Triptolide enhances carboplatin-induced apoptosis by inhibiting nucleotide excision repair (NER) activity in melanoma

Introduction: Carboplatin (CBP) is a DNA damaging drug used to treat various cancers, including advanced melanoma. Yet we still face low response rates and short survival due to resistance. Triptolide (TPL) is considered to have multifunctional antitumor effects and has been confirmed to enhance the cytotoxic effects of chemotherapeutic drugs. Herein, we aimed to investigate the knowledge about the effects and mechanisms for the combined application of TPL and CBP against melanoma. Methods: Melanoma cell lines and xenograft mouse model were used to uncover the antitumor effects and the underlying molecular mechanisms of the alone or combined treatment of TPL and CBP in melanoma. Cell viability, migration, invasion, apoptosis, and DNA damage were detected by conventional methods. The rate-limiting proteins of the NER pathway were quantitated using PCR and Western blot. Fluorescent reporter plasmids were used to test the NER repair capacity. Results: Our results showed that the presence of TPL in CBP treatment could selectively inhibit NER pathway activity, and TPL exerts a synergistic effect with CBP to inhibit viability, migration, invasion, and induce apoptosis of A375 and B16 cells. Moreover, combined treatment with TPL and CBP significantly inhibited tumor progression in nude mice by suppressing cell proliferation and inducing apoptosis. Discussion: This study reveals the NER inhibitor TPL which has great potential in treating melanoma, either alone or in combination with CBP.

Pharmacological Potential of Small Molecules for Treating Corneal Neovascularization

Under healthy conditions, the cornea is an avascular structure which allows for transparency and optimal visual acuity. Its avascular nature is maintained by a balance of proangiogenic and antiangiogenic factors. An imbalance of these factors can result in abnormal blood vessel proliferation into the cornea. This corneal neovascularization (CoNV) can stem from a variety of insults including hypoxia and ocular surface inflammation caused by trauma, infection, chemical burns, and immunological diseases. CoNV threatens corneal transparency, resulting in permanent vision loss. Mainstay treatments of CoNV have partial efficacy and associated side effects, revealing the need for novel treatments. Numerous natural products and synthetic small molecules have shown potential in preclinical studies in vivo as antiangiogenic therapies for CoNV. Such small molecules include synthetic inhibitors of the vascular endothelial growth factor (VEGF) receptor and other tyrosine kinases, plus repurposed antimicrobials, as well as natural source-derived flavonoid and non-flavonoid phytochemicals, immunosuppressants, vitamins, and histone deacetylase inhibitors. They induce antiangiogenic and anti-inflammatory effects through inhibition of VEGF, NF-κB, and other growth factor receptor pathways. Here, we review the potential of small molecules, both synthetics and natural products, targeting these and other molecular mechanisms, as antiangiogenic agents in the treatment of CoNV.

Therapeutic effects of triptolide from Tripterygium wilfordii Hook. f. on interleukin-1-beta-induced osteoarthritis in rats

Osteoarthritis (OA) is a common yet destructive disease affecting the articular cartilage, and is a major cause of immense suffering and disability for millions of people. Previous studies have shown that triptolide (TPL), an active compound derived from Tripterygium wilfordii, has potent immunosuppressive and anti-inflammatory activities useful for treating chronic diseases. However, whether TPL has immunosuppressive activity against OA is not known. In this study, we assessed the therapeutic effects of TPL on interleukin-1-beta (IL-1β)-induced OA in rats. Histological and protein analyses revealed that TPL not only could inhibit interleukin-6 (IL-6) and cyclooxygenase-2 (COX2) protein expression in cells and disrupt inflammation, but it also reduced the expression of matrix metalloproteinase (MMP)-3 and 13. Our results also supported the ability of TPL to suppress the osteoprotegerin/receptor activator of nuclear factor kappa-beta (NF-κB)/receptor activator of NF-κB ligand (OPG/RANK/RANKL) and NF-κB signaling pathways induced by IL-1β. Together these data suggest that TPL may be a potentially valuable treatment for OA, regulating associated inflammation and pain.

Triptolide attenuates laser-induced choroidal neovascularization via M2 macrophage in a mouse model

PURPOSE

To investigate whether triptolide has inhibitory effects on the development of choroidal neovascularization (CNV), together with its underlying anti-angiogenic mechanisms.

METHODS

CNV was induced in C57BL/6 J mice using laser photocoagulation. Triptolide at concentrations of 0.035 and 0.07 mg/kg body weight (BW) or the same volume of phosphate-buffered saline (PBS) was intraperitoneally injected into mice 2 days before laser photocoagulation, which was continued daily till the end of the experiment. CNV areas were measured on day 7. The numbers of M1, M2, and F4/80⁺ macrophages were detected on day 1, 3, and 7 in each group. The levels of vascular endothelial growth factor (VEGF) and inflammatory molecules,including intercellular adhesion molecule (ICAM)-1,tumor necrosis factor (TNF)-α, and interleukin 6 (IL-6) were determined by enzyme-linked immunosorbent assay. Cell proliferation, migration, and tube-formation assays were performed in vitro.

RESULTS

Triptolide at doses of 0.035 mg/kg BW (66,562 ± 39,253 μm², n = 5, P＜0.05) and 0.07 mg/kg BW (37,271 ± 25,182 μm², n = 5, P＜0.001) significantly reduced CNV areas by 54.9 and 74.8 %, respectively, compared with PBS control (147,699 ± 112,900 μm², n = 5) in a dose-dependent manner. Protein levels of VEGF, ICAM-1, TNF-α, and IL-6 in the RPE-choroid-sclera complex were significantly downregulated by triptolide treatment on day 3, which was in accordance with the reduced number of infiltrated F4/80⁺ macrophages and the reduced ratio of M2/F4/80⁺ macrophages. However, no toxic effects of triptolide on the retina or other systemic organs were observed. In addition, triptolide treatment exerted inhibitory effects on cell proliferation, migration, and tube formation in vitro in a concentration-dependent manner.

CONCLUSIONS

Triptolide has therapeutic potential in CNV owing to its anti-angiogenic effect.

Toxic effects of flufenoxuron on development and vascular formation during zebrafish embryogenesis

Flufenoxuron, a chitin synthesis inhibitor that is widely used in developed countries as an insecticide, is rarely degraded in the environment. In addition to that in insects, flufenoxuron-mediated non-targeted death in organisms such as lizards and bees has been reported. However, the toxic effects of this compound on vascular development during embryogenesis, as well as the underlying mechanism, have not yet been elucidated. In the present study, we assessed abnormal development and cardiovascular damage induced by flufenoxuron in zebrafish embryos. Exposed zebrafish had malformed eyes and pathological characteristics such as heart and yolk sac edema. In accordance with developmental inhibition, cell cycle regulatory genes were dysregulated in zebrafish embryos upon exposure to flufenoxuron. We also discovered that this agent can disrupt vascular formation by interfering with angiogenesis-associated genes including the genes encoding vascular endothelial growth factor Aa (vegfaa), vegfc, fms-related tyrosine kinase 1 (flt1), and flt4 in zebrafish embryos. These anti-angiogenic effects of flufenoxuron were further verified using a well-known angiogenesis model, namely human umbilical vein endothelial cells. In conclusion, our results suggest that flufenoxuron inhibits overall development and angiogenesis during embryogenesis.