Experiments designed to assess if localized tumors can systemically affect heart function have been performed in Drosophila, using imaginal-disc-specific expression of oncogenic alleles of Ras85D and Pi3K92E, or eye-specific overexpression of yki. Although all three are observed to impact heart function, specific effects vary; cardiac phenotypes indicative of cachexia are not observed. The yki model was characterized further; although yki overexpression in the eye results in hyperplastic overgrowth specifically in the eye, in 3-5 day-old flies compromised cardiac function is observed. The cardiac phenotypes can be rescued by feeding of antioxidants, supporting the hypothesis that yki-induced tumor-like overgrowth causes a systemic increase in ROS, affecting cardiac function. It is hypothesized that cardiac dysfunction precedes changes associated with cachexia.
yki encodes a transcriptional co-activator protein that is negatively regulated by Hippo signaling (see the Human Disease Model report 'cancer, multiple, Hippo signaling pathway', FBhh0000764). Overexpression of an activated form of yki in the developing eye has been used to model cachexia in flies; see the Human Disease Model report 'cachexia, yki-induced eye tumor model' (FBhh0001322).
[updated Sep. 2021 by FlyBase; FBrf0222196]
Many cancer patients undergo heart-related complications resulting in high incidences of mortality. It is generally hypothesized that cardiac dysfunction in cancer patients occurs due to cardiotoxicity induced by therapeutic agents, used to treat cancers and/or cancer-induced cachexia. It is not known if localized tumors or unregulated cell growth systemically affect heart function before treatment, and/or prior to the onset of cachexia (FBrf0250374).
Moderate-scoring ortholog of human YAP1; lower-scoring ortholog of WWTR1 (1 Drosophila to 2 human). Dmel\yki shares 31% identity and 45% similarity with YAP1; it shares 25% identity and 34% similarity with WWTR1.