Antimycin A sensitizes cells to TRAIL-induced apoptosis through upregulation of DR5 and downregulation of c-FLIP and Bcl-2

A Second Life for Seafood Waste: Therapeutical Promises of Polyhydroxynapthoquinones Extracted from Sea Urchin by-Products

Coping with a zero-waste, more sustainable economy represents the biggest challenge for food market nowadays. We have previously demonstrated that by applying smart multidisciplinary waste management strategies to purple sea urchin (Paracentrotus lividus) food waste, it is possible to obtain both a high biocompatible collagen to produce novel skin substitutes and potent antioxidant pigments, namely polyhydroxynapthoquinones (PHNQs). Herein, we have analyzed the biological activities of the PHNQs extract, composed of Spinochrome A and B, on human skin fibroblast cells to explore their future applicability in the treatment of non-healing skin wounds with the objective of overcoming the excessive oxidative stress that hinders wound tissue regeneration. Our results clearly demonstrate that the antioxidant activity of PHNQs is not restricted to their ability to scavenge reactive oxygen species; rather, it can be traced back to an upregulating effect on the expression of superoxide dismutase 1, one of the major components of the endogenous antioxidant enzymes defense system. In addition, the PHNQs extract, in combination with Antimycin A, displayed a synergistic pro-apoptotic effect, envisaging its possible employment against chemoresistance in cancer treatments. Overall, this study highlights the validity of a zero-waste approach in the seafood chain to obtain high-value products, which, in turn, may be exploited for different biomedical applications.

Synergistic Anticancer Effect of Gemcitabine Combined With Impressic Acid or Acankoreanogein in Panc-1 Cells by Inhibiting NF-κB and Stat 3 Activation

Natural products have presented potentiality to improve the outcomes of cancer therapies. Impressic acid (E12-1) and acankoreanogein (E13-1), important activity compounds in Acanthopanax trifoliatus (L.) Merr., show widely biological activities. In this study, we isolated E12-1 and E13-1 from Acanthopanax trifoliatus (L.) Merr., and investigated their improvement effect in gemcitabine (GEM) treatment in Panc-1 cells. The results showed that GEM in combination with E12-1 or E13-1 showed stronger inhibition on the growth and induction of apoptosis in Panc-1 cells compared to GEM, E12-1, or E13-1 alone. GEM in combination with E12-1or E13-1 also strongly inhibited cell migration. Mechanistic investigation showed that GEM in combination with E12-1or E13-1 effectively inhibited the activition of nuclear factor kappa-light-chain-enhancer of activated B cells and Stat 3. Overall, GEM in combination with E12-1 or E13-1 might be an effective strategy for the prevention of prostate cancer.

ShDcR3 sensitizes TRAIL-resistant HCC cells by inducing caspase-dependent apoptosis while suppressing NF-κB dependent cFLIPL expression

Evidence has shown that most hepatocellular carcinoma (HCC) cells are resistant to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. However, the molecular mechanisms underlying TRAIL-mediated apoptosis resistance are not well understood. In this study, we reported that downregulation of Decoy receptor 3 (DcR3) expression by lentiviral vectors carrying shRNA against DcR3 (LV-ShDcR3, shDcR3) in Huh7 both greatly enhanced TRAIL-mediated apoptosis and reduced cell proliferation capability. In addition, silencing DcR3 resulted in upregulation of the cell apoptotic regulators including Bid, caspase-3, and caspase-8. Caspase inhibitors inhibited shDcR3-mediated cell death, which indicated that downregulation of DcR3 expression in Huh7 cells increased TRAIL-induced caspase-dependent apoptotic cell death. Furthermore, although the knockdown of DcR3 altered the expression of some Bcl-2- and IAP-family proteins, this change was inhibited by pretreatment with a pancaspase inhibitor, which indicated the cytotoxic effect of shDcR3 was not due to the expression of these proteins. In contrast, shDcR3 significantly inhibited TRAIL-induced transcription factor nuclear κB (NF-κB) activation through the IκB kinase (IKK) pathway, as well as inhibited TRAIL-induced increases in FLICE-inhibitory protein long form (cFLIP_L) expression at the transcriptional level. Silencing cFLIP_L expression mimicked the cytotoxic effect of shDcR3 on TRAIL-mediated cell apoptosis. Moreover, overexpression of cFLIP_L effectively prevented the increase in cell apoptosis in Huh7 cells co-treated with TRAIL and shDcR3. Taken together, our findings indicated that silencing DcR3 sensitizes TRAIL-mediated apoptosis in HCC cells by inhibiting NF-κB.

