Several components of the Wnt signaling cascade have been shown to function either as tumor suppressor proteins or as oncogenes in multiple human cancers, underscoring the relevance of this pathway ...in oncogenesis and the need for further investigation of Wnt signaling components as potential targets for cancer therapy. Here, using expression profiling analysis as well as in vitro and in vivo functional studies, we show that the Wnt pathway component BCL9 is a novel oncogene that is aberrantly expressed in human multiple myeloma as well as colon carcinoma. We show that BCL9 enhances beta-catenin-mediated transcriptional activity regardless of the mutational status of the Wnt signaling components and increases cell proliferation, migration, invasion, and the metastatic potential of tumor cells by promoting loss of epithelial and gain of mesenchymal-like phenotype. Most importantly, BCL9 knockdown significantly increased the survival of xenograft mouse models of cancer by reducing tumor load, metastasis, and host angiogenesis through down-regulation of c-Myc, cyclin D1, CD44, and vascular endothelial growth factor expression by tumor cells. Together, these findings suggest that deregulation of BCL9 is an important contributing factor to tumor progression. The pleiotropic roles of BCL9 reported in this study underscore its value as a drug target for therapeutic intervention in several malignancies associated with aberrant Wnt signaling.
Genes induced in colon cancer provide novel candidate biomarkers of tumor phenotype and aggressiveness. We originally identified KIAA1199 (now officially called CEMIP) as a transcript highly induced ...in colon cancer: initially designating the transcript as Colon Cancer Secreted Protein 1. We molecularly characterized CEMIP expression both at the mRNA and protein level and found it is a secreted protein induced an average of 54-fold in colon cancer. Knockout of CEMIPreduced the ability of human colon cancer cells to form xenograft tumors in athymic mice. Tumors that did grow had increased deposition of hyaluronan, linking CEMIP participation in hyaluronan degradation to the modulation of tumor phenotype. We find CEMIP mRNA overexpression correlates with poorer patient survival. In stage III only (n = 31) or in combined stage II plus stage III colon cancer cases (n = 73), 5-year overall survival was significantly better (p = 0.004 and p = 0.0003, respectively) among patients with low CEMIP expressing tumors than those with high CEMIP expressing tumors. These results demonstrate that CEMIP directly facilitates colon tumor growth, and high CEMIP expression correlates with poor outcome in stage III and in stages II+III combined cohorts. We present CEMIP as a candidate prognostic marker for colon cancer and a potential therapeutic target.
The TGF beta type II receptor (RII) was found to be mutated within a polyadenine tract in 100 of 111 (90%) colorectal cancers with microsatellite instability. Other polyadenine tracts of similar ...length were mutated in these samples but not as frequently as RII. In most cases, the polyadenine tract mutations affected both alleles of RII, and in four tumors heterozygous for the polyadenine mutations, three had additional mutations that were expected to inactivate the other RII allele. These genetic data support the idea that RII behaves like a tumor suppressor during CR cancer development and is a critical target of inactivation in mismatch repair-deficient tumors.
We previously demonstrated that mutational inactivation of transforming growth factor beta type II receptors (RIIs) is very common among the 13% of human colon cancers with microsatellite ...instability. These mutations principally cluster in the BAT-RII polyadenine sequence repeat. Among microsatellite stable (MSS) colon cancers, we now find that non-BAT-RII point mutations inactivate RII in another 15% of cases, thus doubling the known number of colon cancers in which RII mutations are pathogenetic. Functional analysis confirms that these mutations inactivate RII signaling. Moreover, another 55% of MSS colon cancers demonstrate a transforming growth factor beta signaling blockade distal to RII. The transforming growth factor beta pathway and RII in particular are major targets for inactivation in MSS colon cancers as well as in colon cancers with microsatellite instability.
The murine nm23 gene suppresses the metastatic behavior of malignant rodent tumor lines, and reduced nm23 expression correlates with increased likelihood of lymph node metastases in human breast ...cancers. More recent data have demonstrated the existence of two human nm23 gene homologues, nm23-H1 and nm23-H2, and have shown that deletion of nm23-H1 alleles occurs in some colon carcinomas associated with poor prognosis. These findings suggest that nm23-H1 encodes for suppression of colon carcinoma metastasis. In contrast, we have previously reported that total nm23 messenger RNA (mRNA) expression is increased to similar levels in colon tumors of both high and low metastatic potential.
This study was designed to reconcile our previous findings with the recent report of nm23-H1 allelic deletion in human colon cancers associated with poor prognosis. Our purpose was to examine human colon cancers for inactivation of two candidate metastasis suppressor genes, nm23-H1 and nm23-H2, either by mutation or by loss of gene transcription.
We used ribonuclease protection assays to analyze human colon tumors for the level of nm23-H1 (43 samples) and nm23-H2 (41 samples) transcript (mRNA) expression and the presence of mutations that could inactivate potential suppressor function.
