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Introducción. El cáncer colorrectal tiene una alta incidencia en la población mundial. Diversas vías moleculares están involucradas en su desarrollo, entre ellas, la inestabilidad cromosómica, la inestabilidad microsatelital y la epigenética. Objetivo. Hacer la caracterización molecular de 44 individuos con cáncer colorrectal esporádico. Materiales y métodos. El análisis de mutaciones en los genes APC, KRAS, TP53 y BRAF se hizo mediante secuenciación de Sanger; la inestabilidad microsatelital se determinó mediante electroforesis capilar utilizando cinco marcadores de repetición corta en tándem (Short Tandem Repeat) y el estado de metilación del promotor del gen MLH1 se hizo con la técnica MS-PCR (Methylation-Specific PCR). Resultados. La frecuencia de mutación de los genes APC, KRAS y TP53 fue del 18,1, 25 y 4,5 %, respectivamente; las mutaciones detectadas se localizaron con mayor frecuencia en el colon derecho. La frecuencia de inestabilidad microsatelital fue del 27,2 % y el 73,1 % en los tumores con metilación en el gen MHL1, y el 91,6 % de los tumores con inestabilidad microsatelital presentaba metilación en el gen MLH1. En el grupo de tumores con estabilidad microsatelital, las mutaciones en los genes APC, KRAS y TP53 fueron más frecuentes que en el grupo de tumores con inestabilidad microsatelital. La metilación del gen MLH1 fue la alteración más predominante. Conclusiones. En los pacientes con cáncer colorrectal evaluados se demostró la presencia de alteraciones moleculares en las diferentes vías genéticas, las cuales son comunes en su carcinogénesis. Los pacientes presentaron un perfil de mutaciones diferente al de otras poblaciones. Los hallazgos obtenidos en este estudio confirman la heterogeneidad molecular descrita en el desarrollo del cáncer colorrectal.
Introduction: Colorectal cancer has a high incidence in the world population. Different molecular pathways, such as chromosomal instability, microsatellite instability, and epigenetics are involved in its development. Objective: To perform molecular characterization in 44 individuals with sporadic colorectal cancer. Materials and methods: We conducted mutation analyses of the APC, KRAS, TP53 y BRAF genes using Sanger sequencing techniques; microsatellite instability was determined by capillary electrophoresis with five STR genetic markers while the methylation status of the MHL1 promotor gene was analyzed using methylation-specific PCR. Results: APC, KRAS, and TP53 genes mutation frequency was 18.1%, 25%, and 4.5%, respectively; the somatic mutations detected were located more frequently in the right colon. The frequency of microsatellite instability was 27.2% and 73.1% of the tumors had the MHL1 gene methylated while 91.6% of microsatellite instability-positive tumors had the methylated MLH1 gene. The mutation profile of microsatellite stability tumors APC, KRAS, and TP53 genes was more frequent than in the microsatellite instability-positive tumors. The methylation of the MLH1 gene was the most predominant molecular alteration. Conclusions: We identified molecular alterations in different genetic pathways of the colorectal cancer patients evaluated, which are common in the carcinogenesis of this cancer. These patients showed a different mutational profile compared to other populations. Our findings confirm the molecular heterogeneity described in the development of colorectal cancer.
Subject(s)
Colorectal Neoplasms/genetics , Oncogenes , Genes, Tumor Suppressor , Genetic Heterogeneity , Microsatellite Instability , EpigenomicsABSTRACT
Ring finger protein 43 (RNF43) is a ring-type E3 ubiquitin ligase.As a negative regulater of Wnt signaling pathway, RNF43 has an important anti-tumor effect.The mutation of RNF43 may cause abnormal activation of Wnt signaling pathway, and then promote invasion, metastasis and proliferation of tumor cell.In addition, the act of RNF43 protein in the Wnt signal pathway is expected to be a molecular target in the therapy of cancer.In recent years, with the gradual deepening of related research, the molecular structure of RNF43 protein and its mechanism of action with the Wnt pathway-related proteins have been gradually clear.In clinical, RNF43 protein analogs and related vaccine also show the important position in the therapy of cancer.
