FABP4 promotes invasion and metastasis of colon cancer by regulating fatty acid transport

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.

Study of the Performance of Gas Chromatographic Columns Under Severe Injection Loading

A systematic study was conducted to observe the effect on column performance of a series of 600 consecutive injections of human adipose tissue extract, both cleaned and uncleaned. Ten different column packings were used and included single and mixed nonpolar and polar liquid phases. The column characteristics observed were peak height response, efficiency, on-column conversion of p,p’-DDT to p,p’- DDD, and peak configuration. Repetitive injections of uncleaned and high lipid content human adipose tissue extract resulted in decreased performance of most columns in response, efficiency, and compound conversion. However, all columns could be maintained and restored to full or nearly full performance capacity by daily changing of the glass injection port insert used for off-column injection and the glass wool plug at column inlet.