Mechanism of counterattack of colorectal cancer cell by Fas/Fas ligand system

Gut microbiome: decision-makers in the microenvironment of colorectal cancer

Colorectal cancer (CRC) is a common malignancy of the gastrointestinal tract, accounting for the second most common cause of gastrointestinal tumors. As one of the intestinal barriers, gut bacteria form biofilm, participate in intestinal work, and form the living environment of intestinal cells. Metagenomic next-generation sequencing (mNGS) of the gut bacteria in a large number of CRC patients has been established, enabling specific microbial signatures to be associated with colorectal adenomato-carcinoma. Gut bacteria are involved in both benign precursor lesions (polyps), in situ growth and metastasis of CRC. Therefore, the term tumorigenic bacteria was proposed in 2018, such as Escherichia coli, Fusobacterium nucleatum, enterotoxigenic Bacteroides fragilis, etc. Meanwhile, bacteria toxins (such as cytolethal distending toxin (CDT), Colibactin (Clb), B. fragilis toxin) affect the tumor microenvironment and promote cancer occurrence and tumor immune escape. It is important to note that there are differences in the bacteria of different types of CRC. In this paper, the role of tumorigenic bacteria in the polyp-cancer transformation and the effects of their secreted toxins on the tumor microenvironment will be discussed, thereby further exploring new ideas for the prevention and treatment of CRC.

Unveiling immunogenic cell death-related genes in colorectal cancer: an integrated study incorporating transcriptome and Mendelian randomization analyses

Immunogenic cell death (ICD), a type of cell death that activates the tumor-specific immune response and thus exerts anti-tumor effects, is an emerging target in tumor therapy, but research on ICD-related genes (ICDGs) in colorectal cancer (CRC) remains limited. This study aimed to identify the CRC-specific ICDGs and explore their potential roles. Through RNA sequencing for tissue samples from CRC patients and integration with The Cancer Genome Atlas (TCGA) data, we identified 33 differentially expressed ICDGs in CRC. We defined the ICD score based on these genes in single-cell data, where a high score indicated an immune-active microenvironment. Additionally, molecular subtypes identified in bulk RNA data showed distinct immune landscapes. The ICD-related signature constructed with machine learning effectively distinguished patients' prognosis. The summary data-based Mendelian randomization (SMR) and colocalization analysis prioritized CFLAR for its positive association with CRC risk. Molecular docking revealed its stable binding with chemotherapeutic drugs like irinotecan. Furthermore, experimental validation confirmed CFLAR overexpression in CRC samples, and its knockdown inhibited tumor cell proliferation. Overall, this study expands the understanding of the potential roles and mechanisms of ICDGs in CRC and highlights CFLAR as a promising target for CRC.

Natural compounds regulate the PI3K/Akt/GSK3β pathway in myocardial ischemia-reperfusion injury

The PI3K/Akt/GSK3β pathway is crucial in regulating cardiomyocyte growth and survival. It has been shown that activation of this pathway alleviates the negative impact of ischemia-reperfusion. Glycogen synthase kinase-3 (GSK3β) induces apoptosis through stimulation of transcription factors, and its phosphorylation has been suggested as a new therapeutic target for myocardial ischemia-reperfusion injury (MIRI). GSK3β regulatory role is mediated by the reperfusion injury salvage kinase (RISK) pathway, and its inhibition by Akt activation blocks mitochondrial permeability transition pore (mPTP) opening and enhances myocardial survival. The present article discusses the involvement of the PI3K/Akt/GSK3β pathway in cardioprotective effects of natural products against MIRI.Abbreviations: Akt: protein kinase B; AMPK: AMP-activated protein kinase; ATP: adenosine triphosphate; Bad: bcl2-associated agonist of cell death; Bax: bcl2-associated x protein; Bcl-2: B-cell lymphoma 2; CK-MB: Creatine kinase-MB; CRP: C-reactive-protein; cTnI: cardiac troponin I; EGCG: Epigallocatechin-3-gallate; Enos: endothelial nitric oxide synthase; ER: endoplasmic reticulum; ERK ½: extracellular signal‑regulated protein kinase ½; GSK3β: glycogen synthase kinase-3; GSRd: Ginsenoside Rd; GSH: glutathione; GSSG: glutathione disulfide; HO-1: heme oxygenase-1; HR: hypoxia/reoxygenation; HSYA: Hydroxysafflor Yellow A; ICAM-1: Intercellular Adhesion Molecule 1; IKK-b: IκB kinase; IL: interleukin; IPoC: Ischemic postconditioning; IRI: ischemia-reperfusion injury; JNK: c-Jun N-terminal kinase; Keap1: kelch-like ECH-associated protein- 1; LDH: lactate dehydrogenase; LVEDP: left ventricular end diastolic pressure; LVP: left ventricle pressure; LVSP: left ventricular systolic pressure; MAPK: mitogen-activated protein kinase; MDA: malondialdehyde; MIRI: myocardial ischemia-reperfusion injury; MnSOD: manganese superoxide dismutase; mPTP: mitochondrial permeability transition pore; mtHKII: mitochondria-bound hexokinase II; Nrf-1: nuclear respiratory factor 1; Nrf2: nuclear factor erythroid 2-related factor; NO: nitric oxide; PGC-1α: peroxisome proliferator‑activated receptor γ coactivator‑1α; PI3K: phosphoinositide 3-kinases; RISK: reperfusion injury salvage kinase; ROS: reactive oxygen species; RSV: Resveratrol; SOD: superoxide dismutase; TFAM: transcription factor A mitochondrial; TNF-α: tumor necrosis factor-alpha; VEGF-B: vascular endothelial growth factor B.

