Elevated level of neuroserpin is an indication for the resistance to gambogic acid-induced apoptosis and oxidative stress in triple-negative breast cancer cells.

Background: The triple-negative breast cancer (TNBC) subtype, characterized by loss of HER2, estrogen, and progesterone receptors, displays aggressive phenotype and poor prognosis compared to other BC subtypes. Since the TNBC cells are devoid of receptors, endocrine therapy is an ineffective option for TNBC patients, necessitating canonical chemotherapy strategies to treat TNBC. It is crucial to use alternative and natural agents to support chemotherapy in TNBC. Objectives: To clarify the molecular mechanism of the tumorigenic effects of gambogic acid (GA) on TNBC cells with different epithelial character since GA has a wide spectrum of anticancer activity for most cancer types. Methods: We determined the cytotoxic dose of GA incubation of TNBC cells (MDA-MB-231 and BT-20 cells) for 24 h. We performed the MTT test and toluidine blue (TB) staining protocol for TNBC cells. We analyzed E-cadherin, N-cadherin, Bax, and neuroserpin mRNAs in both cells by qPCR. We evaluated apoptosis using DAPI staining and assessed the ROS using the 2',7'-dichlorofluorescin diacetate (DCFH-DA) method. Results: We determined the IC50 concentrations of GA in MDA-MB-231 and BT-20 cells to be 315.8 nM and 441.8 nM, respectively. TB staining showed that BT-20 cells survive at excessive cytotoxic doses of GA, while most of the MDA-MB-231 cells were killed. Also, we found that BT-20 cells are more resistant to GA-induced apoptosis and oxidative stress than the MDA-MB-231 cells. qPCR results showed that GA upregulated neuroserpin, an oxidative stress-relieving factor in the BT-20 cells, but not in the MDA-MB-231 cells. Conclusions: The elevated level of neuroserpin could be a predictive marker to determine the development of resistance to chemotherapeutic agents.

The dicyano compound induces autophagic or apoptotic cell death via Twist/c-Myc axis depending on metastatic characteristics of breast cancer cells.

BACKGROUND: Breast cancer (BC) is a heterogeneous disease with various subtypes, therefore, the illumination of distinctive mechanisms between subtypes for the development of novel treatment strategies is important. Here, we revealed the antiproliferative effects of our customized dicyano compound (DC) on BC cells. METHODS AND RESULTS: We determined the antiproliferative effect of the DC on non-metastatic MCF-7 and metastatic MDA-MB-231 cell lines by MTT. We evaluated protein levels of LC3BI-II and p62 to detect effects of the DC on autophagy. Furthermore, we examined whether the DC induce apoptosis in MCF-7 and MDA-MB-231 cells by performing TUNEL and western blotting. We showed that the DC induces autophagic cell death in MDA-MB-231 while it leads to apoptosis in MCF-7, demonstrating that DC can induce different cell death mechanisms in BC cells according to what they represent subtypes. To understand the reason of different cell response to the DC, we evaluated the expressions of several regulator proteins involved in survival, cell arrest and proliferation. All findings revealed that c-Myc expression is directly correlated with autophagy induction in BC cells and it could be a marker for the selection of cell death mechanism against anti-cancer drugs. Interestingly, we showed that the overexpression of Twist, responsible for metastatic features of BC cells, imitates the effects of autophagy on c-Myc expression in MCF-7 cells, indicating that it is implicated in both the regulation of c-Myc as a upstream factor and subsequently the selection of cell death mechanisms. CONCLUSION: Taken together, we suggest that Twist/c-Myc axis may have a role in different response to the DC-induced cell death pathways in BC subtypes with different invasive characteristics.

NF-κB-Induced Upregulation of miR-548as-3p Increases Invasion of NSCLC by Targeting PTEN.

BACKGROUND: Non-Small Cell Lung Cancer (NSCLC) is an aggressive cancer type due to high metastatic capacity. Nuclear Factor Kappa B (NF-κB) is a consistently active transcription factor in malignant lung cancer cells and has crucial significance in NSCLC progression. It is also implicated in the transcriptional regulation of many genes including microRNAs (miRNAs) that function as tumor suppressor or oncogene. It has been increasingly reported that several miRNAs defined as gene members are induced by NF-κB. The present study aimed to find novel miRNAs that are regulated by NF-κB. METHODS: Chromatin Immunoprecipitation Sequencing (ChIP-Seq) experiment and bioinformatic analysis were used to determine NF-κB-dependent miRNAs. Western blot analysis, quantitative real-time polymerase chain reaction (qRT-PCR), luciferase reporter gene assays were carried out to investigate the target genes of miRNAs. To determine biologic activity, transwell invasion and MTT assay were carried out on H1299 NSCLC cell line. miRNA expression level was evaluated in metastatic and non-metastatic tissue samples of NSCLC patients. RESULTS: ChIP-Seq and qRT-PCR experiments showed that miR-548as-3p is transcriptionally regulated by NF- κB in response to Tumor Necrosis Factor-α (TNF-α) treatment. Then, we found that tumor suppressor Phosphatase and Tension homolog (PTEN) is a direct target of miR-548as-3p. Furthermore, miR-548as-3p mediates phosphatidylinositol-3-OH kinase (PI3K)/Akt pathway and NF-κB-implicated genes including Matrix Metalloproteinases 9 (MMP9), Slug and Zeb1. We further showed that miR-548as-3p increased invasiveness of NSCLC cells and was upregulated in metastatic tumor tissues compared to non-metastatic ones. CONCLUSION: All these findings provide a miRNAs-mediated novel mechanism for NF-κB signaling and that miR-548as-3p could be a biomarker for NSCLC metastasis.

