64P - Developing novel therapeutics for bladder cancer leveraging drosophila models

Background

The prevalence of bladder cancer (BC) has been increasing worldwide. Particularly, patients carrying the Basal/Squamous BC (BSBC) have poor prognosis. Mammalian models such as cultured human BSBC cells and their xenografts have provided critical insights into its mechanisms, but effective therapeutics for BSBC is still lacking. Recently, the fruit fly Drosophila has made significant contributions to cancer research. Here, we employed Drosophila to generate the first fly model reproducing the BSBC genotypes and to discover novel therapeutic candidates for BSBC treatment.

Methods

BSBC often harbors mutations in genes ‘A’, ‘B’ and/or ‘C’. To model various alteration patterns in Drosophila, we employed the binary GAL4/UAS system, which targets expression of exogenous transgenes to a desired fly tissue. We prepared GAL4 driver strains expressing a transcription factor GAL4 specifically in the eye cells and wing cells (GMR-GAL4 and nub-GAL4, respectively, for validating transgene functions), or the Malpighian tubule which corresponds to human bladder (for modeling BSBC genotypes). We also generated UAS transgenic strains which carry mutated cDNA and/or shRNA sequences as transgenes downstream of the GAL4 target UAS sequence.

Results

Previous studies have reported that induction of wild-type A in fly eyes causes ‘rough eye’ phenotype by promoting apoptosis, which we confirmed using the eye-specific GMR-GAL4 driver. We found that additional expression of missense-mutated A or knockdown of A by shRNA rescued the phenotype as expected. Furthermore, we confirmed that overexpression of B using the same driver increased the fly eye size as previously reported. Using the wing-specific nub-GAL4 driver, we validated that knockdown of C by shRNA reduced the fly wing area, verifying its reported function to control tissue growth.

Conclusions

The eye and wing phenotypes induced by transgenes were consistent with their reported functions and our expectation, proving our strategy effective in validating functions of the transgenes and in modeling the BSBC genotypes in flies. We will next perform whole-body assays such as comprehensive genetic and drug screenings using these flies to demonstrate the mechanisms of BSBC pathogenesis and to develop novel BSBC treatments.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.