However, little is known about the therapeutic efficacy of PARP inhibitors in the treatment of cervical cancer, either as a single agent or in combination with MAPK4 knockout

However, little is known about the therapeutic efficacy of PARP inhibitors in the treatment of cervical cancer, either as a single agent or in combination with MAPK4 knockout. survival was analyzed using Kaplan-Mier method. Colony formation, immunofluorescence and western blotting were used to examine the effects of MAPK4 knockout or over-expression on cervical cancer cells after radiation treatment. Drug-sensitivity of cervical cancer cells to PARP1 inhibitors, olaparib or veliparib, was analyzed by CCK-8 cell viability assays, and the 50% inhibitory concentration (IC50) was quantified using GraphPad Prism. The functional effects of MAPK4 knockout on the sensitivity of cervical cancer to radiation treatment and PARP1 inhibitors were further examined using xenograft tumor mouse models in vivo. Results Cervical cancer patients with high MAPK4 mRNA expression have lower survival rate. After radiation treatment, the colony number of MAPK4 knockout cells was markedly reduced, and the markers for DNA double-chain breakage were significantly up-regulated. In addition, MAPK4 knockout reduced protein kinase B (AKT) phosphorylation, whereas its over-expression resulted in opposite effects. In MAPK4 KO cells with irradiation treatment, inhibition of AKT phosphorylation promoted DNA double-chain breakage. Constitutive activation of AKT (CA-AKT) increased the levels of phosphorylated-AKT (p-AKT), and DNA repair-related proteins, phosphorylated-DNA-dependent protein kinase (p-DNA-PK) Smad7 and RAD51 recombinase (RAD51). Furthermore, MAPK4 knockout was found to affect the sensitivity of cervical cancer cells to poly ADP-ribose polymerase 1 (PARP1) inhibitors by activating the phosphorylation of AKT. Moreover, in vivo results demonstrated that MAPK4 knockout enhanced the sensitivity of cervical cancer to radiation and PARP1 inhibitors in mouse xenograft models. Conclusions Collectively, our data suggest that combined application of MAPK4 knockout and PARP1 inhibition can be used as therapeutic strategy in radiation treatment for advanced cervical carcinoma. test for two groups and ANOVA for multiple groups. Variation within each group of data was estimated, and the variance between groups was statistically compared. leaf exudate and radiation induce apoptosis and further GSK3368715 dihydrochloride improve Alkaline phosphatase (ALP) activity compared with treatment with AE or radiation alone [25]. Our data in this study demonstrated that MAPK4 knockout could enhance the sensitivity of cervical cancer cells to radiation treatment both in vitro and in vivo, suggesting that targeting MAPK4 may be a promising radiosensitizer. As an atypical member of the mitogen-activated protein (MAP) kinase family, MAPK4 knockout mice are viable and fertile and exhibit no gross morphological or physiological anomalies. However, MAPK4-deficient mice manifest depression-like behavior in forced-swimming tests, indicating that the MAPK4 has acquired specialized functions through evolutionary diversification [26]. So far, little is known about the physiological function of MAPK4 and its involvement in diseases, including cancer. Although gene expression profiling data provided by The Cancer Genome Atlas (TCGA) show that MAPK4 expression is correlated with the survival rates in patients with lung cancer, bladder cancer and glioma, its functions and mechanism of actions in lung cancer and colon cancer were recently identified GSK3368715 dihydrochloride [13]. Wang et al. demonstrated that over-expression of MAPK4 leads to oncogenic effects, and MAPK4 inhibition suppresses cell proliferation and xenograft tumor growth. Mechanistically, MAPK4 activates the phosphorylation of AKT at threonine 308 and serine 473 [14]. Our data in this study demonstrated that cervical cancer patients with high MAPK4 expression had GSK3368715 dihydrochloride lower survival probability and MAPK4 deletion blocked AKT phosphorylation in cervical cancer cells. AKT phosphorylation has previously been described to cooperate GSK3368715 dihydrochloride with DNA-PKcs and was involved in DNA damage repair. AKT1 is a regulatory component in the homologous recombination repair of DNA-DSB in a Rad51-dependent manner in non-small cell lung cancer cells [27]. Single knockdown of Akt1 and Akt2 leads to a decrease in Rad51 foci formation and significantly reduces Rad51 protein level in colon cancer cells [28]. Moreover, Akt1-T308A/S473A-expressing cells are characterized by increased radiosensitivity compared to Akt1-WT (wild type)-expressing cells in long-term colony formation assays [29]. Dual targeting of mTORC1 and AKT1 inhibits DNA-DSB repair, leading to radiosensitization of solid tumor cells [30]. We found that MAPK4-knockout cervical cancer cells showed lower AKT phosphorylation level, and had heightened sensitivity to radiation treatment and PARP1 inhibitors. In regard to the upstream regulation of MAPK4, two miRNAs have been reported to specifically target.