Trabectedin and Campthotecin Synergistically Eliminate Cancer Stem Cells in Cell-of-Origin Sarcoma Models

Abstract

Trabectedin has been approved for second-line treatment of soft tissue sarcomas. However, its efficacy to target sarcoma initiating cells has not been addressed yet. Here, we used pioneer models of myxoid/round cell liposarcoma (MRCLS) and undifferentiated pleomorphic sarcoma (UPS) developed from transformed human mesenchymal stromal/stem cells (MSCs) to evaluate the effect of trabectedin in the cell type responsible for initiating sarcomagenesis and their derived cancer stem cells (CSC) subpopulations. We found that low nanomolar concentrations of trabectedin efficiently inhibited the growth of sarcoma-initiating cells, induced cell cycle arrest, DNA damage and apoptosis. Interestingly, trabectedin treatment repressed the expression of multiple genes responsible for the development of the CSC phenotype, including pluripotency factors, CSC markers and related signaling pathways. Accordingly, trabectedin induced apoptosis and reduced the survival of CSC-enriched tumorsphere cultures with the same efficiency that inhibits the growth of bulk tumor population. In vivo, trabectedin significantly reduced the mitotic index of MRCLS xenografts and inhibited tumor growth at a similar extent to that observed in doxorubicin-treated tumors. Combination of trabectedin with campthotecin (CPT), a chemotherapeutic drug that shows a robust anti-tumor activity when combined with alkylating agents, resulted in a very strong synergistic inhibition of tumor cell growth and highly increased DNA damage and apoptosis induction. Importantly, the enhanced anti-tumor activity of this combination was also observed in CSC subpopulations. These data suggest that trabectedin and CPT combination may constitute a novel strategy to effectively target both the cell-of-origin and CSC subpopulations in sarcoma.

SOX2 Expression and Transcriptional Activity Identifies a Subpopulation of Cancer Stem Cells in Sarcoma with Prognostic Implications

“…In experiments aimed to evaluate the effect of anti-tumor drugs, mice with tumor xenografts with a volume of approximately 300 mm 3 were randomly assigned to receive the following intravenous treatments: vehicle (saline, every 7 days up to 3 doses), EC-8042 (18 mg/Kg; every 3/4 days up to 5 doses), trabectedin (0.15 mg/Kg; every 7 days up to 3 doses), doxorubicin (4 mg/Kg; every 7 days up to 3 doses) or paclitaxel (20 mg/Kg; every 7 days up to 3 doses). Treatment schedules were optimized according to the therapeutic window of the different drugs [36][37][38]. To analyze the effect of the conditional knockdown of SOX2, mice inoculated with cells expressing or not the Tet-pLKO-puro-SOX2 lentiviral vector received a daily intraperitoneal dose of doxycycline (50 mg/kg).…”

Cytotoxic and Apoptotic Effects of Trabectedin on Breast Cancer Stem Cells

“…Martinez-Cruzado ve ark., sarkoma hücrelerinden elde edilen KKH alt grupla-rında trabektedinin konsantrasyona bağlı olarak apoptozu indüklediğini tespit etmişlerdir. 9 Açıkgöz ve ark.nın çalışmasında, trabektedinin prostat kanseri kök hücrelerinde apoptozu doza bağlı olarak indüklediğini ayrıca trabektedinin IC 50 konsantrasyonları uygulandığında kaspaz-3, kaspaz-8, kaspaz-9, p53 moleküllerini artırdığı, Bcl-2 molekülünü ise azalttığını göstermiştir. 10…”

“…8 Daha önceki çalışmalarda, trabektedinin, sarkoma kanseri kök hücrelerinde hücre canlılığını inhibe ettiği, apoptozisi indüklediği ve DNA hasarına neden olduğu gösterilmiştir. 9 Prostat kanseri kök hücrelerinde ise G2/M hücre siklusu blokajına neden olarak apoptozisi indüklediği ortaya konmuştur. 10 Ancak trabektedinin meme kanseri kök hücreleri üzerindeki etkileri detaylı olarak çalışılmamıştır.…”

The multikinase inhibitor EC‐70124 synergistically increased the antitumor activity of doxorubicin in sarcomas

“…Sarcomas comprise a group of aggressive malignancies which are suggested to develop from transformed mesenchymal stromal/stem cells (MSCs) . Despite advances in the clinical management of these diseases, the overall survival for patients presenting with metastatic and recurrent disease continues to be dismal and cytotoxic drugs like doxorubicin remain as the mainstay for first‐line treatments . However, advanced sarcomas often show resistance to doxorubicin, mainly through the overexpression of members of ATP binding cassette (ABC) transmembrane family of transporters which act as efflux pumps for anti‐cancer drugs .…”

“…1,2 Despite advances in the clinical management of these diseases, the overall survival for patients presenting with metastatic and recurrent disease continues to be dismal 3 and cytotoxic drugs like doxorubicin remain as the mainstay for first-line treatments. 4,5 However, advanced sarcomas often show resistance to doxorubicin, mainly through the overexpression of members of ATP binding cassette (ABC) transmembrane family of transporters which act as efflux pumps for anti-cancer drugs. 6 Therefore, the development of therapeutic strategies able to prevent drug resistance would undoubtedly improve current sarcoma treatments.…”