SGLT2 inhibition slows tumor growth in mice by reversing hyperinsulinemia

Abstract

Background: Obesity confers an increased risk and accelerates the progression of multiple tumor types in rodents and humans, including both breast and colon cancer. Because sustained weight loss is rarely achieved, therapeutic approaches to slow or prevent obesity-associated cancer development have been limited, and mechanistic insights as to the obesity-cancer connection have been lacking.

Methods: E0771 breast tumors and MC38 colon tumors were treated in vivo in mice and in vitro with two mechanistically different insulin-lowering agents, a controlled-release mitochondrial protonophore (CRMP) and sodium-glucose cotransporter-2 (SGLT2) inhibitors, and tumor growth and glucose metabolism were assessed. Groups were compared by ANOVA with Bonferroni's multiple comparisons test.

Results: Dapagliflozin slows tumor growth in two mouse models (E0771 breast cancer and MC38 colon adenocarcinoma) of obesity-associated cancers in vivo, and a mechanistically different insulin-lowering agent, CRMP, also slowed breast tumor growth through its effect to reverse hyperinsulinemia. In both models and with both agents, tumor glucose uptake and oxidation were not constitutively high, but were hormone-responsive. Restoration of hyperinsulinemia by subcutaneous insulin infusion abrogated the effects of both dapagliflozin and CRMP to slow tumor growth.

Conclusions: Taken together, these data demonstrate that hyperinsulinemia per se promotes both breast and colon cancer progression in obese mice, and highlight SGLT2 inhibitors as a clinically available means of slowing obesity-associated tumor growth due to their glucose- and insulin-lowering effects.

Keywords: Glucose; Insulin; Obesity; Tumor metabolism.

Fig 1

Dapagliflozin slows E0771 breast tumor growth in an insulin-dependent manner. a, b Urine and plasma glucose concentrations. Unless otherwise designated, all measurements were performed in 5-h fasted mice. c Plasma insulin. d, e Tumor 2-deoxyglucose uptake and V_PDH/V_CS. f Tumor size. *P < 0.05, ***P < 0.001, ****P < 0.0001 vs. chow, ++P < 0.01, ++++P < 0.0001 vs. HFD + dapagliflozin, with the color of the symbols indicating the group compared to the group designated by the symbols. In all panels, data are the mean ± S.E.M. of n = 5 per group. Groups were compared by ANOVA with Bonferroni’s multiple comparisons test

Fig. 2

Impact of SGLT2 inhibitors and insulin on E0771 cell metabolism and division in vitro. a Glucose uptake. b V_PDH/V_CS. c Cell division. In all cell studies, data are the mean ± S.E.M. of n = 4 replicates. Data were compared by ANOVA with Bonferroni’s multiple comparisons test, in which each group was compared to the mean of the vehicle-treated cells

Fig. 3

A controlled-release mitochondrial protonophore slows E0771 breast tumor growth in an insulin-dependent manner. a Liver triglyceride content. In all panels, unless otherwise specified, all mice were fasted for 5 h before they were studied. b, c Plasma glucose and insulin concentrations. d Tumor 2-deoxyglucose uptake and V_PDH/V_CS. f Tumor size. **P < 0.01 vs. chow, #P < 0.05, ##P < 0.01 vs. HFD + CRMP, with the color of the symbols indicating the group compared to the group designated by the symbols. In all panels, data are the mean ± S.E.M. of n = 5–6 per group. Groups were compared by ANOVA with Bonferroni’s multiple comparisons test

Fig. 4

Impact of DNP and insulin on E0771 cell metabolism and division in vitro. a Glucose uptake. b V_PDH/V_CS. In all samples, this ratio was below the limit of detection (0.5%) in 500 μM DNP-treated cells. c Cell division. In all cell studies, data are the mean ± S.E.M. of n = 4 replicates. Data were compared by ANOVA with Bonferroni’s multiple comparisons test, in which each group was compared to the mean of the vehicle-treated cells

Fig. 5

Dapagliflozin slows MC38 colon adenocarcinoma tumor growth in an insulin-dependent manner. a, b Urine and plasma glucose concentrations. In all panels, mice were fasted for 5 h before studies were performed. c Plasma insulin concentrations. d, e Tumor glucose uptake and V_PDH/V_CS. f Tumor size. *P < 0.05, **P < 0.01, ***P < 0.001 vs. chow; +P < 0.05, ++P < 0.01, +++P < 0.001 vs. HFD + dapagliflozin. The color of the symbols indicates the group compared to the group designated by the symbols. In all panels, data are the mean ± S.E.M. of n = 5–6 per group, with groups compared by ANOVA with Bonferroni’s multiple comparisons test

Fig. 6

Neither SGLT2 inhibitors nor β-OHB directly alter MC38 tumor cell division. a Impact of SGLT2 inhibitors and insulin on MC38 cell glucose uptake in vitro. In panels a–d, n = 4 in vitro replicates, with groups compared by ANOVA with Bonferroni’s multiple comparisons test, in which each group was compared to the vehicle-treated cells (**P < 0.01, ***P < 0.001, ****P < 0.0001). b V_PDH/V_CS. c Cell division. d Impact of β-OHB and insulin on cell division. e Plasma β-OHB concentrations after 4 weeks of β-OHB supplementation in drinking water, which was removed 2 h before plasma was obtained. f Tumor size. In panels e and f, n = 8 per group, with groups compared by the two-tailed unpaired Student’s t test. All data are presented as the mean ± S.E.M

Fig. 7

Insulin signaling is dynamically activated under postprandial conditions in MC38 tumors. a Plasma insulin concentrations during an oral glucose tolerance test. In both panels, n = 4–10 per time point. b Tumor Akt pSer473 phosphorylation during the glucose tolerance test. All groups were compared to time zero by ANOVA with Bonferroni’s multiple comparisons test. Data are the mean ± S.E.M