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Objective To analyze the transcription level of new tumor suppressor gene SLC5A8 mRNA in colorectal cancer tissues.Methods Collected specimens of 23 cases with colorectal cancer and cut out carcinoma tissues and Pericarcinomatous tissue respectively,then used real time fluorescent quantitative PCR (RT-qPCR)to detect the transcription level of gene SLC5A8 mRNA,and the results of carcinoma tissues and pericarcinomatous tissues were analyzed by t test.Results The transcription level of new tumor suppressor gene SLC5A8 mRNA in colorectal cancer tissues is significantly lower than pericarcinomatous tissue (P =0.002).Conclusion The expression of gene SLC5A8 in colorectal cancer tissues is declining or missing,suggesting it has a certain relationship with the incidence of colorectal cancer.
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Objective To investigate the expressions of PTEN and p21 genes in Hazak patients with esophageal can-cer. Methods The expressions of PTEN and p21 genes were detected by RT-PCR in 48 samples (cancer tissues and nor-mal tissues) of patients with esophageal cancer. The relationship between the expressions of PTEN and p21 genes, tumor dif-ferentiation, TNM stage, clinical phase and lymph node metastasis were analyzed. Results The positive rates of PTEN gene were 75%and 45.8%in cancer and distant normal tissues. The expression of PTEN was significantly higher in cancer tis-sues than that of distant normal tissues (χ2=8.537,P＜0.05). The positive rates of p21 gene were 95.8%and 97.9%in cancer and distant normal tissues, and no significant difference between them (χ2=0.344,P>0.05). There was no correlation be-tween expressions of PTEN and p21and the tumor differentiation, the depth of invasion and lymph node metastasis in esopha-geal cancer. Conclusion PTEN and p21 genes are not the primary genes for the carcinogenesis of esophageal cancer in Hazak.
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ObjectiveTo investigate the effects of heterogeneous phosphatase and tensinhomologue deleted on chromosome ten (PTEN) on cell cycles,proliferation,invasion,tumorigenicity,metastasis and the expressions of vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR)proteins in human pancreas cancer cell line ( ASPC-1 ).MethodsASPC-1 cells was transfected with plasmid pE-PTEN containing PTEN,and empty plasmid pE-PTEN transfection was used as control,then ASPC-1-pE-PTEN (A-pE-P) cell and ASPC-1-pE (A-pE) cell was obtained.The expression of PTEN mRNA was determined by RT-PCR. PTEN,VEGF and EGFR proteins were measured by cell immunohistochemical method.Clone formation assay was used to observe the numbers of clone.Transwell was used to test the invasion ability of cells.The growths of tumor were detected by nude mice subcutaneous injection of cancer cells in vivo.Results Compared with ASPC-1,the expressions of PTEN mRNA of A-pE-P increased by 179.3％,and the expressions of PTEN protein were also significantly increased.The expressions of VEGF protein were significantly decreased.The expressions of EGFR protein were not significantly changed.Number of G2/M phase cells was significantly increased from (26.81 ± 1.03)％ to (31.5 ± 1.76)％ (P ＜0.05).The numbers of clone was decreased by 28％ (P ＜0.05).The number of penetrating cells was decreased[(46.3 ±6.6) vs (63.8 ±7.5) per high power field,P ＜0.05].The tumor volumes were significantly reduced [(142.4 ±30.9) vs (202.7 ±43.6) mm3,P ＜0.05].The tumor inhibitory rate was 42.4％.The distant metastases were significantly reduced [(2.0 ±0.7) vs (5.0 ± 1.3),P ＜0.01 ].Conclusions Heterogeneous PTEN can not only inhibit the proliferation,invasion and metantasis of ASPC-1 cells,arrest the cell growth at G2/M phase,but also decrease the expressions of VEGF.
