In 2018, (1) we demonstrated the feasibility of targeting loss of the Hippo signaling pathway in NF2-deficient papillary kidney cancers. Papillary renal cell carcinomas (PRCC) are a histologically and genetically heterogeneous group of tumors that represent 15-20% of all kidney neoplasms and may require diverse therapeutic approaches. Alteration of the NF2 tumor suppressor gene, encoding a key regulator of the Hippo signaling pathway, is observed in 22.5% of PRCC. The Hippo signaling pathway controls cell proliferation by regulating the transcriptional activity of Yes-Associated Protein, YAP1. Loss of NF2 results in aberrant YAP1 activation. The Src family kinase member Yes also regulates YAP1 transcriptional activity. When we investigated the importance of YAP and Yes activity in three NF2-deficient PRCC cell lines, we found that NF2-deficiency correlated with increased expression of YAP1 transcriptional targets, and siRNA-based knockdown of YAP1 and Yes1 downregulated this pathway and dramatically reduced cell viability. Dasatinib and saracatinib have potent inhibitory effects on Yes and treatment with either resulted in downregulation of YAP1 transcription targets, reduced cell viability, and G0-G1 cell cycle arrest. Xenograft models for NF2-deficient PRCC also demonstrated reduced tumor growth in response to dasatinib. Thus, inhibiting Yes and the subsequent transcriptional activity of YAP1 had a substantial anti-tumor cell effect both in vitro and in vivo and may provide a viable therapeutic approach for patients with NF2-deficient PRCC. (2) In order to better target glycolysis in glycolytic cancer cells, we participated in developing a novel, potent, cell-active pyrazole-based inhibitor of lactate dehydrogenase (LDH). Utilization of a quantitative high-throughput screening paradigm facilitated hit identification, while structure-based design and multiparameter optimization enabled development of compounds with potent biochemical and cell-based inhibition of LDH enzymatic activity. Lead compounds exhibit low nM inhibition of both LDHA and LDHB, submicromolar inhibition of celular lactate production, and inhibition of glycolysis in MiaPaCa2 pancreatic cancer and A673 Ewing's sarcoma cells. Moreover, robust target engagement of LDHA by lead compounds was demonstrated using the cellular thermal shift assay (CETSA), and drug-target residence time was determined via SPR. Analysis of these data suggests that drug-target residence time (off-rate) may be an important attribute to consider for obtaining potent cell-based and durable in vivo inhibition of this cancer metabolism target. Indeed, our lead LDH inhibitor demonstrates potent in vivo on-target activity.
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