TGF-ß-SMAD-miR-520e axis regulates NSCLC metastasis through a TGFBR2-mediated negative-feedback loop.

Transforming growth factor-ß (TGF-ß) pathway plays crucial roles during the carcinogenesis and metastasis. TGF-ß receptor 2 (TGFBR2) is a key molecule for the regulation of TGF-ß pathway and frequently downregulated or lost in several cancer types including non-small cell lung cancer (NSCLC), and TGF-ß pathway is often regulated by negative-feedback mechanisms, but little is known about the mechanism of TGFBR2 downregulation in NSCLC. Here, we found that the expression of miR-520e is upregulated in metastatic tumor tissues compared with non-metastatic ones, and its expression is inversely correlated with that of TGFBR2 in clinical samples. We also discovered that TGF-ß dramatically increased the expression of miR-520e, which targeted and downregulated TGFBR2, and the suppression of miR-520e significantly impaired TGF-ß-induced TGFBR2 downregulation. Chromatin immunoprecipitation-PCR experiments further showed that miR-520e is transcriptionally induced by SMAD2/3 in response to TGF-ß. Our findings reveal a novel negative-feedback mechanism in TGF-ß signaling and the expression level of miR-520e could be a predictive biomarker for NSCLC metastasis.

The crosstalk between p38 and Akt signaling pathways orchestrates EMT by regulating SATB2 expression in NSCLC cells.

Epithelial-mesenchymal transition is a crucial event for metastasis and could be mediated by several pathways such as phosphoinositide 3-kinase/Akt, mitogen-activated protein kinases, as well as many epigenetic regulators. Special AT-rich sequence-binding protein 2 is an epigenetic regulator involved in epithelial-mesenchymal transition and osteoblastic differentiation. It has been reported that the crosstalk between several pathways is responsible for the regulation of epithelial-mesenchymal transition in cancer cells. However, crosstalks between p38 and Akt pathways involved in epithelial-mesenchymal transition are still unknown. We recently reported that there is a crosstalk between p38 and Akt pathways in non-small-cell lung carcinoma cells, and this crosstalk is associated with E-cadherin and special AT-rich sequence-binding protein 2 expressions. Therefore, we aimed to determine whether this crosstalk has a mediator role in the regulation of epithelial-mesenchymal transition in non-small-cell lung carcinoma. Our results showed that inhibition of p38 leads to the disruption of this crosstalk via decreased expression of phosphatase and tensin homolog (PTEN) and subsequently increased activation of Akt in non-small-cell lung carcinoma cells. Then, we found that p38 inhibition upregulated special AT-rich sequence-binding protein 2 expression and reversed epithelial-mesenchymal transition in non-small-cell lung carcinoma cells. Furthermore, special AT-rich sequence-binding protein 2 knockdown abolished the effect of p38 inhibition on epithelial-mesenchymal transition in non-small-cell lung carcinoma cells. In conclusion, our results strongly indicate that the crosstalk between p38 and Akt pathways can determine special AT-rich sequence-binding protein 2 expression and epithelial character of non-small-cell lung carcinoma cells, and special AT-rich sequence-binding protein 2 is a critical epigenetic regulator for epithelial-mesenchymal transition mediated by p38 pathway in non-small-cell lung carcinoma. Our findings will contribute to illuminate the molecular mechanisms of the epithelial-mesenchymal transition process that has a critical significance for lung cancer metastasis.

Downregulation of SATB2 is critical for induction of epithelial-to-mesenchymal transition and invasion of NSCLC cells.

OBJECTIVES: The epithelial-to-mesenchymal transition (EMT) is considered as a key step in invasion of cancer cells. There are several regulator proteins responsible for induction of EMT, but underlying mechanisms are still unclear. SATB2 is an epigenetic regulator involved in osteoblastic differentiation. The role of SATB2 in EMT and invasion of NSCLC cells is unknown. Therefore, we aimed to explain roles of SATB2 with underlying molecular mechanisms in EMT and invasion of NSCLC cells. MATERIALS AND METHODS: We used A549 and NCI-H1650 cells as a model to evaluate the effects of SATB2 in EMT and invasion of NSCLC cells. Cell culture, western blot analysis, siRNA-mediated gene knockdown, and invasion assay were performed in this study. RESULTS AND CONCLUSION: In this study, we investigated the regulatory role of SATB2 expression in TGF-ß-induced EMT and invasion of NSCLC cells, and found that SATB2 is downregulated in A549 cells and TGF-ß can induce EMT in these cells, however, TGF-ß can not induce EMT in SATB2 expressing cells such as H1650, PC3, II-18, Hcc78 and Hcc193. Our results demonstrated that SATB2 knockdown is sufficient to induce generation of fibroblast-like morphology, EMT and invasion of NSCLC cells by upregulating the expressions of Slug, Twist and Zeb1. Moreover, SATB2 knockdown promotes TGF-ß-induced EMT and invasion in NSCLC cells. These results strongly suggest that SATB2 prevents induction of EMT by suppressing expression of EMT-inducing transcription factors in NSCLC cells. Furthermore, SATB2 could inhibit tumour initiation by suppressing stemness marker genes such as CD44, Nanog, Oct-4A and Sox-2. Consequently, our results clearly indicate that SATB2 plays pivotal role in EMT, invasion and stemness of NSCLC cells.