Exosomal Circ_FMN2 Derived from the Serum of Colorectal Cancer Patients Promotes Cancer Progression by miR-338-3p/MSI1 Axis.

BACKGROUND: Colorectal cancer (CRC) is a common malignancy of the gastrointestinal tract with high incidence and mortality. Exosomal circular RNA (circRNA) has been shown to be associated with the malignant progression of cancers, including CRC. Circ_0005100 (named as circ_FMN2) has been shown to promote CRC cell proliferation and migration. However, whether exosomal circ_FMN2 participated in CRC progression remains unclear. METHODS: Exosomes were isolated from the serum of CRC patients and then identified using transmission electron microscope. Western blot assay was used to test the protein levels of exosome markers, proliferation-related marker, metastasis-related markers and musashi-1 (MSI1). The expression levels of circ_FMN2, microRNA (miR)-338-3p and MSI1 were detected by qPCR. Flow cytometry, colony formation assay, MTT assay, and transwell assay were employed to measure cell cycle, apoptosis, colony formation ability, viability, migration and invasion. Dual-luciferase reporter assay was performed to assess the interaction between miR-338-3p and circ_FMN2 or MSI1. BALB/c nude mice was used to conduct animal experiments. RESULTS: Circ_FMN2 was overexpressed in the exosomes of CRC patient's serums and CRC cells. Overexpressed exosomal circ_FMN2 could promote CRC cell proliferation, metastasis, and suppress apoptosis. Circ_FMN2 acted as miR-338-3p sponge. MiR-338-3p overexpression reversed the promotion effect of circ_FMN2 on CRC progression. MSI1 was found to be a target of miR-338-3p, and its overexpression revoked the inhibitory effect of miR-338-3p on CRC progression. Furthermore, exosomal circ_FMN2 overexpression also could facilitate CRC tumor growth in vivo. CONCLUSION: Exosomal circ_FMN2 accelerated CRC progression through miR-338-3p/MSI1 axis, revealing that exosomal circ_FMN2 might be a target for CRC treatment.

Blocking the Notch signal transduction pathway promotes tumor growth in breast cancer by promoting the expression of suppressible inflammatory factors.

Background: Breast cancer is the most common malignant tumor among all female tumors. It seriously affects the health and lives of patients, and poses a significant economic burden. The study of the molecular mechanisms of breast cancer occurrence, proliferation and growth and development is of great clinical significance. Methods: Notch1 knockout mice were obtained by gene targeting. The expression of inflammatory factor arginase-1 in each group of tumors was observed by immunofluorescence staining. Semi-quantitative detection of Notch1, Arginase-1, and proteins belonging to the PI3K-AKT pathway by western blot. The expression level of interleukin-3 (IL-3), and IL-4 in serum was quantified by enzyme linked immunosorbent assay (ELISA). Results: In this study, Notch1 knockout in mice promoted the cell proliferation of breast cancer. Further study on molecular mechanisms demonstrated that the increased cell proliferation resulted from the activation of the PI3K-AKT signal transduction pathway. In addition, the expression of the M2-type inflammatory factor arginase-1 significantly increased, which was dependent on the activation of the PI3K-AKT pathway, indicating that Notch1 knockout in mice promoted the polarization of tumor-associated macrophages (TAMs). Consistent with this, IL-3 and IL-4 expression also significantly increased in the serum of Notch1 knockout mice. Conclusions: According to our results, Notch1 knockout in mice significantly promoted the cell proliferation of breast cancer, not only by activating the PI3K-AKT pathway, but also by promoting the polarization of TAMs towards the M2-type phenotype.

ZEB1 represses biogenesis of circ-DOCK5 to facilitate metastasis in esophageal squamous cell carcinoma via a positive feedback loop with TGF-ß.

