Exosomes derived from cancer-associated fibroblasts promote tumorigenesis, metastasis and chemoresistance of colorectal cancer by upregulating circ_0067557 to target Lin28.

BACKGROUND: Cancer associated fibroblasts (CAFs) can remodel tumor microenvironment by secreting exosomes. This study aimed to investigate the role of exosomes derived from cancer-associated fibroblasts in colorectal cancer (CRC) progression. METHODS: Circular RNA (circRNA) array was used to identify differentially expressed circRNAs in exosomes from normal fibroblasts (NFs) and CAFs, and confirmed one differentially expressed circRNA circ_0067557 by real-time PCR. The effect of circ_0067557 on proliferation, metastasis, chemoresistance and apoptosis was verified by wound heal, tranwell, CCK8, sphere-forming and flow cytometry assay. RESULTS: Circ_0067557 expression in exosomes from CAFs was higher than those from NFs. CAF-derived exosomes promoted the proliferation, migration, invasion and chemoresistance of CRC cells while suppressed apoptosis. Silencing of circ_0067557 inhibited malignant phenotypes of CRC cells by targeting Lin28A and Lin28B. Moreover, CAF-derived exosomes enhanced the growth of CRC xenograft tumors. CONCLUSION: Circ_0067557/Lin28A and Lin28B signal axis may be a potential therapy target for CRC.

Unraveling temporal and spatial biomarkers of epithelial-mesenchymal transition in colorectal cancer: insights into the crucial role of immunosuppressive cells.

The occurrence and progression of tumors can be established through a complex interplay among tumor cells undergoing epithelial-mesenchymal transition (EMT), invasive factors and immune cells. In this study, we employed single-cell RNA sequencing (scRNA-seq) and spatially resolved transcriptomics (ST) to evaluate the pseudotime trajectory and spatial interactive relationship between EMT-invasive malignant tumors and immune cells in primary colorectal cancer (CRC) tissues at different stages (stage I/II and stage III with tumor deposit). Our research characterized the spatiotemporal relationship among different invasive tumor programs by constructing pseudotime endpoint-EMT-invasion tumor programs (EMTPs) located at the edge of ST, utilizing evolution trajectory analysis integrated with EMT-invasion genes. Strikingly, the invasive and expansive process of tumors undergoes remarkable spatial reprogramming of regulatory and immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), regulatory T cells (Treg), and exhausted T cells (Tex). These EMTP-adjacent cell are linked to EMT-related invasion genes, especially the C-X-C motif ligand 1 (CXCL1) and CXCL8 genes that are important for CRC prognosis. Interestingly, the EMTPs in stage I mainly produce an inflammatory margin invasive niche, while the EMTPs in stage III tissues likely produce a hypoxic pre-invasive niche. Our data demonstrate the crucial role of regulatory and immunosuppressive cells in tumor formation and progression of CRC. This study provides a framework to delineate the spatiotemporal invasive niche in CRC samples.

The prognostic impacts of PABPC1 expression on gastric cancer patients.

Aim: To assess the prognostic impacts of PABPC1 on gastric cancer (GC) patients. Methods: The expression levels of PABPC1 in GC tissues and normal gastric tissues were initially compared via bioinformatics analysis. Immunohistochemical staining was accomplished to assess the expression of PABPC1 in the included GC patients. Then the impacts of PABPC1 expression on survival of GC patients were evaluated by Cox regression and Kaplan-Meier analyses. Results: The expression levels of PABPC1 in gastric tissues were significantly higher than those in normal gastric tissues (paired, p = 0.002; unpaired, p = 3.60e-9). By Kaplan-Meier, it was demonstrated that high expression of PABPC1 was significantly associated with worse overall and disease-free survival. Furthermore, high PABPC1 expression was demonstrated to be an independent predictive factor for both overall (p = 0.013; hazard ratio = 2.058; 95% CI: 1.162-3.644) and disease-free (p = 0.018; hazard ratio = 2.284; 95% CI: 1.153-4.524) survival. Conclusion: PABPC1 is a potential prognostic biomarker for GC patients.

