Prostaglandin E2 Promotes Colorectal Cancer Stem Cell Expansion and Metastasis in Mice

S100A8 facilitates the migration of colorectal cancer cells through regulating macrophages in the inflammatory microenvironment

Previous studies have shown that S100 calcium-binding protein A8 (S100A8) contributes to the survival and migration of colorectal cancer (CRC) cells. However, whether S100A8 participates in the progression and metastasis of CRC via the regulation of macrophages in the tumor inflammatory microenvironment remains unknown. In this study, phorbol myristate acetate (PMA) was used to induce the differentiation of THP-1 monocytes to macrophages. MTT assay, western blot analysis, immunofluorescence staining, semi-quantitative RT-PCR (semi-PCR), quantitative real-time PCR (qPCR), Gaussia luciferase activity assay and ELISA were performed to analyze the roles and molecular mechanisms of S100A8 in the modulation of macrophages. MTT assay, flow cytometric analysis, Hoechst staining, wound healing and Transwell migration assay were used to test the effect of S100A8 on the viability and migration of CRC cells co-cultured with macrophages in the inflammatory microenvironment. We found that THP-1 monocytes were induced by PMA and differentiated to macrophages. S100A8 activated the NF-κB pathway in the macrophages and promoted the expression of miR-155 and inflammatory cytokines IL-1β and TNF-α in the inflammatory microenvironment mimicked by lipopolysaccharides (LPS). Furthermore, S100A8 contributed to augment the migration but not the viability of the CRC cells co-cultured with the macrophages in the inflammatory microenvironment. Altogether, our study demonstrated that S100A8 facilitated the migration of CRC cells in the inflammatory microenvironment, and the underlying molecular mechanisms may be partially attributed to the overexpression of miR-155, IL-1β and TNF-α through activation of the NF-κB pathway in macrophages.

The NF-κB Pathway and Cancer Stem Cells

The NF-κB transcription factor pathway is a crucial regulator of inflammation and immune responses. Additionally, aberrant NF-κB signaling has been identified in many types of cancer. Downstream of key oncogenic pathways, such as RAS, BCR-ABL, and Her2, NF-κB regulates transcription of target genes that promote cell survival and proliferation, inhibit apoptosis, and mediate invasion and metastasis. The cancer stem cell model posits that a subset of tumor cells (cancer stem cells) drive tumor initiation, exhibit resistance to treatment, and promote recurrence and metastasis. This review examines the evidence for a role for NF-κB signaling in cancer stem cell biology.

Effects of NSAIDs on the risk factors of colorectal cancer: a mini review

Evidence from epidemiological and experimental studies has shown that non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer (CRC). The function of NSAIDs and the molecular targets for chemopreventive effects on CRC have been extensively studied and their data were reported. However, the relation between NSAIDs and the risk factors of CRC have not been fully elucidated yet. Thus, relations between NSAIDs and the risk factors of CRC, such as overweight and obesity, alcohol, aging, hypertriglyceridemia and smoking, are summarized with our data and with recent reported data in this review.

Inflammation in gastric cancer: Interplay of the COX-2/prostaglandin E2 and Toll-like receptor/MyD88 pathways

Cyclooxygenase‐2 (COX‐2) and its downstream product prostaglandin E₂ (PGE₂) play a key role in generation of the inflammatory microenvironment in tumor tissues. Gastric cancer is closely associated with Helicobacter pylori infection, which stimulates innate immune responses through Toll‐like receptors (TLRs), inducing COX‐2/PGE₂ pathway through nuclear factor‐κB activation. A pathway analysis of human gastric cancer shows that both the COX‐2 pathway and Wnt/β‐catenin signaling are significantly activated in tubular‐type gastric cancer, and basal levels of these pathways are also increased in other types of gastric cancer. Expression of interleukin‐11, chemokine (C‐X‐C motif) ligand 1 (CXCL1), CXCL2, and CXCL5, which play tumor‐promoting roles through a variety of mechanisms, is induced in a COX‐2/PGE₂ pathway‐dependent manner in both human and mouse gastric tumors. Moreover, the COX‐2/PGE₂ pathway plays an important role in the maintenance of stemness with expression of stem cell markers, including CD44, Prom1, and Sox9, which are induced in both gastritis and gastric tumors through a COX‐2/PGE₂‐dependent mechanism. In contrast, disruption of Myd88 results in suppression of the inflammatory microenvironment in gastric tumors even when the COX‐2/PGE₂ pathway is activated, indicating that the interplay of the COX‐2/PGE₂ and TLR/MyD88 pathways is needed for inflammatory response in tumor tissues. Furthermore, TLR2/MyD88 signaling plays a role in maintenance of stemness in normal stem cells as well as gastric tumor cells. Accordingly, these results suggest that targeting the COX‐2/PGE₂ pathway together with TLR/MyD88 signaling, which would suppress the inflammatory microenvironment and maintenance of stemness, could be an effective preventive or therapeutic strategy for gastric cancer.