A novel potential inflammation-nutrition biomarker for predicting lymph node metastasis in clinically node-negative colon cancer

Background

The purpose of this study is to investigate the predictive significance of (platelet × albumin)/lymphocyte ratio (PALR) for lymph node metastasis (LNM) in patients with clinically node-negative colon cancer (cN0 CC).

Methods

Data from 800 patients with primary CC who underwent radical surgery between March 2016 and June 2021 were reviewed. The non-linear relationship between PALR and the risk of LNM was explored using a restricted cubic spline (RCS) function while a receiver operating characteristic (ROC) curve was developed to determine the predictive value of PALR. Patients were categorized into high- and low-PALR cohorts according to the optimum cut-off values derived from Youden's index. Univariate and multivariate logistic regression analyses were used to identify the independent indicators of LNM. Sensitivity analysis was performed to repeat the main analyses with the quartile of PALR.

Results

A total of eligible 269 patients with primary cN0 CC were retrospectively selected. The value of the area under the ROC curve for PALR for predicting LNM was 0.607. RCS visualized the uptrend linear relationship between PALR and the risk of LNM (p-value for non-linearity > 0.05). PALR (odds ratio = 2.118, 95% confidence interval, 1.182-3.786, p = 0.011) was identified as an independent predictor of LNM in patients with cN0 CC. A nomogram incorporating PALR and other independent predictors was constructed with an internally validated concordance index of 0.637. The results of calibration plots and decision curve analysis supported a good performance ability and the sensitivity analysis further confirmed the robustness of our findings.

Conclusion

PALR has promising clinical applications for predicting LNM in patients with cN0 CC.

CD4 T-cell immune stimulation of HER2 + breast cancer cells alters response to trastuzumab in vitro

Introduction

The HER2 + tumor immune microenvironment is composed of macrophages, natural killer cells, and tumor infiltrating lymphocytes, which produce pro-inflammatory cytokines. Determining the effect of T-cells on HER2 + cancer cells during therapy could guide immunogenic therapies that trigger antibody-dependent cellular cytotoxicity. This study utilized longitudinal in vitro time-resolved microscopy to measure T-cell influence on trastuzumab in HER2 + breast cancer.

Methods

Fluorescently-labeled breast cancer cells (BT474, SKBR3, MDA-MB-453, and MDA-MB-231) were co-cultured with CD4 + T-cells (Jurkat cell line) and longitudinally imaged to quantify cancer cell viability when treated with or without trastuzumab (10, 25, 50 and 100 μg/mL). The presence and timing of T-cell co-culturing was manipulated to determine immune stimulation of trastuzumab-treated HER2 + breast cancer. HER2 and TNF-α expression were evaluated with western blot and ELISA, respectively. Significance was calculated using a two-tailed parametric t-test.