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Objective To investigate the significance and expression of PTEN, MLL in T lymphoblastic lymphoma/leukaemia(T-LBL/ALL). Methods Seventy-six cases of T-LBL/ALL were studied by using immunohistochemical EnVision method for PTEN. Fluorescence in-situ hybridization (FISH) for MLL gene (located on chromosome 11q23) was performed to detect its breakage and amplification. Results Among the 76 cases ofT- LBL/ALL, the positive rate of PTEN was 64.47 % (49/76), lower than that in reactivated lymphoid tissue (100 %, 20/20) (λ2= 19.220, P ＜0.05). PTEN expression was reversely correlated to theclinical stage, Ki-67 index and LDH level (P ＜0.05). Among the 76 cases, MLL gene with breakage of 11q23 was detected in 13 cases (17.11%), and amplification in 18 cases (23.68 %). Survival rate ot MLL gene breakage group was lower than that of non-breakage group (25.0 %, 43.6 %). Survival rate of MLL gene amplification group was lower than that of non-amplification group too (17.1%, 42.7 %). Both of breakage and amplification were related to prognosis ( λ 2 = 11.357, λ 2 = 4.533; P ＜0.05). Conclusion Anti-oncogene PTEN down-regulation may play an important role on the development and proceeding of T-LBL/ALL. MLL gene with breakage and amplification of 11q23 are helpful to predict prognosis of T-LBL/ALL. The case with MLL gene breakage and amplification of T-LBL/ALL may have a poor prognosis. It hints this group maybe a subtype of T-LBL/ALL.
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BACKGROUND/AIMS: X-linked inhibitor of apoptosis (XIAP) is the most potent member of the IAP family that exerts antiapoptotic effects. Recently, XIAP-associated factor 1 (XAF1) and two mitochondrial proteins, Smac/DIABLO and HtrA2, have been identified to negatively regulate the caspase-inhibiting activity of XIAP. We explored the candidacy of XAF1, Smac/DIABLO and HtrA2 as a tumor suppressor in colonic carcinogenesis. METHODS: Expression and mutation status of the genes in 10 colorectal carcinoma cell lines and 40 primary tumors were examined by quantitative PCR analysis. RESULTS: XAF1 transcript was not expressed or present at extremely low levels in 60% (6/10) of cancer cell lines whereas Smac/DIABLO and HtrA2 are normally expressed in all cell lines examined. Tumor-specific loss or reduction of XAF1 was also found in 35% (14/40) of matched tissue sets obtained from the same patients. XAF1 transcript was reactivated in all the low expressor cell lines by treatment with the demethylating agent 5-aza-2'-deoxycytidine. Moreover, bisulfite DNA sequencing analysis for 34 CpG sites in the promoter region revealed a strong association between hypermethylation and gene silencing. Restoration of XAF1 expression resulted in enhanced apoptotic response to etoposide and 5-flurouracil, whereas knockdown of XAF1 expression by siRNA transfection significantly inhibited chemotherapeutic drug-induced apoptosis. CONCLUSIONS: XAF1 undergoes epigenetic gene silencing in a considerable proportion of human colon cancers by aberrant promoter hypermethylation, suggesting that XAF1 inactivation might be implicated in colonic tumorigenesis.
Subject(s)
Humans , Cell Line, Tumor , Colonic Neoplasms/genetics , DNA Methylation , English Abstract , Gene Expression Regulation, Neoplastic , Gene Silencing , Intracellular Signaling Peptides and Proteins/genetics , Mitochondrial Proteins/genetics , Neoplasm Proteins/genetics , Promoter Regions, Genetic , Serine Endopeptidases/geneticsABSTRACT
Mutations of the tumor-suppressor gene p53 have been found in 30-50% cases of hepatocellular carcinoma (HCC). In this study, E1-negative adenoviral vector encoding wild-type p53 under the control of the human cytomegalovirus promoter (AdCMV-p53w) was constructed to evaluate its therapeutic efficacy against tumor nodules developing after injection of HuH7 cell lines in ten nude mice. When each nodule had reached 10 mm in perpendicular diameter, 1.5 x 10(8) pfu of AdCMV-p53w per session was injected intratumorally as follows: In group I (n=3), five sessions were injected every other day. In group II (n=3), only one session. Group III (n=4) as negative controls. The mice were sacrificed at 28 days post AdCMV-p53w injection. Tumor growth was significantly suppressed and delayed in group I and II compared to group III as compared by tumor volume at the end of observation. These results suggest that AdCMV-p53w may not only be effective in treating HCCs expressing mutant p53, but also useful as a local injectable gene therapy.