Twist2 contributes to cisplatin-resistance of ovarian cancer through the AKT/GSK-3β signaling pathway

Investigation of role of CpG methylation in some epithelial mesenchymal transition gene in a chemoresistant ovarian cancer cell line

Ovarian cancer is one of the lethal gynecologic cancers. Chemoresistance is an essential reason for treatment failure and high mortality. Emerging evidence connects epithelial-mesenchymal transition (EMT) like changes and acquisition of chemoresistance in cancers. Including EMT, DNA methylation influences cellular processes. Here, EMT-like changes were investigated in cisplatin-resistant A2780 ovarian cancer cells (A2780cis), wherein role of DNA methylation in some EMT genes regulations was studied. Cell viability assay was carried out to test the sensitivity of A2780, and A2780cis human cancer cell lines to cisplatin. Differential mRNA expression of EMT markers using qPCR was conducted to investigate EMT like changes. CpG methylation role in gene expression regulation was investigated by 5-azacytidine (5-aza) treatment. DNA methylation changes in EMT genes were identified using Methylscreen assay between A2780 and A2780cis cells. In order to evaluate if DNA methylation changes are causally underlying EMT, treatment with 5-aza followed by Cisplatin was done on A2780cis cells. Accordingly, morphological changes were studied under the microscope, whereas EMT marker's gene expression changes were investigated using qPCR. In this respect, A2780cis cell line has maintained its cisplatin tolerance ability and exhibits phenotypic changes congruent with EMT. Methylscreen assay and qPCR study have revealed DNA hypermethylation in promoters of epithelial adhesion molecules CDH1 and EPCAM in A2780cis compared to the cisplatin-sensitive parental cells. These changes were concomitant with gene expression down-regulation. DNA hypomethylation associated with transcription up-regulation of the mesenchymal marker TWIST2 was observed in the resistant cells. Azacytidine treatment confirmed DNA methylation role in regulating gene expression of CDH1, EPCAM and TWIST2 genes. A2780cis cell line undergoes EMT like changes, and EMT genes are regulated by DNA methylation. To that end, a better understanding of the molecular alterations that correlate with chemoresistance may lead to therapeutic benefits such as chemosensitivity restoration.

The Post-Translational Regulation of Epithelial-Mesenchymal Transition-Inducing Transcription Factors in Cancer Metastasis

Epithelial-mesenchymal transition (EMT) is generally observed in normal embryogenesis and wound healing. However, this process can occur in cancer cells and lead to metastasis. The contribution of EMT in both development and pathology has been studied widely. This transition requires the up- and down-regulation of specific proteins, both of which are regulated by EMT-inducing transcription factors (EMT-TFs), mainly represented by the families of Snail, Twist, and ZEB proteins. This review highlights the roles of key EMT-TFs and their post-translational regulation in cancer metastasis.

Epithelial-mesenchymal transition as a mechanism of resistance to tyrosine kinase inhibitors in clear cell renal cell carcinoma

Tyrosine kinase inhibitors (TKIs) are widely accepted as treatment for metastatic clear cell renal cell carcinoma (ccRCC). However, most patients eventually experience disease progression despite TKI treatment, even if the initial response is favorable. To define the underlying mechanism of TKI resistance, 10 TKI-treated metastatic ccRCC cases in which tumor samples were harvested before treatment and immediately after disease progression were examined. Gene expression profiles and copy number variations of matched pre- and post-treatment tumor samples were investigated. Altered biologic characteristics were confirmed in sunitinib-resistant ccRCC cell lines, which were generated by long-term treatment with sunitinib-containing media. Gene transcript levels related to the cell cycle and epithelial-mesenchymal transition (EMT) were significantly upregulated in the treated tumor samples compared with the pre-treatment samples. The mitotic count and sarcomatoid component were significantly increased in treated tumor samples. Alteration of EMT-related genes was also demonstrated in a sunitinib-resistant ccRCC cell line that showed enhanced migration and invasion compared to the parent cell line. siRNA-induced inhibition of EMT-related gene expression significantly suppressed the migration and invasion capacity of TKI-resistant cell lines. The present study shows that both ccRCC cases that progressed after TKI treatment and sunitinib-resistant ccRCC cell lines demonstrated alteration of EMT-related gene expression and enhancement of EMT-related behavior. These results suggest that EMT may explain the aggressive behavior of TKI-resistant ccRCC.

