Chemical genetic screens reveal defective lysosomal trafficking as synthetic lethal with NF1 loss.

Neurofibromatosis type 1, a genetic disorder caused by germline mutations in NF1, predisposes patients to the development of tumors, including cutaneous and plexiform neurofibromas (CNs and PNs), optic gliomas, astrocytomas, juvenile myelomonocytic leukemia, high-grade gliomas, and malignant peripheral nerve sheath tumors (MPNSTs), which are chemotherapy- and radiation-resistant sarcomas with poor survival. Loss of NF1 also occurs in sporadic tumors such as glioblastoma (GBM), melanoma, breast, ovarian, and lung cancers. We performed a high-throughput screen for compounds that were synthetic lethal with NF1 loss, which identified several leads, including the small molecule Y102. Treatment of cells with Y102 perturbed autophagy, mitophagy, and lysosome positioning in NF1-deficient cells. A dual proteomics approach identified the BORC complex, which is required for lysosome positioning and trafficking, as a potential target of Y102. Knockdown of a BORC complex subunit using siRNA recapitulated the phenotypes observed with Y102 treatment. Our findings demonstrate that the BORC complex may be a promising therapeutic target for NF1-deficient tumors.