ZEB1 is an important transcription factor that plays a critical role in TGF-ß-induced epithelial-mesenchymal transition (EMT) and tumor metastasis. However, the mechanisms by which ZEB1 regulates metastasis in esophageal squamous cell carcinoma (ESCC) remain largely unknown. Here, we identified a novel circular RNA, circ-DOCK5, the biogenesis of which is directly regulated by ZEB1 and ZEB1-repressed RNA-binding protein eIF4A3. Tissue microarray analysis identified circ-DOCK5 to be downregulated in ESCC tissues, and its downregulation correlated with poor prognosis. Moreover, circ-DOCK5 increased the stability of miR-627-3p by functioning as a "reservoir" for miR-627-3p to partially reverse the ZEB1-enhanced migration and invasion in ESCC. MiR-627-3p inhibited the expression of TGFB2 and the secretion of TGF-ß, which further resulted in downregulation of ZEB1 and suppression of TGF-ß-induced EMT. In vivo experiments showed that ZEB1 promoted metastasis in ESCC by regulating expression of circ-DOCK5. Therefore, the present study revealed that ZEB1-mediated downregulation of circ-DOCK5 facilitates metastasis in ESCC by forming a positive feedback loop with TGF-ß by altering the miR-627-3p/TGFB2 signaling. Targeting this signaling pathway may help suppress progression in ESCC.

Circ_0055625 knockdown inhibits tumorigenesis and improves radiosensitivity by regulating miR-338-3p/MSI1 axis in colon cancer.

BACKGROUND: Radiotherapy is a main therapeutic method for cancers, including colon cancer. In the current study, we aim to explore the effects of circular RNA (circRNA) circ_0055625 in the progression and radiosensitivity of colon cancer and the underlying mechanism. METHODS: The expression of circ_0055625 and musashi homolog 1 (MSI1) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). MSI1 protein expression was determined by Western blot. Cell proliferation was assessed by cell counting kit-8 (CCK-8) and colony formation assays. Cell survival fraction, apoptosis, and invasion were investigated by colony formation assay, flow cytometry analysis, and transwell invasion assay, respectively. Cell migration was detected by wound-healing and transwell migration assays. The binding relationship between microRNA-338-3p (miR-338-3p) and circ_0055625 or MSI1 was predicted by online databases and identified by Dual-Luciferase Reporter Assay. The effects of circ_0055625 silencing on the tumor formation and radiosensitivity of colon cancer in vivo were explored by in vivo tumor formation assay. RESULTS: Circ_0055625 and MSI1 were upregulated in colon cancer tissues and cells relative to control groups. Radiation treatment apparently increased the expression of circ_0055625 and MSI1 in colon cancer cells. Circ_0055625 knockdown or MSI1 silencing repressed cell proliferation, migration, and invasion and promoted cell apoptosis and radiosensitivity in colon cancer. Also, circ_0055625 silencing-mediated effects were attenuated by MSI1 overexpression. Additionally, circ_0055625 silencing reduced MSI1 expression, which could be attenuated by miR-338-3p inhibitor. Mechanically, circ_0055625 acted as a sponge for miR-338-3p to regulate MSI1. Furthermore, circ_0055625 knockdown hindered tumor growth and improved radiosensitivity in vivo. CONCLUSION: Circ_0055625 repression inhibited the progression and radioresistance of colon cancer by downregulating MSI1 through sponging miR-338-3p. This result might provide a theoretical basis for improving the therapy of colon cancer with radiation.

Inhibition of proliferation and migration and induction of apoptosis in glioma cells by silencing TLR4 expression levels via RNA interference.

The objective of the present study was to investigate the expression levels of toll-like receptor 4 (TLR4) in glioma cells and the mechanisms underlying its regulatory effects on proliferation, migration and apoptosis of glioma cells. A total of three TLR4 silencing short hairpin (sh)RNA plasmids were established, and Lipofectamine® was used to the transfect the human glioma cell line U-87MG. Transfection efficiency was measured via flow cytometry. The interference plasmid exhibiting the largest silencing effect on TLR4 was screened for subsequent experiments using puromycin. Reverse transcription-quantitative PCR and western blot analysis were used to detect the TLR4 gene and protein expression levels, respectively, in stably transfected cells. Flow cytometry measured cell cycle and apoptosis and a wound healing assay was employed to assess the migration ability of transfected cells. The proliferation of transfected cells was detected using Cell Counting Kit-8 assay. TLR4-sh2 exhibited the highest transfection efficiency. Following transfection of U-87MG cells with TLR4-sh2 and negative control (NC) plasmids for 48 h and screening by puromycin, stable transfected cells were named U-87MG-Sh and U-87MG-NC cells respectively. The TLR4 gene and protein expression levels in the U-87MG-Sh cells were significantly lower than in U-87MG and U-87MG-NC cells. The apoptosis rate and the percentage of G0/1 cells were significantly higher, whereas the cell proliferation rate was notably lower, in U-87MG-Sh cells than in the U-87MG-NC and U-87MG cells. The proliferation rate and the cell migration ability of U-87MG-Sh cells were significantly lower than those of U-87MG-NC and U-87MG cells. TLR4 is associated with the proliferation of glioma cells. Inhibition of TLR4 expression levels significantly inhibited proliferation of glioma cells and induced apoptosis. The present study provided insights into the mechanisms associated with the development, progression and invasion ability of glioma cells.

