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.

PECAM-1 drives ß-catenin-mediated EndMT via internalization in colon cancer with diabetes mellitus.

BACKGROUND: Diabetes mellitus (DM) is considered to be a risk factor in carcinogenesis and progression, although the biological mechanisms are not well understood. Here we demonstrate that platelet-endothelial cell adhesion molecule 1 (PECAM-1) internalization drives ß-catenin-mediated endothelial-mesenchymal transition (EndMT) to link DM to cancer. METHODS: The tumor microenvironment (TME) was investigated for differences between colon cancer with and without DM by mRNA-microarray analysis. The effect of DM on colon cancer was determined in clinical patients and animal models. Furthermore, EndMT, PECAM-1 and Akt/GSK-3ß/ß-catenin signaling were analyzed under high glucose (HG) and human colon cancer cell (HCCC) supernatant (SN) or coculture conditions by western and immunofluorescence tests. RESULTS: DM promoted the progression and EndMT occurrence of colon cancer (CC). Regarding the mechanism, DM induced PECAM-1 defection from the cytomembrane, internalization and subsequent accumulation around the cell nucleus in endothelial cells, which promoted ß-catenin entry into the nucleus, leading to EndMT occurrence in CC with DM. Additionally, Akt/GSK-3ß signaling was enhanced to inhibit the degradation of ß-catenin, which regulates the process of EndMT. CONCLUSIONS: PECAM-1 defects and/or internalization are key events for ß-catenin-mediated EndMT, which is significantly boosted by enhanced Akt/GSK-3ß signaling in the DM-associated TME. This contributes to the mechanism by which DM promotes the carcinogenesis and progression of CC. Video Abstract.

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.

MiR-30-5p suppresses cell chemoresistance and stemness in colorectal cancer through USP22/Wnt/ß-catenin signaling axis.

Colorectal cancer (CRC) remains both common and fatal, and its successful treatment is greatly limited by the development of stem cell-like characteristics (stemness) and chemoresistance. MiR-30-5p has been shown to function as a tumor suppressor by targeting the Wnt/ß-catenin signaling pathway, but its activity in CRC has never been assessed. We hypothesized that miR-30-5p exerts anti-oncogenic effects in CRC by regulating the USP22/Wnt/ß-catenin signaling axis. In the present study, we demonstrate that tissues from CRC patients and human CRC cell lines show significantly decreased miR-30-5p family expression. After identifying the 3'UTR of USP22 as a potential binding site of miR-30-5p, we constructed a luciferase reporter containing the potential miR-30-5p binding site and measured the effects on USP22 expression. Western blot assays showed that miR-30-5p decreased USP22 protein expression in HEK293 and Caco2 CRC cells. To evaluate the effects of miR-30-5p on CRC cell stemness, we isolated CD133 + CRC cells (Caco2 and HCT15). We then determined that, while miR-30-5p is normally decreased in CD133 + CRC cells, miR-30-5p overexpression significantly reduces expression of stem cell markers CD133 and Sox2, sphere formation, and cell proliferation. Similarly, we found that miR-30-5p expression is normally reduced in 5-fluorouracil (5-FU) resistant CRC cells, whereas miR-30-5p overexpression in 5-FU resistant cells reduces sphere formation and cell viability. Inhibition of miR-30-5p reversed the process. Finally, we determined that miR-30-5p attenuates the expression of Wnt/ß-catenin signaling target genes (Axin2 and MYC), Wnt luciferase activity, and ß-catenin protein levels in CRC stem cells.

Ubiquitin-Specific Peptidase 22 Contributes to Colorectal Cancer Stemness and Chemoresistance via Wnt/ß-Catenin Pathway.

BACKGROUND/AIMS: Two major barriers to the successful treatment of colorectal cancer (CRC) are the development of stem cell-like characteristics (stemness) and chemoresistance. Ubiquitin-specific peptidase 22 (USP22) is a deubiquitinating enzyme and putative CRC marker that has emerged as a potential cause of both phenomena in CRC. There is evidence that USP22 acts through the Wnt/ß-catenin pathway and that downregulation of the latter may reduce chemoresistance. METHODS: In this study, we used CRC tissue specimens from human patients as well as human CRC cell lines to evaluate the role of USP22 in CRC stemness and chemoresistance in vitro and in vivo. RT-PCR and western blot were used for gene expression analyses. Immunohistochemistry was performed for USP22 expression in clinical samples. CD133 levels were analyzed by flow cytometry. Sphere formation and MTT assays were used for self-renewal and proliferation analysis. Chemoresistance was evaluated by cell viability and sphere formation assays. RESULTS: We found a significant increase of USP22 in recurrent CRC and chemoresistant CRC cells as compared to primary CRC and non-chemoresistant CRC cells, respectively. We then demonstrated that USP22 mediates CRC cell chemoresistance through the Wnt/ß-catenin pathway and that reducing USP22 in CRC cells diminishes chemoresistance. CONCLUSIONS: Having established the crucial role of USP22 in CRC stemness and chemoresistance, this study suggests that USP22 may be an ideal genetic target in the treatment of chemoresistant CRC.

EphA3 promotes malignant transformation of colorectal epithelial cells by upregulating oncogenic pathways.

Ephrin Type-A Receptor 3 (EphA3) belongs to the ephrin receptor subfamily of the protein tyrosine kinase family, and plays an important role in embryogenesis and neurogenesis. This study aimed to investigate the role of EphA3 in promoting malignant transformation of colorectal epithelial cells, and explore underlying molecular mechanisms. Colorectal cancer tissue specimens from 68 patients were analyzed for EphA3 expression. EphA3 expression levels were manipulated in rat colon epithelial cell lines. We found that EphA3 expression level in tumor tissues was associated with patient age (P = 0.015), tumor differentiation (P = 0.001), and lymph node metastasis (P = 0.039). Overexpression of EphA3 and its constitutively active mutants promoted colony formation, migration and invasion, and tumorigenicity of colon epithelial cells in nude mice. The cDNA and lncRNA microarray profiling data revealed that differentially expressed genes and lncRNAs in EphA3 or mutant-transfected cells were associated with cell proliferation, invasion and angiogenesis. Our findings reveal the mechanisms underlying the oncogenic activities of EphA3 in colorectal cells, which could provide novel targets for the prevention, early diagnosis, and treatment of colorectal cancer.