Hypoxia-induced galectin-3 enhances RhoA function to activate the motility of tumor cells in non-small cell lung cancer
Hypoxia-induced galectin-3 enhances RhoA function to activate the motility of tumor cells in non-small cell lung cancer
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DOI：
10.3892/or.2018.6915
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发表时间：
2019-02-01
期刊：
影响因子：
4.2
通讯作者：
Hanaoka, Jun
中科院分区：
文献类型：
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作者：
Kataoka, Yoko;Ohshio, Yasuhiko;Hanaoka, Jun
Galectin-3 在肿瘤进展中起着至关重要的作用。然而，在非小细胞肺癌（NSCLC）中，低氧肿瘤微环境是否增强半乳糖凝集素3诱导的细胞运动仍不清楚。我们研究了缺氧下 NSCLC 细胞中 galectin-3 的表达，以及 galectin-3 影响肿瘤侵袭性的可能分子机制。使用逆转录 PCR 和蛋白质印迹法评估缺氧下 NSCLC 细胞系中的 Galectin-3 水平。为了阐明内源性半乳糖凝集素 3 的作用，使用划痕和侵袭实验研究了 NSCLC 细胞中半乳糖凝集素 3 敲低的效果。采用免疫组化方法检测57例pN0M0浸润性肺腺癌中半乳糖凝集素3的表达及其临床病理意义。 NSCLC 细胞系 A549 和 LK-2 中半乳糖凝集素 3 的 mRNA 和蛋白水平均因缺氧而上调。划痕和侵袭实验显示，缺氧条件下细胞迁移和侵袭活性显着增加，但半乳糖凝集素 3 敲低则降低。值得注意的是，向培养基中添加半乳糖凝集素 3 并不能改善因半乳糖凝集素 3 敲低而受损的细胞运动性。为了阐明内源性半乳糖凝集素3在缺氧条件下增强肿瘤细胞运动的作用，我们重点关注RhoA的功能。质膜中的 RhoA 水平（而非细胞质中）在缺氧条件下升高，而半乳糖凝集素 3 敲低则降低。 RhoA 活性在缺氧条件下显着增强，并被半乳糖凝集素 3 敲除有效抑制。在 pN0M0 浸润性肺腺癌患者中，肿瘤细胞上较高的半乳糖凝集素 3 表达与肿瘤细胞侵入微血管和术后肿瘤复发显着相关。这些数据表明，在缺氧的 NSCLC 细胞中，半乳糖凝集素 3 水平的上调增加了 RhoA 在质膜上的定位，从而增强了与侵袭性细胞运动相关的 RhoA 活性。在 pN0M0 侵袭性肺腺癌中，galectin-3 是预测根治性手术后肿瘤复发的潜在生物标志物。
Galectin-3 plays crucial roles in tumor progression. However, in non-small cell lung cancer (NSCLC), it remains unclear whether the hypoxic tumor microenvironment enhances galectin-3-induced cell motility. We investigated galectin-3 expression in NSCLC cells under hypoxia, and the possible molecular mechanisms by which galectin-3 influences tumor aggressiveness. Galectin-3 levels in NSCLC cell lines under hypoxia were assessed using reverse transcription PCR and western blotting. To clarify the role of endogenous galectin-3, the effect of galectin-3 knockdown in NSCLC cells was investigated using scratch and invasion assays. The expression and clinicopathological significance of galectin-3 in 57 patients with pN0M0 invasive pulmonary adenocarcinoma were investigated by immunohistochemistry. Both mRNA and protein levels of galectin-3 in the NSCLC cell lines A549 and LK-2 were upregulated by hypoxia. As revealed by scratch and invasion assays, the cell migratory and invasive activities were significantly increased under hypoxia, but were reduced by galectin-3 knockdown. Notably, addition of galectin-3 to the media did not improve the cell motility impaired by galectin-3 knockdown. To clarify the role of endogenous galectin-3 in the enhancement of tumor cell motility under hypoxia, we focused on the function of RhoA. RhoA level in the plasma membrane, but not in the cytoplasm, was increased under hypoxia and decreased by galectin-3 knockdown. RhoA activity was significantly enhanced under hypoxia and effectively inhibited by galectin-3 knockdown. In patients with pN0M0 invasive pulmonary adenocarcinoma, higher galectin-3 expression on tumor cells was significantly associated with tumor cell invasion into microvessels and tumor recurrence after surgery. These data demonstrate that in NSCLC cells under hypoxia, upregulated galectin-3 levels increase the localization of RhoA to the plasma membrane, thus enhancing RhoA activity, which is associated with aggressive cell motility. In pN0M0 invasive pulmonary adenocarcinoma, galectin-3 is a potential biomarker for predicting tumor recurrence after radical surgery.