Inhibition of Migration and Invasion in Melanoma Cells by β-Escin via the ERK/NF-κB Signaling Pathway

Escin's Multifaceted Therapeutic Profile in Treatment and Post-Treatment of Various Cancers: A Comprehensive Review

Although modern medicine is advancing at an unprecedented rate, basic challenges in cancer treatment and drug resistance remain. Exploiting natural-product-based drugs is a strategy that has been proven over time to provide diverse and efficient approaches in patient care during treatment and post-treatment periods of various diseases, including cancer. Escin-a plant-derived triterpenoid saponin-is one example of natural products with a broad therapeutic scope. Initially, escin was proven to manifest potent anti-inflammatory and anti-oedematous effects. However, in the last two decades, other novel activities of escin relevant to cancer treatment have been reported. Recent studies demonstrated escin's efficacy in compositions with other approved drugs to accomplish synergy and increased bioavailability to broaden their apoptotic, anti-metastasis, and anti-angiogenetic effects. Here, we comprehensively discuss and present an overview of escin's chemistry and bioavailability, and highlight its biological activities against various cancer types. We conclude the review by presenting possible future directions of research involving escin for medical and pharmaceutical applications as well as for basic research.

β-Escin reduces cancer progression in aggressive MDA-MB-231 cells by inhibiting glutamine metabolism through downregulation of c-myc oncogene

BACKGROUND

The c-myc oncogene, which causes glutamine dependence in triple negative breast cancers (TNBC), is also the target of one of the signaling pathways affected by β-Escin.

METHODS AND RESULTS

We sought to determine how c-myc protein affects glutamine metabolism and the proteins, glutamine transporter alanine-serine-cysteine 2 (ASCT2) and glutaminase (GLS1), in β-Escin-treated MDA-MB-231 cells using glutamine uptake and western blot analysis. Cell viability, colony formation, migration and apoptosis were also evaluated in MDA-MB-231 cells in response to β-Escin treatment using MTS, colony forming, wound healing, and Annexin-V assay. We determined that β-Escin decreased glutamine uptake and reduced c-myc and GLS1 protein expressions and increased the expression of ASCT2. In addition, this inhibition of glutamine metabolism decreased cell proliferation, colony formation and migration, and induced apoptosis.

CONCLUSIONS

In this study, it was suggested that β-Escin inhibits glutamine metabolism via c-myc in MDA-MB-231 cells, and it is thought that as a result of interrupting the energy supply in these cells via c-myc, it results in a decrease in the carcinogenic properties of the cells. Consequently, β-Escin may be promising as a therapeutic agent for glutamine-dependent cancers.

Natural Products: A Promising Therapeutics for Targeting Tumor Angiogenesis

Tumor-associated angiogenesis is a key target for anti-cancer therapy. The imbalance between pro-angiogenic and anti-angiogenic signals elicited by tumor cells or tumor microenvironment always results in activating "angiogenic switch". Tumor angiogenesis functions in multi-aspects of tumor biology, including endothelial cell apoptosis, tumor metastasis, and cancer stem cell proliferation. Numerous studies have indicated the important roles of inexpensive and less toxic natural products in targeting tumor angiogenesis-associated cytokines and apoptotic signaling pathways. Our current knowledge of tumor angiogenesis is based mainly on experiments performed on cells and animals, so we summarized the well-established models for angiogenesis both in vitro and in vivo. In this review, we classified and summarized the anti-angiogenic natural agents (Polyphenols, Polysaccharides, Alkaloids, Terpenoids, Saponins) in targeting various tumor types according to their chemical structures at present, and discussed the mechanistic principles of these natural products on regulating angiogenesis-associated cytokines and apoptotic signaling pathways. This review is to help understanding the recent progress of natural product research for drug development on anti-tumor angiogenesis.

Escin inhibits angiogenesis by suppressing interleukin‑8 and vascular endothelial growth factor production by blocking nuclear factor‑κB activation in pancreatic cancer cell lines

Pancreatic cancer (PaCa) is one of the most aggressive types of cancer. Thus, the development of new and more effective therapies is urgently required. Escin, a pentacyclic triterpenoid from the horse chestnut, has been reported to exhibit antitumor potential by reducing cell proliferation and blocking the nuclear factor‑κB (NF‑κB) signaling pathway in several types of cancer. Our previous study reported that NF‑κB enhanced the secretion of interleukin (IL)‑8 and vascular endothelial growth factor (VEGF), thereby inducing angiogenesis in PaCa cell lines. In the present study, it was examined whether escin inhibited angiogenesis by blocking NF‑κB activation in PaCa. It was initially confirmed that escin, at concentrations >10 µM, significantly inhibited the proliferation of several PaCa cell lines. Next, using immunocytochemical staining, it was found that escin inhibited the nuclear translocation of NF‑κB. Furthermore, ELISA confirmed that NF‑κB activity in the escin‑treated PaCa cells was significantly inhibited and reverse transcription‑quantitative PCR showed that the mRNA expression levels of tumor necrosis factor‑α‑induced IL‑8 and VEGF were significantly suppressed following escin treatment in the PaCa cell lines. ELISA also showed that escin decreased the secretion of IL‑8 and VEGF from the PaCa cells. Furthermore, tube formation in immortalized human endothelial cells was inhibited following incubation with the supernatants from escin‑treated PaCa cells. These results indicated that escin inhibited angiogenesis by reducing the secretion of IL‑8 and VEGF by blocking NF‑κB activity in PaCa. In conclusion, escin could be used as a novel molecular therapy for PaCa.

Curcumol inhibits the proliferation and metastasis of melanoma via the miR-152-3p/PI3K/AKT and ERK/NF-κB signaling pathways

Melanoma is the most aggressive and treatment-resistant form of skin cancer. Curcumol is a Chinese medicinal herb traditionally used as a cancer remedy. However, the molecular mechanisms underlying the anticancer activity of curcumol in melanoma remains largely unknown. In the present study, we observed that Curcumol decreased mouse melanoma B16 cell proliferation and migration. The xenograft tumor assay showed that curcumol reduced melanoma volume and lung metastasis. Curcumol upregulated the expression of E-cadherin and downregulated the expression of N-cadherin, MMP2 and MMP9 in mouse melanoma B16 cell. Western blot analysis revealed that curcumol reduced the translocation of p65 to the nucleus and decreased p-ERK. Furthermore, curcumol attenuated c-MET, P13K and p-AKT protein expression and upregulated miR-152-3p gene expression. The dual-luciferase reporter assay indicated that c-MET was a target gene of miR-152-3p. Reduced expression of miR-152-3p partially attenuated the effect of curcumol on mouse melanoma B16 cell proliferation and migration. The decrease in c-MET, P13K and p-AKT protein expression following curcumol treatment in mouse melanoma B16 cells was notably attenuated by the miR-152-3p inhibitor. Taken together, our findings suggested that curcumol attenuated melanoma progression and concomitantly suppressed ERK/NF-κB signaling and promoted miR-152-3p expression to inactivate the c-MET/PI3K/AKT signaling pathway.