Canagliflozin increases adenoma burden in female APCMin/+ mice

The diabetes drug canagliflozin acts primarily by inhibiting glucose reuptake by the sodium glucose transporter 2 (SGLT2) in the kidney proximal tubule, thereby lowering serum glucose levels. Canagliflozin also acts on SGLT1, a related transporter responsible for glucose uptake in the small intestine and more distal kidney tubules. Several cancers overexpress SGLT1 and SGLT2, where these transporters fuel tumor metabolism. A recent study by NIAs Interventions Testing Program (ITP) showed that canagliflozin treatment extends lifespan in male mice. Since cancer is the major cause of death in most mouse strains, including the UM-HET3 strain used by the ITP, this observation suggests that canagliflozin might exert anti-cancer effects in this context. Here, we treated a commonly-used mouse neoplasia model -- the intestinal adenoma-prone APCMin/+ strain -- with canagliflozin, to test the effects of drug treatment on tumor burden. Surprisingly, canagliflozin increased the total area of intestine involved by adenomas, an effect that was most marked in the distal intestine and in female mice. Immunohistochemical analysis suggested that canagliflozin may not influence adenoma growth via direct SGLT1/2 inhibition in neoplastic cells themselves. Instead, our results are most consistent with a model whereby canagliflozin aggravates adenoma development by altering the anatomic distribution of intestinal glucose absorption, as evidenced by increases in postprandial GLP-1 levels consistent with delayed glucose absorption. Our results suggest that canagliflozin exacerbates adenomatosis in the APCMin/+ model via complex, cell-non-autonomous mechanisms, and hint that sex differences in incretin responses may underlie differential effects of this drug on lifespan.