Lay abstract Previous studies have reported that PABPC1 is involved in a series of biological processes and participates in many cancers. However, the specific role of PABPC1 in different cancers varies significantly, and PABPC1 has not been fully investigated in gastric cancer (GC). In the present study, it was demonstrated that PABPC1 was significantly upregulated in GC and its high expression in GC was significantly associated with worse overall and disease-free survival, indicating the potential of PABPC1 as a novel prognostic biomarker for GC.

Determining the effects of Ephrin Type B Receptor 6 and Type A Receptor 3 on facilitating colorectal epithelial cell malignant transformation.

Ephrin Type-A Receptor 3 (EphA3) and Ephrin Type-B Receptor 6 (EphB6) belong to the ephrin receptor group consisting of the largest subset of receptor tyrosine kinases (RTKs) and are essential for neurogenesis and embryogenesis. The current study aimed to evaluate their functional roles in transforming colorectal epithelial cells and dissect the underlying molecular mechanisms. We observed altered EphA3 and EphB6 expression in tumor tissues as compared to normal tissues in a tissue microarray study. Enforced EphB6 expression promoted IMCE cell proliferation, migration, and invasion in vitro and tumor formation in nude mice, with a stronger oncogenic activity than EphA3. Pathway analysis of differentially expressed genes from a gene microarray study provided important insight into potential mechanisms through which EphB6 may regulate the malignant transformation of colorectal epithelial cells. This study represents the first demonstration of EphB6 in enhancing colorectal epithelial cell transformation, suggesting its stipulative role in the early stage of colorectal tumorigenesis. Our findings primarily uncover novel biomarkers and therapeutic targets of colorectal cancer.

Effects of the fibroblast activation protein on the invasion and migration of gastric cancer.

OBJECTIVE: Cancer-associated fibroblasts (CAFs) are one of the most important components of tumor microenvironment. CAFs are believed to play an important role in tumor invasion and metastasis. Recently, fibroblast activation protein (FAP), a type II integral membrane glycoprotein belonging to the serine protease family, has emerged as a specific marker of CAFs. FAP was overexpressed in stromal fibroblasts of solid malignancies, however, the role of FAP on the process of invasion and metastasis of gastric carcinomas is still unknown. METHODS: Expression of FAP level was detected by immunohistochemistry in 60 gastric cancer surgical specimens (28 with omentum metastasis and 32 without), 20 normal human gastric tissues and omentum of 10 nonneoplastic gastric diseases. Fibroblasts were isolated from patient's tissues in the distal normal zones and tumor zones respectively, which were correspondingly designated as normal zone fibroblasts (NFs) and cancer-associated fibroblasts (CAFs). To explore the effects of FAP on NFs or CAFs, fibroblasts were co-cultured with human gastric cancer cell line MGC-803 cells. The ability of invasion and migration of MGC-803 cells was evaluated after transfecting FAP siRNA into CAFs of gastric carcinomas. RESULTS: We investigated the level of expression of FAP in surgical specimens, and found overexpressed in CAFs and non-expressed in NFs. Expression of FAP level in CAFs is significantly associated with Lauren classification,the degree of differentiation, depth of tumor invasion and TNM stage, but it is not correlated to age and gender in gastric carcinoma patients. There was positive correlation between the FAP level with metastasis to the omentum(p < 0.05, R(2) = 0.2736, p < 0.05, R(2) = 0.1479). In addition, the invasion and migration abilities of MGC-803 cells were significantly increased when cells were co-cultured with CAFs. On the other hand, invasion and migration abilities were significantly decreased by 46.9 and 50.3%, respectively, after knocking down FAP in CAFs.Further, NFs did not have appreciable effect on the invasion and migration of MGC-803 cells. CONCLUSIONS: Our findings showed that FAP was overexpressed in CAFs of gastric carcinomas, and siRNA-mediated knock down of FAP significantly suppressed invasion and migration of MGC-803 cells. FAP may be an important regulator in the invasion and migration of gastric cancer and may provide a novel therapeutic target in gastric carcinomas.

