The NOTCH4-GATA4-IRG1 axis as a novel target in early-onset colorectal cancer

The early onset of colorectal cancer (CRC) in individuals younger than 50 years is an emerging phenomenon, and obesity is a strong risk factor. Inflammatory mechanisms are mediated by immune cells, with macrophages and their phenotypical changes playing a significant role in CRC. Obesity-related hormones, such as leptin and adiponectin, affect macrophage polarization and cytokine expression. Macrophage metabolism, and therefore polarization, directly affects tumor progression and survival in patients with CRC. Altered obesity-related hormone levels induce phosphoinositide kinase-3 (PI3K)/serine-threonine-protein kinase (AKT) activation in colon cancer, causing increased cell survival, hyperplasia, and proliferation. Investigating the effects of obesity-related mechanisms on PI3K/Akt signaling can provide new insights for targeting mechanisms in CRC and obesity among the young. Central molecules for the control of cell proliferation, differentiation, and tumorigenesis within the gastrointestinal tract include downstream targets of the PI3K/AKT pathway, such as Neurogenic locus notch homolog 4 (Notch4) and GATA binding proteins (GATA). Leptin and adiponectin both alter gene expression within this pathway, thereby affecting TAM-mediated CRC progression. Our goal is to introduce the NOTCH4-GATA4-IRG1 axis as a link between inflammation and sporadic CRC and to discuss this pathway as a new potential immunotherapeutic target in individuals affected with obesity and early-onset CRC.     

METTL3介导EZH2 m6A修饰在结直肠癌5-氟尿嘧啶耐药中的作用机制研究

摘要 目的：探讨甲基转移酶样蛋白3（METTL3）在5-氟尿嘧啶耐药中的作用机制。方法：大剂量间歇诱导法建立5-FU耐药细胞株。在耐药组细胞中分别敲减METTL3及EZH2抑制GSK343处理。qPCR及Western blot检测METTL3和EZH2表达。CCK-8检测各组细胞增殖情况。m6A甲基化RNA免疫沉淀技术分析EZH2 mRNA m6A修饰修饰情况。结果：各药物浓度处理下的耐药组细胞增殖活性与未处理细胞无显著差异（P>0.05）而原代细胞组肠癌细胞较未处理细胞在0.5-10 μg/mL处理下细胞增殖活性显著减低（P<0.01）。耐药组细胞与原代细胞组相比,METTL3及EZH2表达水平显著升高（P<0.01）。耐药组细胞METTL3敲减后或GSK343处理后,在0.5 μg/mL-10 μg/mL浓度间下的细胞增殖活性与0 μg/mL处理细胞增殖活性相比显著减低（P<0.05）。耐药组细胞METTL3敲减细胞的EZH2表达与对照细胞比,显著下调（P<0.01）。m6A甲基化RNA免疫沉淀实验显示耐药组细胞METTL3敲减细胞的EZH2 mRNA m6A修饰水平（m6A富集度为6361.95±67.47%）,较未敲减细胞修饰水平（396.30±57.74）显著减低（P<0.01）。结论：METTL3在肠癌细胞5-FU耐药抵抗中起到关键作用,靶向抑制METTL3有望成为缓解肠癌耐药的重要分子靶点。     

宫腔镜下电切术与刮宫术治疗子宫内膜息肉合并不孕症的疗效比较及术后妊娠的影响因素分析

摘要 目的：比较宫腔镜下电切术与宫腔镜下刮宫术治疗子宫内膜息肉合并不孕症的疗效,并分析术后妊娠的影响因素。方法：选取2018年10月～2020年9月我院收治的318例子宫内膜息肉合并不孕症患者,其中接受宫腔镜下电切术治疗的159例归为电切术组,接受宫腔镜下刮宫术治疗的159例归为刮宫术组,术后均随访12个月,比较两组手术相关指标、子宫内膜厚度、月经量和围术期并发症、息肉复发率、临床妊娠率,多因素Logistic回归分析术后妊娠的影响因素。结果：电切术组术中出血量低于刮宫术组（P＜0.05）,两组患者手术时间、住院时间比较无差异（P＞0.05）。两组患者术后12个月子宫内膜厚度较术前降低,且电切术组术后子宫内膜厚度低于刮宫术组（P＜0.05）。两组患者术后1个月、术后3个月月经量较术前逐渐减少,且电切术组较刮宫术组变化更明显（P＜0.05）。电切术组息肉复发率低于刮宫术组,而临床妊娠率高于刮宫术组（P＜0.05）,两组患者围术期并发症总发生率比较差异无统计学意义（P＞0.05）。多因素Logistic回归分析结果显示,年龄≥35岁、多发息肉、息肉直径≥1 cm、宫角息肉、术后子宫内膜厚度≥13 mm、术后息肉复发是影响子宫内膜息肉合并不孕症患者术后妊娠的危险因素（P＜0.05）。结论：宫腔镜下电切术治疗子宫内膜息肉合并不孕症患者疗效较宫腔镜下刮宫术更为显著,其术后妊娠率受年龄、息肉类型、息肉直径、息肉部位、术后子宫内膜厚度、术后息肉复发等因素影响。     

TRPC1 and ORAI1 channels in colon cancer

Colon cancer cells, like other types of cancer cells, undergo the remodeling of the intracellular Ca²⁺ homeostasis that contributes to cancer cell hallmarks including enhanced cell proliferation, migration, and survival. Colon cancer cells display enhanced store-operated Ca²⁺ entry (SOCE) compared with their non-cancer counterparts. Colon cancer cells display an abnormal expression of SOCE molecular players including Orai1 and TRPC1 channels, and the stromal interacting molecule (STIM) 1 and 2. Interestingly, upregulation of Orai1 and TRPC1 channels and their contribution to SOCE are associated with cancer malignancy in colon cancer cells. In a specific cellular model of colon cancer, whereas in non-cancer colon cells SOCE is composed of the Ca²⁺ release activated (CRAC) currents, in colon cancer cells SOCE is composed of CRAC- and cationic, non-selective store operated (SOC) currents. Former SOCs are mediated by TRPC1 channels. Moreover, colon cancer cells also display dysregulation of the expression of 1,4,5-triphosphate receptors (IP₃R) that could contribute to the enhanced SOCE. Another important factor underlying the enhanced SOCE is the differential mitochondrial modulation of the CRAC and SOC currents in non-cancer and colon cancer cells. In colon cancer cells, mitochondria take up more Ca²⁺ that prevent the Ca²⁺-dependent inactivation of the SOCs, leading to sustained Ca²⁺ entry. Notably, the inhibition of SOCE in cancer colon cells abolishes their cancer hallmarks. Robust evidence has shown the efficiency of non-steroidal anti-inflammatory drugs (NSAIDs) and difluoromethylornithine (DFMO) to reverse the enhanced cell proliferation, migration, and apoptosis resistance of cancer cells. In colon cancer cells, both NSAIDs and DFMO decrease SOCE, but they target different molecular components of SOCE. NSAIDs decrease the Ca²⁺ uptake by mitochondria, limiting their ability to prevent the Ca²⁺-dependent inactivation of the SOCs that underlie SOCE. On the other hand, DFMO inhibits the expression of TRPC1 channels in colon cancer cells, eliminating their contribution to SOCE. The identification of players of SOCE in colon cancer cells may help to better understand the remodeling of the Ca²⁺ homeostasis in cancer. Importantly, the use of different pharmacological tools that target different SOCE molecular players in colon cancer cells may play a pivotal role in designing better chemoprevention strategies.     

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.