pregna-4-17-diene-3-16-dione and Skin-Neoplasms

Programmed death-ligand 1 (PD-L1) is an immune checkpoint molecule, that is overexpressed in non-small cell lung cancer (NSCLC) and has been associated with the response to anti-PD-1/PD-L1 immunotherapy. Z-guggulsterone (Z-GS), an active compound extracted from the gumresin of the Commiphora mukul tree, has been shown to have anti-tumor effects in NSCLC in our previous study. However, whether Z-GS could affect PD-L1 expression levels in tumor cells remains unknown. In this study, we verified the inhibitory effects of Z-GS on NSCLC cell viability and cell cycle progression in vitro, and mouse Lewis lung carcinoma (LLC) tumor growth in vivo. Notably, Z-GS treatment increased PD-L1 surface and mRNA expression levels, and gene transcription in NSCLC cells, in a dose- and time-dependent manner. Mechanistic experiments showed that the upregulation of PD-L1 was mediated, partly by farnesoid X receptor inhibition, and partly by the activation of the Akt and Erk1/2 signaling pathways in Z-GS-treated NSCLC cells. In vivo, Z-GS treatment dose-dependently increased PD-L1 expression levels in mouse LLC tumor models. Overall, our findings demonstrated a promoting role for Z-GS in PD-L1 expression in NSCLC and provided mechanistic insights, that may be used for further investigation into synergistic combined therapies.

Topics: Animals; B7-H1 Antigen; Carcinoma, Lewis Lung; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Commiphora; Humans; Lung Neoplasms; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Neoplasms, Experimental; Oncogene Protein v-akt; Pregnenediones; Receptors, Cytoplasmic and Nuclear; RNA, Small Interfering; Skin Neoplasms; Up-Regulation

Guggulsterone (GUG), a resin of the Commiphora mukul tree, has been used in ayurvedic medicine for centuries to treat a variety of ailments. Recent studies have suggested that GUG may also possess anticancer effects. In the present study, we show that GUG possesses antitumor-promoting effects in SENCAR mouse skin tumorigenesis model. We first determined the effect of topical application of GUG to mice against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced conventional markers and other novel markers of skin tumor promotion. We found that topical application of GUG (1.6 micromol per mouse) 30 min prior to TPA (3.2 nmol per mouse) application onto the skin of mice afforded significant inhibition against TPA-mediated increase in skin edema and hyperplasia. Topical application of GUG was also found to result in substantial inhibition against TPA-induced epidermal (i) ornithine decarboxylase (ODC) activity; (ii) ODC, cyclooxygenase-2 and inducible nitric oxide synthase protein expressions; (iii) phosphorylation of extracellular signal-regulated kinase 1/2, c-jun N-terminal kinases and p38; (iv) activation of NF-kappaB/p65 and IKK alpha/beta and (v) phosphorylation and degradation of I kappaB alpha. We next assessed the effect of topically applied GUG on TPA-induced skin tumor promotion in 7,12-dimethyl benz[a]anthracene-initiated mice. Compared with non-GUG-pretreated mice, animals pretreated with GUG showed significantly reduced tumor incidence, lower tumor body burden and a significant delay in the latency period for tumor appearance from 5 to 11 weeks. These results provide the first evidence that GUG possesses anti-skin tumor-promoting effects in SENCAR mice and inhibits conventional as well as novel biomarkers of tumor promotion. In summary, GUG could be useful for delaying tumor growth in humans.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Antineoplastic Agents, Phytogenic; Cyclooxygenase 2 Inhibitors; Edema; Female; Hyperplasia; I-kappa B Kinase; I-kappa B Proteins; MAP Kinase Signaling System; Mice; Mice, Inbred SENCAR; NF-kappa B; NF-KappaB Inhibitor alpha; Nitric Oxide Synthase Type II; Ornithine Decarboxylase Inhibitors; Phosphorylation; Pregnenediones; Skin; Skin Neoplasms; Tetradecanoylphorbol Acetate