Glucopiericidin A

Reported as two antirenal cell carcinoma (RCC) drug candidates, marine-derived compounds piericidin A (PA) and glucopiericidin A (GPA) exhibit hepatotoxicity in renal carcinoma xenograft mice. Proteomics and transcriptomics reveal the hepatotoxicity related with cholesterol disposition since RCC is characterized by cholesterol accumulation. PA/GPA aggravate hepatotoxicity in high-cholesterol diet (HCD)-fed mice while exhibiting no toxicity in chow diet-fed mice. High cholesterol accumulation in liver is liver X receptor (LXR)-mediated cytochrome P450 family 7 subfamily a member 1 (CYP7A1) depression and low-density lipoprotein receptor (LDLR) activation. The farnesoid X nuclear receptor (FXR) is also depressed with a downregulated target gene OSTα. Different from PA directly combined with LXRα as an inhibitor, GPA exists as a prodrug in the liver and exerts toxic effects due to transformation into PA. Surface plasmon resonance (SPR) and docking results of 17 piericidins illustrate that glycosides exert no LXRα binding activity. A longer survival time of GPA-treated mice indicates that further exploration in anti-RCC drug research should focus on reducing glycosides transformed into PA and concentrating in the kidney tumor rather than the liver for lowering the risk of hepatotoxicity.

Anti-renal cell carcinoma (RCC) agents with new mechanisms of action are urgently needed. Twenty-seven natural products of the piericidin class, including 17 new ones, are obtained from a marine-derived Streptomyces strain, and several of them show strong inhibitory activities against ACHN renal carcinoma cells. By exploring the mechanisms of two representative natural piericidin compounds, piericidin A (PA) and glucopiericidin A (GPA), peroxiredoxin 1 (PRDX1) is detected as a potential target by transcriptome data of PA-treated ACHN cells, as well as the paired RCC tumor versus adjacent nontumor tissues. PA and GPA induce cell apoptosis through reducing the reactive oxygen species level caused by upregulated PRDX1 mRNA and protein level subsequently and exhibit potent antitumor efficacy in nude mice bearing ACHN xenografts, with increasing PRDX1 expression in tumor. The interaction between PA/GPA and PRDX1 was supported by the docking analysis and surface plasmon resonance. Moreover, the translocation of PRDX1 into the nucleus forced by PA/GPA is proposed to be a key factor for the anti-RCC procedure. Piericidins provide a novel scaffold for further development of potent anti-RCC agents, and the new action mechanism of these agents targeting PRDX1 may improve upon the limitations of existing targeted drugs for the treatment of renal cancer.

The mangrove-sediment-derived actinomycete strain Streptomyces psammoticus SCSIO NS126 was found to have productive piericidin metabolites featuring anti-renal cell carcinoma activities. In this study, in order to explore more diverse piericidin derivatives, and therefore to discover superior anti-tumor lead compounds, the NS126 strain was further fermented at a 300-L scale under optimized fermentation conditions. As a result, eight new minor piericidin derivatives (piericidins L-R (1-7) and 11-demethyl-glucopiericidin A (8)) were obtained, along with glucopiericidin B (9). The new structures including absolute configurations were determined by spectroscopic methods coupled with experimental and calculated electronic circular dichroism. We also proposed plausible biosynthetic pathways for these unusual post-modified piericidins. Compounds 1 and 6 showed selective cytotoxic activities against OS-RC-2 cells, and 2-5 exhibited potent cytotoxicity against HL-60 cells, with IC50 values lower than 0.1 μM. The new piericidin glycoside 8 was cytotoxic against ACHN, HL-60 and K562, with IC50 values of 2.3, 1.3 and 5.5 μM, respectively. The ability to arrest the cell cycle and cell apoptosis effects induced by 1 and 6 in OS-RC-2 cells, 2 in HL-60 cells, and 8 in ACHN cells were then further investigated. This study enriched the structural diversity of piericidin derivatives and confirmed that piericidins deserve further investigations as promising anti-tumor agents.