生物信息学分析筛选结直肠癌靶基因及评估预后价值

为寻找与结直肠癌发展和预后相关的潜在关键基因及信号通路.从美国国立信息中心NCBI的GEO数据库获得结直肠癌基因表达数据集GSE106582,通过PCA对样本进行分组,利用GEO2R进行综合分析,筛选结直肠癌与癌旁对照组的差异表达基因;通过DAVID在线工具对差异表达基因进行GO本体分析和KEGG通路富集分析,初步分析...     

Apical membrane localization of the adenomatous polyposis coli tumor suppressor protein and subcellular distribution of the beta-catenin destruction complex in polarized epithelial cells

The adenomatous polyposis coli (APC) protein is implicated in the majority of hereditary and sporadic colon cancers. APC is known to function as a tumor suppressor through downregulation of beta-catenin as part of a high molecular weight complex known as the beta-catenin destruction complex. The molecular composition of the intact complex and its site of action in the cell are still not well understood. Reports on the subcellular localization of APC in various cell systems have differed significantly and have been consistent with an association with a cytosolic complex, with microtubules, with the nucleus, or with the cortical actin cytoskeleton. To better understand the role of APC and the destruction complex in colorectal cancer, we have begun to characterize and isolate these complexes from confluent polarized human colon epithelial cell monolayers and other epithelial cell types. Subcellular fractionation and immunofluorescence microscopy reveal that a predominant fraction of APC associates tightly with the apical plasma membrane in a variety of epithelial cell types. This apical membrane association is not dependent on the mutational status of either APC or beta-catenin. An additional pool of APC is cytosolic and fractionates into two distinct high molecular weight complexes, 20S and 60S in size. Only the 20S fraction contains an appreciable portion of the cellular axin and small but detectable amounts of glycogen synthase kinase 3beta and beta-catenin. Therefore, it is likely to correspond to the previously characterized beta-catenin destruction complex. Dishevelled is almost entirely cytosolic, but does not significantly cofractionate with the 20S complex. The disproportionate amount of APC in the apical membrane and the lack of other destruction complex components in the 60S fraction of APC raise questions about whether these pools of APC take part in the degradation of beta-catenin, or alternatively, whether they could be involved in other functions of the protein that still must be determined.     

Immunization with a plant-produced colorectal cancer antigen

Cancer vaccination has become an important focus of oncology in recent years. Active immunization with tumor-associated antigens such as colorectal cancer antigen GA733-2 is thought to potentially overcome the reoccurrence of metastasis. As recombinant protein production in bioreactors is costly and subject to growing safety concerns, we tested plants as an alternative for the expression of a potential colorectal cancer vaccine. Comparing colorectal cancer antigen GA733-2 produced in tobacco plants with the same antigen produced in insect cell culture, we found a similar humoral immune response to injection of either of the two antigen preparations into mice. Some minor differences were observed in the cellular response that might be due to impurities. Our studies compare for the first time, immunization with the same antigen expressed in either plants or insect cell culture. This will provide important data for use of plants as production systems of therapeutics.     

PPARalpha agonists stimulate progastrin production in human colorectal carcinoma cells

The three subtypes of peroxisome proliferator activated-receptors (PPARalpha, delta and gamma) control the storage and metabolism of fatty acids. Treatment of rats with the PPARalpha ligand ciprofibrate increases serum gastrin concentrations, and several lines of evidence suggest that non-amidated gastrins act as growth factors for the colonic mucosa. The aim of the present study was to investigate the expression of PPARs and the effect of PPAR ligands on gastrin production and cell proliferation in human colorectal carcinoma (CRC) cell lines. mRNAs for all three PPAR subtypes were detected by PCR in all CRC cell lines tested. The concentrations of progastrin, but not of glycine-extended or amidated gastrin, measured by radioimmunoassay in LIM 1899 conditioned media and cell extracts were significantly increased by treatment with the PPARalpha ligand clofibrate. Similar increases in progastrin were seen following treatment with the PPARalpha ligands ciprofibrate and fenofibrate, but not with bezafibrate, gemfibrozil or Wy 14643. The PPARgamma agonist rosiglitazone had no significant effect on progastrin production. The PPARalpha ligand clofibrate also stimulated proliferation of the LIM 1899 cell line. We conclude that some PPARalpha ligands increase progastrin production by the human CRC cell line LIM 1899, and that clofibrate increases proliferation of LIM 1899 cells. These studies have revealed a relationship between PPARs and gastrin, two regulatory molecules implicated in the pathogenesis of CRC.     

Proteome analysis of human colon cancer by two-dimensional difference gel electrophoresis and mass spectrometry

Two-dimensional difference gel electrophoresis (2-D DIGE) coupled with mass spectrometry (MS) was used to investigate tumor-specific changes in the proteome of human colorectal cancers and adjacent normal mucosa. For each of six patients with different stages of colon cancer, Cy5-labeled proteins isolated from tumor tissue were combined with Cy3-labeled proteins isolated from neighboring normal mucosa and separated on the same 2-D gel along with a Cy2-labeled mixture of all 12 normal/tumor samples as an internal standard. Over 1500 protein spot-features were analyzed in each paired normal/tumor comparison, and using DIGE technology with the mixed-sample internal standard, statistically significant quantitative comparisons of each protein abundance change could be made across multiple samples simultaneously without interference due to gel-to-gel variation. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and tandem (TOF/TOF) MS provided sensitive and accurate mass spectral data for database interrogation, resulting in the identification of 52 unique proteins (including redundancies due to proteolysis and post-translationally modified isoforms) that were changing in abundance across the cohort. Without the benefit of the Cy2-labeled 12 sample mixture internal standard, 42 of these proteins would have been overlooked due to the large degree of variation inherent between normal and tumor samples.     

