Stauprimide is a staurosporine analog that promotes embryonic stem cell (ESC) differentiation by inhibiting nuclear localization of the MYC transcription factor NME2, which in turn results in downregulation of MYC transcription. Given the critical role the oncogene MYC plays in tumor initiation and maintenance, we explored the potential of stauprimide as an anticancer agent. Here we report that stauprimide suppresses MYC transcription in cancer cell lines derived from distinct tissues. Using renal cancer cells, we confirmed that stauprimide inhibits NME2 nuclear localization. Gene expression analysis also confirmed the selective down-regulation of MYC target genes by stauprimide. Consistent with this activity, administration of stauprimide inhibited tumor growth in rodent xenograft models. Our study provides a unique strategy for selectively targeting MYC transcription by pharmacological means as a potential treatment for MYCdependent tumors.MYC | stauprimide | NME2 | nuclear localization | cancer T he transcription factor MYC participates in diverse cellular processes by regulating the transcription of a large number of genes involved in gene expression, cell division, apoptosis, cell adhesion, stem cell self-renewal and differentiation, and metabolism (1-3). MYC is an oncogene whose expression is elevated in up to 75% of all cancers with various tissue origins (4); MYC expression levels also correlate with prognostic outcomes in patients of various types of malignancies (5, 6). In addition to its well-established roles in tumor initiation and cancer cell survival and proliferation, MYC has been shown to be involved in tumor microenvironment remodeling, drug resistance, and cancer stem cell maintenance (7-9). Recent studies have also revealed a role for MYC in regulating the transcription of immune checkpoint genes, including CD47 and PD-L1 in cancer cells, suggesting that MYC is involved in cancer escape from immune surveillance (10).Overexpression of MYC is able to induce malignant transformation in skin (11), lung (12), liver (13), breast (14, 15), and hematopoietic cells (16) in transgenic mouse models, and termination of MYC overexpression results in halted cancer cell proliferation, increased apoptosis and terminal differentiation, and tumor regression. Furthermore, inhibition of endogenous MYC by the inducible expression of a dominant-negative variant of MYC, Omomyc, is able to induce tumor regression in transgenic mouse models of lung cancer (17). More intriguingly, transient deactivation of MYC overexpression (18) and episodic expression of Omomyc (19) have been shown to induce irreversible tumor regression in osteosarcoma and lung cancer transgenic mouse models, suggesting the potential of MYCtargeted anticancer therapies.Drug discovery efforts have attempted to directly and indirectly modulate MYC-dependent transcription. For example, compounds have been identified that disrupt the interaction between MYC and its transcriptional partner MAX to suppress downstream gene transcription (20)(21)(22)(23)(2...