10058-F4: Small-Molecule c-Myc-Max Dimerization Inhibitor for Apoptosis Research

Executive Summary: 10058-F4 is a validated, cell-permeable inhibitor that specifically disrupts c-Myc-Max heterodimerization, thereby blocking c-Myc-driven transcriptional programs (Kotian et al., 2024, DOI). In acute myeloid leukemia (AML) cell lines, 10058-F4 induces dose-dependent apoptosis, with significant effects at 100 μM after 72 hours (APExBIO, product page). The compound’s efficacy extends to in vivo models, where it inhibits tumor growth in prostate cancer xenografts (DU145, PC-3) in SCID mice. Mechanistically, it induces mitochondrial pathway apoptosis via Bcl-2 family modulation and cytochrome C release. It is chemically defined as (5E)-5-[(4-ethylphenyl)methylidene]-2-sulfanylidene-1,3-thiazolidin-4-one and is available from APExBIO in solid form for research use.

Biological Rationale

c-Myc is a proto-oncogene encoding a transcription factor that regulates cell proliferation, metabolism, and apoptosis. Its oncogenic activity depends on heterodimerization with the Max protein, forming a complex that binds DNA at E-box sequences and activates gene expression relevant to cell growth and telomerase regulation (Kotian et al., 2024). Dysregulation of c-Myc/Max is implicated in multiple cancers, including AML and prostate cancer. Blocking this interaction offers a direct strategy to suppress oncogenic transcription and promote apoptosis. 10058-F4 was developed to fill this molecular targeting gap, providing a tool for dissecting c-Myc-dependent pathways in both normal and cancerous cells.

Mechanism of Action of 10058-F4

10058-F4 is a small-molecule inhibitor that binds the c-Myc bHLHZip domain, preventing its heterodimerization with Max (Kotian et al., 2024). This disruption halts c-Myc-Max complex formation, blocking DNA binding and subsequent transcriptional activation of c-Myc targets, including TERT (telomerase reverse transcriptase). By suppressing c-Myc-driven transcription, 10058-F4 reduces c-Myc mRNA and protein levels. This leads to cell cycle arrest and apoptosis, predominantly via the mitochondrial pathway: decreased anti-apoptotic Bcl-2, increased pro-apoptotic Bax, and release of cytochrome C into the cytosol. These effects have been confirmed in both cellular and in vivo models. Chemical properties: molecular weight 249.35 g/mol; soluble at ≥24.9 mg/mL in DMSO and ≥2.64 mg/mL in ethanol; insoluble in water (APExBIO).

Evidence & Benchmarks

• 10058-F4 inhibits c-Myc-Max dimerization and reduces TERT mRNA levels in human pluripotent stem cells (Kotian et al., 2024).
• Induces apoptosis in AML cell lines (HL-60, U937, NB-4) in a dose-dependent manner; significant induction observed at 100 μM after 72 hours (APExBIO).
• Triggers cytochrome C release and modulates Bcl-2 family proteins, indicating mitochondrial pathway involvement (Kotian et al., 2024).
• In vivo, intravenous administration in SCID mice with DU145 and PC-3 xenografts results in tumor growth inhibition, though efficacy varies by model (APExBIO).
• Low-dose 10058-F4 rapidly increases H3K27me3 at the TERT promoter, repressing telomerase transcription (Kotian et al., 2024).

This article extends the scope of '10058-F4 (SKU A1169): Optimizing c-Myc-Max Inhibition' by directly benchmarking quantitative in vitro and in vivo results and integrating recent findings on telomerase regulation. For a detailed mechanistic discussion of c-Myc-driven apoptosis and translational implications, see 'Disrupting the c-Myc/Max Axis: Strategic Frontiers in Translational Research', which this article updates with 2024 data.

Applications, Limits & Misconceptions

Applications:

• Apoptosis assays in AML and solid tumor research (APExBIO).
• Dissection of c-Myc-driven transcriptional programs, including TERT regulation (Kotian et al., 2024).
• Functional studies of mitochondrial apoptosis pathways (Bcl-2 family, cytochrome C release).
• Preclinical evaluation in xenograft cancer models.

Common Pitfalls or Misconceptions

• 10058-F4 is not effective in water-based buffers due to insolubility; DMSO or ethanol are required as solvents (APExBIO).
• Long-term storage of stock solutions is not recommended; freshly prepared solutions ensure maximal bioactivity.
• Not all tumor types respond equally; efficacy may vary by c-Myc dependency of the model.
• Does not inhibit c-Myc independently of Max; specifically targets the c-Myc/Max interface.
• For in vivo applications, pharmacokinetic and off-target effects should be evaluated for each model.

For a scenario-driven protocol guide, see '10058-F4: Small-Molecule c-Myc Inhibitor for Apoptosis Assays', which this article clarifies by providing updated benchmarks and mechanistic context.

Workflow Integration & Parameters

• Solubility: Dissolve 10058-F4 at ≥24.9 mg/mL in DMSO or ≥2.64 mg/mL in ethanol; not soluble in aqueous buffers (APExBIO).
• Storage: Store solid at -20°C; avoid long-term storage of solutions—prepare fresh before use.
• Experimental Conditions: AML cell lines: 100 μM, 72 hours, DMSO vehicle; in vivo: intravenous, SCID mice, dose per protocol.
• Controls: Always include DMSO-only vehicle controls and, if possible, a known c-Myc inhibitor comparator.
• Readouts: Apoptosis (Annexin V/PI), cell cycle (flow cytometry), c-Myc and TERT transcript/protein quantitation (qPCR, Western blot).

Conclusion & Outlook

10058-F4 (SKU A1169) from APExBIO is a rigorously benchmarked, small-molecule c-Myc-Max dimerization inhibitor, enabling precise interrogation of oncogenic, apoptotic, and telomerase regulatory pathways in cancer biology. Its validated mechanism and reproducible activity in both in vitro and in vivo models make it a standard for apoptosis research and c-Myc pathway studies. Ongoing research continues to refine its application range and explore next-generation c-Myc inhibitors with enhanced selectivity and pharmacokinetics (Kotian et al., 2024).