Results

The viability of HER2 + cancer cells significantly decreased when exposed to 25 μg/mL trastuzumab and T-cells, compared to cancer cells exposed to trastuzumab without T-cells (p = 0.01). The presence of T-cells significantly increased TNF-α expression in trastuzumab-treated cancer cells (p = 0.02). Conversely, cancer cells treated with TNF-α and trastuzumab had a similar decrease in viability as trastuzumab-treated cancer cells co-cultured with T-cells (p = 0.32).

Conclusions

The presence of T-cells significantly increases the efficacy of targeted therapies and suggests trastuzumab may trigger immune mediated cytotoxicity. Increased TNF-α receptor expression suggest cytokines may interact with trastuzumab to create a state of enhanced response to therapy in HER2 + breast cancer, which has potential to reducing tumor burden.

Colorectal cancer (CRC) as a multifactorial disease and its causal correlations with multiple signaling pathways

Colorectal cancer (CRC) is the third most common malignancy and one of the leading causes of cancer-related death among men worldwide. CRC is a multifactor digestive pathology, which is a huge problem faced not only by clinicians but also by researchers. Importantly, a unique feature of CRC is the dysregulation of molecular signaling pathways. To date, a series of reviews have indicated that different signaling pathways are disordered and have potential as therapeutic targets in CRC. Nevertheless, an overview of the function and interaction of multiple signaling pathways in CRC is needed. Therefore, we summarized the pathways, biological functions and important interactions involved in CRC. First, we investigated the involvement of signaling pathways, including Wnt, PI3K/Akt, Hedgehog, ErbB, RHOA, Notch, BMP, Hippo, AMPK, NF-κB, MAPK and JNK. Subsequently, we discussed the biological function of these pathways in pathophysiological aspects of CRC, such as proliferation, apoptosis and metastasis. Finally, we summarized important interactions among these pathways in CRC. We believe that the interaction of these pathways could provide new strategies for the treatment of CRC.

miR-590-5P inhibits the progression of tongue squamous cell carcinoma by targeting FasL

OBJECTIVE

This study evaluated microRNA-590-5P (miR-590-5P), which functions as an anti-onco-miRNA in TSCC by downregulating FasL expression.

METHODS

In this study, immunohistochemistry was used to detect FasL protein expression in 30 OSCC samples and 8 normal oral mucosa tissue samples. Target Scan was used to predict miRNAs that target FasL. Luciferase reporter assays were used to confirm the effects of miRNA on FasL. Subsequently, the SCC3 tongue cancer cell line was transfected with a miR-590-5P mimic or miR-590-5P inhibitor. qPCR and Western blots were used to detect the expression levels of miR-590-5P and FasL. SCC3 cell viability, apoptosis and growth were assayed by MTT assays, colony formation assays, and a xenograft model.

RESULTS

FasL expression was significantly higher in OSCC tissue samples than in normal oral mucosa tissue samples. miR-590-5P could downregulate the expression of FasL in vitro via direct binding to its 3'-untranslated region (3'-UTR). Overexpression of miR-590-5P inhibited the proliferation of SCC3 cells. Moreover, miR-590-5P increased the sensitivity of SCC3 cells to the chemotherapeutic agent cisplatin (DDP) and led to a significant decrease in colony formation ability. The xenograft experiment confirmed that miR-590-5P can suppress the development of TSCC.

CONCLUSIONS

These results suggest that miR-590-5P targets FasL to inhibit the development of tongue cancer and that miR-590-5P may be a novel therapeutic target for TSCC.

Cytotoxic T Cells and Granzyme B Associated with Improved Colorectal Cancer Survival in a Prospective Cohort of Older Women

