Triptolide-Mediated Apoptosis by Suppression of Focal Adhesion Kinase through Extrinsic and Intrinsic Pathways in Human Melanoma Cells

5-methylthiopentyl Isothiocyanate, a Sulforaphane Analogue, Inhibits Pro-inflammatory Cytokines by Regulating LPS/ATP-mediated NLRP3 Inflammasome Activation

BACKGROUND

Pro-inflammatory cytokines secreted from activated macrophages and astrocytes are crucial mediators of inflammation for host defense. Among them, the secretion of IL-1β, a major pro-inflammatory cytokine, is especially mediated by the activation of NLRP3 inflammasome. Pro-IL-1β, which is produced in response to the invaded pathogens, such as LPS, is cleaved and matured in the NLRP3 inflammasome by the recognition of ATP. Excessively activated IL-1β induces other immune cells, resulting in the up-regulation of inflammation. Therefore, regulation of NLRP3 inflammasome can be a good strategy for alleviating inflammation.

OBJECTIVE

Our study aimed to examine whether 5-methylthiopentyl isothiocyanate, a sulforaphane analogue (berteroin), has an anti-inflammatory effect on the NLRP3 inflammasome activation induced by LPS and ATP.

METHODS

Primary bone marrow-derived macrophages (BMDMs) and astrocytes were stimulated by LPS and ATP with the treatment of 5-methylthiopentyl isothiocyanate, a sulforaphane analogue. The secretion of pro-inflammatory cytokines was measured by ELISA, and the expression level of NLRP3 inflammasome-associated proteins was detected by western blot. The association of NLRP3 inflammasome was assessed by co-immunoprecipitation, and the formation of ASC specks was evaluated by fluorescent microscope.

RESULTS

5-methylthiopentyl isothiocyanate, a sulforaphane analogue (berteroin), decreased the release of pro-inflammatory cytokines, IL-1β, and IL-6 in the BMDMs. Berteroin notably prevented the formation of both NLRP3 inflammasome and ASC specks, which reduced the secretion of IL-1β. Additionally, berteroin reduced the IL-1β secretion and cleaved IL-1β expression in the primary astrocytes.

DISCUSSION AND CONCLUSION

These results indicated the anti-inflammatory effects of 5- methylthiopentyl isothiocyanate (berteroin) by regulating NLRP3 inflammasome activation, suggesting that berteroin could be the potential natural drug candidate for the regulation of inflammation.

The molecular mechanisms of vulpinic acid induced programmed cell death in melanoma

BACKGROUNDS

Malignant melanoma is an aggressive skin tumor with a rapidly increasing incidence and there is not yet a successful treatment strategy. Vulpinic acid (VA) is derived from secondary metabolites from lichen species. In the current study, we, for the first time, investigated the anti-cancer effects of VA and the underlying mechanism VA induced programmed cell death in melanoma.

METHODS

The anti-cancer effects of VA on melanoma cells were evaluated by the xCELLigence system, flow cytometry, caspase-3 activity and RT-PCR analysis.

RESULTS

Our results showed that VA had a strong anti-proliferative effect on A-375 melanoma cells without damaging human epidermal melanocyte cells. Additionally, VA promoted apoptotic cell death through G2/M arrest and the activation of both intrinsic and extrinsic apoptosis pathways according to the analysis of 88 genes associated with apoptosis by qRT-PCR.

CONCLUSIONS

Our findings suggest that VA could become an alternative topical and transdermal treatment strategy in the treatment of maligned melanoma cancer. However, further investigations are needed to assess the underlying molecular mechanism of VA mediated apoptotic cell death in the treatment of melanoma.

Engineering Exosomes Endowed with Targeted Delivery of Triptolide for Malignant Melanoma Therapy

Malignant melanoma is considered the most aggressive skin carcinoma with invasive growth patterns. Triptolide (TPL) possesses various biological and pharmacological activities involved in cancer treatment. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce cancer cell apoptosis by binding to DR5 highly expressed on cancer cells. Exosomes are natural nanomaterials with low immunogenicity, nontoxicity, and excellent biocompatibility and have been extensively used as emerging delivery vectors for diverse therapeutic cargos. Herein, a delivery system based on TRAIL-engineered exosomes (TRAIL-Exo) for loading TPL for targeted therapy against malignant melanoma is proposed and systematically investigated. Our results showed that TRAIL-Exo/TPL could improve tumor targetability, enhance cellular uptake, inhibit proliferation, invasion, and migration, and induce apoptosis of A375 cells through activating the extrinsic TRAIL pathway and the intrinsic mitochondrial pathway in vitro. Moreover, intravenous injection of TRAIL-Exo/TPL significantly suppressed tumor progression and reduced the toxicity of TPL in the melanoma nude mouse model. Together, our research presents a novel strategy for high-efficiency exosome-based drug-delivery nanocarriers and provides an alternative dimension for developing a promising approach with synergistic therapeutic efficacy and targeting capacity for melanoma treatment.