Blocking the Notch signal transduction pathway promotes tumor growth in osteosarcoma by affecting polarization of TAM to M2 phenotype.

BACKGROUND: Osteosarcoma is a primary malignant tumor that seriously affects the health and life of patients. It is of great clinical significance to explore the molecular mechanism of osteosarcoma development and develop the corresponding therapeutic targets. Th1/Th2 cytokines in the normal human body are in a state of dynamic balance. When this balance is destroyed, it is related to many diseases such as a tumor, autoimmune disease, microbial infection, transplant rejection, among many others. METHOD: The model of mouse tumor-associated macrophage (TAM) was induced by being co-cultured with inducer granulocyte-macrophage colony stimulating factor (GM-CSF) and osteosarcoma S180 cells. The Notch1 knockout mice were obtained by gene targeting technology. The distribution of M1- and M2-type TAMs in the tumor was visualized by immunofluorescence staining. And the western-blot testing was used to detect and quantified the protein level of Notch1 and Th1/Th2-type cytokines. RESULTS: In this study, the polarization of TAMs to the M2 phenotype occurred after coculture with osteosarcoma S180 cells and secretion level Th1/Th2-type cytokines changed. Also, the expression level of Notch1 reduced significantly. Further, the critical transcription factor Notch1 of the Notch signaling pathway was knocked out in mice. The tumor volume of Notch1 knockout mice was significantly more extensive than of the control mice. The results of microstructural observation on tumor showed that M2-type TAMs infiltrated into tumor increased with increased expression of Th2-type cytokines, but M1-type TAMs reduced with reduced expression of Th1-type cytokines. CONCLUSIONS: According to our results, the Notch signal transduction pathway participates in tumor occurrence and growth with a negative role by maintaining Th1/Th2 balance.

ADAMTS8 Inhibits Progression of Esophageal Squamous Cell Carcinoma.

A disintegrin and metallopeptidase with thrombospondin motifs (ADAMTSs), which is frequently dysregulated in cancers and is involved in carcinogenesis and cancer progression. The present study identified that ADAMTS8 expression is downregulated in esophageal squamous cell carcinoma (ESCC) tissues when compared with nontumor tissue. The expression of ADAMTS8 is closely associated with clinical stage and lymph node metastasis in patients with ESCC. Furthermore, functional studies have shown that ADAMTS8 overexpression could reduce abilities of proliferation, migration, and invasion and promote apoptosis of ESCC cells. Meanwhile, monocyte chemotactic protein-1 and interleukin-6 are markedly deregulated by ADAMTS8 overexpression. Consistently, in vivo data showed that ADAMTS8 overexpression led to a reduction in tumor growth. These results indicate that altering ADAMTS8 expression could modify the outcomes of ESCC by inhibiting cell proliferation and invasion, while promoting the apoptosis of ECSS cells. Thus, ADAMTS8 represents a potential therapeutic target for ESCC therapy.

ZEB1-Mediated Transcriptional Upregulation of circWWC3 Promotes Breast Cancer Progression through Activating Ras Signaling Pathway.

