10058-F4: A Cell-Permeable c-Myc-Max Dimerization Inhibitor for Apoptosis and Cancer Research

Executive Summary: 10058-F4 is a chemically defined small-molecule that selectively disrupts c-Myc-Max dimerization, a prerequisite for c-Myc transcriptional activity (APExBIO). This inhibition leads to reduced c-Myc mRNA and protein expression, resulting in cell cycle arrest and apoptosis via the mitochondrial pathway (Stern et al., 2024). Its efficacy is validated in vitro in acute myeloid leukemia (AML) cell lines and in vivo in prostate cancer xenograft models. The compound is highly soluble in DMSO and ethanol, but insoluble in water, and is supplied as a solid for research applications only. 10058-F4 supports advanced studies in cancer biology, apoptosis, and telomerase regulation, with APExBIO as the originating supplier.

Biological Rationale

c-Myc is a proto-oncogene encoding a basic helix-loop-helix leucine zipper (bHLH-LZ) transcription factor. c-Myc dimerizes with Max to bind E-box sequences in DNA, activating genes involved in proliferation, metabolism, and apoptosis (Disrupting c-Myc/Max: Strategic Innovation in Apoptosis). Abnormal c-Myc activity is implicated in numerous cancers, including AML and prostate cancer. c-Myc also regulates TERT, the catalytic subunit of telomerase, which is essential for telomere maintenance in stem and cancer cells (Stern et al., 2024). Small-molecule inhibitors like 10058-F4 enable targeted disruption of c-Myc-mediated transcriptional programs, providing tools for dissecting oncogenic signaling and apoptosis in model systems. This article extends the mechanistic depth of prior reviews on 10058-F4 applications by providing updated benchmarks and workflow specifics.

Mechanism of Action of 10058-F4

10058-F4, formally (5E)-5-[(4-ethylphenyl)methylidene]-2-sulfanylidene-1,3-thiazolidin-4-one, selectively inhibits c-Myc-Max heterodimerization by binding to c-Myc at the bHLH-LZ interface (product page). This prevents c-Myc from associating with Max, blocking its DNA binding activity. As a result, c-Myc-dependent transcription is suppressed, leading to downregulation of cell cycle and telomerase genes, including TERT (Stern et al., 2024). The downstream effect includes decreased Bcl-2 family protein expression, cytochrome C release, and induction of mitochondrial apoptosis. 10058-F4 is cell-permeable and acts in both adherent and suspension cell lines.

Evidence & Benchmarks

• 10058-F4 effectively inhibits c-Myc-Max dimerization in vitro, with IC₅₀ values in the low micromolar range (Stellas et al., APExBIO).
• In human AML cell lines (HL-60, U937, NB-4), 10058-F4 induces apoptosis in a dose-dependent manner; significant effects observed at 100 μM after 72 hours (Stern et al., 2024).
• In SCID mice with DU145 or PC-3 prostate cancer xenografts, intravenous 10058-F4 suppresses tumor growth, though efficacy varies by tumor model (Stern et al., 2024).
• c-Myc/Max inhibition by 10058-F4 leads to reduced TERT mRNA, linking c-Myc function to telomerase regulation in stem and cancer cells (Stern et al., 2024).
• 10058-F4 is highly soluble in DMSO (≥24.9 mg/mL) and ethanol (≥2.64 mg/mL), but insoluble in water (APExBIO).

This article updates and integrates the mechanistic and application perspectives from strategic guidance on c-Myc/Max inhibition by providing new data on telomerase regulation and workflow optimization.

Applications, Limits & Misconceptions

• Dissection of c-Myc-dependent transcription in cancer and stem cell models.
• Apoptosis assays in leukemia, prostate cancer, and other c-Myc-driven cell lines.
• Preclinical studies on the role of c-Myc in TERT and telomerase regulation (Stern et al., 2024).
• Modeling mitochondrial apoptosis via Bcl-2 family and cytochrome C release.

Common Pitfalls or Misconceptions

• 10058-F4 is not a pan-Myc inhibitor; it is specific for c-Myc-Max dimerization and does not inhibit other Myc family members (e.g., N-Myc, L-Myc) unless via similar interfaces.
• It is not effective in c-Myc-negative cell lines or tumors not driven by c-Myc/Max activity.
• The compound is not suitable for in vivo use in aqueous vehicles due to insolubility in water; DMSO or ethanol must be used as solvents.
• Long-term storage of 10058-F4 solutions is not recommended due to compound instability; fresh solutions should be prepared for each experiment (APExBIO).
• Observed variability in in vivo tumor inhibition suggests model-specific pharmacodynamics; dose and schedule optimization are required for each system.

This article clarifies the scope and boundaries of 10058-F4 application beyond the overview in previous mechanistic reviews, emphasizing experimental design considerations.

Workflow Integration & Parameters

• 10058-F4 is provided as a solid by APExBIO (product page).
• Stock solutions: dissolve at ≥24.9 mg/mL in DMSO or ≥2.64 mg/mL in ethanol; vortex to ensure homogeneity.
• Working solutions: dilute to final concentrations (e.g., 10–100 μM) in cell culture medium; maintain final DMSO/ethanol concentration ≤0.1% for cell viability.
• Storage: solid material at -20°C; use solutions promptly; avoid repeated freeze-thaw cycles.
• For apoptosis assays, incubate cells for 24–72 hours and assess caspase activation, Annexin V staining, or mitochondrial membrane potential.
• In vivo: administer intravenously in DMSO/ethanol-based vehicles; monitor tumor volume and animal health per protocol.

Conclusion & Outlook

10058-F4 is a robust, cell-permeable c-Myc-Max dimerization inhibitor, validated in apoptosis, telomerase, and cancer studies. Its selective mechanism, effective solubility profile, and well-characterized benchmarks make it a valuable research tool for oncology and stem cell biology. Ongoing research is refining its applications in telomerase regulation and model-specific cancer therapy (Stern et al., 2024). For the latest protocols, refer to the APExBIO 10058-F4 product page.