Investigating synergistic impact of diet-induced hyperinsulinemia and mutant Kras on colorectal cancer metastasis

Purpose: This study examines how chronic high-fat-sugar (HFS) diet-induced metabolic dysfunction affects cancer metastasis in an in vivo, genetically engineered iKAP model (inducible Kras, Apc, and p53) (Boutin et al., Genes & Development, 2017, 31:370). Methods: 8-10 weeks old mice are randomized to either a 10% low-fat-sugar/LFS (healthy diet) or a 45% high-fat-sugar/HFS (western-style diet) to induce hyperinsulinemia and metabolic dysfunction before tumor initiation. The development of metabolic dysfunction is monitored using Echo-MRI for alterations in body composition, a glucose tolerance test (GTT), and endpoint steatosis. Upon tumor induction, tumor growth rates are measured to compare tumor burden in relation to diet and Kras mutation status. Micro- and macro-metastases are being recorded and compared using micro-CT imaging and endpoint tissue histopathology. In parallel, a complementary in vitro study using a panel of isogenic colorectal cancer cell lines is underway to evaluate the effect of insulin-mediated cell migration and invasion through scratch and trans-well assays, as well as downstream signaling analyses by Western blot. Result: Our preliminary in vivo findings demonstrate signals of metabolic dysfunctions, including higher body fat percentage, lower glucose tolerance, and the development of hepatic steatosis in HFS-fed iKAP mice. Mice on the 45% high-fat diet showed higher liver disease scores compared to those on the 10% fat diet. Inclusions of hepatocyte ballooning and inflammation were noticeably increased in the high-fat group. Current findings indicate a diet-dependent increase in liver steatosis in 45% HFS mice relative to the 10% control group. Conclusion: Based on preliminary findings, an HFS diet effectively induces metabolic dysfunction in the iKAP in vivo model. This context may support investigating hyperinsulinemia-oncogenic Kras crosstalk in CRC progression and metastasis. Additional mice and sex-based analyses will further validate and strengthen these findings. Moving forward, chronic hyperinsulinemia reprograms metabolism and intracellular signaling in the presence of mutant Kras to expand tumor metastatic spread, is an open question.