Zinc finger E-box binding homeobox 1 (ZEB1) has been widely recognized as an important driver of tumor growth and metastasis. However, nothing is known about ZEB1-regulated circular (circ)RNAs in cancer. In the current study, we evaluated the function of a novel ZEB1-regulated circRNA derived from the WWC3 gene locus, circWWC3 in breast cancer progression. We found that ZEB1 upregulated circWWC3 expression but not the linear WWC3 mRNA expression. circWWC3 is highly expressed in breast cancer tissues and is associated with the poor prognosis of breast cancer patients. Silencing of circWWC3 significantly suppresses the proliferation, migration, and invasion of breast cancer cells. Mechanically, circWWC3 upregulates multiple oncogenes' expression of the Ras signaling pathway through acting as the sponge of microRNA (miR)-26b-3p and miR-660-3p. Moreover, short hairpin (sh)RNA-mediated knockdown of circWWC3 partially antagonized ZEB1-mediated breast cancer growth and metastasis in vivo. Our findings reveal that ZEB1-mediated upregulation of circWWC3 promotes breast cancer progression through activating Ras signaling pathway, which provides a potential therapeutic target and prognostic biomarker for breast cancer.

Tumor suppressive miR-6775-3p inhibits ESCC progression through forming a positive feedback loop with p53 via MAGE-A family proteins.

Accumulating evidences indicate that microRNAs (miRNAs) play vital roles in multiple diseases, including cancer. In the present study, we showed that miR-6775-3p plays a tumor suppressive role in esophageal squamous cell carcinoma (ESCC). High expression miR-6775-3p is associated with good clinical outcomes of ESCC patients. Over-expression of miR-6775-3p inhibited tumor growth and liver metastasis of ESCC xenograft tumors. Enforced expression of miR-6775-3p inhibited ESCC cell proliferation, migration, and invasion. KEGG pathway analysis revealed that miR-6775-3p was associated with the genes on "pathway in cancer". Mechanically, miR-6775-3p inhibited the expression of tumor antigens MAGE-A family through direct binding the 3'UTR region of MAGE-A mRNAs, and attenuated MAGE-A-inhibited transcriptional activity of tumor suppressor p53. In addition, miR-6775-3p also directly inhibits its host gene SLC7A5 which has been reported to play oncogenic roles in cancer progression. Interestingly, miR-6775-3p and its host gene SLC7A5 were directly transcriptionally induced by p53. Thus, for the first time, our study proposed a novel positive feedback regulation between miR-6775-3p and p53 via MAGE-A family, which plays crucial role in ESCC progression.

Circular RNA ciRS-7 Maintains Metastatic Phenotypes as a ceRNA of miR-1299 to Target MMPs.

Circular RNA ciRS-7 has been reported to act as a competing endogenous RNA (ceRNA) of the miRNA miR-7, resulting in reduced miR-7 activity and increased miR-7-targeted transcripts. However, it is unknown if ciRS-7 harbors other miRNAs with regulatory roles in triple-negative breast cancer (TNBC). The present study determined that the expression of ciRS-7 in TNBC clinical specimens and representative cells is significantly higher than other breast cancer subtypes. Functionally, downregulation of ciRS-7 inhibited cell migration and invasion of TNBC cells. Knockdown of ciRS-7 expression also inhibited the liver and lung metastasis of TNBC cells in vivo Mechanistic studies revealed that ciRS-7 contains 20 miR-1299-binding sites and functions as a ceRNA of miR-1299 in TNBC cells. High expression of ciRS-7 maintains the high migration and invasion properties of TNBC cells by acting as a ceRNA of miR-1299 to enhance the expression of matrix metalloproteinases family members (MMP).Implications: Circular RNA ciRS-7 is highly expressed in TNBC tumor specimens and cells, and its downregulation inhibits cell migration and invasion of TNBC cells in vitro and in vivo In addition, ciRS-7 functions as a ceRNA of miR-1299 to enhance the expression of MMPs, which maintains the high migration and invasion properties of TNBC cells. Mol Cancer Res; 16(11); 1665-75. ©2018 AACR.

The expression of ANXA3 and its relationship with the occurrence and development of breast cancer.

