Changjie Chen

Mitochondrial Dysfunction Promotes Breast Cancer Cell Migration and Invasion through HIF1α Accumulation via Increased Production of Reactive Oxygen Species

Although mitochondrial dysfunction has been observed in various types of human cancer cells, the molecular mechanism underlying mitochondrial dysfunction mediated tumorigenesis remains largely elusive. To further explore the function of mitochondria and their involvement in the pathogenic mechanisms of cancer development, mitochondrial dysfunction clones of breast cancer cells were generated by rotenone treatment, a specific inhibitor of mitochondrial electron transport complex I. These clones were verified by mitochondrial respiratory defect measurement. Moreover, those clones exhibited increased reactive oxygen species (ROS), and showed higher migration and invasive behaviors compared with their parental cells. Furthermore, antioxidant N-acetyl cysteine, PEG-catalase, and mito-TEMPO effectively inhibited cell migration and invasion in these clones. Notably, ROS regulated malignant cellular behavior was in part mediated through upregulation of hypoxia-inducible factor-1 α and vascular endothelial growth factor. Our results suggest that mitochondrial dysfunction promotes cancer cell motility partly through HIF1α accumulation mediated via increased production of reactive oxygen species.

Arsenic trioxide suppresses transcription of hTERT through down-regulation of multiple transcription factors in HL-60 leukemia cells

Acute promyelocytic leukemia (APL) is largely caused by the t(15,17) chromosome translocation, leading to the production of the PML/retinoic acid receptor alpha fusion. All-trans retinoic acid (ATRA) and arsenic trioxide (ATO), as a monotherapy or combination therapy, have been successfully used to treat APL primarily by targeting the degradation of the fusion protein. We previously observed that ATO treatment induced cell death in APL cell line HL-60 accompanied by inhibition of the human telomere reverse transcriptase (hTERT) activity, a critical enzyme responsible for the control of cell replication and transformation in cancer cells. In the present study, we investigated the underlying mechanism by which hTERT activity is inhibited by ATO in HL-60 cells. Our results showed that ATO down-regulated the expression of hTERT at both mRNA and protein levels. Further molecular analysis revealed that the expression of four transcription factors Sp1, c-Myc, NF-κB and USF2, which are located in the proximate promoter region (-1126 to -47) of hTERT, was also suppressed by ATO. Notably, we observed that down-regulation of these four factors by their siRNAs potentiates ATO-induced cell growth inhibition and apoptosis. Therefore, our results provide a novel mechanism of action of ATO for the treatment of APL.

Arsenic Trioxide Targets miR-125b in Glioma Cells

BACKGROUND Arsenic trioxide (As2O3) has been demonstrated to suppress tumorigenesis in human glioma. However, the exact molecular mechanisms by which As2O3 exerts its tumor suppressor functions are elusive. Therefore, it is warranted to explore the underlying mechanism of As2O3-mediated anti-tumor activity in glioma. METHODS To achieve our goal, we used multiple approaches including MTT assay, apoptosis, Real-time RT-PCR, Western blotting, invasion assay, and gene transfection. RESULTS We observed that A22O3 inhibited cell growth and induced apoptosis as well as suppressed migration and invasion in human glioma cells. Moreover, we found that As2O3 down-regulated miR-125b expression and subsequently up-regulated its target gene Bak1 expression. Furthermore, we identified that As2O3 exerts its anti-tumor activity partly through regulation of miR-125b. CONCLUSIONS Our present study suggests that As2O3 could be a potential therapeutic agent for treatment of human glioma.

Proteomic-based Analysis for Identification of Proteins Involved in 5-fluorouracil Resistance in Hepatocellular Carcinoma

BACKGROUND Hepatocellular carcinoma (HCC) has high mortality partly due to acquiring drug resistance during chemotherapy treatment. Therefore, it is necessary to explore the underlying mechanism of drug resistance. METHODS We used 2-DE and MALDI-TOF-MS analysis to explore the possible molecular insight into 5-FU resistance in HCC. The differentially expressed proteins were validated by Western blot analysis. RESULTS We identified 102 unique proteins including p16, maspin, PRDX6, PSMB7, MYL6, PHB, and HSP27 with alteration in SMMC- 7721/5-FU. Furthermore, down-regulation of PRDX6 and PSMB7 enhanced SMMC-7721/5-FU cells to 5-FU sensitivity. CONCLUSIONS Our study suggests that targeting drug resistant genes such as PRDX6 and PSMB7 could be a novel approach to overcome 5-FU resistance in HCC cells.

