Neochamaejasmine A promotes apoptosis and cell cycle arrest in B16F10 melanoma cells via JNK and p38 MAPK signaling pathway

BACKGROUND

The incidence of melanoma is increasing over the last 30 years. The most common treatments, such as surgery, chemotherapy, and radiotherapy, frequently cause serious damage to the body. It is therefore critical to develop a new therapeutic strategy for the treatment of melanoma.

OBJECTIVES

This research aims to evaluate the anti-tumor effect of Neochamaejasmine A (NCA) on B16F10 melanoma cells and the underlying molecular mechanisms.

METHODS

The CCK-8 kit was utilized to assay the influence of NCA on the vitality of B16F10 cells. Modifications in morphology B16F10 cells were observed using a phase-contrast microscope. Apoptosis of B16F10 melanoma cells was assessed by Hoechst 33258, Annexin V and propidium iodide staining. Cell cycle was detected using a commercial kit by flow cytometry. The mRNA and protein expression levels associated with apoptosis and cell cycle arrest were detected by RT-PCR and Western blot. The expression level of pathway proteins was assessed using Western blot.

RESULT

It was found that the proliferation of B16F10 cells was inhibited by NCA in concentration- and time-dependent manners. NCA promoted apoptosis by halting the cell cycle at the G2/M phase. After treatment with NCA, cell apoptosis was confirmed by Hoechst 33258 staining. NCA triggered the cell cycle to seize at the G2/M stage by downregulating cyclin B1 and cyclin-dependent kinase 2 (CDC2) expression. Moreover, the mRNA and protein expression of cleaved caspase-9 and Bcl-2-associated X-protein (Bax) were increased, whereas there was a decline in the expression of B-cell lymphoma 2 (Bcl-2). The p-p38/p38 and phosphorylated c-Jun N-terminal kinase (p-JNK/JNK) ratio were also elevated by NCA. The apoptosis and G2/M cell cycle arrest were inhibited in cells co-treated with the p38 inhibitor SB203580 and JNK inhibitor SP600125. The expression of apoptosis- related proteins Bax was decreased and Bcl-2 was increased.

CONCLUSION

The findings of this study showed that NCA could induce apoptosis and cell cycle arrest in B16F10 melanoma cells by activating JNK and p38 MAPK signaling pathway.

The inhibition mechanism of the uptake of lamivudine via human organic anion transporter 1 by Stellera chamaejasme L. extracts

Stellera chamaejasme L. is a traditional Chinese medicine with a long history to treat stubborn skin ulcer, and it also has antiviral and antitumor effects. Neochamaejasmine B (NCB), Neochamaejasmine A (NCA) and Chamaechromone (CMC) are the major components in dried roots of Stellera chamaejasme L.. Our studies suggested that NCB, NCA and CMC are inhibitors of Organic anion transporter 1 (OAT1). OAT1 is encoded by solute carrier family 22 member 6 gene (SLC22A6) in humans and plays a critical role in the organic anion drug uptake and excretion in the kidney. Lamivudine is the typical substrate of OAT1 and is frequently used in combination with other antiviral drugs in clinical antiviral treatments. The aim of this study is to investigate the interaction and its mechanism between these bi-flavone components in Stellera chamaejasme L. and lamivudine via OAT1 both in vitro and in vivo. In vitro, the uptake studies in Madin-Darby canine kidney (MDCK) cells overexpressing OAT1 suggested that NCB inhibited the uptake of 6-CFL and lamivudine.Similar results were obtained for NCA and CMC. NCB was a noncompetitive and competitive inhibitor interaction with OAT1. IC₅₀ values of NCB, NCA and CMC for inhibiting OAT1-mediated lamivudine transport were 2.46, 8.35 and 0.61 μmol·L^-1, respectively. In vivo, the pharmacokinetic results of lamivudine in rats showed that the mean area under the plasma concentration-time curve (AUC_0-∞) and maximal plasma concentration (C_max) of lamivudine after co-administration is increased 2.94-fold and 1.87-fold, respectively, compared to lamivudine administration alone. The results of interactions between lamivudine and these bi-flavone components in Stellera chamaejasme L. extracts via OAT1 in vivo are consistent with studies in vitro. The inhibition of OAT1-mediated uptake of lamivudine by NCB, NCA and CMC is the possible mechanism for Stellera chamaejasme L. extracts improving the oral bioavailability of lamivudine in rats.