Goodwin C Rory, Rath Prakash, Oyinlade Olutobi, Lopez Hernando, Mughal Salman, Xia Shuli, Li Yunqing, Kaur Harsharan, Zhou Xin, Ahmed A Karim, Ho Sandra, Olivi Alessandro, Lal Bachchu
Department of Neurology, The Hugo W. Moser Research Institute at Kennedy Krieger Inc., United States; Department of Neurosurgery, The Johns Hopkins University, School of Medicine, Baltimore, MD, United States; Department of Neurosurgery, Duke University Medical Center, Durham, NC, United States.
Department of Neurology, The Hugo W. Moser Research Institute at Kennedy Krieger Inc., United States; Department of Neurosurgery, The Johns Hopkins University, School of Medicine, Baltimore, MD, United States.
Clin Neurol Neurosurg. 2018 Aug;171:26-33. doi: 10.1016/j.clineuro.2018.02.041. Epub 2018 Mar 9.
Receptor tyrosine kinases (RTK), such as c-Met and epidermal growth factor receptor (EGFR), are implicated in the malignant progression of glioblastoma. Studies show that RTK systems can co-modulate distinct and overlapping oncogenic downstream signaling pathways. EGFRvIII, a constitutively activated EGFR deletion mutant variant, leads to increased tumor growth and diminishes the tumor growth response to HGF: c-Met pathway inhibitor therapy. Conversely, activation of the c-Met pathway diminishes the tumor growth response to EGFR pathway inhibitors. Previously we reported that EGFRvIII and c-Met pathway inhibitors synergize to inhibit tumor growth in isogenic GBM cell lines engineered to express EGFRvIII. More recently, studies suggest that despite targeting RTK signaling in glioblastoma multiforme, a subpopulation of stem-like tumor-propagating cells can persist to replenish the tumor cell population leading to tumor recurrence.
Mayo 39 and Mayo 59 xenograft lines were cultured and xenografts were maintained. Subcutaneous xenograft lines were serially passaged in nude mice to generate subcutaneous xenografts. Xenografts were implanted in 6-8 week old nude mice. Once tumors reached a substantial size (150 mm), mice were randomly divided into 4 groups: 1) control vehicle, 2) Crizotinib (crizo), 3) Erlotinib (erlot), or 4) Crizotinib + Erlotinib, (n = 5 per group).
Crizotinib (c-Met pathway inhibitor) and Erlotinib (EGFR pathway inhibitor) in combination significantly inhibited tumor growth, phospho-EGFRvIII, phospho-Met, phospho-AKT, phospho-MAPK, and neurosphere growth in Mayo 39 and Mayo 59 primary GBM subcutaneous xenografts. The expression of the stem cell markers Nestin, Musashi, Olig 2 and Sox2 were also significantly down-regulated by c-Met inhibition, but no additive down-regulation was seen by co-treatment with Erlotinib.
These results are consistent with and corroborate our previous findings demonstrating that targeting these two parallel pathways with c-Met and EGFR inhibitor therapy provides substantial anti-tumor activity in glioblastoma models.
受体酪氨酸激酶（RTK），如c-Met和表皮生长因子受体（EGFR），与胶质母细胞瘤的恶性进展有关。研究表明，RTK系统可以共同调节不同的和重叠的致癌下游信号通路。EGFRvIII是一种组成性激活的EGFR缺失突变体变体，可导致肿瘤生长增加，并降低肿瘤对HGF：c-Met通路抑制剂治疗的生长反应。相反，c-Met通路的激活会降低肿瘤对EGFR通路抑制剂的生长反应。此前我们报道，EGFRvIII和c-Met通路抑制剂协同作用，可抑制经基因工程改造以表达EGFRvIII的同基因胶质母细胞瘤细胞系中的肿瘤生长。最近的研究表明，尽管在多形性胶质母细胞瘤中靶向RTK信号传导，但一小部分干细胞样肿瘤增殖细胞可以持续存在，以补充肿瘤细胞群体，导致肿瘤复发。
培养Mayo 39和Mayo 59异种移植瘤系并维持异种移植瘤。将皮下异种移植瘤系在裸鼠中连续传代以产生皮下异种移植瘤。将异种移植瘤植入6-8周龄的裸鼠体内。一旦肿瘤达到相当大的尺寸（150毫米），将小鼠随机分为4组：1）对照载体，2）克唑替尼（crizo），3）厄洛替尼（erlot），或4）克唑替尼+厄洛替尼，（每组n = 5）。
克唑替尼（c-Met通路抑制剂）和厄洛替尼（EGFR通路抑制剂）联合使用可显著抑制Mayo 39和Mayo 59原发性胶质母细胞瘤皮下异种移植瘤的肿瘤生长、磷酸化EGFRvIII、磷酸化Met、磷酸化AKT、磷酸化MAPK和神经球生长。c-Met抑制也显著下调了干细胞标志物巢蛋白、马斯ashi、Olig 2和Sox2的表达，但与厄洛替尼联合治疗未见相加性下调。
这些结果与我们之前的发现一致并得到证实，即使用c-Met和EGFR抑制剂疗法靶向这两条平行通路在胶质母细胞瘤模型中提供了显著的抗肿瘤活性。