MicroRNA MIR21 (miR-21) and PTGS2 Expression in Colorectal Cancer and Patient Survival

PURPOSE

Prostaglandin-endoperoxide synthase 2 (PTGS2, cyclooxygenase-2; a target of aspirin) produces inflammatory mediator prostaglandin E2 (PGE2), and contributes to colorectal neoplasia development. PTGS2-driven inflammatory responses can induce tumor expression of microRNA MIR21 (miR-21) that can increase local PGE2 level by downregulating PGE2-metabolizing enzymes. We hypothesized that the prognostic association of tumor MIR21 expression level in colorectal carcinoma might depend on inflammatory tumor microenvironment and be stronger in tumors expressing high-level PTGS2.

EXPERIMENTAL DESIGN

Utilizing 765 rectal and colon cancer specimens in the Nurses' Health Study and the Health Professionals Follow-up Study, we measured MIR21 expression by quantitative reverse transcription PCR, and PTGS2 expression by immunohistochemistry. Cox proportional hazards regression model was used to assess statistical interaction between MIR21 and PTGS2 in colorectal cancer-specific survival analysis, controlling for potential confounders including microsatellite instability, CpG island methylator phenotype, LINE-1 methylation level, and KRAS, BRAF, and PIK3CA mutations.

RESULTS

Tumor MIR21 expression level was associated with higher colorectal cancer-specific mortality (Ptrend = 0.029), and there was a statistically significant interaction between MIR21 and PTGS2 (Pinteraction = 0.0004). The association between MIR21 expression and colorectal cancer-specific mortality was statistically significant in PTGS2-high cancers (multivariable hazard ratio of the highest vs. lowest quartile of MIR21, 2.28; 95% confidence interval, 1.42-3.67; Ptrend = 0.0004) but not in PTGS2-absent/low cancers (Ptrend = 0.22).

CONCLUSIONS

MIR21 expression level in colorectal carcinoma is associated with worse clinical outcome, and this association is stronger in carcinomas expressing high-level PTGS2, suggesting complex roles of immunity and inflammation in tumor progression. Clin Cancer Res; 22(15); 3841-8. ©2016 AACR.

Obesity and colorectal cancer: molecular features of adipose tissue

The huge part of population in developed countries is overweight or obese. Obesity is often determined by body mass index (BMI) but new accurate methods and ratios have recently appeared to measure body fat or fat located in the intestines. Early diagnosis of obesity is crucial since it is considered an increasing colorectal cancer risk factor. On the one hand, colorectal cancer has been strongly associated with lifestyle factors. A diet rich in red and processed meats may increase colorectal cancer risk; however, high-fiber diets (grains, cereals and fruits) have been associated with a decreased risk of colorectal cancer. Other life-style factors associated with obesity that also increase colorectal cancer risk are physical inactivity, smoking and high alcohol intake. Cutting-edge studies reported that high-risk transformation ability of adipose tissue is due to production of different pro-inflammatory cytokines like IL-8, IL-6 or IL-2 and other enzymes like lactate dehydrogenase (LDH) and tumour necrosis factor alpha (TNFα). Furthermore, oxidative stress produces fatty-acid peroxidation whose metabolites possess very high toxicities and mutagenic properties. 4-hydroxy-2-nonenal (4-HNE) is an active compounds that upregulates prostaglandin E2 which is directly associated with high proliferative colorectal cancer. Moreover, 4-HNE deregulates cell proliferation, cell survival, differentiation, autophagy, senescence, apoptosis and necrosis via mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PIK3CA)—AKT and protein kinase C pathways. Other product of lipid peroxidation is malondialdehyde (MDA) being able to regulate insulin through WNT-pathway as well as having demonstrated its mutagenic capability. Accumulation of point mutation enables genomic evolution of colorectal cancer described in the model of Fearon and Vogelstein. In this review, we will summarize different determination methods and techniques to assess a truthfully diagnosis and we will explain some of the capabilities that performs adipocytes as the largest endocrine organ.

Epigenetic and Immune Regulation of Colorectal Cancer Stem Cells

Colorectal cancer stem cells (CSCs) were initially considered to be a subset of undifferentiated tumor cells with well-defined phenotypic and molecular markers. However, emerging evidence indicates instead that colorectal CSCs are heterogeneous subsets of tumor cells that are continuously reshaped by the dynamic interactions between genetic, epigenetic, and immune factors in the tumor microenvironment. Thus, the colorectal CSC phenotypes and responsiveness to therapy may not only be a tumor cell-intrinsic feature, but also depend on tumor-extrinsic microenvironmental factors. Furthermore, emerging evidence also implicates colorectal CSCs in potential immune evasion. Therefore, understanding how colorectal CSC-intrinsic mechanisms cooperate with the extrinsic microenvironmental factors to dynamically shape colorectal CSC resistance to chemotherapy and immunotherapy holds great promise for development of targeted CSC therapies of advanced human CRC.