Cachexia-associated adipose loss induced by tumor-secreted leukemia inhibitory factor is counterbalanced by decreased leptin
Gurpreet K. Arora, … , Puneeth Iyengar, Rodney E. Infante
Gurpreet K. Arora, … , Puneeth Iyengar, Rodney E. Infante
Published July 26, 2018
Citation Information: JCI Insight. 2018;3(14):e121221. https://doi.org/10.1172/jci.insight.121221.
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Research Article Metabolism Oncology

Cachexia-associated adipose loss induced by tumor-secreted leukemia inhibitory factor is counterbalanced by decreased leptin

Abstract

Cachexia syndrome consists of adipose and muscle loss, often despite normal food intake. We hypothesized that cachexia-associated adipose wasting is driven in part by tumor humoral factors that induce adipocyte lipolysis. We developed an assay to purify secreted factors from a cachexia-inducing colon cancer line that increases lipolysis in adipocytes and identified leukemia inhibitory factor (LIF) by mass spectrometry. Recombinant LIF induced lipolysis in vitro. Peripheral LIF administered to mice caused >50% loss of adipose tissue and >10% reduction in body weight despite only transient hypophagia due to decreasing leptin. LIF-injected mice lacking leptin (ob/ob) resulted in persistent hypophagia and loss of adipose tissue and body weight. LIF’s peripheral role of initiating lipolysis in adipose loss was confirmed in pair-fed ob/ob mouse studies. Our studies demonstrate that (a) LIF is a tumor-secreted factor that promotes cachexia-like adipose loss when administered peripherally, (b) LIF directly induces adipocyte lipolysis, (c) LIF has the ability to sustain adipose and body weight loss through an equal combination of peripheral and central contributions, and (d) LIF’s central effect is counterbalanced by decreased leptin signaling, providing insight into cachexia’s wasting, despite normophagia.

Authors

Gurpreet K. Arora, Arun Gupta, Sriram Narayanan, Tong Guo, Puneeth Iyengar, Rodney E. Infante

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Figure 2

Recombinant LIF induces adipocyte lipolysis through ATGL using its canonical signaling pathway.

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Recombinant LIF induces adipocyte lipolysis through ATGL using its canon...
(A) Gel-filtration chromatography of recombinant proteins. WT recombinant leukemia inhibitory factor (rLIF) and rLIF K159A were purified as described in Methods. Buffer C (1 ml) containing 5–6 mg of rLIF (red) or rLIF K159A (blue) was loaded on to a Tricorn 10/300 Superdex 200 column and chromatographed at a flow rate of 0.5 ml/min. Absorbance at 280 nm (A280) was monitored continuously to identify rLIF (red) and rLIF K159A (blue). Maximal A280 values for each protein (rLIF, 576 mAU; rLIF K159A, 728 mAU) were normalized to 1. (Inset) The indicated protein (4 μg of each) was subjected to 15% SDS/PAGE and stained with Coomassie. (B–D) Differentiated adipocytes in a 12-well format were treated in a final volume of 1.5 ml of medium E supplemented with either the indicated concentration of rLIF or rLIF K159A (B and C) or with 30 nM isoprotererenol or 1 ng/ml rLIF in the absence or presence of the indicated concentration of Atglistatin (D). After incubation for 20 hours at 37˚C, medium was collected and glycerol concentration was measured using the adipocyte lipolysis assay (B and D), or adipocyte cells were harvested and subjected to IB analysis (C, 10 μg/lane) with the indicated antibody as described in Methods. Each data point represents the mean ± SEM of the absolute glycerol concentration over background (B) or the relative change in medium glycerol concentration compared with conditions containing rLIF without Atglistatin (red, 26 μM) or isoproterenol without Atglistatin (black, 83 μM) (D). (E) SVF adipocytes were differentiated in a 48-well format as described in Methods. Differentiated adipocytes in 48-well format were treated in a final volume of 300 μl of medium E supplemented with 1 ng/ml rLIF in the absence or presence of 3 μg/ml of the indicated antibody. After incubation for 20 hours at 37˚C, medium was collected and glycerol concentration was measured using the adipocyte lipolysis assay as described in Methods. Data is shown as dot plots with bars representing mean ± SEM of the relative change in medium glycerol concentration compared with conditions containing rLIF without antibody (32 μM). (A–E) These results were confirmed in 2 (E) or 3 (A–D) independent experiments. *P < 0.05, **P < 0.01, and ***P < 0.001 based on Student’s t test.