Tobacco,alcohol, and <Emphasis Type="Italic">p53</Emphasis> overexpression in early colorectal neoplasia

Background  

The p53 tumor suppressor gene is commonly mutated in colorectal cancer. While the effect of p53 mutations on colorectal cancer prognosis has been heavily studied, less is known about how epidemiologic risk factors relate to p53 status, particularly in early colorectal neoplasia prior to clinically invasive colorectal cancer (including adenomas, carcinoma in situ (CIS), and intramucosal carcinoma).     

Expression of full-length p53 and its isoform Δp53 in breast carcinomas in relation to mutation status and clinical parameters

Background  

The tumor suppressor gene p53 (TP53) controls numerous signaling pathways and is frequently mutated in human cancers. Novel p53 isoforms suggest alternative splicing as a regulatory feature of p53 activity.     

Multi-panel assay of serum autoantibodies in colorectal cancer

Background

Although serum p53 autoantibodies (s-p53-Abs) are induced even in the early stages of colorectal cancer, their positive rate is only approximately 20%. Therefore, we assessed the possibility of using other serum autoantibodies to increase the positive rates for detecting colorectal cancer.

Methods

Autoantibodies against 17 tumor antigens (p53, RalA, HSP70, Galectin1, KM-HN-1, NY-ESO-1, p90, Sui1, HSP40, CyclinB1, HCC-22-5, c-myc, PrxVI, VEGF, HCA25a, p62, and Annexin II) were evaluated in 279 patients with colorectal cancer and 74 healthy controls. Cutoff values were fixed at mean?+?3 standard deviations of serum titers in healthy controls.

Results

Autoantibodies with the highest positive rates were p53 (20%), RalA (14%), HSP70 (12%), and Galectin1 (11%). Combination assays using multiple autoantibodies increased the positive rates based on the number of autoantibodies used. Positive rates of 56, 62, 66, 71, and 73% were obtained with 6, 9, 11, 14, and 17 antibodies, respectively, for the overall disease. Moreover, these autoantibodies showed relatively high positive rates even during stage 0/I disease (55 and 70% with 6 and 17 antibodies, respectively).

Conclusion

The measurement of set of 17 autoantibodies allowed autoantibody profiling in patients with colorectal cancer. The combination assay of six tumor antigens (p53, RalA, HSP70, Galectin1, KM-HN-1, and NY-ESO-1) achieved a positive rate of 56%. Such high positive rates will be helpful for detecting colorectal cancer regardless of tumor stages.

     

No germline mutations in the histone acetyltransferase gene <Emphasis Type="Italic">EP300</Emphasis> in <Emphasis Type="Italic">BRCA1</Emphasis> and <Emphasis Type="Italic">BRCA2</Emphasis> negative families with breast cancer and gastric,pancreatic, or colorectal cancer

Introduction  

Mutations in BRCA1, BRCA2, ATM, TP53, CHK2 and PTEN account for many, but not all, multiple-case breast and ovarian cancer families. The histone acetyltransferase gene EP300 may function as a tumour suppressor gene because it is sometimes somatically mutated in breast, colorectal, gastric and pancreatic cancers, and is located on a region of chromosome 22 that frequently undergoes loss of heterozygosity in many cancer types. We hypothesized that germline mutations in EP300 may account for some breast cancer families that include cases of gastric, pancreatic and/or colorectal cancer.     

Expression of cyclooxygenase-2 in colorectal adenocarcinoma is associated with p53 accumulation and hdm2 overexpression

Elevated cyclooxygenase-2 (COX-2) expression has been observed in various types of cancer. Induction of COX-2 expression has been reported to increase invasiveness and angiogenesis of tumours. While COX-2 overexpression has been repeatedly proven to promote tumor growth, little is known about what initiates its induction. There has been evidence to suggest that COX-2 expression is normally suppressed by wild-type p53 but not mutant p53, suggesting that loss of p53 function may result in the induction of COX-2 expression. Loss of p53 function is not only caused by gene mutation, but also through the overexpression of its negative regulator, so called human double minute 2 (hdm2). The aim of this study was to examine the correlation between COX-2 overexpression, p53 accumulation and HDM2 overexpression, as indications of p53 anomalies, and their relationship to clinicopathologic features of colorectal adenocarcinoma. Tumor tissues and the adjacent normal mucosa were obtained from 73 colorectal cancer patients who underwent curative resection at Maharaj Nakorn Chiang Mai Hospital. Protein levels of COX-2, p53 and HDM2 were determined by Western blot analysis. No normal colorectal tissues possessed detectable levels of COX-2, p53 or HDM2. In contrast, 38.3% (28 cases), 54.8% (40 cases) and 8.2% (6 cases) of tumour tissues were found to express COX-2, p53 and HDM2, respectively. Interestingly, there was a significantly positive relationship between COX-2 overexpression and p53 accumulation and/or HDM2 overexpression (P=0.007). Higher COX-2 overexpression was observed in p53-accumulated or HDM2 overexpressed-tumours (22/43 cases, 51.1%) in comparison to tumours with no evidence of p53 and HDM2 alterations (6/30 cases, 20%). The results obtained from this study indicate that overexpression of COX-2 is frequently associated with p53 protein accumulation and HDM2 overexpression, therefore the COX-2 overexpression observed in colorectal cancer cells may be partly due to the dysfunction of p53. Although mutation of p53 has been previously reported to be associated with COX-2 induction, to our knowledge, this is the first study to show the relationship between HDM2 overexpression and COX-2 overexpression.     