Anticancer Effects of Resveratrol-Loaded Solid Lipid Nanoparticles on Human Breast Cancer Cells

In this study, resveratrol-loaded solid lipid nanoparticles (Res-SLNs) were successfully designed to treat MDA-MB-231 cells. The Res-SLNs were prepared using emulsification and low-temperature solidification method. The Res-SLNs were spherical, with small size, negative charge, and narrow size distribution. Compared with free resveratrol, the Res-SLNs displayed a superior ability in inhibiting the proliferation of MDA-MB-231 cells. In addition, Res-SLNs exhibited much stronger inhibitory effects on the invasion and migration of MDA-MB-231 cells. Western blot analysis revealed that Res-SLNs could promote the ratio of Bax/Bcl-2 but decreased the expression of cyclinD1 and c-Myc. These results indicate that the Res-SLN may have great potential for breast cancer treatment.

Involvement of miR-451 in resistance to paclitaxel by regulating YWHAZ in breast cancer

MicroRNAs (miRNAs) have been identified as major post-transcriptional regulators of the initiation and progression of human cancers, including breast cancer. However, the detail role of miR-451 has not been fully elucidated in breast cancer. In this study, we aimed to investigate the biological role and molecular mechanisms of miR-451 in drug resistance in breast cancer cell lines and in xenograft model. We show that miR-451 is decreased in human breast cancer specimens and in paclitaxel-resistant (PR) cells. Ectopic expression of miR-451 could inhibit the cell migration and invasion, promoted apoptosis, induced cell-cycle arrest Furthermore, tyrosine3-monooxygenase/tryptophan5-monooxygenase activation protein zeta (YWHAZ) was identified as a direct target of miR-451. Remarkably, the expression of YWHAZ is inversely correlated with the level of miR-451 in human breast cancer samples. Co-treatment with miR-451 mimics and YWHAZ-siRNA significantly enhanced YWHAZ knockdown in both SKBR3/PR and MCF-7/PR cells Moreover, miR-451 markedly inhibited expression of β-catenin via YWHAZ and subsequently inhibited downstream gene cyclin D1, c-Myc expression. The results of xenograft model in vivo showed that intratumor injection of miR-451 agomir induced a tumor-suppressive effect in SKBR3/PR drug-resistant xenograft model. Taken together, our findings suggested that miR-451 might be considered as important and potential target in paclitaxel-resistant breast cancer treatment.

The N-terminal polypeptide derived from viral macrophage inflammatory protein II reverses breast cancer epithelial-to-mesenchymal transition via a PDGFRα-dependent mechanism

NT21MP, a 21-residue peptide derived from the viral macrophage inflammatory protein II, competed effectively with the natural ligand of CXC chemokine receptor 4 (CXCR4), stromal cell-derived factor 1-alpha, to induce apoptosis and inhibit growth in breast cancer. Its role in tumor epithelial-to-mesenchymal transition (EMT) regulation remains unknown. In this study, we evaluated the reversal of EMT upon NT21MP treatment and examined its role in the inhibition of EMT in breast cancer. The parental cells of breast cancer (SKBR-3 and MCF-7) and paclitaxel-resistant (SKBR-3 PR and MCF-7 PR) cells were studied in vitro and in combined immunodeficient mice. The mice injected with SKBR-3 PR cells were treated with NT21MP through the tail vein or intraperitoneally with paclitaxel or saline. Sections from tumors were evaluated for tumor weight and EMT markers based on Western blot. In vitro, the effects of NT21MP, CXCR4 and PDGFRα on tumor EMT were assessed by relative quantitative real-time reverse transcription–polymerase chain reaction, western blot and biological activity in breast cancer cell lines expressing high or low levels of CXCR4. Our results illustrated that NT21MP could reverse the phenotype of EMT in paclitaxel-resistant cells. Furthermore, we found that NT21MP governed PR-mediated EMT partly due to controlling platelet-derived growth factors A and B (PDGFA and PDGFB) and their receptor (PDGFRα). More importantly, NT21MP down-regulated AKT and ERK1/2 activity, which were activated by PDGFRα, and eventually reversed the EMT. Together, these results indicated that CXCR4 overexpression drives acquired paclitaxel resistance, partly by activating the PDGFA and PDGFB/PDGFRα autocrine signaling loops that activate AKT and ERK1/2. Inhibition of the oncogenic EMT process by targeting CXCR4/PDGFRα-mediated pathways using NT21MP may provide a novel therapeutic approach towards breast cancer.

