Wentong Li

Downregulation of LncRNA GAS5 causes trastuzumab resistance in breast cancer

Therapeutic resistance to trastuzumab caused by dysregulation of long noncoding RNAs (lncRNAs) is a major obstacle to clinical management of HER2-positive breast cancer. To investigate which lncRNAs contribute to trastuzumab resistance, we screened a microarray of lncRNAs involved in the malignant phenotype of trastuzumab-resistant SKBR-3/Tr cells. Expression of the lncRNA GAS5 was decreased in SKBR-3/Tr cells and in breast cancer tissue from trastuzumab-treated patients. Inhibition of GAS5 promoted SKBR-3 cell proliferation, and GAS5 knockdown partially reversed lapatinib-induced inhibition of SKBR-3/Tr cell proliferation. GAS5 suppresses cancer proliferation by acting as a molecular sponge for miR-21, leading to the de-repression of phosphatase and tensin homologs (PTEN), the endogenous target of miR-21. Moreover, mTOR activation associated with reduced GAS5 expression was required to suppress PTEN. This work identifies GAS5 as a novel prognostic marker and candidate drug target for HER2-positive breast cancer.

PTTG1 Promotes Migration and Invasion of Human Non-small Cell Lung Cancer Cells and is modulated by miR-186

Deeper mechanistic understanding of non-small cell lung cancer (NSCLC), a leading cause of total cancer-related deaths, may facilitate the establishment of more effective therapeutic strategies. In this study, pituitary tumor transforming gene (PTTG1) expression was associated with lymph node and distant metastasis in patients with NSCLC and was correlated with patient survival. Reduction of PTTG1 by small interfering RNA (siRNA) inhibits the migration and invasion of NSCLC cells by mediating matrix metalloproteinases expression. To the best of our knowledge, this study is the first to report that PTTG1 promotes epidermal growth factor (EGF) induced the phosphorylation of LIN-11, Isl1 and MEC-3 protein domain kinase and cofilin, a critical step in cofilin recycling and actin polymerization. Additionally, EGF-induced Akt phosphorylation was suppressed through knockdown of PTTG1. Interestingly, miR-186 can modulate PTTG1 protein expression. As observed from the animal experiment in this study, knockdown of PTTG1 through siRNA and overexpression of miR-186 inhibited invasive activity of NSCLC cells toward the SCID mice lung. In summary, our in vitro and in vivo results indicate that PTTG1 modulated by miR-186 has an important function in NSCLC invasion/metastasis. This study identified both PTTG1 and miR-186 as potential anti-invasion targets for therapeutic intervention in NSCLC.

miR-153 inhibits epithelial–mesenchymal transition by targeting metadherin in human breast cancer

Epithelial–mesenchymal transition (EMT) is a crucial step in epithelial cancer invasion and metastasis. miR-153 has been identified as a key EMT suppressor. Accordingly, this study aimed to determine the possible relation of miR-153 downregulation to EMT through MTDH modulation. The miR-153 and MTDH expression profiles of human breast cancer specimen were determined by qPCR and evaluated by correlation analysis. Cell viability and clonogenic assays were applied to explore the impact of miR-153 on suppression of proliferation and oncogenic potential of breast cancer cells. Cell migration and invasion assays were used for the functional analysis of miR-153 in MCF-7 and MDA-MB-231 cells. Luciferase assay was adopted to identify MTDH as a new direct target of miR-153. Ectopic expression of miR-153 could significantly inhibit tumor growth and impair the migration and invasion of breast cancer cells. Overexpression of miR-153 simultaneously increased E-cadherin, decreased vimentin expression, and downmodulated EMT-associated transcription factors. miR-153 was negatively correlated with MTDH in cell lines and clinical samples. Overexpression of miR-153 significantly suppressed MTDH, as demonstrated by in vitro MTDH 3′-untranslated region luciferase report assay. MTDH is a direct downstream target of miR-153 and is involved in the miR-153-induced suppression of the migration and invasion of breast cancer cells. Our findings indicate that miR-153 functions as a tumor suppressor and miR-153/MTDH link is a promising therapeutic target for breast cancer.

miR‐199a‐5p regulates β1 integrin through Ets‐1 to suppress invasion in breast cancer