Reduced messenger RNA expression level of p21CIP1 in human colorectal carcinoma tissues and its association with p53 gene mutation

p21Cip1 was first isolated as one of the cyclin-dependent kinase (Cdk) interacting proteins induced by wild-type p53 gene product, and it appears to play an essential regulatory role in the control of cell proliferation as a potent, tight-binding inhibitor of cyclin-Cdk complex that blocks the G₁/S transition of the cell cycle. We have now examined the p21Cip1 mRNA expression levels in 16 surgically excised human colorectal tumor and non-tumor tissues by Northern-blot analysis with reference to the identification of p53 gene mutations. p53 gene mutations were detected in 6 tumor tissues but not in the other 10 tissues by the polymerase chain reaction—single strand conformation polymorphism (PCR-SSCP) method and following direct sequencing. The mean p21Cip1 mRNA expression level in tumor tissues was significantly suppressed compared to that of non-tumor tissues, irrespective of p53 gene mutations. In p53 gene mutation-detected cases, the mean expression level of p21Cip1 mRNAs of tumor tissues was about 60% of that of cases without p53 gene mutation. Moreover, the relative mRNA expression levels of p21Cip1 significantly decreased as the pathohistological stages progressed by Dukes' staging system, while in patients with liver metastasis these levels were significantly suppressed compared to those of patients without organ metastasis. These results indicate that reduced expression of p21Cip1 mRNA is critical for growth activity and malignant potential of human colorectal carcinoma, and that the decrease in p21Cip1 mRNA level is due to p53 gene mutation as well as other mechanisms during human colorectal carcinogenesis. © 1996 Wiley-Liss, Inc.     

Up-regulation and clinical relevance of novel helicase homologue DHX32 in colorectal cancer

Background

This study aimed to find novel biomarkers for colorectal cancer.

Methods

Fluorescent mRNA differential display PCR (DD-PCR) was used to screen the genes differentially expressed in colorectal cancer tissues and their adjacent tissues. The differentially expressed genes were confirmed by real-time PCR and then their clinical relevance (such as association with tumor location and lymph gland metastasis) was further investigated.

Results

We identified by DD-PCR a novel RNA helicase, DHX32, which showed higher expression in colorectal cancer tissues than their adjacent tissues, and this result was confirmed by real time RT-PCR. In addition, we found that the level of DHX32 gene expression in colorectal cancer was significantly associated with cancer location, lymph gland metastasis, cancer nodal status, differentiation grade, and Dukes, stage.

Conclusion

DHX32 may play an important role in the development of colorectal cancer and could serve as a novel biomarker for colorectal cancer after additional investigation.     

p53 gene mutations in early colorectal carcinoma. de novo vs. adenoma-carcinoma sequence

p53 gene mutations in early and advanced colorectal cancer were detected by PCR-SSCP analysis. Early colorectal cancer was classified intode novo cancer and polyp-forming cancer, respectively, according to morphology and presence of adenomatous components. A total of 94 paraffin-embedded tissue specimens from patients with colorectal cancer were analysed.p53 gene mutations were detected in 40.0% (12/30) of de novo cancer, 36.7% (11/30) of polyp-forming cancer, and 44% (15/34) of advanced cancer. p53 mutations were detected at a high frequency in both types of early colorectal cancer as well as in advanced cancer. No correlations were found between p53 mutations and clinicopathological data. Our data suggest that the p53 gene mutations occurred in the early colorectal cancer stage of carcinogenesis regardless of the pathway. © 1995 Wiley-Liss, Inc.     

Patterns and Biologic Features of p53 Mutation Types in Korean Breast Cancer Patients

Purpose

The p53 gene is one of the most frequently mutated genes in breast cancer. We investigated the patterns and biologic features of p53 gene mutation and evaluated their clinical significance in Korean breast cancer patients.

Methods

Patients who underwent p53 gene sequencing were included. Mutational analysis of exon 5 to exon 9 of the p53 gene was carried out using polymerase chain reaction-denaturing high performance liquid chromatography and direct sequencing.