PURPOSE: To investigate the expression of ANXA3 in breast cancer tissues and normal breast tissues and its relationship with the clinicopathological features. METHODS: The expression levels of ANXA3 mRNA and protein were determined by fluorescent quantitative RT-PCR and Western blot, respectively, in 81 samples from breast cancer tissues and normal breast tissues. Flow cytometry, used to detect the cell cycle, further analyzed the differences in the cell proliferation indexes between cancer and the normal tissues. In addition, the correlation between the gene and protein expression levels of ANXA3 and the cell proliferation indexes in breast cancer tissues was calculated. RESULTS: The expression levels of ANXA3 mRNA and protein were significantly higher in breast cancer tissues than in control samples. Furthermore, their expression patterns were significantly different in patients with different axillary lymph node metastasis states, with or without vascular tumor thrombus, and with different molecular classifications. The expression of ANXA3 mRNA and protein in patients with triple-negative breast cancer was significantly higher than in Luminal A and B types. However, no significant differences were detected in the expression levels in other subtypes. Compared to normal tissues, the cell proliferation indexes of breast cancer tissues were significantly higher, and presented significant positive correlations with the ANXA3 gene and protein expression levels. CONCLUSION: The expression of ANXA3 might play a crucial role in promoting the occurrence, development, and metastasis of breast cancer. It could serve as an important marker involved in the invasion and metastasis states, and the prognosis of breast cancer.

Circular RNA ciRS-7 accelerates ESCC progression through acting as a miR-876-5p sponge to enhance MAGE-A family expression.

As the most well-known circular RNA, ciRS-7 (also termed CDR1as) has been reported to act as a miR-7 sponge, resulting in reduced miR-7 activity and increased miR-7-targeted transcripts. Here, we showed that ciRS-7 is up-regulated in esophageal squamous cell carcinoma (ESCC), and is associated with the poor clinicopathological parameters of ESCC patients. Moreover, over-expression of ciRS-7 increased the proliferation, migration and invasion of ESCC cells. Mechanistic studies revealed that ciRS-7 contains nineteen miR-876-5p binding sites and acts as a miR-876-5p sponge. Over-expression of ciRS-7 resulted in the reduced tumor-repressive function of miR-876-5p on its downstream target MAGE-A family. In animal experiments, enforced ciRS-7 increased ESCC tumor growth and metastasis through targeting miR-876-5p/MAGE-A family axis. Collectively, our study provided novel evidence that ciRS-7 accelerates ESCC progression by acting as a miR-876-5p sponge to enhance MAGE-A family expression.

MAGE-A11 is activated through TFCP2/ZEB1 binding sites de-methylation as well as histone modification and facilitates ESCC tumor growth.

Recently, we have reported that the product of Melanoma Antigens Genes (MAGE) family member MAGE-A11 is an independent poor prognostic marker for esophageal squamous cell carcinoma (ESCC). However, the reason how MAGE-A11 is activated in ESCC progression still remains unclear. In the current study, we demonstrated that DNA methylation and the subsequent histone posttranslational modifications play crucial roles in the regulation of MAGE-A11 in ESCC progression. We found that the methylation rate of TFCP2/ZEB1 binding site on MAGE-A11 promoter in ESCC tissues and cells is higher than the normal esophageal epithelial tissues and cells. Transcription factors TFCP2 and ZEB1 directly bind MAGE-A11 promoter and regulate the endogenous MAGE-A11 expression in a methylation-dependent manner in ESCC cells. Following MAGE-A11 promoter methylation, the methyl-CpG-binding protein MeCP2 was found to bind the methylated MAGE-A11 promoter to mediate histone deactylation by recruiting HDAC1 and HDAC2. Simultaneously, histone inactivation marks including H3K27me3 as well as H3K9me3 were increased, whereas histone activation mark H3K4me3 was decreased. HDAC inhibitor Trichostatin A (TSA) increased DNA methylase inhibitor Decitabine (DAC)-induced MAGE-A11 expression. siRNA-mediated knockdown of histone methltransferase EZH2 or DZNep (a EZH2 inhibitor) treatment increased DAC-induced MAGE-A11 expression. Our results indicate that MAGE-A11 is activated through DNA demethylation, histone acetylation and histone methylation in ESCC, and its activation promotes ESCC tumor growth.

