Alberto Morán

Cooperative role of telomerase activity and p16 expression in the prognosis of non-small-cell lung cancer.

PURPOSE: Telomerase activity and p16 expression can be considered two of the most important molecular markers implicated in tumorigenesis. Our main aim was to study the cooperative role of both molecular alterations in the prognosis of patients surgically resected for non–small-cell lung cancer (NSCLC). PATIENTS AND METHODS: We have determined telomerase activity and p16 expression in a series of 98 prospectively collected NSCLC specimens obtained from patients who had undergone surgery without other treatment. Telomerase activity was investigated by a telomeric repeat amplification protocol enzyme-linked immunosorbent assay–based procedure, and p16 expression was examined by Western blot. Associations with survival were evaluated. RESULTS: Positive results for telomerase activity were found in 82% of the cases, and this variable correlated with poor differentiation and recurrence of tumors. Lack of p16 expression was observed in 61% of tumors, and a significant association with tumor recurrence was also ...

Impairment of Stromelysin-1 Transcriptional Activity by Promoter Mutations in High Microsatellite Instability Colorectal Tumors

Colorectal tumorigenesis is characterized by the sequential inactivation of a series of tumor suppressor genes (microsatellite-stable tumors) and genetic or epigenetic alterations in mismatch repair genes in nonpoliposic hereditary tumours and 13% to 15% of sporadic colorectal cancer [high microsatellite instability (MSI-H) tumors]. We hypothesized a molecular mechanism for MSI-H colorectal tumors related to matrix metalloproteinase 3 (MMP-3) promoter mutations, down-regulation of MMP-3 expression, and impairment of MMP-9 activation. We have now analyzed the 2.2-kb full MMP-3 promoter to assess the mutation distribution. The mutations found are restricted to the polymorphic region that includes the zinc-binding protein (ZBP-89) binding element. To show that these alterations were the cause of the low expression of this gene, we have generated three constructs with different MMP-3 promoters (wild type and two mutants) and we have expressed them in SW480 human colorectal cells. The basal transcriptional activity of wild-type MMP-3 promoter was much higher than the mutants activity. In addition, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced transcriptional activity of wild-type MMP-3 promoter was 10-fold higher than the mutants activity. Dexamethasone inhibited the basal transcriptional activity of wild-type MMP-3 promoter and of the two mutants found in the MSI-H subgroup of colorectal tumors. Significantly, dexamethasone almost completely blunted the TPA-induced effect on wild-type MMP-3 promoter transcriptional activity and on the mutants, even below their basal activity. Our data show that mutations found in the polymorphic region of the MMP-3 promoter from MSI-H colorectal tumors impair its basal and induced transcriptional activity, which may contribute to their better clinical outcome.

Differential Wnt Pathway Gene Expression and E-Cadherin Truncation in Sporadic Colorectal Cancers with and without Microsatellite Instability

Purpose: Alterations in the Wnt pathway play a major role in colorectal cancer with high (MSI-H) or low microsatellite instability (MSS/MSI-L). However, the differential impact of the Wnt pathway components on these tumors is poorly understood. MMP-3 (stromelysin-1) promoter is a target of the mutator phenotype in sporadic colorectal cancer. Among MMP-3 targets, we investigated E-cadherin integrity status in both groups of tumors. Because beta-catenin is the main effector of the Wnt pathway, we have also investigated the differential cellular status of beta-catenin. Experimental Design: Expression profiles of 114 genes related to the Wnt pathway were analyzed by oligo microarrays in 48 tumors classified by their MSI status. In addition, we analyzed 48 sporadic colorectal cancers for E-cadherin integrity status. We performed investigation of beta-catenin and cyclin D1 by immunohistochemistry using tissue arrays containing 96 tumors. Results: Our data show that a group of genes that negatively regulate Wnt signaling are downregulated in MSS/MSI-L as compared with MSI-H colorectal tumors. E-cadherin truncation was significantly higher in MSS/MSI-L as compared with MSI-H tumors. Moreover, MSI-H tumors showed low or null beta-catenin nuclear presence, whereas the group of tumors classified as MSS or MSI-L displayed a high content of the nuclear beta-catenin location. Conclusions: Our results suggest that the differential expression of genes that negatively regulate the Wnt pathway, as well as the status of E-cadherin and beta-catenin in MSI-H or MSS/MSI-L colorectal tumors, shed some light on the different clinical behavior showed by the two groups.

