Drosophila midgut tumor-induced insulin resistance systemically remodels lymph gland hematopoiesis during cancer cachexia

Cancer cachexia involves systemic metabolic deregulation along with classical features of muscle wasting, lipolysis, and chronic inflammation. While tumor non-autonomous effects on peripheral organs are recognized, how the tumor rewires the circulating immune cells and hematopoiesis remains unclear. We utilized a Drosophila larval cancer cachexia model by expressing yki3SA in the adult midgut precursors (AMP), which gives rise to a tumor in the larval midgut and recapitulates key cachectic phenotypes, including insulin resistance. Tumor-induced cachexia results in perturbed blood cell homeostasis with a reduced niche and aberrant blood cell differentiation in the larval hematopoietic organ, the lymph gland (LG). Bulk RNA-seq analysis of circulating hemocytes from tumor-bearing larvae revealed upregulation of multiple cachectic ligands, notably ImpL2, an insulin antagonist. We demonstrate that elevated ImpL2 levels reduce LG niche size and promote aberrant blood cell differentiation. Elevated ImpL2 levels and systemic insulin resistance in the tumor-induced cachexia conditions result in abrogation of insulin signaling in the niche-progenitor micro-environment in the LG. DE-cadherin levels in the primary LG lobe are perturbed, and Wingless signaling is down-regulated, driving prohemocyte differentiation. A genetic mimic of systemic ImpL2 overexpression or high sugar diet (HSD) conditions recapitulates these LG phenotypes due to abrogation of the Insulin-Wingless signaling axis. Hemocyte-specific ImpL2 depletion in HSD-fed larvae rescued these defects, suggesting a regulatory role for circulating hemocyte-derived ImpL2. Our findings reveal that hemocyte-derived factors actively contribute to systemic insulin resistance, causing hematopoietic remodeling in cancer cachexia.