Background: Host immune response may predict the course of colorectal cancer. We examined the survival of 468 colorectal cancer patients associated with two tumor-infiltrating immune biomarkers, the number of cytotoxic T lymphocytes (CTLs), and the activated CTLs, as reflected by the number of cells expressing granzyme B (GZMB) in the prospective Iowa Women's Health Study.Methods: Using paraffin-embedded tissue samples, we constructed and immunostained tumor microarrays with CD8 (for CTL) and GZMB antibodies. We scored CTL and GZMB densities in tumor epithelial and stromal tissues and also created a composite score for each biomarker (sum of the scores across tissue compartments). Cox regression estimated the HR and 95% confidence intervals (CI) for all-cause and colorectal cancer-specific death associated with each composite score.Results: CTL and GZMB composite scores were positively correlated (r = 0.65) and each biomarker was inversely correlated with stage at diagnosis. Both composite scores were higher in proximal colon tumors and tumors characterized by MSI-high, CIMP-high, or BRAF mutation status. HRs (95% CI) were 0.53 (0.38-0.75; Ptrend = 0.0004) and 0.66 (0.51-0.86; Ptrend = 0.002) for all-cause death, respectively, and 0.30 (0.18-0.51; Ptrend < 0.0001) and 0.41 (0.27-0.63; Ptrend < 0.0001) for colorectal cancer-related death, respectively. Including CTL and GZMB scores simultaneously in the model significantly improved the predictive performance of the models for all-cause and colorectal cancer-related death.Conclusions: Higher tumor infiltration with CTL and GZMB cells is associated with improved all-cause and cancer-specific survival of colorectal cancer patients.Impact: Both the number of CTLs and GZMB appear to be useful prognostic factors in colorectal cancer, irrespective of stage. Cancer Epidemiol Biomarkers Prev; 26(4); 622-31. ©2016 AACR.

Combination Treatment with Sublethal Ionizing Radiation and the Proteasome Inhibitor, Bortezomib, Enhances Death-Receptor Mediated Apoptosis and Anti-Tumor Immune Attack

Sub-lethal doses of radiation can modulate gene expression, making tumor cells more susceptible to T-cell-mediated immune attack. Proteasome inhibitors demonstrate broad anti-tumor activity in clinical and pre-clinical cancer models. Here, we use a combination treatment of proteasome inhibition and irradiation to further induce immunomodulation of tumor cells that could enhance tumor-specific immune responses. We investigate the effects of the 26S proteasome inhibitor, bortezomib, alone or in combination with radiotherapy, on the expression of immunogenic genes in normal colon and colorectal cancer cell lines. We examined cells for changes in the expression of several death receptors (DR4, DR5 and Fas) commonly used by T cells for killing of target cells. Our results indicate that the combination treatment resulted in increased cell surface expression of death receptors by increasing their transcript levels. The combination treatment further increases the sensitivity of carcinoma cells to apoptosis through FAS and TRAIL receptors but does not change the sensitivity of normal non-malignant epithelial cells. Furthermore, the combination treatment significantly enhances tumor cell killing by tumor specific CD8⁺ T cells. This study suggests that combining radiotherapy and proteasome inhibition may simultaneously enhance tumor immunogenicity and the induction of antitumor immunity by enhancing tumor-specific T-cell activity.

Significance of Fas and FasL protein expression in cardiac carcinoma and local lymph node tissues

OBJECTIVE

To investigate the relation of Fas and Fas ligand (FasL) protein expression with carcinogenesis and metastasis of cardiac carcinoma.

METHODS

Immunohistochemistry was used to detect Fas and FasL protein expression in 64 cardiac carcinoma tissue samples and 20 normal gastric tissue samples. Relation between FasL and Fas expression, age and gender of gastric cancer patients, and pathological subtype and lymph node metastasis of gastric cancer was analyzed.

RESULTS

The Fas expression level was significantly higher in normal gastric tissue samples than in cardiac carcinoma tissue samples (85.0% vs. 25.0%, P<0.001), while the FasL expression level was significantly lower in normal gastric tissue samples than in cardiac carcinoma tissue samples (30.0% vs. 81.3%, P<0.001). The Fas expression level was significantly higher in invasive lymph nodes than in non-invasive lymph nodes (82.9% vs. 56.5%, P<0.003) and in well-differentiated gastric carcinoma tissue samples than in poorly-differentiated cardiac carcinoma tissue samples (50.0% vs. 18.0%, P=0.015). The FasL expression level was significantly lower in well-differentiated cardiac carcinoma tissue samples than in poorly- differentiated cardiac carcinoma tissue samples (42.9% vs. 84.0%, P=0.021). The Fas and FasL expression levels (25.0% and 81.3%) were significantly different in cardiac carcinoma tissue samples (P<0.001), but had a non-linear correlation (P=0.575).

CONCLUSION

Abnormal Fas and FasL expressions in cardiac carcinoma and lymph node tissues are involved in carcinogenesis and metastasis of gastric cancer.

