Autophagy inhibition in 3T3-L1 adipocytes breaks the crosstalk with tumor cells by suppression of adipokine production

Abstract

Several studies have revealed the functional importance of autophagy in both adipogenesis and carcinogenesis. Here, we investigated autophagy as a link between tumorigenesis and adipogenesis using 3T3-L1 cells, which have been shown to closely mimic the in vivo differentiation process. The relative levels of LC3-II/I showed that autophagy was the highest after 4-6 days of initiation of differentiation and it diminished thereafter. Furthermore, chloroquine (CQ), a late autophagy inhibitor, effectively inhibited adipogenic differentiation of 3T3-L1 cells, suggesting that autophagy may have a positive impact on adipogenic differentiation. Notably, real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that CQ completely blocked the mRNA expression of three adipokines (adiponectin, leptin, and peroxisome proliferator-activated receptor-γ (PPARγ)), which increased proportionally to adipocyte differentiation. Using adipokine antibody arrays, we also found that among 38 adipokines examined, 6 adipokines were significantly differentially regulated in mature adipocytes compared to those in preadipocytes. A comparative analysis of adipokine production revealed that CQ-treated adipocytes displayed a profile similar to that of preadipocytes. Subsequently, CQ treatment significantly inhibited the migration capacity of v-Haras-transformed cells in both 3T3-L1 adipocyte-conditioned medium and co-culture with 3T3-L1 using a transwell plate. Taken together, our results suggest that autophagy inhibition blocks the production of mediators relevant to the adipogenic process and may significantly contribute to reducing obesity-related cancer risk.

Transcription Factor E2F1 Knockout Promotes Mice White Adipose Tissue Browning Through Autophagy Inhibition

“…Cells were incubated for 21 days, and the media changed every 3 days. Murine 3T3-L1 preadipocyte cells were cultured and differentiated as previously described ( Hwang and Lee, 2020 ). To assess the effect of autophagy on adipocyte differentiation, the autophagic inhibitor (3-MA), an inhibitor of phosphoinositide 3 kinase that specifically inhibits autophagosome formation at 5 mM (MCE, China), were added to the media before adipogenic differentiation.…”

Mitochondrially targeted tamoxifen alleviates markers of obesity and type 2 diabetes mellitus in mice

“…Adipogenesis has been shown to affect the composition and regeneration of adipose tissue during obesity 27 . Since adipocyte differentiation occurs in two steps 28,29 , MitoTam and tamoxifen were added to pre-adipocytes at two different time points (Fig. 7a), and evaluations were performed after completion of adipogenesis (day 9).…”

Effects of Energy Levels on Autophagy, Adipogenic Differentiation and Lipid Metabolism in Subcutaneous and Visceral Pre-Adipocytes

“…It has also been reported that autophagy plays a key role in the process of differentiation and examining the responses of differentiation; thus, autophagy could be a possible marker (Dong and Czaja, 2011;Goldman et al, 2011). In a recent study, its similar impairment of adipocyte differentiation was observed in 3T3-L1 pre-adipocytes in which microtubule -associated protein 1A/1B-light chain-3 (LC-3) was removed (Hwang and Lee, 2020), or the autophagy process was blocked by chemical inhibitors (Park et al, 2017). Another study has also reported that removal of gene 5 or 7 related to autophagy in the mice reduces lipid biosynthesis and decreases overall body mass of fat tissues (Zhang et al, 2009).…”