Background The prognosis of colon cancer is poor for metastasis, while the mechanism, especially adipocytes related, is not yet clear. The purpose of this study is to determine the effects of fatty acid binding protein 4 (FABP4), a transporter for lipids, on colon cancer progression. Methods The distribution of lipids and FABP4 was tested in the colon cancer tissues and adjacent normal tissues, and their relationship was also verified in vitro. Experiments about cellular invasion, migration and proliferation were performed to detect the impacts of FABP4 on the biological behaviors of colon cancer, and the positive results were checked in vivo. Meanwhile, the regulatory role of FABP4 in the energy and lipid metabolism was evaluated by the levels of triglyceride, ATP, LDH, glycerol and NEFA. At last, GO and KEGG analysis based on FABP4 overexpressed cells was performed, and the AKT pathway and epithelial–mesenchymal transition (EMT)-related proteins were determined by Western blot. Results Higher accumulation of lipids and stronger FABP4 transcription were observed in colon cancer tissues. Having been incubated with adipose tissue extract and overexpressed FABP4, colon cancer cells demonstrated enhanced lipid accumulation. In functional experiments, co-culture with adipose tissue extract significantly enhanced the invasion and migration of colon cancer cells, as well as the energy and lipid metabolism, and all these processes were reversed by FABP4 inhibitor. In addition, the metastasis of FABP4-overexpressed colon cancer cells was also significantly enhanced in vitro and in vivo. In terms of mechanism, the bioinformatics analysis showed that FABP4 was enriched in 11 pathways related to metabolic processes in FABP4 overexpressed cells. Finally, FABP4 overexpression improved EMT progression of colon cancer, as evidenced by the upregulation of Snail, MMP-2 and MMP-9, the downregulation of E-cadherin. The expression of p-Akt was also elevated. Conclusion FABP4 overexpression could increase FAs transport to enhance energy and lipid metabolism, and activate AKT pathway and EMT to promote the migration and invasion of colon cancer cells.

BackgroundLipocalin 2 (LCN2), an innate immune protein, plays a pivotal role in promoting sterile inflammation by regulating immune responses. However, the role of LCN2 in diverse cancers remains poorly defined. This research aimed to investigate the correlation between LCN2 expression and immunity and visualize its prognostic landscape in pan-cancer.MethodsRaw data in regard to LCN2 expression in cancer patients were acquired from TCGA and GTEx databases. Besides, we investigated the genomic alterations, expression pattern, and survival analysis of LCN2 in pan-cancer across numerous databases, including cBioPortal and GEPIA database. The correlation between LCN2 expression and tumor immune infiltration was explored via TIMER, and we utilized CIBERSORT and ESTIMATE computational methods to assess the proportion of tumor-infiltrating immune cells (TIICs) and the amount of stromal and immune components from TCGA database. Protein–Protein Interaction analysis was performed in GeneMANIA database, and gene functional enrichment was performed by Gene Set Enrichment Analysis (GSEA).ResultsOn balance, tumor tissue had a higher LCN2 expression level compared with that in normal tissue. Elevated expression of LCN2 was related to poor clinical regimen with OS and RFS. There were significant positive correlations between LCN2 expression and TIICs, including CD8+ T cells, CD4+ T cells, B cells, neutrophils, macrophages, and dendritic cells. Moreover, markers of TIICs exhibited different LCN2-related immune infiltration patterns. GSEA analysis showed that the expression of LCN2 was related to retinol metabolism, drug metabolism cytochrome P450 and metabolism of xenobiotics by cytochrome P450.ConclusionsThese findings suggested that LCN2 might serve as a biomarker for immune infiltration and poor prognosis in cancers, shedding new light on therapeutics of cancers.

MircoRNA (miRNA) are a group of small, non–coding, regulatory RNA with an average length of approximately 22 nucleotides, which mostly modulate gene expression post–transcriptionally through complementary binding to the 3ʹ‐untranslated region (3ʹ‐UTR) of multiple target genes. Emerging evidence has shown that miRNA are frequently dysregulated in a variety of human malignancies. Among them, microRNA‐145 (miR‐145) has been increasingly identified as a critical suppressor of carcinogenesis and therapeutic resistance. Resistance to tumor therapy is a challenge in cancer treatment due to the daunting range of resistance mechanisms. We reviewed the status quo of recent advancements in the knowledge of the functional role of miR‐145 in therapeutic resistance and the tumor microenvironment. It may serve as an innovative biomarker for therapeutic response and cancer prognosis.