In vivo Effects in Melanoma of ROCK Inhibition-Induced FasL Overexpression

Ectopic Fas-ligand (FasL) expression in tumor cells is responsible for both tumor escape through tumor counterattack of Fas-positive infiltrating lymphocytes and tumor rejection though inflammatory and immune responses. We have previously shown that RhoA GTPase and its effector ROCK negatively control FasL membrane expression in murine melanoma B16F10 cells. In this study, we found that B16F10 treatment with the ROCK inhibitor H1152 reduced melanoma development in vivo through FasL membrane overexpression. Although H1152 treatment did not reduce tumor growth in vitro, pretreatment of tumor cells with this inhibitor delayed tumor appearance, and slowed tumor growth in C57BL/6 immunocompetent mice. Thanks to the use of mice-bearing mutated Fas receptors (B6/lpr), we found that reduced tumor growth, observed in immunocompetent mice, was linked to FasL overexpression induced by H1152 treatment. Tumor growth analysis in immunosuppressed NUDE and IFN-γ-KO mice highlighted major roles for T lymphocytes and IFN-γ in the H1152-induced tumor growth reduction. Histological analyses of subcutaneous tumors, obtained from untreated versus H1152-treated B16F10 cells, showed that H1152 pretreatment induced a strong intratumoral infiltration of leukocytes. Cytofluorometric analysis showed that among these leukocytes, the number of activated CD8 lymphocytes was increased. Moreover, their antibody-induced depletion highlighted their main responsibility in tumor growth reduction. Subcutaneous tumor growth was also reduced by repeated intravenous injections of a clinical ROCK inhibitor, Fasudil. Finally, H1152-induced ROCK inhibition also reduced pulmonary metastasis implantation independently of T cell-mediated immune response. Altogether, our data suggest that ROCK inhibitors could become interesting pharmacological molecules for melanoma immunotherapy.

Decoy receptor 3 suppresses FasL-induced apoptosis via ERK1/2 activation in pancreatic cancer cells

Resistance to Fas Ligand (FasL) mediated apoptosis plays an important role in tumorigenesis. Decoy receptor 3 (DcR3) is reported to interact with FasL and is overexpressed in some malignant tumors. We sought to investigate the role of DcR3 in resistance to FasL in pancreatic cancer. We compared expression of apoptosis related genes between FasL-resistant SW1990 and FasL-sensitive Patu8988 pancreatic cell lines by microarray analysis. We explored the impact of siRNA knockdown of, or exogenous supplementation with, DcR3 on FasL-induced cell growth inhibition in pancreatic cancer cell lines and expression of proteins involved in apoptotic signaling. We assessed the level of DcR3 protein and ERK1/2 phosphorylation in tumor and non-tumor tissue samples of 66 patients with pancreatic carcinoma. RNAi knockdown of DcR3 expression in SW1990 cells reduced resistance to FasL-induced apoptosis, and supplementation of Patu8988 with rDcR3 had the opposite effect. RNAi knockdown of DcR3 in SW1990 cells elevated expression of caspase 3, 8 and 9, and reduced ERK1/2 phosphorylation (P < 0.05), but did not alter phosphorylated-Akt expression. 47 tumor tissue specimens, but only 15 matched non-tumor specimens stained for DcR3 (χ(2) = 31.1447, P < 0.001). The proliferation index of DcR3 positive specimens (14.26  ±  2.67%) was significantly higher than that of DcR3 negative specimens (43.58  ±  7.88%, P < 0.01). DcR3 expression positively correlated with p-ERK1/2 expression in pancreatic cancer tissues (r = 0.607, P < 0.001). DcR3 enhances ERK1/2 phosphorylation and opposes FasL signaling in pancreatic cancer cells.

High Fas expression in gastric carcinoma cells as a factor correlating with the occurrence of metastases to regional lymph nodes

PURPOSE

The aim of this study was to evaluate the correlation of the expression of Fas and Fas-L proteins in gastric carcinoma cells on the occurrence of metastases to regional lymph nodes.

MATERIAL/METHODS

The study included 89 patients treated surgically for gastric carcinoma. The evaluated clinicomorphological parameters were verified based on both histopathological material collected at surgery and intraoperative image. Fas and Fas-L expression was evaluated immunohistochemically in the neoplastic tissue of the removed gastric tumors.

RESULTS

A statistically significant positive correlation between Fas expression in gastric carcinoma cells and the number of regional lymph nodes affected by metastases was observed (p<0.05). No such correlation was noticed with respect to Fas-L. A statistically significant correlation between the depth of neoplastic infiltration of the stomach wall (T feature) and the number of affected lymph nodes was observed (p<0.05). No statistically significant correlations in the other examined clinicomorphological features and the number of metastatic lymph nodes was observed.