N-terminal polypeptide derived from vMIP-II exerts its antitumor activity by inhibiting the CXCR4 pathway in human glioma

Emerging evidence demonstrates that the stromal derived factor-1 (SDF-1α)/CXCR4 axis is associated with tumor aggressiveness and metastasis, including glioma, the most common brain cancer. In the present study, we demonstrated that a novel designed peptide NT21MP of viral macrophage inflammatory protein II, targeting CXCR4 inhibits SDF-1α-induced activation in glioma. The effects of NT21MP on CXCR4 expression, cell survival and migration were assessed on the human glioma cell line U251 and SHG-44 exposed to SDF-1α, by western blotting, MTT assay, flow cytometry and Transwell migration assay. Our results illustrated that NT21MP inhibited SDF-1α induced proliferation, migration and invasion by upregulated pro-apoptotic genes (Bak1 and caspase-3) and downregulated Bcl-2/Bax as well as cell cycle regulators (cyclin D1 and CDK4) to arrest cell cycle in G0/G1 phase and promote apoptosis. By RT-qPCR and immunofluorescence we found that CXCR4 was highly expressed in SHG-44 cells. Our results from wound healing and Transwell invasion assays indicated silencing of CXCR4 significantly inhibited the SDF-1α-induced migration and invasion; similarly, flow cytometry showed that treatment with si-CXCR4 affected cell cycle and induced cell apoptosis in SHG-44. However, these effects were significantly weakened by NT21MP. In conclusion, the present study indicates that NT21MP plays a regulatory role in the SDF-1α/CXCR4 axis and further manages the invasion, migration, apoptosis and cell cycle of glioma cells. Thus, NT21MP might represent a novel therapeutic approach against glioma.

Curcumin-Loaded Solid Lipid Nanoparticles Enhanced Anticancer Efficiency in Breast Cancer

Curcumin (Cur) has been widely used in medicine, due to its antibacterial, anti-inflammatory, antioxidant, and antitumor effects. However, its clinic application is limited by its instability and poor solubility. In the present wok, curcumin was loaded into solid lipid nanoparticles (SLNs), in order to improve the therapeutic efficacy for breast cancer. The results measured using transmission electron microscopy (TEM) indicated that Cur-SLNs have a well-defined spherical shape; the size was about 40 nm with a negative surface charge. The drug loading and encapsulation efficiency in SLNs reached 23.38% and 72.47%, respectively. The Cur-SLNs showed a stronger cytotoxicity against SKBR3 cells. In vitro cellular uptake study demonstrated a high uptake efficiency of the Cur-SLNs by SKBR3 cells. Moreover, Cur-SLNs induced higher apoptosis in SKBR3 cells, compared to cells treated by free drug. In addition, Western blot analysis revealed that Cur-SLNs could promote the ratio of Bax/Bcl-2, but decreased the expression of cyclin D1 and CDK4. These results suggested that Cur-SLNs could be a potential useful chemotherapeutic formulation for breast cancer therapy.

NT21MP negatively regulates paclitaxel-resistant cells by targeting miR‑155‑3p and miR‑155-5p via the CXCR4 pathway in breast cancer

Evidence has shown that microRNAs (miRNAs) are vital in cell growth, migration, and invasion by inhibiting their target genes. A previous study demonstrated that miRNA (miR)-155-3p and miR-155-5p exerted opposite effects on cell proliferation, apoptosis, migration and invasion in breast cancer cell lines. An miRNA microarray was used to show that miR-155-3p was downregulated whereas miR-155-5p was upregulated in paclitaxel-resistant (PR) cells compared with parental breast cancer cells. However, the role of miR-155 in breast cancer cell invasion and metastasis remains to be elucidated. A 21-residue peptide derived from the viral macrophage inflammatory protein II (NT21MP), competes with the ligand of CXC chemokine receptor 4 (CXCR4) and its ligand stromal cell-derived factor-1α, inducing cell apoptosis in breast cancer. The present study aimed to identify the underlying mechanism of action of miR-155-3p/5p and NT21MP in PR breast cancer cells. Quantitative polymerase chain reaction, western blotting, wound-healing, cell cycle and apoptosis assays, and Cell Counting kit-8 assay were used to achieve this goal. The combined overexpression of miR-155-3p with NT21MP decreased the migration and invasion ability and increased the number of apoptotic and arrested cells in the G0/G1 phase transition in vitro. The knockdown of miR-155-5p combined with NT21MP had a similar effect on PR breast cancer cells. Furthermore, the ectopic expression of their target gene myeloid differentiation primary response gene 88 (MYD88) or tumor protein 53-induced nuclear protein 1 (TP53INP1) combined with NT21MP enhanced the sensitivity of the breast cancer cells to paclitaxel. Taken together, these findings suggested that miR-155-3p/5p and their target genes MYD88 and TP53INP1 may serve as novel biomarkers for NT21MP therapy through the CXCR4 pathway for improving sensitivity to paclitaxel in breast cancer.