The PIK3CA E542K and E545K mutations promote glycolysis and proliferation via induction of the β-catenin/SIRT3 signaling pathway in cervical cancer

Abstract

BackgroundThe study aims to present the effect of PIK3CA E542K and E545K mutations on glucose metabolism and proliferation and identify their underlying mechanisms in cervical cancer.MethodsThe maximum standard uptake value (SUVmax) of tumors was detected by18F-FDG PET/CT scan. In vitro, glycolysis analysis, extracellular acidification rate analysis, and ATP production were used to evaluate the impact of PIK3CA E542K and E545K mutations on glucose metabolism. The expression level of key glycolytic enzymes was evaluated by western blotting and immunohistochemical staining in cervical cancer cells and tumor tissues, respectively. Immunofluorescence analysis was used to observe the nuclear translocation of β-catenin. The target gene of β-catenin was analyzed by using luciferase reporter system. The glucose metabolic ability of the xenograft models was assessed by SUVmax from microPET/CT scanning.ResultsCervical cancer patients with mutant PIK3CA (E542K and E545K) exhibited a higher SUVmax value than those with wild-type PIK3CA (P = 0.037), which was confirmed in xenograft models. In vitro, enhanced glucose metabolism and proliferation was observed in SiHa and MS751 cells with mutant PIK3CA. The mRNA and protein expression of key glycolytic enzymes was increased. AKT/GSK3β/β-catenin signaling was highly activated in SiHa and MS751 cells with mutant PIK3CA. Knocking down β-catenin expression decreased glucose uptake and lactate production. In addition, the nuclear accumulation of β-catenin was found in SiHa cells and tumors with mutant PIK3CA. Furthermore, β-catenin downregulated the expression of SIRT3 via suppressing the activity of the SIRT3 promotor, and the reduced glucose uptake and lactate production due to the downregulation of β-catenin can be reversed by the transfection of SIRT3 siRNA in SiHa cells with mutant PIK3CA. The negative correlation between β-catenin and SIRT3 was further confirmed in cervical cancer tissues.ConclusionsThese findings provide evidence that the PI3K E542K and E545K/β-catenin/SIRT3 signaling axis regulates glucose metabolism and proliferation in cervical cancers with PIK3CA mutations, suggesting therapeutic targets in the treatment of cervical cancers.Trial registrationFUSCC 050432–4-1212B. Registered 24 December 2012 (retrospectively registered).Electronic supplementary materialThe online version of this article (10.1186/s13045-018-0674-5) contains supplementary material, which is available to authorized users.

Targeting PI3K in cancer: mechanisms and advances in clinical trials

“…PIK3CA (phosphatidylinositol 3-kinase, catalytic, α-polypeptide), the gene encoding the p110α subunit, are frequently mutated or amplified in the most common human cancers, such as breast cancers, colon cancer, gastric cancer, cervical cancer, prostate cancer, and lung cancer [26][27][28][29][30][31]. Most mutations cluster around two hotspots: E545K (exon 9) in the helical phosphatidylinositol kinase homology domain, which reduces inhibition of p110α by the regulatory subunit p85; H1047 (exon 20) near the end of the catalytic domain, which increases interaction of p110α with lipid membranes [32,33]. E542K is also one of the most frequently observed PIK3CA mutations [33,34].…”

“…Most mutations cluster around two hotspots: E545K (exon 9) in the helical phosphatidylinositol kinase homology domain, which reduces inhibition of p110α by the regulatory subunit p85; H1047 (exon 20) near the end of the catalytic domain, which increases interaction of p110α with lipid membranes [32,33]. E542K is also one of the most frequently observed PIK3CA mutations [33,34]. In colorectal cancer, exon 9 plays a more important role than exon 20, whereas in endometrial cancer, the opposite pattern was described, suggesting that different mutations of PIK3CA may have specific effects on downstream carcinogenic signals [35].…”

Role of PI3K/AKT pathway in cancer: the framework of malignant behavior

“…Considerable overall genetic alterations of PI3K/AKT pathway in CC have emerged with PIK3CA (39%) and PTEN (13%, Table 1). In particular, the mutations of PIK3CA E542K and E545K promote glycolysis and proliferation of CC in vitro and vivo [212]. NBPF1, ARHGAP17, miR-99b, -181a2/181b2, -338, -383, -433 and -489, as well as LncRNA ANRIL, CRNDE, NEAT1 and LINC01305 are involved in the proliferation, invasion, autophagy or EMT via PI3K/AKT pathway [213][214][215][216][217][218][219][220][221][222][223][224].…”

Targeting of β-Catenin Reverses Radioresistance of Cervical Cancer with the PIK3CA-E545K Mutation

“…Western blotting was used to determine the expression level of proteins in cells. The operation of Western blotting was performed as described previously (22)…”

“…In our previous work, it was demonstrated that PIK3CA was the gene with the highest mutation rate among the 16 targetable oncogenes in cervical cancer, and the mutation rate was 13.6% reported in the study of 771 cervical cancer specimens (20,21). E545K is the most common hotspot mutation of PIK3CA in cervical cancer with the mutation rate accounted for 58% in all variations of PIK3CA (22). The present study concentrates on investigating whether the PIK3CA-E545K mutation leads to irradiation resistance in cervical cancer and on further exploring the potential mechanism, which is of significance in that it can supply the experimental basis for clinical trials designed for improvement of radiosensitivity in cervical cancer.…”