CONCLUSION

A positive Fas expression correlates with more frequent occurrence of metastases to regional lymph nodes. Determination of this protein expression in cancer cells prior to surgery may be helpful for planning the surgical procedure, especially with respect to the extent of lymph node excision.

Expression of apoptosis regulating proteins identifies stage II and III colon cancer patients with high risk of recurrence

BACKGROUND AND OBJECTIVES

Deregulation of apoptosis related genes may be associated with poor outcome in cancer. Aim of the present study was to investigate the prognostic role of expression levels of apoptosis related proteins in stage II and III colon cancer.

METHODS

From tumor samples of 386 stage II and III colon cancer patients, DNA was isolated and tissue microarrays were constructed. Expression of Bcl-2, Bcl-X, BAX, XIAP, Fas, FasL and c-FLIP was evaluated and PCR-based microsatellite instability analysis was performed.

RESULTS

High FasL expressing tumors were associated with high disease recurrence rates in stage II colon cancer patients overall, as was low Bcl-X expression in microsatellite stable stage II patients. In stage II patients, a multivariable model based on FasL and Bcl-XL expression revealed a significant association with disease free survival (DFS). In stage III colon cancer patients, low Bcl-2, low BAX and low Fas expression levels were associated with worse outcome. In these patients a multivariable model based on angioinvasion and Bcl-2, Fas and FasL expression was significantly associated with DFS.

CONCLUSIONS

Stage II patients with low Bcl-X and high FasL protein expression levels and stage III patients with low Fas, high FasL and low Bcl-2 expression could be considered as high risk for disease recurrence.

Comparative study of the in situ immune response in oral and nasal mucosal leishmaniasis

Mucosal Leishmaniasis (ML) may occur in both nasal and oral mucosa. However, despite the impressive tissue destruction, little is known about the oral involvement. To compare some changes underlying inflammation in oral and nasal ML, we performed immunohistochemistry on mucosal tissue of 20 patients with ML (nasal [n = 12]; oral [n = 8] lesions) and 20 healthy donors using antibodies that recognize inflammatory markers (CD3, CD4, CD8, CD22, CD68, neutrophil elastase, CD1a, CLA, Ki67, Bcl-2, NOS2, CD62E, Fas and FasL). A significantly larger number of cells, mainly T cells and macrophages, were observed in lesions than in healthy tissue. In addition, high nitric oxide synthase 2 (NOS2) expression was associated with a reduced detection of parasites, highlighting the importance of NOS2 for parasite elimination. Oral lesions had higher numbers of neutrophils, parasites, proliferating cells and NOS2 than nasal lesions. These findings, together with the shorter duration of oral lesions and more intense symptoms, suggest a more recent inflammatory process. It could be explained by lesion-induced oral cavity changes that lead to eating difficulties and social stigma. In addition, the frequent poor tooth conservation and gingival inflammation tend to amplify tissue destruction and symptoms and may impair and confuse the correct diagnosis, thus delaying the onset of specific treatment.

Fas/FasL expression in colorectal cancer. An immunohistochemical study

The objective of the current study was to assess the expression of Fas ligand (FasL) and Fas receptor (FasR) as the proteins of the post-mitochondrial apoptotic pathway in colorectal carcinoma and to investigate correlations between their expression and chosen clinico-pathological parameters. The protein expression was analyzed in 50 colorectal carcinoma patients, using the immunohistochemical method. Reaction for FasR was weak in 75.5% and strong in 24.5% of the study patients, as compared to normal glandular epithelium where FasR expression was strong in 100% of cases. On the other hand, FasL expression was found to be weak in 30% and strong in 70% of colorectal cancer patients, as compared to its lack in 100% of normal colorectal epithelium. Statistical analysis showed strong expression of FasL was found to correlate statistically significantly with vascular invasion (p = 0.005). No correlations of FasL and FasR expression in the main mass of tumor was found between other clinic-pathological parameters. Fas ligand and Fas receptor appeared to be of little usefulness as prognostic factors for different groups of colorectal carcinoma patients. However, these proteins could become good therapeutic targets for colorectal carcinoma since their expression differs distinctly between normal intestinal epithelium and cancer cells, and known is the mechanism by which cancer cells escape death via apoptosis-inducing Fas/FasL pathway disorders.