Role of epithelial–mesenchymal transition regulated by twist basic helix-loop-helix transcription factor 2 (Twist2) in embryo implantation in mice

In a previous study we found the expression of epithelial–mesenchymal transition (EMT) biomarkers, including E-cadherin and N-cadherin, was significantly altered in uterine endometrium during embryo implantation via regulation by microRNA (miRNA)-429 and protocadherin-8 (Pcdh8). As a natural continuation of the previous study, the aim of the present study was to explore the role of EMT during embryo implantation and the potential activity of twist basic helix-loop-helix transcription factor 2 (Twist2) in regulating embryo implantation. A pregnancy model was established by naturally mating adult female ICR mice with fertile males. A pseudopregnancy model was established by mating fertile female ICR mice with vasectomised males. An invitro model of embryo implantation was established by the coculture of Ishikawa and JAR spheroids. Endometrial tissue during the peri-implantation period was collected, as were Ishikawa cells, JAR cells and cocultured cells. The expression of EMT markers (E-cadherin, N-cadherin, vimentin and cytokeratin) and Twist2 was detected invivo and invitro using the western blot analysis during embryo implantation. The expression of N-cadherin and vimentin (mesenchymal markers) was upregulated in the invitro implantation model, with downregulation of E-cadherin and cytokeratin (epithelial markers) expression. The expression of N-cadherin, vimentin and Twist2 increased significantly at the implantation sites at the time of implantation (Day 5), whereas the expression of E-cadherin and cytokeratin decreased. Location of Twist2 during embryo implantation was detected by immunohistochemistry (IHC), which revealed that it was extensively expressed in endometrial glandular epithelium and luminal epithelium at implantation sites on Day 5. The effect of the expression of Twist2 on embryo implantation was evaluated by suppressing Twist2 using Twist2-short interference (si) RNA in invivo and invitro models. The numbers of implanted embryos and the implantation rate were compared invivo and invitro. Western blot analysis showed that suppression of Twist2 led to upregulation of E-cadherin and cytokeratin, accompanied by downregulation of N-cadherin and vimentin (P<0.05). The number of implanted embryos after Twist2-siRNA interference was lower than in normal pregnancy (mean (±s.d.) 2.4±0.5 vs 6.8±1.3 respectively; P<0.05). These findings suggest the involvement of EMT in embryo implantation. The suppression of Twist2 could suppress embryo implantation by regulating EMT.

Epithelial-mesenchymal-transition-inducing transcription factors: new targets for tackling chemoresistance in cancer?

Chemoresistance remains a major complication of cancer treatments. Recent data provide strong evidence that chemoresistance is linked to epithelial-mesenchymal transition (EMT), a latent developmental process, which is re-activated during cancer progression. EMT involves transcriptional reprogramming and is driven by specific EMT transcription factors (EMT-TFs). In this review, we provide support for the idea that EMT-TFs contribute to the development of resistance against cancer therapy and discuss how EMT-TFs might be targeted to advance novel therapeutic approaches to the treatment of cancer.

Knockout of the placenta specific 8 gene radiosensitizes nasopharyngeal carcinoma cells by activating the PI3K/AKT/GSK3β pathway

The present study investigated the radiosensitizing effect of placenta specific 8 (PLAC8) in nasopharyngeal carcinoma (NPC) cells. A PLAC8-knockout CNE2 cell line was constructed using the CRISPR/Cas9 system. The CCK-8 assay demonstrated knockout of PLAC8 significantly reduced cell proliferation and cell survival after irradiation compared to both control cells and non-irradiated PLAC8-knockout cells. The clonogenic assay showed knockout of PLAC8 enhanced the radiosensitivity of NPC cells. Flow cytometry revealed knockout of PLAC8 increased apoptosis and G2/M phase arrest after irradiation. Western blotting demonstrated knockout of PLAC8 was associated with increased levels of γHA2X, a higher BAX:BCL-2 ratio, and increased levels of phosphorylated-Akt and phosphorylated-GSK-3β. Overall, this study indicates PLAC8 contributes to radioresistance in NPC by inhibiting the PI3K/AKT/GSK3β pathway.

14, 15-EET induces breast cancer cell EMT and cisplatin resistance by up-regulating integrin αvβ3 and activating FAK/PI3K/AKT signaling

Background

14,15-epoxyeicosatrienoic acid (14,15-EET) is an important lipid signaling molecule involved in the regulation of tumor metastasis, however, the role and molecular mechanisms of 14,15-EET activity in breast cancer cell epithelial-mesenchymal transition (EMT) and drug resistance remain enigmatic.

