pep005 and ingenol

Actinic keratoses (AKs) exist on a continuum with squamous cell carcinoma and can occur as sub-clinical and clinically visible lesions in cancerized fields on sun-damaged skin. Ingenol mebutate effectively treats AKs on areas up to 25 cm. Phase I, multicenter, open-label, uncontrolled, non-randomized trial. Patients received ingenol mebutate gel for three consecutive days on approximately 250 cm. Of 61 patients, 10 (face =8; arm =2) had ingenol mebutate in whole blood at subnanomolar levels (0.235-0.462 nM). The assayed metabolites were below the lower limit of quantification. Local skin responses increased during Days 1-4 and declined thereafter, approaching baseline by Day 16. Most adverse events were pain/pruritus of mild or moderate intensity.. Subnanomolar systemic exposure to ingenol mebutate was measured after application of the gel to approximately 250 cm

Topics: Administration, Cutaneous; Aged; Aged, 80 and over; Area Under Curve; Arm; Diterpenes; Face; Female; Gels; Half-Life; Humans; Keratosis, Actinic; Male; Middle Aged; Pruritus; ROC Curve; Scalp; Skin; Treatment Outcome

Antiretroviral therapy (ART) does not cure HIV-1 infection due to the persistence of proviruses in long-lived resting T cells. Strategies targeting these latently infected cells will be necessary to eradicate HIV-1 in infected individuals. Protein kinase C (PKC) activation is an effective mechanism to reactivate latent proviruses and allows for recognition and clearance of infected cells by the immune system. Several ingenol compounds, naturally occurring PKC agonists, have been described to have potent latency reversal activity. We sought to optimize this activity by synthesizing a library of novel ingenols via esterification of the C-3 hydroxyl group of the ingenol core, which itself is inactive for latency reversal. Newly synthesized ingenol derivatives were evaluated for latency reversal activity, cellular activation, and cytotoxicity alongside commercially available ingenols (ingenol-3,20-dibenzoate, ingenol 3-hexanoate, and ingenol-3-angelate) in HIV latency cell lines and resting CD4

Topics: Antiretroviral Therapy, Highly Active; CD4-Positive T-Lymphocytes; Cell Line, Tumor; Diterpenes; HIV Infections; HIV-1; Humans; Jurkat Cells; Protein Kinase C; Proviruses; Virus Activation; Virus Latency

Ingenol mebutate possesses significant cytotoxicity and is clinically used to treat actinic keratosis. However, ingenol mebutate undergoes acyl migration which affects its bioactivity. Compound 3-O-angeloyl-20-O-acetyl ingenol (AAI, also known as 20-O-acetyl-ingenol-3-angelate or PEP008) is a synthetic derivative of ingenol mebutate. In this work, we report the AAI synthesis details and demonstrate AAI has higher cytotoxicity than ingenol mebutate in a chronic myeloid leukemia K562 cell line. Our data indicate that the increased activity of AAI originates from the improved intracellular stability of AAI rather than the increased binding affinity between AAI and the target protein protein kinase Cδ (PKCδ). AAI inhibits cell proliferation, induces G2/M phase arrest, disrupts the mitochondrial membrane potential, and stimulates apoptosis, as well as necrosis in K562 cells. Similar to ingenol mebutate, AAI activates PKCδ and extracellular signal regulated kinase (ERK), and inactivates protein kinase B (AKT). Furthermore, AAI also inhibits JAK/STAT3 pathway. Altogether, our studies show that ingenol derivative AAI is cytotoxic to K562 cells and modulates PKCδ/ERK, JAK/STAT3, and AKT signaling pathways. Our work suggests that AAI may be a new candidate of chemotherapeutic agent.

Topics: Antineoplastic Agents; Apoptosis; Cell Proliferation; Diterpenes; Extracellular Signal-Regulated MAP Kinases; Humans; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Signal Transduction

Ingenol 3-benzoates were investigated with respect to chemical stability, pro-inflammatory effects, cell death induction and PKCδ activation. A correlation between structure, chemical stability and biological activity was found and compared to ingenol mebutate (ingenol 3-angelate) used for field treatment of actinic keratosis. We also provided further support for involvement of PKCδ for induction of oxidative burst and cytokine release. Molecular modeling and dynamics calculations corroborated the essential interactions between key compounds and C1 domain of PKCδ.

Topics: Antineoplastic Agents; Benzoates; Cell Death; Cytokines; Diterpenes; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Keratosis, Actinic; Models, Molecular; Molecular Docking Simulation; Molecular Structure; Protein Kinase C-delta; Protein Kinase Inhibitors; Skin Neoplasms; Structure-Activity Relationship

Ingenol 3-angelate (I3A) is one of the active ingredients in Euphorbia peplus, which has been used in traditional medicine. Here, we report the initial characterization of I3A as a protein kinase C (PKC) ligand. I3A bound to PKC-alpha in the presence of phosphatidylserine with high affinity; however, under these assay conditions, little PKC isoform selectivity was observed. PKC isoforms did show different sensitivity and selectivity for down-regulation by I3A and phorbol 12-myristate 13-acetate (PMA) in WEHI-231, HOP-92, and Colo-205 cells. In all of the three cell types, I3A inhibited cell proliferation with somewhat lower potency than did PMA. In intact CHO-K1 cells, I3A was able to translocate different green fluorescent protein-tagged PKC isoforms, visualized by confocal microscopy, with equal or higher potency than PMA. PKC-delta in particular showed a different pattern of translocation in response to I3A and PMA. I3A induced a higher level of secretion of the inflammatory cytokine interleukin 6 compared with PMA in the WEHI-231 cells and displayed a marked biphasic dose-response curve for the induction. I3A was unable to cause the same extent of association of the C1b domain of PKC-delta with lipids, compared with PMA or the physiological regulator diacylglycerol, and was able to partially block the association induced by these agents, measured by surface plasmon resonance. The in vitro kinase activity of PKC-alpha induced by I3A was lower than that induced by PMA. The novel pattern of behavior of I3A makes it of great interest for further evaluation.

Topics: Animals; CHO Cells; Cricetinae; Diterpenes; Down-Regulation; Euphorbia; Humans; Interleukin-6; Isoenzymes; Ligands; Liposomes; Protein Kinase C; Tetradecanoylphorbol Acetate