Heat shock protein 90 inhibitor RGRN-305 potently attenuates skin inflammation

Introduction

Chronic inflammatory skin diseases may have a profound negative impact on the quality of life. Current treatment options may be inadequate, offering an unsatisfactory response or side effects. Therefore, ongoing efforts exist to identify novel effective and safe treatments. Heat shock protein (HSP) 90 is a chaperone that promotes the activity of a wide range of client proteins including key proinflammatory molecules involved in aberrant inflammation. Recently, a proof-of-concept clinical trial of 13 patients suggested that RGRN-305 (an HSP90 inhibitor) may be an oral treatment for psoriasis. However, HSP90 inhibition may be a novel therapeutic approach extending beyond psoriasis to include multiple immune-mediated inflammatory skin diseases.

Methods

This study aimed to investigate (i) the anti-inflammatory effects and mechanisms of HSP90 inhibition and (ii) the feasibility of topical RGRN-305 administration (new route of administration) in models of inflammation elicited by 12-O-tetradecanoylphorbol-13-acetate (TPA) in primary human keratinocytes and mice (irritative dermatitis murine model).

Results/Discussion

In primary human keratinocytes stimulated with TPA, a Nanostring® nCounter gene expression assay demonstrated that HSP90 inhibition with RGRN-305 suppressed many proinflammatory genes. Furthermore, when measured by quantitative real-time polymerase chain reaction (RT-qPCR), RGRN-305 significantly reduced the gene expression of TNF, IL1B, IL6 and CXCL8. We next demonstrated that topical RGRN-305 application significantly ameliorated TPA-induced skin inflammation in mice. The increase in ear thickness (a marker of inflammation) was significantly reduced (up to 89% inhibition). In accordance, RT-qPCR of the ear tissue demonstrated that RGRN-305 robustly reduced the gene expression of proinflammatory markers (Tnf, Il1b, Il6, Il17A and Defb4). Moreover, RNA sequencing revealed that RGRN-305 mitigated TPA-induced alterations in gene expression and suppressed genes implicated in inflammation. Lastly, we discovered that the anti-inflammatory effects were mediated, at least partly, by suppressing the activity of NF-κB, ERK1/2, p38 MAPK and c-Jun signaling pathways, which are consistent with previous findings in other experimental models beyond skin inflammation. In summary, HSP90 inhibition robustly suppressed TPA-induced inflammation by targeting key proinflammatory cytokines and signaling pathways. Our findings suggest that HSP90 inhibition may be a novel mechanism of action for treating immune-mediated skin disease beyond psoriasis, and it may be a topical treatment option.

Pharmacological studies of rhizomes of extract of Cyperus tegetum, emphasized on anticancer, anti-inflammatory and analgesic activity

ETHNOPHARMACOLOGICAL RELEVANCE

With over 950 species, Cyperus is one of the most promising health boosting genera in the Cyperaceae family. Traditional uses of Cyperus sp. have been described for gastrointestinal blood abnormalities, menstrual irregularities, and inflammatory diseases, among others. Cyperus tegetum Roxb belonging to Cyperaceae family, is used in traditional medicine to treat skin cancers.

AIM OF THE STUDY

The present study was carried out to explore the potential effect of the extract of the plant Cyperus tegetum against different pharmacological activity namely inflammatory, analgesic activity as well as skin cancer activity in mice.

MATERIALS AND METHODS

Cytotoxicity of the extract was measured by MTT and Live/death assay on HeLa cell line. Skin cancer was induced by 7,12-dimethylbenz(a) anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) in mice to measure its effects.

RESULT

Stigmasterol and some poly phenolic compounds are identified using HPTLC process from the methanol extract of the rhizome of the plant Cyperus tegetum (CT-II). After confirmation of the presence of different polyphenolic compound and triterpenoids in the extract, it was subject to MTT and Live/death assay on HeLa cell line. From the observation it could be concluded that the IC₅₀ of the extract is 300 μg/ml. Thus, the CTII was evaluated further for its in vivo anticancer property. In the tumorigenesis study, the number of tumor growths, the area and weight of the tumor significantly decreases with increment in the dose of CT-II extract and some elevated enzyme release in renal (creatinine, urea) as well as hepatic (AST, ALT, ALP) enzymes are also controlled with the increased dose of the same extract. The elevated enzyme release may be due to cancer induced rupture of the plasma and cellular damage. This CT-II extract also exhibits some other pharmacological activity like anti-inflammatory and analgesic activity.

CONCLUSION

As metabolic activation via carcinogens and inflammation response plays important role in development of cancer, antioxidant, anti-inflammatory and analgesic properties can be correlated with anti-cancer properties. Taken all the above studies, it was illustrated that the extract of Cyperus tegetum might be a promising compound to reduce skin cancer risk.

3'-Hydroxypterostilbene Inhibits 7,12-Dimethylbenz[a]anthracene (DMBA)/12-O-Tetradecanoylphorbol-13-Acetate (TPA)-Induced Mouse Skin Carcinogenesis

BACKGROUND

A natural pterostilbene analogue isolated from the herb Sphaerophysa salsula, 3'-hydroxypterostilbene (HPSB), exhibits antiproliferative activity in several cancer cell lines; however, the inhibitory effects of HPSB on skin carcinogenesis remains unclear.

