer cells, the growth-inhibitory and apoptosis-inducing effects of LY294002, a PI3K inhibitor, were detected in a concentration-dependent manner, followed by the reduction of phosphorylated Akt levels. Immunohistochemical analyses revealed that frequent overexpression of phosphorylated Akt (Ser473) was detected in 10 (63%) of 16 IPMTs and 14 (70%) of 20 IDACs. It is interesting that the incidence of Akt phosphorylation closely correlated with Ki-67 immunoreactivity and had an inverse association with the number of cases of apoptotic bodies in both IPMT and IDAC. Although there was no good correlation with other clinicopathologic parameters, the two patients with recurrent IPMT had high levels of phosphorylated Akt. CONCLUSION: Our findings suggest that activation of Akt plays an important role during the progression of these pancreatic duct neoplasias at the early stage. Furthermore, inhibition of the PI3K-Akt/PKB pathway may have therapeutic potential in the treatment of pancreatic duct tumors.

Adenocarcinoma↗

PubMed2002

Phosphorylation of Akt/PKB is required for suppression of cancer cell apoptosis and tumor progression in human colorectal carcinoma.

BACKGROUND: Akt/protein kinase B (PKB), which is included in phosphatidyl inositol-3-OH kinase (PI3K) signaling, controls many intracellular processes, such as the suppression of apoptosis and the promotion of the cell cycle. Therefore, the authors investigated phosphorylated Akt (Ser473) in colorectal carcinomas to reveal the role of PI3K signaling during the development of colorectal carcinoma. METHODS: Expression of phosphorylated Akt (Ser473) in two colon carcinoma cell lines (DLD-1 and Colo205) and 65 human colorectal carcinomas was analyzed using western blotting and immunohistochemistry, respectively. Growth inhibition and induction of apoptosis caused by LY294002, a specific inhibitor of PI3K, were also examined in these cell lines. In tumor samples, the level of cell proliferation activity (Ki-67) and number of apoptotic bodies (single stranded DNA) were determined by counting positive cells. RESULTS: LY294002 significantly affected the proliferation and apoptosis of Colo205 cells, suggesting an association with the low phosphorylation level of Akt protein. Immunohistochemic analysis showed that 46% of the tumors had a high level of expression of phosphorylated Akt with a close association with Ki-67 proliferative activity (P < 0.001) and the number of apoptotic bodies (P < 0.001). Akt phosphorylation was also correlated with some clinicopathologic parameters of the malignancies, including depth of invasion, infiltration to venous vessels, lymph node metastasis, and clinicopathologic stage. CONCLUSIONS: The phosphorylated Akt level can monitor cell growth and resistance to apoptosis, indicating that activation of Akt plays an important role during the progression of colorectal carcinomas by helping promote cell growth and rescue cells from apoptosis. These findings also suggest the possibility of using LY294002 for treatment of colorectal carcinoma.

Adult↗

PubMed2002

Minute invasive ductal carcinoma of the residual pancreas after distal pancreatectomy for intraductal papillary-mucinous tumor.

Our report describes a 66-yr-old man who underwent surgical resection of the pancreas twice within a period of 3 yr for primary and recurrent intraductal papillary mucinous tumors (IPMTs). During the second operation, a minute invasive ductal carcinoma (IDC) was accidentally discovered in the resected specimen of the residual pancreas. The similarity and continuity between this IDC and recurrent IPMT were not recognized histologically. A solid tumor was found in the hepatoduodenal ligament 3 mo after the second operation. We performed a third operation, performing laparotomy and intra-operative radiotherapy, but could not extirpate the tumor. A biopsy specimen obtained from the tumor during this third operation revealed adenocarcinoma, and the patient later died because of tumor progression. We immunohistochemically analyzed the expression of HER-2/neu, Smad4, p16, p21, p53, mucin immunophenotypes and the Ki-67 labeling index in this series of pancreatic-duct neoplasias. Overexpression of HER-2/neu and loss of Smad4 were detected in the minute IDC, which was very different from the immunohistochemical features of both the primary and recurrent IPMTs. The IDC also showed a MUC1-positive/MUC2-negative phenotype. Therefore, we suggest that de novo IDC may occur in IPMT patients, especially those with multiple tumor recurrence. The present case may be helpful in understanding the pathogenesis of pancreatic duct lesions.

Adenocarcinoma, Mucinous↗