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

Executive Summary: 10058-F4 is a cell-permeable small-molecule inhibitor that specifically disrupts c-Myc-Max heterodimerization, a critical requirement for c-Myc transcription factor activity and oncogenic signaling (APExBIO A1169). By preventing c-Myc/Max dimer formation, it suppresses c-Myc-driven transcriptional programs and induces apoptosis via the mitochondrial pathway, notably affecting Bcl-2 family proteins and cytochrome C release (Stern et al., 2024). 10058-F4 demonstrates dose-dependent apoptosis induction in AML cell lines (HL-60, U937, NB-4) and significant tumor growth inhibition in prostate cancer xenograft models. The compound is chemically defined as (5E)-5-[(4-ethylphenyl)methylidene]-2-sulfanylidene-1,3-thiazolidin-4-one, with defined solubility and storage parameters. Its unique mechanism and reproducible efficacy make it a valuable research tool for investigating c-Myc-related oncogenic pathways, apoptosis assays, and telomerase regulation (Related analysis).

Biological Rationale

c-Myc is a proto-oncogene encoding a transcription factor that regulates genes essential for cell proliferation, metabolism, and apoptosis. Its oncogenic activity is largely dependent on heterodimerization with Max, allowing DNA binding and transcriptional regulation of target genes (Stern et al., 2024). c-Myc dysregulation is implicated in numerous human cancers, including acute myeloid leukemia (AML) and prostate cancer. Inhibition of c-Myc-Max dimerization interrupts a central oncogenic pathway, directly affecting cell cycle progression and survival. Telomerase reverse transcriptase (TERT) expression, crucial for stem cell maintenance and cancer progression, is also regulated by c-Myc, further underscoring the value of c-Myc inhibition in cancer research (See extended review).

Mechanism of Action of 10058-F4

10058-F4 is a synthetic thiazolidinone derivative that selectively binds to the c-Myc bHLHZip domain, blocking its interaction with Max. This inhibition prevents c-Myc/Max dimer formation, thereby abrogating c-Myc's ability to bind E-box DNA sequences and activate transcription. As a result, downstream gene expression programs driven by c-Myc are suppressed, leading to decreased c-Myc mRNA and protein levels. In cellular models, this translates to cell cycle arrest and initiation of mitochondrial apoptosis, marked by modulation of Bcl-2 family proteins and release of cytochrome C. The compound is cell-permeable, enabling rapid uptake and effect in both in vitro and in vivo systems (Comparison: Application versatility).

Evidence & Benchmarks

• 10058-F4 inhibits c-Myc-Max heterodimerization in vitro, confirmed by co-immunoprecipitation and electrophoretic mobility shift assays (DOI:10.1101/2024.09.23.614488).
• Induces apoptosis in AML cell lines (HL-60, U937, NB-4) in a dose-dependent manner, with significant effects at 100 μM after 72 hours incubation (DOI:10.1101/2024.09.23.614488).
• Reduces c-Myc mRNA and protein levels as measured by qPCR and Western blot (APExBIO).
• Triggers mitochondrial apoptosis, evidenced by Bcl-2 downregulation and cytochrome C release (Related article).
• Suppresses tumor growth in SCID mice xenografted with DU145 or PC-3 prostate cancer cells, following intravenous administration (DOI:10.1101/2024.09.23.614488).
• Demonstrates solubility at ≥24.9 mg/mL in DMSO and ≥2.64 mg/mL in ethanol; insoluble in water (APExBIO).

Applications, Limits & Misconceptions

10058-F4 is used in apoptosis assays, oncogenic pathway studies, and telomerase/Tert regulation research. Its selectivity for c-Myc-Max dimerization provides mechanistic clarity in dissecting c-Myc-driven transcriptional networks. In acute myeloid leukemia and prostate cancer models, it serves as a critical tool for evaluating targeted therapies and understanding c-Myc involvement in apoptosis and cell cycle control (See new insights into TERT regulation). 10058-F4 has also been employed to investigate mitochondrial apoptosis pathways and Bcl-2 protein dynamics.

Common Pitfalls or Misconceptions

• 10058-F4 is not a pan-Myc family inhibitor; it does not universally block all Myc-related dimers.
• It is ineffective in water-based buffers due to insolubility; DMSO or ethanol is required for solution preparation.
• Long-term storage of solutions is not recommended; fresh preparation is critical for reproducibility.
• Tumor growth inhibition efficacy varies by cancer model and administration route; not all xenografts respond equivalently.
• Does not directly inhibit DNA repair enzymes such as APEX2, but can indirectly affect telomerase/TERT transcription via c-Myc modulation (Stern et al., 2024).

Workflow Integration & Parameters

10058-F4 is supplied by APExBIO as a solid and should be stored at -20°C. For in vitro studies, it is typically reconstituted in DMSO at ≥24.9 mg/mL or ethanol at ≥2.64 mg/mL. Working concentrations for cell-based assays range from 10 to 100 μM, with apoptosis induction observed after 48–72 hours incubation in AML lines. For in vivo studies, intravenous administration protocols should be optimized for each xenograft model. Researchers should avoid repeated freeze-thaw cycles and prepare fresh solutions for each experiment to ensure consistent activity. See the 10058-F4 product page for detailed handling and safety guidelines.

This article extends the discussion in 'Advanced Insights into c-Myc-Max Dimerization Inhibition' by providing updated benchmarks in AML and prostate models, and clarifies recent findings on telomerase regulation as related to c-Myc targeting. For additional mechanistic detail, see the contrast with 'Small-Molecule c-Myc Inhibitor for Apoptosis Assays', which focuses on application troubleshooting, while this review emphasizes molecular mechanism and benchmarked efficacy across models.

Conclusion & Outlook

10058-F4 offers a robust approach for disrupting c-Myc-Max dimerization, enabling precise interrogation of c-Myc-driven oncogenic pathways in vitro and in vivo. Its validated effects on transcriptional repression, apoptosis induction, and tumor growth inhibition make it a cornerstone tool in cancer research and apoptosis assays. Ongoing studies continue to explore its integration with telomerase and DNA repair pathway modulation, broadening its utility in translational and basic cancer biology. For latest protocols and product specifications, consult the official APExBIO resource.