High-throughput and targeted drug screens identify pharmacological candidates against MiT-translocation renal cell carcinoma

Abstract

Background MiT-Renal Cell Carcinoma (RCC) is characterized by genomic translocations involving microphthalmia-associated transcription factor (MiT) family members TFE3, TFEB, or MITF. MiT-RCC represents a specific subtype of sporadic RCC that is predominantly seen in young patients and can present with heterogeneous histological features making diagnosis challenging. Moreover, the disease biology of this aggressive cancer is poorly understood and there is no accepted standard of care therapy for patients with advanced disease. Tumor-derived cell lines have been established from human TFE3-RCC providing useful models for preclinical studies. Methods TFE3-RCC tumor derived cell lines and their tissues of origin were characterized by IHC and gene expression analyses. An unbiased high-throughput drug screen was performed to identify novel therapeutic agents for treatment of MiT-RCC. Potential therapeutic candidates were validated in in vitro and in vivo preclinical studies. Mechanistic assays were conducted to confirm the on-target effects of drugs. Results The results of a high-throughput small molecule drug screen utilizing three TFE3-RCC tumor-derived cell lines identified five classes of agents with potential pharmacological efficacy, including inhibitors of phosphoinositide-3-kinase (PI3K) and mechanistic target of rapamycin (mTOR), and several additional agents, including the transcription inhibitor Mithramycin A. Upregulation of the cell surface marker GPNMB, a specific MiT transcriptional target, was confirmed in TFE3-RCC and evaluated as a therapeutic target using the GPNMB-targeted antibody-drug conjugate CDX-011. In vitro and in vivo preclinical studies demonstrated efficacy of the PI3K/mTOR inhibitor NVP-BGT226, Mithramycin A, and CDX-011 as potential therapeutic options for treating advanced MiT-RCC as single agents or in combination. Conclusions The results of the high-throughput drug screen and validation studies in TFE3-RCC tumor-derived cell lines have provided in vitro and in vivo preclinical data supporting the efficacy of the PI3K/mTOR inhibitor NVP-BGT226, the transcription inhibitor Mithramycin A, and GPNMB-targeted antibody-drug conjugate CDX-011 as potential therapeutic options for treating advanced MiT-RCC. The findings presented here should provide the basis for designing future clinical trials for patients with MiT-driven RCC.

Targeted dephosphorylation of TFEB promotes its nuclear translocation

“…We analyzed the mRNA expression of some known TFEB-target genes in TFEB dTAG/dTAG U2OS cells stably expressing HA-bromoTAG, HA-bromoTAG-PPP2CA or HA-bromoTAG-PPP2CA H118Q by RT-qPCR following 8 h of BDPIC treatment. We observed that compared to DMSO control, BDPIC treatment induced only a slight but significant increase in expression of Fnip 1 , Flcn , 21 , 43 and Gpnmb 47 , 48 , 49 transcripts in cells expressing HA-bromoTAG-PPP2CA but not in those expressing HA-bromoTAG or HA-bromoTAG-PPP2CA H118Q ( Figure 4 C), suggesting that targeted dephosphorylation of TFEB-dTAG by BDPIC is potentially sufficient to cause transcriptional activation of TFEB. The transcription of Hexa , another TFEB-target gene, was not significantly affected by targeted dephosphorylation of TFEB-dTAG by BDPIC ( Figure 4 C).…”

Treatment of metastatic TFE3 microphthalmia transcription factor translocation renal cell carcinoma: a case report

“…Mutations and/or aberrant expression of MiTF/TFE family members have been associated with different types of cancers in humans, such as renal carcinomas, alveolar sarcomas, and melanomas ( 4 ). MiTF/TFE family factors are also involved in the regulation of lysosomal signaling, including mTOR complex 1 (mTORC1) and the Wnt/β-catenin pathway, which are critical for oncogenic signaling ( 5 , 6 ). Most metastatic RCCs are treated with tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor receptor (VEGFR), including pazopanib, sunitinib, sorafenib, bevacizumab, ramucirumab, and cabozantinib ( 1 , 7 - 9 ).…”

Design and validation of a reporter mouse to study the dynamic regulation of TFEB and TFE3 activity through in vivo imaging techniques

“…Dysfunction in TFEB and TFE3 signaling has been observed in neurodegenerative diseases, lysosomal storage disorders, and various types of cancer [ 15 , 20 ]; consistent with this concept, strategies targeting TFEB and TFE3 have shown promise in promoting cellular clearance in cellular and animal models of diseases characterized by the accumulation of metabolic intermediate products or protein aggregates [ 21 ], including lysosomal storage diseases [ 21 , 22 ], Parkinson [ 23–25 ], Alzheimer [ 26–28 ], Huntington diseases [ 29 ], SERPINA1/α1-anti-trypsin deficiency [ 30 ], spinal bulbar muscular atrophy [ 31 ] and diet-induced obesity [ 11 ]. While, several lines of evidence suggest that the identification of clinically compatible MiT/TFE inhibitors may offer a rational therapeutic avenue for the treatment of pathologies induced by TFEB, TFE3 and MITF overexpression or hyperactivation, such as MiT-renal cell carcinoma [ 32 ], Birt-Hogg-Dubé syndrome [ 33 ], tuberous sclerosis [ 34 , 35 ] and malignant melanoma [ 36 ]. Despite the large body of preclinical data suggesting a therapeutic potential of modulating MiT/TFE member, there are currently no clinical applications.…”