JNJ-26481585 (Quisinostat): Precision HDAC Inhibition in Cancer Research

Executive Summary: JNJ-26481585 (Quisinostat) is a highly potent histone deacetylase (HDAC) inhibitor targeting class I enzymes with IC₅₀ values down to 0.11 nM (source: product_spec). It induces hyperacetylation of histone H3, upregulating tumor suppressor genes such as p21 and promoting apoptosis in multiple cancer cell lines (source: product_spec). Quisinostat has been shown to downregulate TRIM21, a key driver of cell proliferation and drug resistance in pituitary adenomas (source: DOI). In vivo, it achieves significant tumor growth inhibition and robust increases in histone acetylation (source: product_spec). APExBIO supplies JNJ-26481585 as a solid or 10 mM DMSO solution for research use only.

Biological Rationale

Histone deacetylases (HDACs) regulate chromatin structure and gene expression by catalyzing the removal of acetyl groups from histone proteins. Aberrant HDAC activity is linked to oncogenic gene silencing and tumor progression. Inhibiting HDACs with agents like JNJ-26481585 restores acetylation, reactivating tumor suppressor pathways and promoting apoptosis (source: workflow_recommendation). Targeting the epigenome is a validated approach for manipulating cancer cell fate and overcoming resistance to conventional therapies.

Mechanism of Action of JNJ-26481585 (Quisinostat)

• JNJ-26481585 selectively inhibits class I HDACs: HDAC1 (IC₅₀ = 0.11 nM), HDAC2 (0.33 nM), and HDAC3 (4.8 nM) (source: product_spec).
• It also exhibits sub-nanomolar inhibition of HDAC4, HDAC10, and HDAC11 (source: product_spec).
• HDAC blockade results in hyperacetylation of histone H3 and activation of tumor suppressor genes such as p21^waf1,cip1 (source: product_spec).
• This leads to cell cycle arrest and apoptosis, as measured by increased Annexin V positivity in vitro (source: workflow_recommendation).
• Quisinostat reduces levels of TRIM21, an E3 ubiquitin ligase implicated in cancer cell proliferation and drug resistance (source: DOI).

Evidence & Benchmarks

• JNJ-26481585 inhibits HDAC1 with an IC₅₀ of 0.11 nM, HDAC2 at 0.33 nM, and HDAC3 at 4.8 nM (source: product_spec).
• Shows anti-proliferative activity across lung, breast, colon, prostate, brain, and ovarian cancer cell lines, with IC₅₀ values from 3.1 to 246 nM (source: product_spec).
• Induces apoptosis, demonstrated by increased Annexin V+ cells in vitro (source: workflow_recommendation).
• In vivo, administration leads to significant tumor growth inhibition and elevated histone acetylation in xenograft models (source: product_spec).
• Quisinostat downregulates TRIM21, disrupting ERK1/2 phosphorylation and reducing proliferation and drug resistance in pituitary adenoma models (source: DOI).

• Applied Use-Cases of JNJ-26481585 (Quisinostat) in Cancer Research: This article extends the workflow insights by providing quantitative benchmarks and newly validated anti-resistance effects.
• TRIM21-ERK1/2 Axis Drives Proliferation and Resistance in Pituitary Tumors: Here, we clarify the direct link between Quisinostat, TRIM21 suppression, and restored drug sensitivity in pituitary models, expanding on mechanistic findings.
• JNJ-26481585 (Quisinostat): Precision Epigenetic Modulation in Tumor Research: We update protocol guidance with new in vivo benchmarks and evidence of apoptosis induction.

Applications, Limits & Misconceptions

JNJ-26481585 is suited for research applications involving epigenetic modulation, apoptosis induction, and overcoming drug resistance in cancer models. It is not approved for diagnostic or medical use in humans. The compound is soluble in DMSO (≥19.2 mg/mL), but insoluble in water and ethanol, which may limit its compatibility with certain assay systems (source: product_spec).

Common Pitfalls or Misconceptions

• JNJ-26481585 is not suitable for clinical or diagnostic applications; it is for research use only (source: product_spec).
• Solubility in DMSO does not guarantee compatibility with all biological buffers—formulation in 20% hydroxypropyl-β-cyclodextrin at pH 8.7 is recommended for animal studies (source: product_spec).
• Long-term storage of solutions can lead to degradation; use solutions promptly after preparation (source: product_spec).
• Not all tumor types may respond equally; efficacy is best established in models with HDAC-driven pathology (source: DOI).
• TRIM21 modulation by Quisinostat has been validated primarily in pituitary adenoma models; generalization to other tumor types requires further evidence (source: DOI).

Workflow Integration & Parameters

Protocol Parameters

• cell proliferation assay | 3.1–246 nM (IC₅₀ range) | human cancer cell lines | Dose-response established in lung, breast, colon, prostate, brain, and ovarian cancer cells | product_spec
• apoptosis (Annexin V) assay | 100 nM (typical) | HeLa and MMQ cells | Induces significant increase in Annexin V+ cells within 24–48 h | workflow_recommendation
• in vivo xenograft tumor inhibition | 10–30 mg/kg, daily, i.p. | mouse models | Achieves significant tumor growth inhibition with increased histone acetylation | product_spec
• compound solubility | ≥19.2 mg/mL (in DMSO) | all research formats | Ensures preparation of concentrated stock solutions | product_spec
• storage conditions | −20°C (solid or solution) | all research formats | Maintains chemical stability and activity | product_spec
• formulation for animal studies | 20% hydroxypropyl-β-cyclodextrin, pH 8.7 | in vivo assays | Enhances solubility and bioavailability in animal models | product_spec

Conclusion & Outlook

JNJ-26481585 (Quisinostat) represents an advanced tool for epigenetic modulation, capable of inducing apoptosis and reversing drug resistance in cancer research settings. Its validated action against class I HDACs and ability to downregulate TRIM21 in pituitary adenoma models highlight its translational potential (source: DOI). Future directions should focus on expanding its application to additional tumor models and optimizing workflow integration for reproducibility. For more details, see the APExBIO JNJ-26481585 (Quisinostat) product page.