Methods

The 14, 15-EET level in serum and in tumor or non-cancerous tissue from breast cancer patients was measured by ELISA. qRT-PCR and western blot analyses were used to examine expression of integrin αvβ3. The role of 14, 15-EET in breast cancer cell adhesion, invasion was explored by adhesion and Transwell assays. The role of 14, 15-EET in breast cancer cell cisplatin resistance in vitro was determined by MTT assay. Western blot was conducted to detect the protein expressions of EMT-related markers and FAK/PI3K/AKT signaling. Xenograft models in nude mice were established to explore the roles of 14, 15-EET in breast cancer cells EMT and cisplatin resistance in vivo.

Results

In the present study, we show that serum level of 14, 15-EET increases in breast cancer patients and 14, 15-EET level of tumor tissue is higher than that of non-cancerous tissue. Moreover, 14, 15-EET increases integrin αvβ3 expression, leading to FAK activation. 14, 15-EET induces breast cancer cell EMT via integrin αvβ3 and FAK/PI3K/AKT cascade activation in vitro. Furthermore, we find that 14, 15-EET induces breast cancer cells EMT and cisplatin resistance in vivo, αvβ3 integrin and the resulting FAK/PI3K/AKT signaling pathway are responsible for 14, 15-EET induced-breast cancer cells cisplatin resistance.

Conclusions

Our findings suggest that inhibition of 14, 15-EET or inactivation of integrin αvβ3/FAK/PI3K/AKT pathway could serve as a novel approach to reverse EMT and cisplatin resistance in breast cancer cells.

TWIST1 drives cisplatin resistance and cell survival in an ovarian cancer model, via upregulation of GAS6, L1CAM, and Akt signalling

Epithelial ovarian cancer (EOC) is the most deadly gynaecologic malignancy due to late onset of symptoms and propensity towards drug resistance. Epithelial-mesenchymal transition (EMT) has been linked to the development of chemoresistance in other cancers, yet little is known regarding its role in EOC. In this study, we sought to determine the role of the transcription factor TWIST1, a master regulator of EMT, on cisplatin resistance in an EOC model. We created two Ovcar8-derived cell lines that differed only in their TWIST1 expression. TWIST1 expression led to increased tumour engraftment in mice, as well as cisplatin resistance in vitro. RNA sequencing analysis revealed that TWIST1 expression resulted in upregulation of GAS6 and L1CAM and downregulation of HMGA2. Knockdown studies of these genes demonstrated that loss of GAS6 or L1CAM sensitized cells to cisplatin, but that loss of HMGA2 did not give rise to chemoresistance. TWIST1, in part via GAS6 and L1CAM, led to higher expression and activation of Akt upon cisplatin treatment, and inhibition of Akt activation sensitized cells to cisplatin. These results suggest TWIST1- and EMT-driven increase in Akt activation, and thus tumour cell proliferation, as a potential mechanism of drug resistance in EOC.

Expression profile of Twist, vascular endothelial growth factor and CD34 in patients with different phases of osteosarcoma

The aim of the present study was to investigate the clinical significance of Twist, vascular endothelial growth factor (VEGF) and CD34 expression in osteosarcoma (OS) in order to elucidate potential therapeutic targets for the treatment of OS. Immunohistochemistry was performed to detect the protein expression of Twist, VEGF and CD34 in OS and osteochondroma (OC) tissues. The ratio of the protein expression of Twist and VEGF in OS and OC tissues as well as at different phases of OS was compared using chi-squared tests. Microvessel density (MVD), as determined by CD34 labeling, in OS and OC tissue as well as at different phases of OS was compared using the Student's t-test. In addition, associations between Twist, VEGF and MVD were assessed using the Spearman's rank correlation test. The results revealed that out of the 32 OS tissues examined, 56.25% exhibited Twist positive expression, 71.88% exhibited VEGF positive expression and the MVD was increased compared with that of the OC tissue. The positive rate of Twist and VEGF expression in phase III OS tissues was significantly increased compared with that in phase I/II OS tissues (Twist: χ²=5.732, P=0.018; VEGF: χ²=7.513, P=0.006). The MVD in phase III OS tissues (31.08±3.36 per field) was significantly higher compared with that of the phase I/II OS tissues (41.2±4.17 per field; t=7.536, P<0.001). Spearman's rank correlation analysis revealed that Twist expression was positively associated with VEGF expression (r=0.371, P=0.002) and with MVD (r=0.393, P=0.001) in OS; in addition, VEGF expression was found to have a positive correlation with MVD (r=0.469, P=0.001). In conclusion, the results of the present study demonstrated that OS tissues exhibited elevated Twist and VEGF expression as well as MVD compared with OC tissue. In addition, metastatic OS (phase III) exhibited an increased positive rate of Twist and VEGF expression as well as MVD values compared with non-metastatic OS (phase I/II). Furthermore associations were detected between Twist and VEGF expression as well as VEGF and MVD. Therefore, inhibition of Twist expression may have potential therapeutic use for the treatment of OS.