Neural stem cells induce M2 polarization of macrophages through the upregulation of interleukin-4.

Macrophages are divided into two types: M1- and M2-type macrophages. Both types of macrophages serve important roles during the process of inflammation. M1-type macrophages release various pro-inflammatory cytokines, such as IL-1, IFN-γ and other inflammatory mediators, such as nitric oxide, glutamate and reactive oxygen species to generate inflammation. In contrast, M2-type macrophages counteract the pro-inflammatory M1 conditions and promote tissue repair by secreting anti-inflammatory cytokines, such as IL-10. In spinal cord injury (SCI), an imbalance in M1/M2 macrophages leads to irreversible tissue destruction. Thus, it is crucial to increase the number of M2-type macrophages and promote M2 polarization of macrophages in SCI. Accordingly, in this study an in vitro co-culture system was established to investigate the effect of neural stem cells (NSCs) on macrophages. The results of the present study demonstrated that NSCs induced M2 polarization and suppressed M1 polarization of macrophages in an interleukin (IL)-4-dependent manner. Furthermore, the nuclear factor (NF)-κB/p65 signaling pathway was involved in the M1 polarization of macrophages and NSCs suppressed the activation of the NF-κB/p65 pathway in an IL-4-dependent manner to induce M2 macrophage polarization. These findings provide more insight into SCI and help to identify novel treatment strategies.

The Role of Fluoxetine in Activating Wnt/ß-Catenin Signaling and Repressing ß-Amyloid Production in an Alzheimer Mouse Model.

Fluoxetine (FLX) is one of the selective serotonin reuptake inhibitors (SSRIs) antidepressants, which could be used to relieve depression and anxiety among AD patients. This study was designed to search for new mechanisms by which fluoxetine could activate Wnt/ß-catenin signaling pathway and reduce amyloidosis in AD brain. Fluoxetine was administered via intragastric injection to APP/tau/PS1 mouse model of Alzheimer's disease (3×Tg-AD) mice for 4 months. In the hippocampus of AD mouse model, there could be observed neuronal apoptosis, as well as an increase in Aß (amyloid-ß) production. Moreover, there is a strong association between down-regulation of Wnt/ß-catenin signaling and the alteration of AD pathology. The activity of protein phosphatases of type 2A (PP2A) could be significantly enhanced by the treatment of fluoxetine. The activation of PP2A, caused by fluoxetine, could then play a positive role in raising the level of active ß-catenin, and deliver a negative impact in GSK3ß activity in the hippocampal tissue. Both the changes mentioned above would lead to the activation of Wnt/ß-catenin signaling. Meanwhile, fluoxetine treatment would reduce APP cleavage and Aß generation. It could also prevent apoptosis in 3×Tg-AD primary neuronal cell, and have protective effects on neuron synapse. These findings imply that Wnt/ß-catenin signaling could be a potential target outcome for AD prevention, and fluoxetine has the potential to be a promising drug in both AD prevention and treatment.

Effects of cancer-associated fibroblasts on the migration and invasion abilities of SGC-7901 gastric cancer cells.

The aim of the current study was to investigate the correlation of cancer-associated fibroblasts (CAFs) with the migration and invasion abilities of gastric cancer cells. Gastric CAFs were grown in primary cultures. The in vitro model of interaction of SGC7901 gastric cancer cells with gastric CAFs was established by the use of Transwell co-culture cells to analyze the influence of CAFs on the migration and invasion abilities of SGC7901 cells. The results revealed that i) human gastric CAFs highly expressed vimentin, fibroblast-activated protein and smooth muscle actin in the in vitro passage culture process; ii) the migration and invasion ability of SGC-7901 cells in the CAF-conditioned medium group (98.67±13.49, 34.40±4.63) were significantly higher compared to those of the DMEM group without serum (78.47±10.59, 26.93±3.99; P<0.01). The interactions of CAFs and the extracellular matrix with SGC-7901 cells may significantly increase the migration and invasion abilities of SGC-7901 cells.

