Cancer Biology and Experimental Therapeutics, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
J Exp Clin Cancer Res. 2019 Aug 30;38(1):382. doi: 10.1186/s13046-019-1360-3.
Ovarian carcinomas are the deadliest gynecological malignancies owing to their high rate of recurrence and high resistance to platinum-based chemotherapy. Recent studies have shown platinum-dependent enrichment of ovarian tumors with side population as well as cancer stem cells, which are highly resistant to the treatment. To overcome this treatment-limiting factor, we sought to combine cisplatin with eugenol, a natural substance known to have anti-cancer effects.
The efficiency of combining cisplatin with eugenol was first tested in vitro on two ovarian cancer cell lines SKOV3 and OV2774 using the WST1 and the flow cytometry techniques. The effect of this combination on ovarian cancer stem cells was determined by the tumorsphere formation assay, while the implication of the Notch pathway was evaluated post-ectopic expression of the Hes1 gene. The resulting changes in the expression of several markers was assessed by immunoblotting, immunofluorescence as well as quantitative RT-PCR. Cell sorting was also used to isolate specific ovarian cancer sub-population of cells. Furthermore, tumor-bearing mouse models were utilized to prove the potential therapeutic value of the cisplatin/eugenol combination treatment in vivo.
We have shown that adding eugenol to cisplatin-treated ovarian cancer cells synergistically inhibited their growth and survival through induction of apoptosis. Importantly, this sequential inhibition strongly reduced the proportion of side population cells and suppressed cisplatin-dependent enrichment in ovarian cancer stem cells. Additionally, while increase in the level of Hes1 promoted stemness and enhanced resistance to cisplatin, cisplatin/eugenol cotreatment inhibited the Notch-Hes1 pathway and strongly downregulated the drug resistance ABC transporter genes. These findings were confirmed in vivo by showing that cisplatin/eugenol cotherapy inhibited tumor growth in animals, reduced the proportion and self-renewal capacities of cancer stem cells and significantly improved disease-free survival of tumor-bearing animals compared with either therapy alone.
These results indicate that cisplatin/eugenol sequential combination could be of great therapeutic value for ovarian cancer patients through targeting the Notch-Hes1 pathway and the consequent elimination of the resistant cancer stem cells.
卵巢癌是妇科恶性肿瘤中致死率最高的一种，因为其复发率高，对铂类化疗药物高度耐药。最近的研究表明，卵巢肿瘤中存在铂类依赖性侧群细胞和癌症干细胞富集现象，这些细胞对治疗具有高度耐药性。为了克服这一治疗限制因素，我们试图将顺铂与丁香酚（一种具有抗癌作用的天然物质）联合使用。
首先使用 WST1 和流式细胞术在 SKOV3 和 OV2774 两种卵巢癌细胞系中体外测试顺铂与丁香酚联合使用的效率。通过肿瘤球形成实验确定该联合用药对卵巢癌干细胞的影响，同时通过异位表达 Hes1 基因评估 Notch 通路的影响。通过免疫印迹、免疫荧光和定量 RT-PCR 评估几种标志物的表达变化。还使用细胞分选来分离特定的卵巢癌细胞亚群。此外，还利用荷瘤小鼠模型证明顺铂/丁香酚联合治疗在体内的潜在治疗价值。
我们表明，在顺铂处理的卵巢癌细胞中添加丁香酚通过诱导细胞凋亡协同抑制其生长和存活。重要的是，这种序贯抑制强烈降低了侧群细胞的比例，并抑制了卵巢癌干细胞中铂类药物依赖性富集。此外，尽管 Hes1 水平的增加促进了干性并增强了对顺铂的耐药性，但顺铂/丁香酚联合治疗抑制了 Notch-Hes1 通路，并强烈下调了耐药性 ABC 转运体基因。这些发现通过显示顺铂/丁香酚联合治疗抑制动物肿瘤生长、减少癌症干细胞的比例和自我更新能力以及与单独使用任一药物相比显著提高荷瘤动物的无病生存率在体内得到证实。
这些结果表明，顺铂/丁香酚序贯联合治疗可能通过靶向 Notch-Hes1 通路和随后消除耐药性癌症干细胞，对卵巢癌患者具有重要的治疗价值。