Results

A total of 497 patients were eligible for the present study and p53 gene mutations were detected in 71 cases (14.3%). Mutation of p53 was significantly associated with histologic grading (p<0.001), estrogen receptor and progesterone receptor status (p<0.001), HER2 status (p<0.001), Ki-67 (p=0.028), and tumor size (p=0.004). The most frequent location of p53 mutations was exon 7 and missense mutation was the most common type of mutation. Compared with patients without mutation, there was a statistically significant difference in relapse-free survival of patients with p53 gene mutation and missense mutation (p=0.020, p=0.006, respectively). Only p53 missense mutation was an independent prognostic factor for relapse-free survival in multivariate analysis, with an adjusted hazard ratio of 2.29 (95% confidence interval, 1.08-4.89, p=0.031).

Conclusion

Mutation of the p53 gene was associated with more aggressive clinicopathologic characteristics and p53 missense mutation was an independent negative prognostic factor in Korean breast cancer patients.     

Phosphorylated AKT expression is associated with PIK3CA mutation, low stage, and favorable outcome in 717 colorectal cancers

BACKGROUND:

AKT (AKT1, AKT2, and AKT3) was a downstream effector of phosphatidylinositide‐3‐kinase (PI3K) and played crucial roles in protein synthesis, cellular metabolism, survival, and proliferation. The PI3K/AKT pathway was commonly activated in human cancers and was recognized as a potential target for anticancer therapy. Nonetheless, clinical, molecular, or prognostic features of AKT‐activated colon cancer remained uncertain.

METHODS:

Using a database of 717 colon and rectal cancers in the Nurses' Health Study and the Health Professionals Follow‐up Study, Ser473 phosphorylated AKT (p‐AKT) expression was detected in 448 (62%) tumors by immunohistochemistry. Cox proportional hazards model was used to compute mortality hazards ratio (HR), adjusting for clinical and tumoral features, including PIK3CA, KRAS, BRAF, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), LINE‐1 methylation, TP53 (p53), and FASN (fatty acid synthase).

RESULTS:

Tumor p‐AKT expression was associated with PIK3CA mutation (odds ratio [OR], 1.77; 95% confidence interval [CI], 1.12‐2.80; P = .015). p‐AKT expression was significantly associated with longer colorectal cancer‐specific survival in Kaplan‐Meier analysis (log‐rank P = .0005), univariate Cox regression (HR, 0.62; 95% CI, 0.47‐0.82; P = .0006) and multivariate analysis (adjusted HR, 0.75; 95% CI, 0.56‐0.99; P = .048) adjusting for clinical and molecular variables including PIK3CA, MSI, CIMP and LINE‐1 hypomethylation. p‐AKT expression was inversely associated with high stage (III‐IV) (adjusted OR, 0.63; 95% CI, 0.45‐0.88, P = .0071).

CONCLUSIONS:

p‐AKT expression in colorectal cancer is associated with low stage and good prognosis. p‐AKT may serve as a tissue biomarker to identify patients with superior prognosis and a possible therapeutic target (analogous to estrogen receptor ESR1 in breast cancer). Cancer 2011. © 2010 American Cancer Society.     

The Wnt/β-catenin pathway regulates growth and maintenance of colonospheres

Background  

Recent evidence suggests that epithelial cancers, including colorectal cancer are driven by a small sub-population of self-renewing, multi-potent cells termed cancer stem cells (CSCs) which are thought to be responsible for recurrence of cancer. One of the characteristics of CSCs is their ability to form floating spheroids under anchorage-independent conditions in a serum-free defined media. The current investigation was undertaken to examine the role of Wnt/β-catenin pathway in regulating the growth and maintenance of colonospheres. Human colon cancer cells HCT-116 (p53 wild type; K-ras mutant), HCT-116 (p53 null; K-ras mutant) and HT-29 (p53 mutant) were used.     

Clinical significance of the expression of connexin26 in colorectal cancer

Background

Connexin26 (Cx26) is one of the connexins (Cxs) family members which form gap junction channels. Cx26 is considered to be a tumor suppressor gene. However, recent studies revealed that over expression of Cx26 is associated with a poor prognosis in several human cancers. This study investigated the correlation between Cx26 expression and the clinicopathological features and P53 expression in colorectal cancer.

Methods

One hundred and fifty-three patients who underwent a curative resection were studied. Tissue samples were investigated by immunohistochemical staining using antibodies for Cx26 and P53. Moreover, apoptotic cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) staining.

Results

Cx26 expression was found in 83 cases (54.2%) and P53 expression in 71 cases (46.4%). A correlation was observed between the Cx26 expression and recurrence, histology, and p53 expression (P < 0.05). Cx26 positive tumors had significantly longer survival than Cx26 negative tumors (P < 0.05). A multivariate Cox analysis demonstrated that Cx26 expression was an independent prognostic factor (P < 0.05). However, no significant correlation was observed between Cx26 and AI.

Conclusion

This study suggests that Cx26 expression is an independent prognostic factor in patients that undergo a curative resection of colorectal cancer.