Li Qi, Qin Xiaoling, Kou Xiaotong, Li Jingyu, Li Zhongsha, Chen Chang
The Biotherapy Center, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang 150086, P.R. China.
Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China.
Exp Ther Med. 2022 Apr;23(4):282. doi: 10.3892/etm.2022.11211. Epub 2022 Feb 15.
Cancer cells frequently exhibit an acidic extracellular microenvironment, where inversion of the transmembrane pH gradient is associated with tumor proliferation and metastasis. To elucidate a new therapeutic target against cancer, the current study aimed to determine the mechanism by which the dipeptidyl peptidase-4 inhibitor anagliptin regulates the cellular pH gradient and concomitant extracellular acidosis during cancer progression. A total of 5x10 CT-26 cells (resuspended in phosphate buffer saline) were injected subcutaneously in the right flank of male BALB/c mice (weighing 25-28 g). The tumor samples were harvested, and lactate was detected using a lactate assay kit. Immunohistochemistry was used to detect the Ki67 and PCNA. MTT assay and flow cytometric were used to detect cell viability. Intracellular pH was detected by fluorescence pH indicator. The results revealed that anagliptin effectively reduced tumor growth, but did not affect the body weight of treated mice. Anagliptin reduced the accumulation of lactate in tumor sample. Treatment with anagliptin stimulated the apoptosis of CT-26 cells. And lactate excretion inhibition is accompanied by an increase in extracellular pH (pHe) after treatment with anagliptin. Furthermore, anagliptin induced intracellular acidification and reversed the low pHe gradient via monocarboxylate transporter-4 (MCT-4)-mediated lactate excretion. Additionally, anagliptin reversed the aberrant transmembrane extracellular/intracellular pH gradient by suppressing MCT-4-mediated lactate excretion, while also reducing mitochondrial membrane potential and inducing apoptosis. These data revealed a novel function of anagliptin in regulating lactate excretion from cancer cells, suggesting that anagliptin may be used as a potential treatment for cancer.
癌细胞常常呈现出酸性的细胞外微环境，其中跨膜pH梯度的反转与肿瘤增殖和转移相关。为了阐明一种新的抗癌治疗靶点，本研究旨在确定二肽基肽酶-4抑制剂阿格列汀在癌症进展过程中调节细胞pH梯度和伴随的细胞外酸中毒的机制。将总共5×10个CT-26细胞（重悬于磷酸盐缓冲盐水中）皮下注射到雄性BALB/c小鼠（体重25 - 28克）的右腹侧。收获肿瘤样本，使用乳酸检测试剂盒检测乳酸。免疫组织化学用于检测Ki67和PCNA。MTT法和流式细胞术用于检测细胞活力。通过荧光pH指示剂检测细胞内pH。结果显示，阿格列汀有效抑制肿瘤生长，但不影响治疗小鼠的体重。阿格列汀减少了肿瘤样本中乳酸的积累。阿格列汀治疗刺激了CT-26细胞的凋亡。并且在阿格列汀治疗后，乳酸排泄抑制伴随着细胞外pH（pHe）的升高。此外，阿格列汀通过单羧酸转运蛋白-4（MCT-4）介导的乳酸排泄诱导细胞内酸化并逆转低pHe梯度。此外，阿格列汀通过抑制MCT-4介导的乳酸排泄来逆转异常的跨膜细胞外/细胞内pH梯度，同时还降低线粒体膜电位并诱导凋亡。这些数据揭示了阿格列汀在调节癌细胞乳酸排泄方面的新功能，表明阿格列汀可能用作癌症的潜在治疗药物。
