RESUMO
DT-13 combined with topotecan (TPT) showed stronger antitumour effects in mice subcutaneous xenograft model compared with their individual effects in our previous research. Here, we further observed the synergistically effect in mice orthotopic xenograft model. Metabolomics analysis showed DT-13 combined with TPT alleviated metabolic disorders induced by tumour and synergistically inhibited the activity of the aerobic glycolysis-related enzymes in vivo and in vitro. Mechanistic studies revealed that the combination treatment promoted epidermal growth factor receptor (EGFR) degradation through non-muscle myosin IIA (NM IIA)-induced endocytosis of EGFR, further inhibited the activity of hexokinase II (HK II), and eventually promoted the aerobic glycolysis inhibition activity more efficiently compared with TPT or DT-13 monotherapy. The combination therapy also inhibited the specific binding of HK II to mitochondria. When using the NM II inhibitor (-)002Dblebbistatin or MYH-9 shRNA, the synergistic inhibition effect of DT-13 and TPT on aerobic glycolysis was eliminated in BGC-823 cells. Immunohistochemical analysis revealed selective up-regulation of NM IIA while specific down-regulation of p-CREB, EGFR, and HK II by the combination therapy. Collectively, these findings suggested that this regimen has significant clinical implications, warranted further investigation.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma/tratamento farmacológico , Glicólise/efeitos dos fármacos , Saponinas/uso terapêutico , Neoplasias Gástricas/tratamento farmacológico , Topotecan/uso terapêutico , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carcinoma/enzimologia , Carcinoma/genética , Carcinoma/metabolismo , Linhagem Celular Tumoral , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Sinergismo Farmacológico , Endocitose/efeitos dos fármacos , Receptores ErbB/metabolismo , Feminino , Hexoquinase/antagonistas & inibidores , Hexoquinase/metabolismo , Humanos , Espectroscopia de Ressonância Magnética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Miosina não Muscular Tipo IIA/metabolismo , RNA Interferente Pequeno , Saponinas/farmacologia , Neoplasias Gástricas/enzimologia , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo , Topotecan/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Combination therapy has a higher success rate for many cancers compared to mono-therapy. The treatment of Topotecan (TPT) on gastric cancer (GC) is limited by its toxicity and the potential drug resistance. We found that the combination of the saponin monomer 13 from the dwarf lilyturf tuber (DT-13), performing anti-metastasis and anti-angiogenesis effects, with TPT synergistically induced apoptotic cytotoxicity in GCs with high EGF receptor (EGFR) expression, which was dependent on DT-13-induced endocytosis of EGFR. With TPT, DT-13 promoted EGFR ubiquitin--mediated degradation through myosin IIA-induced and Src/ caveolin-1 (Cav-1)-induced endocytosis of EGFR; inhibited EGFR downstream signalling and then increased the pro-apoptotic effects. Moreover, the synergistic pro-apoptotic efficacy of DT-13 and TPT in GCs with high EGFR expression was eliminated by both the NM II inhibitor (-)-blebbistatin and MYH-9 shRNA. The combination therapy of DT-13 with TPT showed stronger anti-tumour effects in vivo compared with their individual effects. Moreover, the results of combination therapy revealed selective upregulation of pro-apoptotic activity in TUNEL assays and cleaved caspase-3 and NM IIA in immunohischemical analysis; while specific downregulation of p-extracellular regulated kinase 1/2 (p-ERK1/2), EGFR and Cav-1 in immunohischemical analysis. Collectively, these findings have significant clinical implications for patients with tumours harbouring high EGFR expression due to the possible high sensitivity of this regimen.