Department of Pancreatic Surgery, Renmin Hospital, Wuhan University, 238 Jiefang Road, Wuhan, 430060, Hubei Province, China.
Department of Dermatology, Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430014, Hubei Province, China.
J Exp Clin Cancer Res. 2018 Nov 28;37(1):291. doi: 10.1186/s13046-018-0972-3.
Profound chemoresistance remains an intractable obstacle in pancreatic cancer treatment. Pancreatic cancer stem cells (CSCs) and the ubiquitous hypoxic niche have been proposed to account for drug resistance. However, the mechanism involved requires further exploration. This study investigated whether the hypoxic niche enhances gemcitabine-induced stemness and acquired resistance in pancreatic cancer cells by activating the AKT/Notch1 signaling cascade. The therapeutic effects of blockading this signaling cascade on gemcitabine-enriched CSCs were also investigated.
The expression levels of CSC-associated markers Bmi1 and Sox2 as well as those of proteins involved in AKT/Notch1 signaling were measured by Western blot analysis. The expression level of the pancreatic CSC marker CD24 was measured by flow cytometry. Change in gemcitabine sensitivity was evaluated by the MTT assay. The ability of sphere formation was tested by the sphere-forming assay in stem cell medium. The ability of migration and invasion was detected by the transwell migration/invasion assay. A mouse xenograft model of pancreatic cancer was established to determine the effect of Notch1 inhibition on the killing effect of gemcitabine in vivo. The ability of metastasis was investigated by an in vivo lung metastasis assay.
Gemcitabine promoted pancreatic cancer cell stemness and associated malignant phenotypes such as enhanced migration, invasion, metastasis, and chemoresistance. The AKT/Notch1 signaling cascade was activated after gemcitabine treatment and mediated this process. Blockading this pathway enhanced the killing effect of gemcitabine in vivo. However, supplementation with hypoxia treatment synergistically enhanced the AKT/Notch1 signaling pathway and collaboratively promoted gemcitabine-induced stemness.
These findings demonstrate a novel mechanism of acquired gemcitabine resistance in pancreatic cancer cells through induction of stemness, which was mediated by the activation of AKT/Notch1 signaling and synergistically aggravated by the ubiquitous hypoxic niche. Our results might provide new insights for identifying potential targets for reversing chemoresistance in patients with pancreatic cancer.
胰腺癌治疗中存在着严重的化疗耐药问题。胰腺癌肿瘤干细胞（CSC）和普遍存在的低氧微环境被认为是导致耐药的原因。然而，其中涉及的机制仍需进一步研究。本研究旨在探讨低氧微环境是否通过激活 AKT/Notch1 信号级联来增强胰腺癌细胞对吉西他滨诱导的干性和获得性耐药，并研究阻断该信号级联对富含吉西他滨的 CSC 的治疗效果。
通过 Western blot 分析测定与 CSC 相关的标记物 Bmi1 和 Sox2 以及 AKT/Notch1 信号通路相关蛋白的表达水平。通过流式细胞术测定胰腺 CSC 标记物 CD24 的表达水平。通过 MTT 测定评估吉西他滨敏感性的变化。通过在干细胞培养基中的球体形成实验检测球体形成能力。通过 Transwell 迁移/侵袭实验检测迁移和侵袭能力。建立小鼠胰腺癌异种移植模型，以确定 Notch1 抑制对体内吉西他滨杀伤作用的影响。通过体内肺转移实验研究转移能力。
吉西他滨促进了胰腺癌细胞的干性和相关恶性表型，如增强的迁移、侵袭、转移和化疗耐药性。AKT/Notch1 信号级联在吉西他滨处理后被激活，并介导了这一过程。阻断该途径增强了体内吉西他滨的杀伤作用。然而，低氧处理的补充协同增强了 AKT/Notch1 信号通路，并协同促进了吉西他滨诱导的干性。
这些发现表明，通过诱导干性，胰腺癌细胞获得吉西他滨耐药的一种新机制，该机制是通过 AKT/Notch1 信号的激活介导的，并被普遍存在的低氧微环境协同加重。我们的研究结果可能为识别逆转胰腺癌患者化疗耐药的潜在靶点提供新的思路。
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