Drosophila Screening Identifies Dual Inhibition of MEK and AURKB as an Effective Therapy for Pancreatic Ductal Adenocarcinoma

Abstract

Significant progress has been made in understanding the pathogenesis of pancreatic ductal adenocarcinoma (PDAC) by generating and using murine models. To accelerate drug discovery by identifying novel therapeutic targets on a systemic level, here we generated a Drosophila model mimicking the genetic signature in PDAC (KRAS, TP53, CDKN2A, and SMAD4 alterations), which is associated with the worst prognosis in patients. The ‘4-hit’ flies displayed epithelial transformation and decreased survival. Comprehensive genetic screening of their entire kinome revealed kinases including MEK and AURKB as therapeutic targets. Consistently, a combination of the MEK inhibitor trametinib and the AURKB inhibitor BI-831266 suppressed the growth of human PDAC xenografts in mice. In patients with PDAC, the activity of AURKB was associated with poor prognosis. This fly-based platform provides an efficient whole-body approach that complements current methods for identifying therapeutic targets in PDAC. Significance: Development of a Drosophila model mimicking genetic alterations in human pancreatic ductal adenocarcinoma provides a tool for genetic screening that identifies MEK and AURKB inhibition as a potential treatment strategy.

Concurrent targeting of GSK3 and MEK as a therapeutic strategy to treat pancreatic ductal adenocarcinoma

“…To mimic the ‘ 4‐hit ’ genotype observed in PDAC patients, we generated a quadruple‐hit animal model through the application of Drosophila transgenic technology 22 (Figure 1A ). Namely, we targeted cDNA sequences of Drosophila Ras G12D ( dRas G12D ) and Cyclin E ( dCycE ) and shRNA sequences for a TP53 ortholog p53 and a SMAD4 ortholog Med to developing wing discs in larvae.…”

“…Stocks balanced with balancer chromosomes without the Tubby ( Tb ) marker were rebalanced with the balancer FM7c ‐ Tb ‐ RFP , CyO ‐ Tb ‐ RFP , or TM6B carrying Tubby ( Tb ) as a visible marker. 22 To knockdown kinases specifically in the transformed cells, Ser > 4‐hit or ptc > 4‐hit flies were crossed with UAS ‐siRNA flies. Resulting progenies were cultured until adulthood for 11 days at 27°C, and the number of adults was divided by that of total pupae to determine percent viability.…”

“…In total, 86 specimens were used to develop TMA (Table S1 ) 22 and were analyzed for expression of GSK3 using anti‐GSK3β antibody (RRID, AB_2636978; 1:400; Cell Signaling Technology, Berkeley, CA) (Table S2 ). Specimens were scored for the ratio of the number of GSK3β‐positive cancer cells to that of cancer cells in the whole core by two researchers (JF and KCH) who were blinded to the clinical information of the patients.…”

“…In addition, we recently established a whole‐animal platform also for PDAC research by combining Drosophila with mammalian models in a complementary manner. 22 PDAC is often characterized by somatic mutations in four specific genes, namely activation of the oncogene KRAS and inactivation of the tumor suppressor genes CDKN2A , TP53 , and/or SMAD4 . 23 In fact, patients with all four mutations have the worst prognosis among all the PDAC patients, 24 , 25 highlighting the importance of developing a corresponding animal model carrying this ‘ 4‐hit ’ genotype to cause endogenous tumors.…”

“…Through chemical testing, we discovered that a combination of the MEK inhibitor drug trametinib and the AURKB inhibitor BI‐831266 consistently suppressed the growth of human PDAC xenografts in mice. 22 …”