Clinical significance of Fas and FasL protein expression in gastric carcinoma and local lymph node tissues

AIM: To investigate the relation of Fas and Fas ligand (FasL) protein expression with carcinogenesis and metastasis of gastric carcinoma.

METHODS: Immunohistochemistry was used to detect Fas and FasL protein expression in 64 gastric carcinoma tissue samples and 20 normal gastric tissue samples. Relation between FasL and Fas expression, age and gender of gastric cancer patients, and pathological subtype and lymph node metastasis of gastric cancer was analyzed.

RESULTS: The Fas expression level was significantly higher in normal gastric tissue samples than in gastric carcinoma tissue samples (85.0% vs 25.0%, P < 0.001), while the FasL expression level was significantly lower in normal gastric tissue samples than in gastric carcinoma tissue samples (30.0% vs 81.3%, P < 0.001). The Fas expression level was significantly higher in invasive lymph nodes than in non-invasive lymph nodes (82.9% vs 56.5%, P < 0.003) and in well-differentiated gastric carcinoma tissue samples than in poorly-differentiated gastric carcinoma tissue samples (50.0% vs 18.0%, P = 0.015). The FasL expression level was significantly lower in well-differentiated gastric carcinoma tissue samples than in poorly- differentiated gastric carcinoma tissue samples (42.9% vs 84.0%, P = 0.021). The Fas and FasL expression levels (25.0% and 81.3%) were significantly different in gastric carcinoma tissue samples (P < 0.001), but had a non-linear correlation (P = 0.575).

CONCLUSION: Abnormal Fas and FasL expressions in gastric carcinoma and lymph node tissues are involved in carcinogenesis and metastasis of gastric cancer.

Obesity, the PI3K/Akt signal pathway and colon cancer

Obesity is currently reaching epidemic levels worldwide and is a major predisposing factor for a variety of life-threatening diseases including diabetes, hypertension and cardiovascular diseases. Recently, it has also been suggested to be linked with cancer. Epidemiological studies have shown that obesity increases the risk of colon cancer by 1.5-2 fold with obesity-associated colon cancer accounting for 14-35% of total incidence. Several factors, altered in obesity, may be important in cancer development including increased levels of blood insulin, insulin-like growth factor I, leptin, TNF-alpha, IL-6 as well as decreased adiponectin. A unifying characteristic of all these factors is that they increase the activity of the PI3K/Akt signal pathway. The PI3K/Akt signal pathway in turn activates signals for cell survival, cell growth and cell cycle leading to carcinogenesis. Here we review the evidence that PI3K/Akt and its downstream targets are important in obesity-associated colon cancer and thus, that targeted inhibition of this pathway could be employed for the prevention of obesity-associated colon cancer and incorporated into the therapy regime for those with irremovable colon cancers.

Targeting apoptosis as an approach for gastrointestinal cancer therapy

Cancers in the gastrointestinal system account for a large proportion of malignancies and cancer-related deaths with gastric cancer and colorectal cancer being the most common ones. For those patients in whom surgical resection is not possible, other therapeutic approaches are necessary. Disordered apoptosis has been linked to cancer development and treatment resistance. Apoptosis occurs via extrinsic or intrinsic signaling each triggered and regulated by many different molecular pathways. In recent years, the selective induction of apoptosis in tumor cells has been increasingly recognized as a promising approach for cancer therapy. A detailed understanding of the molecular pathways involved in the regulation of apoptosis is essential for developing novel effective therapeutic approaches. Apoptosis can be induced by many different approaches including activating cell surface death receptors (for example, Fas, TRAIL and TNF receptors), inhibiting cell survival signaling (such as EGFR, MAPK and PI3K), altering apoptosis threshold by modulating pro-apoptotic and anti-apoptotic members of the Bcl-2 family, down-regulating anti-apoptosis proteins (such as XIAP, survivin and c-IAP2), and using other pro-apoptotic agents. In this review, the authors reviewed the currently reported apoptosis-targeting approaches in gastrointestinal cancers.