The role of SPARC protein expression in the progress of gastric cancer.

We aimed to investigate the expression of SPARC (secreted protein, acidic and rich in cysteine) in gastric cancer and its relationship with tumor angiogenesis and cancer cells proliferation. Protein expression of SPARC, VEGF, CD34 and Ki-67 in 80 cases of gastric cancer and 30 cases of normal gastric tissue was evaluated by immunohistochemistry. CD34 staining was used as an indicator of microvessel density (MVD). Ki-67 labeling Index (LI) indicated cancer cells proliferation. Statistical analysis was used to investigate its relationship with clinical characteristics, tumor angiogenesis and cancer cells proliferation. SPARC expression was mainly in the stromal cells surrounding the gastric cancer cells, and was statistically significant differences between gastric cancer and normal gastric tissue (P < 0.05). Both the expression of SPARC and VEGF were related to differentiation degree, clinical stage, Lauren classification and lymph node metastasis (P < 0.05). Expression of SPARC was significantly negatively correlated with the expression of VEGF and MVD in gastric cancer tissues. Expression of SPARC was also negatively correlated with Ki-67-LI. Our findings suggest that both the expression of SPARC and VEGF are closed to tumor angiogenesis in gastric cancer, SPARC inhibited tumor angiogenesis but VEGF promoted tumor angiogenesis. SPARC also inhibited cells proliferation of gastric cancer.

Roles of fibroblasts from the interface zone in invasion, migration, proliferation and apoptosis of gastric adenocarcinoma.

AIMS: Interface zone fibroblasts (INFs) are very important in the progression and metastasis of tumours but their effect on the invasion and migration of gastric cancer cells is still unclear. METHODS: Primary fibroblasts were isolated from the distal normal zone (normal zone fibroblasts, NFs), interface zone (INFs) and tumour zone (cancer-associated fibroblasts, CAFs) of 60 human gastric carcinoma tissue samples. The crosstalk between these fibroblasts and human gastric cancer MGC-803 cells was evaluated using an indirect co-culture model in vitro. RESULTS: A high level of fibroblast activation protein (FAP) in the invasion front of gastric cancer was found in the gastric cancer tissue samples and no FAP expression was found in 20 normal gastric tissue samples by immunohistochemistry. High FAP expression was associated with Lauren classification, degree of differentiation, tumour node metastasis stage and depth of tumour invasion (p<0.05 or p<0.01). INFs promoted invasion and migration of MGC-803 cells. The number of invasions in INFs, CAFs and NFs were 120.10±27.53 (95% CI 102.12 to 138.10), 63.00±14.80 (95% CI 53.33 to 72.67) and 14.22±6.20 (95% CI 10.17 to 18.27), respectively; the number of invasions in INFs were 8.45-fold and 1.89-fold higher than those in NFs and CAFs, respectively (p<0.05). The number of migrations in INFs, CAFs and NFs were 118.00±16.83 (95% CI 107.00 to 129.00), 61.00±16.36 (95% CI 50.31 to 71.69) and 24.00±11.52 (95% CI 16.47 to 31.53), respectively; the number of migration in INFs were 4.91-fold and 1.92-fold higher than those in NFs and CAFs, respectively (p<0.05). INFs also significantly promoted cell proliferation and inhibited apoptosis in MGC-803 cells compared with NFs and CAFs (p<0.05). CONCLUSIONS: These findings indicate that INFs exhibit a more robust biological modulatory activity than CAFs and NFs. INFs may be a key factor leading to tumour progression and metastasis and may be of use as a tool for post-treatment surveillance.