Focal adhesion kinase inhibitor PF573228 and death receptor 5 agonist lexatumumab synergistically induce apoptosis in pancreatic carcinoma

Pancreatic cancer has one of the lowest survival rates of all cancers. The mechanism underlying chemo-resistance of pancreatic cancer is not well understood. Our previous article reported that small molecule YM155 induced apoptosis in pancreatic cancer cells via activation of death receptor 5. In this study, we aim to continuously address death receptor 5-mediated apoptosis in chemo-resistant pancreatic carcinoma. We found that in comparison to paired pancreatic cancer tissues and adjacent normal tissues, five of the six cancer tissues had downregulated death receptor 5 and upregulated Bcl-xL. Mono treatment with lexatumumab was not sufficient to induce apoptosis in pancreatic cancer cells, whereas focal adhesion kinase inhibitor PF573228 significantly sensitized lexatumumab-induced apoptosis. Western blotting analysis revealed that lexatumumab and PF573228 combination treatment increased death receptor 5 but decreased Bcl-xL expression. Interestingly, pre-treatment with Bcl-xL inhibitor ABT263 reversed the insensitivity of panc-1 cells to lexatumumab or PF573228-induced apoptosis. Specific small interfering RNA-mediated gene silencing of Bcl-xL effectively sensitized pancreatic cancer cells to lexatumumab or PF573228-induced apoptosis. Furthermore, lexatumumab and PF573228 combination was shown to exhibit significant xenograft pancreatic tumor growth inhibition in SCID mice. Our data provide fundamental evidence to support the notion that lexatumumab and PF573228 co-treatment could be a potentially effective regime for patients with pancreatic cancer.

Antimycin-type depsipeptides: discovery, biosynthesis, chemical synthesis, and bioactivities

This review discusses the isolation, structural variation, biosynthesis, chemical synthesis, and biological activities of antimycin-type depsipeptides.

Marine Drugs Regulating Apoptosis Induced by Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL)

Marine biomass diversity is a tremendous source of potential anticancer compounds. Several natural marine products have been described to restore tumor cell sensitivity to TNF-related apoptosis inducing ligand (TRAIL)-induced cell death. TRAIL is involved during tumor immune surveillance. Its selectivity for cancer cells has attracted much attention in oncology. This review aims at discussing the main mechanisms by which TRAIL signaling is regulated and presenting how marine bioactive compounds have been found, so far, to overcome TRAIL resistance in tumor cells.

Genome mining of Streptomyces ambofaciens

Since the discovery of the streptomycin produced by Streptomyces griseus in the middle of the last century, members of this bacterial genus have been largely exploited for the production of secondary metabolites with wide uses in medicine and in agriculture. They have even been recognized as one of the most prolific producers of natural products among microorganisms. With the onset of the genomic era, it became evident that these microorganisms still represent a major source for the discovery of novel secondary metabolites. This was highlighted with the complete genome sequencing of Streptomyces coelicolor A3(2) which revealed an unexpected potential of this organism to synthesize natural products undetected until then by classical screening methods. Since then, analysis of sequenced genomes from numerous Streptomyces species has shown that a single species can carry more than 30 secondary metabolite gene clusters, reinforcing the idea that the biosynthetic potential of this bacterial genus is far from being fully exploited. This review highlights our knowledge on the potential of Streptomyces ambofaciens ATCC 23877 to synthesize natural products. This industrial strain was known for decades to only produce the drug spiramycin and another antibacterial compound, congocidine. Mining of its genome allowed the identification of 23 clusters potentially involved in the production of other secondary metabolites. Studies of some of these clusters resulted in the characterization of novel compounds and of previously known compounds but never characterized in this Streptomyces species. In addition, genome mining revealed that secondary metabolite gene clusters of phylogenetically closely related Streptomyces are mainly species-specific.