Fig. 1.

Src negatively regulates lipolysis. (a) Correlation of endogenous Src expression to lipid droplets in a panel of lung cancer (left) and renal cell carcinoma cell lines (right). Together with basal protein expression of pSrc and Src, lipid contents were assayed using Oil-red O staining in the panel. (b) Expression of lipolytic genes in lung cancer cells. The mRNA expression of FABP4 and LPL was shown using the RT-PCR assay. (c) Reverse correlation between Src and FABP or LPL. The analysis showed negative Pearson's correlation coefficient for the expression pattern between Src and FABP4 as well as Src and LPL. For biostatistics analysis, data were obtained for lung adenocarcinoma or RCC patients from the cbioportal database. (d-e) Pharmacological inhibition of Src induces FABP4 expression. (d) Expression of FABP4 mRNA (left) and protein (right) was assayed upon treatment of Src inhibitor SU6656 compound in the lung cancer cell lines. Cells were treated with 5 μM of SU6656 for 24, 48, and 72 h and assayed for FABP4 protein expression or 24 h for mRNA expression. (e) Oncogenic Src was exogenously overexpressed in Calu6 cells and followed by FABP4 expression upon SU6656 treatment. Cells were transfected with pEGFP control or wtSrc-GFP followed by SU6656 treatment for 24 h. Data represent mean ± SEM of triplicates. Similar results were observed in at least two independent experiments. Asterisks refer to **P ≤ 0.01; ***P ≤ 0∙001; ****P ≤ 0∙001 (Student's t-test (d) and one-way ANOVA, Tukey's post test (e)). In all RT-PCR data, y-axis represents fold change in gene expression. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)