Effects of PHA-665752 and Cetuximab Combination Treatment on In Vitro and Murine Xenograft Growth of Human Colorectal Cancer Cells with KRAS or BRAF Mutations.

BACKGROUND: It remains unknown whether blockade of c-Met signaling and epidermal growth factor receptor signaling is effective in suppressing the growth of human colorectal cancer (CRC) cells. In this study, we investigated the effects of the c-Met inhibitor PHA-665752 alone and in combination with cetuximab on the growth of human CRC cells in vitro and in mouse xenografts. METHODS: Human CRC cell lines (Caco2, HCT-116, and HT-29) and mice bearing HCT-116 xenografts were treated with cetuximab in the absence or presence of PHA-665752. Cell viability and apoptosis were examined using the MTT and TUNEL assays, respectively. Vimentin was measured by immunohistochemistry as a marker for epithelial-to-mesenchymal transition. Western blotting was used to determine signaling protein expression levels. RESULTS: The MTT assay showed that the growth of Caco2, HCT-116, and HT-29 cells was inhibited by PHA-665752 in a dose-dependent manner, but only Caco2 cell growth was suppressed by cetuximab. Combination treatment with PHA-665752 and cetuximab inhibited the proliferation of Caco2 cells and RAS mutant CRC cell lines. However, relative to the PHA-665752-alone treatment group, HT-29 cells with a BRAF mutation showed no noticeable effect. The mean tumor volume in mice treated with cetuximab in combination with PHA-665752 was significantly smaller than that in the mice treated with only cetuximab (P = 0.033) or PHA-665752 (P < 0.01). Similarly, the expression of vimentin in the mice treated with PHA-665752 in combination with cetuximab was significantly lower than that in the mice treated with cetuximab or PHA-665752 alone (P < 0.05 in each case). TUNEL assays revealed that treatment with PHA-665752 in combination with cetuximab markedly increased CRC cell apoptosis. Western blotting analysis of signaling protein expression showed that PHA- 665752 inhibited Met phosphorylation (P < 0.05). In addition, treatment with cetuximab alone or in combination with PHA-665752 effectively inhibited EGFR phosphorylation (P < 0.05). CONCLUSION: Combination treatment with PHA-665752 and cetuximab suppressed in vitro and in vivo CRC cell growth more than treatment with either agent alone did.

Epigallocatechin-3-gallate promotes apoptosis and reversal of multidrug resistance in esophageal cancer cells.

Evidence for demonstrating the role of the green tea component epigallocatechin-3-gallate (EGCG) in esophageal squamous cell carcinoma cells is limited. In this study, we investigated apoptosis induced by EGCG and the underlying molecular mechanisms in human esophageal squamous cell carcinoma cells. The growth-inhibitory effects of EGCG on esophageal cancer cell (Eca109 and Ec9706) were detected by MTT. Using flow cytometry, we determined the cellular apoptosis, bcl-2, bax and caspase-3 protein expression in Eca109 and Ec9706 cells following treatment with EGCG for 24h. After treatment of Eca109/ABCG2 (an esophageal cancer multidrug resistance cell line) cells with adriamycin (ADM) combined with EGCG for 24h, the cellular apoptosis, mitochondrial membrane potential, ADM concentration in cells and ABCG2 protein expression were detected by flow cytometry. EGCG inhibited the growth of Eca109 and Ec9706 cells in a dose- and time- dependent manner. EGCG induced apoptosis, decreased the bcl-2 protein expression and increased the expression of bax and caspase-3 protein. The rate of apoptosis and ADM concentration in the Eca109/ABCG2 cells following treatment with ADM and EGCG were higher than that with ADM treatment alone, although the mitochondrial membrane potential was significantly lower (P<0.01). EGCG reduced the ABCG2 expression of Eca109/ABCG2 cells. Our data indicated that EGCG inhibited cell growth and induced esophageal cancer cell apoptosis. It reduced the bcl-2 protein expression and increased the bax and caspase-3 protein expression. EGCG reversed multi-drug resistance by reducing ABCG2 expression and increasing the anticancer drug concentration in cancer cells.