We detected only wild-type nm23-H1 and nm23-H2 mRNA. Expression of nm23-H1 mRNA increased in 33 of 41 colon tumors, and expression of nm23-H2 mRNA was elevated in 28 of 41 colon tumors relative to that in matched normal mucosa. Increases in these mRNA levels were similar in tumors of both low and high metastatic potential.
These results suggest that, despite correlation of nm23-H1 allelic deletions with colon cancers associated with poor prognosis, nm23-H1 and nm23-H2 alleles do not directly mediate metastasis suppression in colon carcinoma. Our results leave unexplained the observation that nm23-H1 allelic deletion correlates with metastatic potential of colon carcinomas.
These findings also contrast with the demonstration of nm23 metastasis suppressor activity in murine melanoma and with the correlation of loss of nm23 expression in breast cancer with poor prognosis. It may be that metastasis suppression by the nm23 gene is a tissue-specific phenomenon.
We have recently demonstrated that mutation of the transforming growth factor-beta (TGF-beta) receptor type II (RII) gene is characteristic of colon cancers exhibiting microsatellite instability or ...replication errors (RER+). Moreover, we have shown that RII mutations in these RER+ colon cancers are characteristically frameshift mutations within a 10-bp polyadenine repeat present in the RII-coding region. We now show that RII gene mutations in this polyadenine repeat are also commonly present in RER+ gastric cancers (71%). In contrast, we find these same RII gene mutations are distinctly uncommon in RER+ endometrial cancers (17%, P < 0.02). These results suggest that RII gene mutations confer a growth advantage and are selected for in RER+ cancers of both the upper and lower gastrointestinal tract. The genesis of RER+ endometrial tumors must, however, be by a different route.
Background: Increased DNA methylation is an epigenetic alteration that is common in human cancers and is often associated with transcriptional silencing. Aberrantly methylated DNA has also been ...proposed as a potential tumor marker. However, genes such as vimentin, which are transcriptionally silent in normal epithelium, have not until now been considered as targets for cancer-associated aberrant methylation and for use as cancer markers. Methods: We applied methylation-specific polymerase chain reaction to the vimentin gene, which is transcriptionally silent in normal colonocytes, and compared methylation of vimentin exon 1 in cancer tissues and in fecal DNA from colon cancer patients versus control samples from healthy subjects. Results: Vimentin exon-1 sequences were unmethylated in 45 of 46 normal colon tissues. In contrast, vimentin exon-1 sequences were methylated in 83% (38 of 46) and 53% (57 of 107) of tumors from two independently collected groups of colon cancer patients. When evaluated as a marker for colon cancer detection in fecal DNA from another set of colon cancer patients, aberrant vimentin methylation was detected in fecal DNA from 43 of 94 patients, for a sensitivity of 46% (95% confidence interval CI = 35% to 56%). The sensitivity for detecting stage I and II cancers was 43% (26 of 60 case patients) (95% CI = 31% to 57%). Only 10% (20 of 198 case patients) of control fecal DNA samples from cancer-free individuals tested positive for vimentin methylation, for a specificity of 90% (95% CI = 85% to 94%). Conclusions: Aberrant methylation of exon-1 sequences within the nontranscribed vimentin gene is a novel molecular biomarker of colon cancer and can be successfully detected in fecal DNA to identify nearly half of individuals with colon cancer.
Nm23--into the basement (membrane) Myeroff, L L; Markowitz, S D
JNCI : Journal of the National Cancer Institute,
1994-Dec-21, Letnik:
86, Številka:
24
Journal Article
HLTF Gene Silencing in Human Colon Cancer Moinova, Helen R.; Wei-Dong-Chen; Shen, Lanlan ...
Proceedings of the National Academy of Sciences - PNAS,
04/2002, Letnik:
99, Številka:
7
Journal Article
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Chromatin remodeling enzymes are increasingly implicated in a variety of important cellular functions. Various components of chromatin remodeling complexes, including several members of the SWI/SNF ...family, have been shown to be disrupted in cancer. In this study we identified as a target for gene inactivation in colon cancer the gene for helicase-like transcription factor (HLTF), a SWI/SNF family protein. Loss of HLTF expression accompanied by HLTF promoter methylation was noted in nine of 34 colon cancer cell lines. In these cell lines HLTF expression was restored by treatment with the demethylating agent 5-azacytidine. In further studies of primary colon cancer tissues, HLTF methylation was detected in 27 of 63 cases (43%). No methylation of HLTF was detected in breast or lung cancers, suggesting selection for HLTF methylation in colonic malignancies. Transfection of HLTF suppressed 75% of colony growth in each of three different HLTF-deficient cell lines, but showed no suppressive effect in any of three HLTF-proficient cell lines. These findings show that HLTF is a common target for methylation and epigenetic gene silencing in colon cancer and suggest HLTF is a candidate colon cancer suppressor gene.
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