Progress in studies on the Fas/FasL expression system and colon carcinoma

Cell apoptosis or programmed cell death is the term used to describe active cell death to maintain stability under physiological and pathological conditions. Interaction of the death receptor and death ligand is one of the main ways to induce apoptosis, of which, the Fas/FasL system is considered as the major signal transduction pathway to mediate apoptosis. Colon carcinoma is one of the common malignant tumors that are a threat to human health. The occurrence and development of colon carcinoma is related to the regulation imbalance of cell apoptosis. This article reviews the relationship between the Fas/FasL expression system and the occurrence and development of colon carcinoma.

Colon cancer and the immune system: The role of tumor invading T cells

Colon cancer is still one of the leading causes of cancer death worldwide. Although the host immune system has been shown to react against tumor cells, mainly through tumor infiltrating lymphocytes and NK cells, tumor cells may utilize different ways to escape anti-tumor immune response. Tumor infiltration of CD8+ and CD4+ (T-bet+) effector T cells has been attributed to a beneficial outcome, and the enhancement of T cell activation through T cell receptor stimulation and co-stimulatory signals provides promising strategies for immunotherapy of colon cancer. Growing evidence supports a role for the Fas/FasL system in tumor immunology, although the mechanisms and consequences of FasL activation in colon cancer are not completely understood. In animal models, depletion of regulatory T cells (CD4+ CD25+ T cells) can enhance the anti-tumor immune response under certain conditions. Taken together, recent insights in the immune reaction against colon carcinoma have provided new approaches to immunotherapy, although much remains to be learned about the exact mechanisms.

Expression of matrix metalloproteinase-7 and Fas and their significances in gastric carcinoma

AIM: To investigate the expression of matrix metalloproteinase-7 (MMP-7) and Fas in gastric carcinoma as well as their relationships with clinical characteristics.

METHODS: The expression of MMP-7 and Fas proteins were examined with immunohistochemical technique in the specimens from 82 gastric carcinoma tissues and 30 surrounding normal tissues.

RESULTS: The positive rate of MMP-7 expression was significantly higher in gastric carcinoma than that in the normal tissues (73.2% vs 10%, P < 0.05), while the positive rate of Fas expression was marked lower in gastric carcinoma than that in the normal controls (39.1% vs 93.3%, P < 0.001). The expression of MMP-7 was correlated with lymph node metastasis and TMN staging (P < 0.001), but not with the differentiation of tumor cells (P > 0.05). The expression of Fas was correlated with the differentiation of tumor cells (P < 0.05), but was not correlated with lymph node metastasis and TMN staging (P > 0.05). There was a negative correlation between the expression of MMP-7 and Fas in gastric carcinoma (r = -0.597, P < 0.001).

CONCLUSION: The expression of MMP-7 and Fas are closely correlated with the biological behavior of gastric carcinoma. Meanwhile, a negative correlation exists between MMP-7 and Fas expression.

Influence of antitumor drugs on the expression of Fas system in SW480 colon cancer cells

AIMS

To observe the influence of popular antitumor drugs [5-fluorouracil (5-FU), mitomycin (MMC), cisplatin (CP) and all-trans retinoic acid (ATRA)] on the expression of Fas system in SW480 colon cancer cells.

METHODS

The expressions of Fas/FasL protein and mRNA in colon cancer line SW480 cells before and after the treatment of the antitumor drugs (5-FU, MMC, CP and ATRA) were detected by immunocytochemistry, flow cytometry and reverse-transcriptase polymerase chain reaction. Coculture assays of colon cancer cells and Jurkat cells (Fas-sensitive cells) were performed to observe the counterattack of colon cancer cells to lymphocytes. Apoptosis of Jurkat cells were detected by flow cytometry and fluorescence microscopy.

RESULTS

SW480 expressed high FasL and low Fas without drug treatments. When treated with 5-FU, Fas expression rates in SW480 increased, but FasL remained unchanged. Both Fas and FasL increased significantly when treated with MMC and CP. Most importantly, ATRA could induce SW480 cells to differentiate, increase the expression of Fas and decrease the expression of FasL. The coculture of SW480 cells and Jurkat cells confirmed the function of FasL in the SW480 cells.

CONCLUSION

Certain antitumor drugs can change the expression of the Fas system in SW480 cells in different ways. In vitro, MMC and CP can increase the sensitivity of colon cancer cells to apoptosis signals, but they possibly facilitate immune escape of tumor cells. 5-FU results in immune escape of colon cancer cells. ATRA can down-regulate the possibility of counterattack of colon cancer cells.