The triptolide derivative MRx102 inhibits Wnt pathway activation and has potent anti-tumor effects in lung cancer.

BACKGROUND: The natural compound triptolide has been shown to decrease cell proliferation and induce apoptosis and cellular senescence. We previously demonstrated that triptolide decreases tumor formation and metastasis of human non-small cell lung cancer cells (NSCLC). Due to the toxicity of triptolide, derivatives of the natural compound have been developed that show more favorable toxicity profiles and pharmacokinetics in animal models. The purpose of this study was to evaluate MRx102 as a novel therapeutic for lung cancer. METHODS: Mice injected subcutaneously with H460 lung cancer cells were treated with MRx102 or carboplatin to determine the effect of MRx102 on tumor formation in comparison to standard treatment. Patient-derived xenografts (PDX) with different WIF1 expression levels were treated with MRx102 or cisplatin. We tested the effects of MRx102 treatment on migration and invasion of lung cancer cells using Transwell filters coated with fibronectin and Matrigel, respectively. Tail vein injections using H460 and A549 cells were performed. RESULTS: Here we report that the triptolide derivative MRx102 significantly decreases NSCLC proliferation and stimulates apoptosis. Further, MRx102 potently inhibits NSCLC haptotactic migration and invasion through Matrigel. In vivo, NSCLC tumor formation and metastasis were greatly decreased by MRx102 treatment. The decrease in tumor formation by MRx102 in the patient-derived xenograft model was WIF1-dependent, demonstrating that MRx102 is a potent inhibitor of the Wnt pathway in low WIF1 expressing NSCLC patient tumors. CONCLUSIONS: These results indicate that MRx102 has potent antitumor effects both in vitro and in vivo, and is a potential novel therapy for the treatment of NSCLC.

Triptolide Inhibits Lung Cancer Cell Migration, Invasion, and Metastasis.

BACKGROUND: Triptolide is an extract from Tripterygium wilfordii used in traditional Chinese medicine to treat autoimmune disorders. Triptolide has anticancer effects in vitro and is reported to impair cancer cell migration. We studied whether triptolide inhibits lung cancer cell migration and metastasis. METHODS: We determined the microRNA expression profile of triptolide-treated cells. We tested the effects of triptolide treatment on migration and invasion of lung cancer cells by using Transwell filters coated with fibronectin and Matrigel, respectively. Western blot analyses were used to compare expression of proteins involved in cell migration before and after 10 nmol/L triptolide treatment. Tail vein injections with H358 cells were performed. The mice were treated with 1 mg/kg triptolide or vehicle by intraperitoneal injection three times per week. Lung and liver metastases were compared at 9 weeks. Means of groups were compared by using a t test. RESULTS: Triptolide altered the expression of microRNAs involved in cellular movement and significantly decreased migration and invasion of lung cancer cells from approximately 18 to 3 cells per field (p < 0.001). Triptolide decreases focal adhesion kinase expression, which leads to impairment of downstream signaling. Finally, triptolide-treated mice injected with lung cancer cells significantly decreased metastatic colony formation in the lungs (p < 0.01). CONCLUSIONS: Triptolide decreases lung cancer cell migration and invasion in vitro and inhibits metastatic tumor formation in mice. Triptolide suppresses focal adhesion kinase, which causes deregulation of the migration machinery. These results suggest that triptolide inhibits lung cancer metastasis and should be investigated as a new lung cancer therapy.

Dynamic phosphorylation of tyrosine 665 in pseudopodium-enriched atypical kinase 1 (PEAK1) is essential for the regulation of cell migration and focal adhesion turnover.

Pseudopodium-enriched atypical kinase 1 (PEAK1) is a recently described tyrosine kinase that associates with the actin cytoskeleton and focal adhesion (FA) in migrating cells. PEAK1 is known to promote cell migration, but the responsible mechanisms remain unclear. Here, we show that PEAK1 controls FA assembly and disassembly in a dynamic pathway controlled by PEAK1 phosphorylation at Tyr-665. Knockdown of endogenous PEAK1 inhibits random cell migration. In PEAK1-deficient cells, FA lifetimes are decreased, FA assembly times are shortened, and FA disassembly times are extended. Phosphorylation of Tyr-665 in PEAK1 is essential for normal PEAK1 localization and its function in the regulation of FAs; however, constitutive phosphorylation of PEAK1 Tyr-665 is also disruptive of its function, indicating a requirement for precise spatiotemporal regulation of PEAK1. Src family kinases are required for normal PEAK1 localization and function. Finally, we provide evidence that PEAK1 promotes cancer cell invasion through Matrigel by a mechanism that requires dynamic regulation of Tyr-665 phosphorylation.