Abstract
Introduction: Clear Cell Renal Cell Carcinoma (ccRCC) is the most common type of kidney cancer, presenting with defining characteristics of increased lipid droplets formation, loss of the VHL tumor suppressor, and low levels of fatty acid oxidation (FAO). Obesity is associated with an increase in ccRCC incidence, although obese patients respond better to different therapies, a phenomenon called as obesity paradox. The consumption of diets rich in lipids and leading to obesity has been increasing, but how the dietary composition affects ccRCC progression, or could be modulated in combination with other therapies for better responses is still unclear. In the present study, we aimed to evaluate how different fatty acids (FAs) affect ccRCC behavior and metabolism.
Methods: We used 786-O and 769-P ccRCC cell lines. Palmitic acid (PA), oleic acid (OA), and linoleic acid (LA), which are saturated, monounsaturated, and polyunsaturated fatty acids, respectively were used as stimuli for the cells at 50 or 200µM. All stimuli were diluted in culture media with 5% FBS. Lipid droplets were evaluated by Oil Red O staining; viability was assessed by MTT; protein expression was tested by Western Blotting; Oxygen Consumption rate (OCR) by Seahorse; survival was quantified by clonogenic assay; and mRNA was measured by RT-qPCR.
Results: All FAs increased the amount of lipid droplets compared to the control, but OA was the most potent. PA impaired the growth rate for cells compared to control, and other FAs in both cell lines, and did not increase the expression of cleaved caspase-3. PA, even in a lower concentration [50µM], impaired the formation of colonies for both cell lines compared to control and other FAs. LA impaired colony formation only in the higher concentration [200µM], while OA only induced a difference for 769-P cells at the smaller concentration, increasing the number of colonies. OA, and mainly PA, decreased 769-P cells migration, at the time of 6 and 12 h, while only PA decreased migration for 786-O cells, at the time of 12 h. LA, and mainly PA, increased CPT1a mRNA levels in 786-O cells but did not induce a significant difference to 769-P, and all FAs decreased FASN in both cell lines.
Conclusion: It was demonstrated that OA was a potent inducer of lipid droplet formation, which can be protective in avoiding lipid peroxidation. On the other hand, PA and LA induced fewer lipid droplets probably because they are going to FAO, as we observed increased mRNA CPT1a levels, which is the rate-limiting enzyme in FAO. PA impaired potentially the formation of colonies and growth rate, and it is important to highlight that it was without inducing caspase 3-dependent programmed cell death. Taken together our data suggest that PA could be a target therapy for
ccRCC, but it is still necessary for more studies in vitro and in vivo to evaluate how PA and enriched lipid diet can impact a better outcome for patients.
Citation Format: Isadora Ramos de Andrade, Dazhi Wang, Scott Welford. Effect of different fatty acids on ccRCC behavior and metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5411.