Fruit flies with gut tumors prefer eating Tumor-Fighting Compounds compared to healthy flies: A case of self medication

Amazing stuff! Very specific self medication in insects!

A tumor can change gustatory preferences in the brain for specific chemicals that when eaten treat the tumor, which is not observed in healthy insects!

From the highlights and abstract::

"Highlights

• Gut tumors cause flies to increase their ingestion of anti-tumorigenic compounds

• Gut tumors do not affect avoidance of aversive compounds devoid of anti-tumor effects

• Increased consumption of anti-tumorigenic compounds suppresses gut tumors

• Shift in taste valence due to tumors occurs via a mechanism postsynaptic to taste neurons

Summary

The sense of taste is essential for survival, as it allows animals to distinguish between foods that are nutritious from those that are toxic. However, innate responses to different tastants can be modulated or even reversed under pathological conditions. Here, we examined whether and how the internal status of an animal impacts taste valence by using Drosophila models of hyperproliferation in the gut. In all three models where we expressed proliferation-inducing transgenes in intestinal stem cells (ISCs), hyperproliferation of ISCs caused a tumor-like phenotype in the gut. While tumor-bearing flies had no deficiency in overall food intake, strikingly, they exhibited an increased gustatory preference for aristolochic acid (ARI), which is a bitter and normally aversive plant-derived chemical. ARI had anti-tumor effects in all three of our gut hyperproliferation models. For other aversive chemicals we tested that are bitter but do not have anti-tumor effects, gut tumors did not affect avoidance behaviors. We demonstrated that bitter-sensing gustatory receptor neurons (GRNs) in tumor-bearing flies respond normally to ARI. Therefore, the internal pathology of gut hyperproliferation affects neural circuits that determine taste valence postsynaptic to GRNs rather than altering taste identity by GRNs. Overall, our data suggest that increased consumption of ARI may represent an attempt at self-medication. Finally, although ARI’s potential use as a chemotherapeutic agent is limited by its known toxicity in the liver and kidney, our findings suggest that tumor-bearing flies might be a useful animal model to screen for novel anti-tumor drugs."

Flies’ Taste for Tumor-Fighting Compounds May Aid Drug Discovery | The Scientist Magazine® "Fruit flies with gut tumors showed an increased preference for a bitter antitumor compound compared to healthy flies, suggesting a self-medication strategy. "

Gut tumors in flies alter the taste valence of an anti-tumorigenic bitter compound (open access)

Graphical abstract

Figure 1 Fruit flies with gut tumors exhibit reduced avoidance of ARI but not other bitter tastants