PURPOSE

The aim of this study was to evaluate the inhibitory effects of HPSB on two-stage skin carcinogenesis in mice and its potential mechanism.

STUDY DESIGN AND METHODS

This study investigated the anti-inflammatory and anti-tumor effects of HPSB in the 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated acute skin inflammation and 7,12-dimethylbenz[a]anthracene (DMBA)/TPA-induced two-stage skin carcinogenesis model. In addition, the effects of HPSB on the modulation of the phase I and phase II metabolizing enzymes in the DMBA-induced HaCaT cell model were investigated.

RESULTS

The results provide evidence that topical treatment with HPSB significantly inhibits TPA-induced epidermal hyperplasia and leukocyte infiltration through the down-regulation of cyclooxygenase-2 (COX-2), matrix metalloprotein-9 (MMP-9), and ornithine decarboxylase (ODC) protein expression in mouse skin. Furthermore, HPSB suppresses DMBA/TPA-induced skin tumor incidence and multiplicity via the inhibition of proliferating cell nuclear antigen (PCNA), Cyclin B1 and cyclin-dependent kinase 1 (CDK1) expression in the two-stage skin carcinogenesis model. In addition, pretreatment with HPSB markedly reduces DMBA-induced cytochrome P450 1A1 (CYP1A1) and cytochrome P450 1B1 (CYP1B1) gene expression in human keratinocytes; however, HPSB does not significantly affect the gene expression of the phase II enzymes.

CONCLUSION

This is the first study to show that topical treatment with HPSB prevents mouse skin tumorigenesis. Overall, our study suggests that natural HPSB may serve as a novel chemopreventive agent capable of preventing carcinogen activation and inflammation-associated tumorigenesis.

Decursinol angelate ameliorates 12-O-tetradecanoyl phorbol-13-acetate (TPA) -induced NF-κB activation on mice ears by inhibiting exaggerated inflammatory cell infiltration, oxidative stress and pro-inflammatory cytokine production

Decursinol angelate (DA) is a pyranocoumarin purified from the roots of Angelica gigas. Here, we synthesized DA and determined its anti-inflammatory potential on TPA-induced mice ear inflammation. First, we evaluated the non-toxic behaviour of DA on HaCaT cells. Additionally, we observed the free radical scavenging potential of DA at 60 μM to be 50%. This finding was further supported by nitric oxide assay, malondialdehyde assay, H2DCFDA staining and western blotting analysis of antioxidant enzymes. DA also suppressed the activation and polarization of macrophage phagocytic activity on RAW 264.7 cells. We further evaluated the expression of ICAM-1, MCP-1, MIP-2 and MIP-1β on in-vivo model system. Consequently, DA significantly reduced the production of NF-κB and COX-2 induced proinflammatory cytokine levels on TPA induced ear edema. Inhibition of MAPK and transcriptional factor NF-κB was also validated by western blotting analysis of p-ERK, p-p38, IKKα, IKKγ, IκBα, NF-κB-p65. Immunohistochemistry and immunofluorescence staining of NFκB-p65, TNF-α and IL-1β were also performed to support the findings. Conclusively, these results suggest that topical administration of DA significantly inhibited the expression of pro-inflammatory cytokines by blocking the canonical NF-κB and MAPK pathway. Therefore, we suggest DA as a potent therapeutic compound against skin inflammation related diseases.

12-O-Tetradecanoylphorbol-13-Acetate Induces Keratin 8 Phosphorylation and Reorganization via Expression of Transglutaminase-2

The stiffness of cancer cells is attributable to intermediate filaments such as keratin. Perinuclear reorganization via phosphorylation of specific serine residue in keratin is implicated in the deformability of metastatic cancer cells including the human pancreatic carcinoma cell line (PANC-1). 12-O-Tetradecanoylphorbol-13-acetate (TPA) is a potent tumor promoter and protein kinase C (PKC) activator. However, its effects on phosphorylation and reorganization of keratin 8 (K8) are not well known. Therefore, we examined the underlying mechanism and effect of TPA on K8 phosphorylation and reorganization. TPA induced phosphorylation and reorganization of K8 and transglutaminase-2 (Tgase-2) expression in a time- and dose-dependent manner in PANC-1 cells. These effects peaked after 45 min and 100 nM of TPA treatment. We next investigated, using cystamine (CTM), Tgase inhibitor, and Tgase-2 gene silencing, Tgase-2’s possible involvement in TPA-induced K8 phosphorylation and reorganization. We found that Tgase-2 gene silencing inhibited K8 phosphorylation and reorganization in PANC-1 cells. Tgase-2 gene silencing, we additionally discovered, suppressed TPA-induced migration of PANC-1 cells and Tgase-2 overexpression induced migration of PANC-1 cells. Overall, these results suggested that TPA induced K8 phosphorylation and reorganization via Tgase-2 expression in PANC-1 cells.