Genomic organization of a novel glycosylphosphatidylinositol MAM gene expressed in human tissues and tumors

We report the genomic organization of a novel human gene mapped to chromosome 6p21, encoding a putative glycosylphosphatidylinositol (GPI) anchored protein containing a MAM (meprin, A5 antigen, protein tyrosine phosphatase μ) domain, that we have termed as GPIM (GPI and MAM) protein. GPIM gene consists of an 8.9 kb transcript composed of 17 coding exons spanning about 65.5 kb of genomic DNA. The deduced polypeptide consists of 955 amino acids and exhibits structural features found in different types of cell adhesion molecules (CAMs), such as the presence of immunoglobulin domains, the presence of a MAM domain or the capacity to anchor to the cell membrane by a GPI motif. Expression analysis in normal human tissues revealed that this gene is expressed as a 5 kb and 9.5 kb mRNA. Furthermore, the smaller transcript is highly expressed in some human cancer cell lines, as well as in different primary tumors (lung, colon, uterus, stomach and breast). Interestingly, the gene was higher expressed in several tumor tissues analysed as compared to their corresponding normal tissues. Thus, GPIM is a novel gene codifying a protein with structural features characteristics of some CAMs, which might be involved in the tumor progression.

Methylation profiling in non-small cell lung cancer: Clinical implications

The aim of this study was to identify a panel of methylation markers that distinguish non-small cell lung cancers (NSCLCs) from normal lung tissues. We also studied the relation of the methylation profile to clinicopathological factors in NSCLC. We collected a series of 46 NSCLC samples and their corresponding control tissues and analyzed them to determine gene methylation status using the Illumina GoldenGate Methylation bead array, which screens up to 1505 CpG sites from 803 different genes. We found that 120 CpG sites, corresponding to 88 genes were hypermethylated in tumor samples and only 17 CpG sites (16 genes) were hypomethylated when compared with controls. Clustering analysis of these 104 genes discriminates almost perfectly between tumors and normal samples. Global hypermethylation was significantly associated with a worse prognosis in stage IIIA NSCLC patients (P=0.012). Moreover, hypermethylation of the CALCA and MMP-2 genes were statistically associated to a poor clinical evolution of patients, independently of TNM tumor stage (P=0.06, RR=2.64; P=0.04, RR=2.96, respectively). However, hypermethylation of RASSF1 turned out to be a protective variable (P=0.02; RR=0.53). In conclusion, our results could be useful for establishing a gene methylation pattern for the detection and prognosis of NSCLC.

Loss of Heterozygosity at 3p23 Is Correlated with Poor Survival in Patients with Colorectal Carcinoma

Loss of heterozygosity (LOH) of chromosome 3p has been observed commonly in carcinomas of various tumor tissues, including colorectal carcinoma (CRC). Because there is no report analyzing 3p deletions in relation to patient prognosis in CRC, the authors investigated the prognostic value of LOH on 3p in 87 patients with sporadic CRC.

Telomere function in colorectal cancer

Colorectal cancer is the third most common form of cancer and the second leading cause of cancer-related death in the western world. Tumour cells acquire the hallmarks of cancer during the carcinogenic selection process. Cell immortality is one of the principal features acquired during this process which involves the stabilization of telomere length. It is achieved mainly, by telomerase activation. Thus, the discovery of telomeres and telomerase allowed an understanding of the mechanisms by which cells can become immortalized. Different studies have shown that tumour cells have shorter telomeres than nontumour cells and have detected telomerase activity in the majority of tumours. Survival studies have determined that telomere maintenance and telomerase activity are associated with poor prognosis. Taking into account all the results achieved by different groups, quantification and evaluation of telomerase activity and measurement of telomere length may be useful methods for additional biologic and prognostic staging of colorectal carcinoma.

Differential Expression of Senescence and Cell Death Factors in Non-Small Cell Lung and Colorectal Tumors Showing Telomere Attrition

Objective: The main aim of this work is to investigate the expression of factors related to senescence and cell death pathways in non-small cell lung cancers (NSCLCs) and colorectal cancers (CRCs) in relation to telomere status. Methods: We analyzed 158 tissue samples, 36 NSCLCs, 43 CRCs, and their corresponding control tissues obtained from patients submitted to surgery. Telomere function was evaluated by determining telomerase activity and telomere length. Expression of factors related to senescence, cell death pathways, transformation and tumorigenesis was investigated using arrays. Results were validated by real-time quantitative PCR. Results: Considering tumors with telomere shortening, expression for BNIP3, DAPK1, NDRG1, EGFR, and CDKN2A was significantly higher in NSCLC than in CRC, whereas TP53 was overexpressed in CRC with respect to NSCLC. Moreover, compared to nontumor samples, DAPK1, GADD45A, SHC1, and TP53 were downregulatedin the group of NSCLCs with telomere shortening, and no significant differences were found in CRC. Conclusions: In NSCLC, the failure of pathways which involve factors such as DAPK1, GADD45A, SHC1, and TP53, in response to short telomeres, could promote tumor progression. In CRC, the viability of these pathways in response to short telomeres could contribute to limiting tumorigenesis.