RESUMO
Melanoma is difficult to treat with chemotherapy, prompting the need for new treatments. Protease inhibitors have emerged as promising candidates as tumor cell proteases promote metastasis. Researchers have developed a chimeric form of the Bauhinia bauhinioides kallikrein inhibitor, rBbKIm, which has shown negative effects on prostate tumor cell lines DU145 and PC3. Crataeva tapia bark lectin, CrataBL, targets sulfated oligosaccharides in glycosylated proteins and has also demonstrated deleterious effects on prostate and glioblastoma tumor cells. However, neither rBbKIm nor its derived peptides affected the viability of SK-MEL-28, a melanoma cell line, while CrataBL decreased viability by over 60%. Two peptides, Pep. 26 (Ac-Q-N-S-S-L-K-V-V-P-L-NH2) and Pep. 27 (Ac-L-P-V-V-K-L-S-S-N-Q-NH2), were also tested. Pep. 27 suppressed cell migration and induced apoptosis when combined with vemurafenib, while Pep. 26 inhibited cell migration and reduced nitric oxide and the number of viable cells. Vemurafenib, a chemotherapy drug used to treat melanoma, was found to decrease the release of interleukin 8 and PDGF-AB/BB cytokines and potentiated the effects of proteins and peptides in reducing these cytokines. These findings suggest that protease inhibitors may be effective in blocking melanoma cells and highlight the potential of CrataBL and its derived peptides.
Assuntos
Melanoma , Masculino , Humanos , Vemurafenib/farmacologia , Melanoma/tratamento farmacológico , Linhagem Celular Tumoral , Apoptose , Citocinas/farmacologia , Inibidores de Proteases/farmacologiaRESUMO
Currently available drugs for treatment of glioblastoma, the most aggressive brain tumor, remain inefficient, thus a plethora of natural compounds have already been shown to have antimalignant effects. However, these have not been tested for their impact on tumor cells in their microenvironment-simulated cell models, e.g., mesenchymal stem cells in coculture with glioblastoma cell U87 (GB). Mesenchymal stem cells (MSC) chemotactically infiltrate the glioblastoma microenvironment. Our previous studies have shown that bone-marrow derived MSCs impair U87 growth and invasion via paracrine and cell-cell contact-mediated cross-talk. Here, we report on a plant-derived protein, obtained from Crataeva tapia tree Bark Lectin (CrataBL), having protease inhibitory/lectin activities, and demonstrate its effects on glioblastoma cells U87 alone and their cocultures with MSCs. CrataBL inhibited U87 cell invasion and adhesion. Using a simplified model of the stromal microenvironment, i.e., GB/MSC direct cocultures, we demonstrated that CrataBL, when added in increased concentrations, caused cell cycle arrest and decreased cocultured cells' viability and proliferation, but not invasion. The cocultured cells' phenotypes were affected by CrataBL via a variety of secreted immunomodulatory cytokines, i.e., G-CSF, GM-CSF, IL-6, IL-8, and VEGF. We hypothesize that CrataBL plays a role by boosting the modulatory effects of MSCs on these glioblastoma cell lines and thus the effects of this and other natural lectins and/or inhibitors would certainly be different in the tumor microenvironment compared to tumor cells alone. We have provided clear evidence that it makes much more sense testing these potential therapeutic adjuvants in cocultures, mimicking heterogeneous tumor-stroma interactions with cancer cells in vivo. As such, CrataBL is suggested as a new candidate to approach adjuvant treatment of this deadly tumor.
Assuntos
Capparaceae/química , Células-Tronco Mesenquimais/efeitos dos fármacos , Casca de Planta/química , Extratos Vegetais/farmacologia , Lectinas de Plantas/farmacologia , Inibidores de Proteases/farmacologia , Adesão Celular/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Técnicas de Cocultura , Citocinas/biossíntese , Glioblastoma/metabolismo , Humanos , Células-Tronco Mesenquimais/metabolismo , Metaloproteases/antagonistas & inibidores , Óxido Nítrico/biossíntese , Extratos Vegetais/química , Lectinas de Plantas/química , Inibidores de Proteases/químicaRESUMO
Formation of new blood vessels from preexisting ones, a process known as angiogenesis, is one of the limiting steps for success in treatment of ischemic disorders. Therefore, efforts to understanding and characterize new agents capable to stimulate neovascularization are a worldwide need. Crataeva tapia bark lectin (CrataBL) has been shown to have chemoattractant properties for endothelial cells through the stimulation of migration and invasiveness of human umbilical vein endothelial cells (HUVEC) because it is a positively charged protein with high affinity to glycosaminoglycan. In addition, CrataBL increased the production of chondroitin and heparan sulfate in endothelial cells. These findings orchestrated specific adhesion on collagen I and phosphorylation of tyrosine kinase receptors, represented by vascular endothelial growth factor receptor-2 (VEGFR-2) and fibroblast growth factor receptor (FGFR), whose downstream pathways trigger the angiogenic cascade increasing cell viability, cytoskeleton rearrangement, cell motility, and tube formation. Moreover, CrataBL inhibited the activity of matrix metalloproteases type 2 (MMP-2), a protein related to tissue remodeling. Likewise, CrataBL improved wound healing and increased the number of follicular structures in lesioned areas produced in the dorsum-cervical region of C57BL/6 mice. These outcomes altogether indicate that CrataBL is a pro-angiogenic and healing agent.