Role of Smad4 (DPC4) inactivation in human cancer

The tumor suppressor gene Smad4 (DPC4) at chromosome 18q21.1 belongs to the Smad family, which mediates the TGFbeta signaling pathway suppressing epithelial cell growth. This review summarizes the mutational events of the Smad4 gene in human cancer. The Smad4 gene is genetically responsible for familial juvenile polyposis, an autosomal dominant disease characterized by predisposition to gastrointestinal polyps and cancer. In this syndrome, polyps are formed by inactivation of the Smad4 gene through germline mutation and loss of the unaffected wild-type allele. In pancreatic and colorectal cancer, inactivation of the Smad4 gene through homozygous deletion or intragenic mutation occurs frequently in association with malignant progression. However, mutation of this gene is seen only occasionally in the rest of human cancers. The majority of Smad4 gene mutations in human cancer are missense, nonsense, and frameshift mutations at the mad homology 2 region (MH2), which interfere with the homo-oligomer formation of Smad4 protein and the hetero-oligomer formation between Smad4 and Smad2 proteins, resulting in disruption of TGFbeta signaling. Supporting evidence for the above observation was provided by genetically manipulated mice carrying either a heterozygote of the Smad4 gene or a compound heterozygote of the Smad4 and APC genes, which develop either gastrointestinal polyps/cancer mimicking familial juvenile polyposis or progressed colorectal cancer, respectively.     

Altered mucin expression in the gastrointestinal tract: a review

Early studies of changes in mucin expression in disorders of the gastrointestinal tract focused on alterations in the carbohydrate chain. This review briefly considers the various mechanisms by which such alterations may come about: (a) normal variation, (b) sialic acid alterations, (c) defective assembly of carbohydrate side-chains, (d) changed expression of core proteins and (e) epithelial metaplasia. The availability of monoclonal antibodies to mucin core proteins adds a new dimension to mucin histochemistry. It is now possible to offer explanations for traditional mucin histochemical findings on the basis of lineage-specific patterns of mucin core protein expression. Changes in core protein expression are described in inflammatory, metaplastic and neoplastic disorders of the gastrointestinal tract. The possibility that mucin change could be important in the aetiology of some diseases such as ulcerative colitis and H. pylori gastritis is considered. It is more probable, however, that changes in mucin expression are secondary to reprogramming of cellular differentiation and altered cell turnover. As such they may serve as markers to explain pathogenesis and provide novel diagnostic and prognositc information.     

Cerivastatin enhances the cytotoxicity of 5-fluorouracil on chemosensitive and resistant colorectal cancer cell lines

Cerivastatin is one of the synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors used for the treatment and prevention of hypercholesterolaemia. The observation that patients receiving this drug had a lower incidence at cancer led to our interest in using it as a putative anticancer agent. In this study, we tested the cytotoxicity of cerivastatin on a panel of 5-fluorouracil (5FU) sensitive and resistant cell lines in vitro. Cerivastatin was cytotoxic to both 5FU sensitive and resistant cells. Cerivastatin significantly augmented the cytotoxic effect of 5FU on drug sensitive (6-22-fold) and resistant (229-310-fold) cell lines. Cerivastatin and 5FU acted synergistically. Cerivastatin inhibited nuclear factor kappaB DNA binding activity. The enhancing effect of cerivastatin on 5FU was partially mevalonate pathway independent. Cerivastatin may allow successful 5FU therapy in chemoresistant patients.     

The disturbances of the zinc concentration in the blood in selected neoplasms

A study was carried out on 92 patients (58 males and 34 females) aged 42–76 treated for malignant neoplasm of the gastrointestinal tract (54 patients with colorectal carcinoma, 38 with gastric carcinoma). In all patients, the zinc serum concentration was measured and the results obtained were referred to some epidemiological-clinical factors (sex, age, primary cause of cancer, the stage of clinical progression, and histological type). The results showed that the most pronounced hypozincemia occurred in male patients with mucous membrane carcinoma of the stomach.     

Phase I trial of interleukin-2 and high-dose arginine butyrate in metastatic colorectal cancer

Interleukin-2 (IL-2) and sodium butyrate allow rats to be cured of peritoneal carcinomatosis from colon cancer. We performed a phase I trial of IL-2 and high-dose arginine butyrate (ArgB) in patients with advanced metastatic colorectal cancer. Patients and methods: From April to July 1997, six patients were included in the trail; they had a median age of 52 years, four had a performance status of 0, two had a performance status of 1 with normal biological functions. All patients had received at least two prior lines of chemotherapy. A fixed dose of 18 MIU/m² IL-2,was administered by subcutaneous injection and ArgB was delivered via continuous intravenous infusion on days 1–6 with escalating doses starting at 2 g kg⁻¹ day⁻¹. Results: The planned dose escalation was not possible because of toxicities. A daily ArgB dose of 2 g/kg was delivered for nine cycles. Level 2 (4 g/kg) could not be delivered in three of the six patients because of liver toxicity. The dose-limiting toxicities were fatigue and liver function disturbances. The maximum tolerated dose for ArgB was 3 g kg⁻¹ day⁻¹, in combination with IL-2 at 12 MIU m² day⁻¹. No clinical response was seen. Pharmacokinetic analysis showed large intra- and interindividual variations. Conclusion: This schedule with a high dose of ArgB proved to be highly toxic with liver insufficiency. We will be running another trial with lower doses of ArgB calculated from the schedule used in the experimental model, starting at a dose of 20 mg kg⁻¹ day⁻¹ for ArgB and 200 000 UI kg⁻¹ day⁻¹ IL-2, every 8 h. Received: 13 May 1999 / Accepted: 28 October 1999