Silencing of ANXA3 expression by RNA interference inhibits the proliferation and invasion of breast cancer cells.

The present study aimed to explore the expression of Annexin A3 (ANXA3) in breast cancer cells and the mechanisms involved in the regulatory effects of ANXA3 on proliferation, invasion and migration of breast cancer cells. Fluorescence quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting were used to measure the expression of ANXA3 mRNA and protein in two breast cancer cell lines (MDA-MB-231 and MCF-7). Three ANXA3 silencing shRNA plasmids (ANXA3-sh1-3) and one negative control plasmid were constructed, and the Lipofectamine transfection method was used for transfecting human breast cancer cell line MDA-MB-231. Flow cytometry was used to measure the transfection efficiency. The expression of ANXA3 protein was measured by western blotting. Cell cycle distribution and apoptosis were assessed by flow cytometry. Migration and invasion of the transfected cells were evaluated using wound healing and Transwell assays, respectively. The expression levels of ANXA3 mRNA and protein were significantly higher in the MDA-MB-231 cells than levels in the MCF-7 cells. Western blotting showed that the ANXA3 protein level was significantly lower in the MDA-MB-231-Sh cells than that in the MDA-MB-231 and MDA-MB-231-NC cells. In addition, the percentage of G0/1 cells and the apoptosis rate were significantly higher, while the cell proliferation rate was significantly lower, in the MDA-MB-231-Sh cells when compared with the MDA-MB-231-NC and MDA-MB-231 cells. The cell migration and invasion abilities were also lower in the MDA-MB-231-Sh cells than these abilities in the MDA-MB-231-NC and MDA-MB-231 cells. The present study investigated the relationships between ANXA3 and proliferation, apoptosis, migration and invasion of breast cancer cells to elucidate the mechanisms involved in the development, progression, invasion and metastasis of breast cancer.

c-MET inhibition enhances the response of the colorectal cancer cells to irradiation in vitro and in vivo.

The aim of the present study was to investigate the effect of hepatocyte growth factor receptor (c-MET) inhibition on the viability of colon cancer cells and xenografts exposed to irradiation using short hairpin (sh)RNA or the c-MET inhibitor PHA665752. The underlying mechanisms were also investigated. Human colorectal adenocarcinoma HT-29 cells were infected with a lentivirus expressing shRNAs against c-MET and were irradiated at 0, 2, 4, 6 and 8 Gy. The viability of the cells was assessed by alamarBlue® assays. Mice bearing human colon carcinoma SW620 xenografts were randomly selected to receive 2.5% dimethyl sulfoxide (DMSO), 25 mg/kg PHA665752 intraperitoneally once every 2 days for 3 weeks, irradiation at 10 Gy, or 25 mg/kg PHA665752 intraperitoneally once every 2 days for 3 weeks followed 24 h later by irradiation at 10 Gy. The mean tumor volume (MTV) was measured. The apoptotic rate of cells was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays, and double stranded break marker antibody γ-H2AX and hypoxia inducible factor (HIF)-1α expression was examined by immunohistochemistry. alamarBlue assays revealed that c-MET downregulation by shRNA markedly accentuated the irradiation-induced reduction in the viability of HT-29 cells compared with HT-29 cells irradiated at the same doses (P<0.05). A combination of irradiation and PHA665752 caused an additional reduction in the MTV (382.8±42.4 mm3; P<0.01 vs. irradiation and PHA665752, 998.0±180.6 and 844.8±190.0 mm3, respectively). TUNEL assays revealed that irradiation and PHA665752 alone caused significant apoptosis of the SW620 cells in the tumor xenografts (P<0.01 vs. DMSO). The apoptotic index in the tumor xenografts of mice treated with a combination of irradiation and PHA665752 was significantly increased compared with mice treated with either agent alone (P<0.01). The combination of irradiation and PHA665752 was also associated with a marked increase in γ-H2AX levels and a significant decrease in HIF-1α expression in the xenografts (P<0.01). In conclusion, c-MET inhibition sensitizes colorectal cancer cells to irradiation by enhancing the formation of DNA double strand breaks and possibly alleviating tumor hypoxia.