Knockdown of PKM2 enhances radiosensitivity of cervical cancer cells

Abstract

Background: Pyruvate kinase isozyme type M2 (PKM2) catalyzes the final step in glycolysis and has been found to be up-regulated in multiple human malignancies. However, whether PKM2 regulates the radiosensitivity of human cervical cancer (CC) remains unknown. Methods: The expression of PKM2 in 94 patients with CC in the complete response (CR) and noncomplete response (nCR) groups, was evaluated by immunohistochemistry. The effect of PKM2 inhibition on radiosensitivity, the cell cycle, DNA damage, and apoptosis was evaluated by immunofluorescence analysis, colony formation assay, flow cytometry analysis and Western blotting. Results: PKM2 expression was more highly expressed in the nCR group than that in CR group and PKM2 expression was enhanced in CC cells after ionizing radiation (IR). In addition, knockdown of PKM2 combined with IR significantly reduced cell growth, promoted apoptosis, and enhanced radiosensitivity. Additionally, knockdown of PKM2 with IR resulted in increased phosphorylation of DNA repair checkpoint proteins (ATM) and phosphorylated-H2AX. Moreover, knockdown of PKM2 combined with IR significantly increased the expression of cleaved caspase 3 and caspase 9, whereas Bcl2 expression was suppressed. Furthermore, knockdown of PKM2 combined with IR markedly reduced the expression of several cancer stem cell biomarkers in vitro, including NANOG, OCT4, SOX2, and Bmi1. Conclusions: The results of our study suggests that PKM2 might be involved in mediating CC radiosensitivity and is identified as a potentially important target to enhance radiosensitivity in patients with CC.

Glycolysis-induced drug resistance in tumors—A response to danger signals?

“…As regards glucose transporters, glucose transporter (GLUT) 1, GLUT3, GLUT4, and GLUT5 have been reported to induce antitumor drug resistance [39] , [40] , [41] , [42] , [43] . As to glycolytic enzymes, hexokinase (HK) [23 , [44] , [45] , [46] , 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB) [34 , [47] , [48] , [49] , [50] , fructose biphosphate aldolase (ALDO) [51 , 52] , glyceraldehyde 3-phosphate dehydrogenase (GAPDH) [1 , 37] , phosphoglycerate kinase (PGK) [53 , 54] , enolase (ENO) [1 , 20 , [55] , [56] , [57] , pyruvate kinase (PK) [4 , 15 , [58] , [59] , [60] , [61] , [62] , and lactate dehydrogenase (LDH) [1 , 22 , 27 , 29 , 31 , [63] , [64] , [65] , [66] , [67] , have all been shown being involved in the induction of antitumor drug resistance.…”

“…2 ). As regards stimuli deriving from the TME, one class is represented by antitumor drugs such as chemotherapeutics [18 , 49 , 73 , 91] , TKIs [47 , 82 , 92] , or ionizing radiation [59] . In other words, the same drugs that induce tumor cell glycolysis are also victims of glycolysis-induced drug resistance.…”

<p>Antitumor Effect of miR-1294/Pyruvate Kinase M2 Signaling Cascade in Osteosarcoma Cells</p>

“…12 Our data showed that PKM2 upregulation only partly reversed the effect of miR-1294 on DDPtreated cells, indicating that other targets of miR-1294, apart from PKM2 may contribute to miR-1294-mediated anti-tumor activity, such as IGF1R. Previous studies showed that silencing of PKM2 enhanced radiosensitivity of cervical cancer and non-small cell lung cancer, 28,39 suggesting that miR-1294/PKM2 axis may play a role in radiosensitivity of osteosarcoma.…”

Long non‑coding RNA RP11‑480I12.5 promotes cervical carcinoma progression by regulating the Wnt/β‑catenin signaling pathway

“…All experiments were performed in triplicate. The 2 -ΔΔCq method was used to calculate relative RNA expression (15)(16)(17).…”