Interference with the expression of β-catenin reverses cisplatin resistance in A2780/DDP cells and inhibits the progression of ovarian cancer in mouse model

Cisplatin is a most active drug for the treatment of ovarian cancer; however, acquired cisplatin resistance is easily seen in patients with ovarian cancer. The aim of this study is to clarify the molecular mechanism of cisplatin resistance and try to reverse cisplatin resistance in ovarian cancer lines in vitro and in vivo. First, we used ovarian cancer cell line A2780, and its cisplatin-resistant subline, A2780/DDP as cell model. Cell viability was determined by MTT assay and the IC50 values were observed to increase in a dose- and time-dependent manner. Next, the expression of β-catenin was determined by western blotting analysis, and the results demonstrated that the expression level of β-catenin in A2780/DDP cells was significantly higher than that in A2780 cells (p<0.01). Moreover, we detected the distribution of cytoplasmic and nuclear β-catenin by western blot analysis, which showed that β-catenin was mainly located in nucleus. Compared with A2780 cells, there was no obvious change as the increasing dose of cisplatin in A2780/DDP cells reveal that cisplatin resistance was related to the exrpession of β-catenin. Furthermore, interference with the expression of β-catenin could effectively reverse cisplatin resistance as IC50 was significantly decreased from 123.7 to 42.43 μM in A2780/DDP cells. Additionally, transient interference of β-catenin by siRNA promoted the apoptosis of A2780/DDP cells, for increased apoptosis rates and cleaved caspase-3 levels were detected being treated with cisplatin. Finally, tumorigenicity experiments showed that tumor growth was significantly suppressed in β-catenin shRNA group. The body weight was not significantly changed during the experimental days. In conclusion, all the results showed that cisplatin resistance was partly induced by Wnt/β-catenin signaling pathway. Interfering the expression of β-catenin could reverse cisplatin resistance in vitro and in vivo. Thus, β-catenin could be a potential therapeutic target for the therapy of cisplatin-resistant ovarian cancer.

Acquisition of epithelial-mesenchymal transition and cancer stem-like phenotypes within chitosan-hyaluronan membrane-derived 3D tumor spheroids

Cancer drug development has to go through rigorous testing and evaluation processes during pre-clinical in vitro studies. However, the conventional two-dimensional (2D) in vitro culture is often discounted by the insufficiency to present a more typical tumor microenvironment. The multicellular tumor spheroids have been a valuable model to provide more comprehensive assessment of tumor in response to therapeutic strategies. Here, we applied chitosan-hyaluronan (HA) membranes as a platform to promote three-dimensional (3D) tumor spheroid formation. The biological features of tumor spheroids of human non-small cell lung cancer (NSCLC) cells on chitosan-HA membranes were compared to those of 2D cultured cells in vitro. The cells in tumor spheroids cultured on chitosan-HA membranes showed higher levels of stem-like properties and epithelial-mesenchymal transition (EMT) markers, such as NANOG, SOX2, CD44, CD133, N-cadherin, and vimentin, than 2D cultured cells. Moreover, they exhibited enhanced invasive activities and multidrug resistance by the upregulation of MMP2, MMP9, BCRC5, BCL2, MDR1, and ABCG2 as compared with 2D cultured cells. The grafting densities of HA affected the tumor sphere size and mRNA levels of genes on the substrates. These evidences suggest that chitosan-HA membranes may offer a simple and valuable biomaterial platform for rapid generation of tumor spheroids in vitro as well as for further applications in cancer stem cell research and cancer drug screening.