Increasing evidence has revealed that miR‐199a‐5p is actively involved in tumor invasion and metastasis as well as in the decline of breast cancer tissues. In this research, overexpression of miR‐199a‐5p weakened motility and invasion of breast cancer cells MCF‐7 and MDA‐MB‐231. Upregulation of Ets‐1 increased breast cancer cell invasion, but the mechanism by which miR‐199a‐5p modulates activation of Ets‐1 in breast cancer was not clarified. We investigated the relationship between miR‐199a‐5p and Ets‐1 on the basis of 158 primary breast cancer case specimens, and the results showed that Ets‐1 expression was inversely correlated with endogenous miR‐199a‐5p. Overexpression of miR‐199a‐5p reduced the mRNA and protein levels of Ets‐1 in MCF‐7 and MDA‐MB‐231 cells, whereas anti‐miR‐199a‐5p elevated Ets‐1. siRNA‐mediated Ets‐1 knockdown phenocopied the inhibition invasion of miR‐199a‐5p in vitro. Moreover, luciferase reporter assay revealed that miR‐199a‐5p directly targeted 3′‐UTR of Ets‐1 mRNA. This research revealed that miR‐199a‐5p could descend the levels of β1 integrin by targeting 3′‐UTR of Ets‐1 to alleviate the invasion of breast cancer via FAK/Src/Akt/mTOR signaling pathway. Our results provide insight into the regulation of β1 integrin through miR‐199a‐5p‐mediated Ets‐1 silence and will help in designing new therapeutic strategies to inhibit signal pathways induced by miR‐199a‐5p in breast cancer invasion.

TGF β1 Mediates Epithelial Mesenchymal Transition via β6 Integrin Signaling Pathway in Breast Cancer

Background: To understand the function of β6 integrin and elucidate its signaling pathways in TGF-β-induced EMT in breast cancer. Methods: The interactions between TGF-β1 and β6 integrin were measured by coimmunoprecipitation. The EMT responses, phospherlation of PI3K/Akt and COX-2 expression were determined by real-time PCR, transwell assay, and western blot after the blockage of β6 integrin. Results: TGF-β1 and β6 integrin could bind with each other. Blockage of β6 integrin rescued TGF-β1-induced EMT phenotype and reduced expression of COX-2 via dephosphorylation of PI3K/Akt. Conclusions: β6 integrin plays a critical role in TGF-β1-induced EMT and overexpression of COX-2 in breast cancer.

Silencing of COX-2 by RNAi Modulates Epithelial-Mesenchymal Transition in Breast Cancer Cells Partially Dependent on the PGE 2 Cascade

In order to prove whether downregulation of COX-2 (Cyclooxygenase-2) could modulate the epithelial- mesenchymal transition (EMT) of breast cancer, celecoxib and siRNA were respectively used to inhibit COX-2 function and expression in MDA-MB-231 cells. The EMT reversal effect in the RNAi treated group was better than that of the celecoxib group while there were no obvious differences in the medium PGE2 levels between the two groups. The results show that COX-2 pathways may contribute considerably to EMT of breast cancer cells, partially dependent on the PGE2 cascade. Akt2, ZEB2 and Snail were measured to clarify the underlying mechanisms of COX-2 on EMT; COX-2 may modulate EMT of breast cancer by regulating these factors. This finding may be helpful to elucidate the mechanisms of selective COX-2 inhibitor action in EMT modulation in breast cancer.

HSPC159 promotes proliferation and metastasis by inducing epithelial-mesenchymal transition and activating the PI3K/Akt pathway in breast cancer

HSPC159 is a novel human galectin‐related protein that has been shown to be involved in carcinogenesis. Little is known about HSPC159 expression and function in breast cancer. Herein we showed that HSPC159 was aberrantly expressed in both breast cancer cell lines and tumor tissues and that its expression was associated with poor prognosis of breast cancer patients. Using gain‐ and loss‐of‐function methods we found that HSPC159 enhanced breast cancer cell proliferation and metastasis in vitro and in vivo. Mechanistically, HSPC159 was found to induce epithelial‐mesenchymal transition (EMT) and the F‐actin polymerization process of breast cancer cells. Moreover, HSPC159 promoted proliferation, migration and invasion through activating the PI3K/Akt signaling pathway in breast cancer. In conclusion, our findings showed that HSPC159 contributed to breast cancer progression through the PI3K/Akt pathway and might serve as a potential therapeutic target for the treatment of breast cancer.

Amplification and the clinical significance of circulating cell-free DNA of PVT1 in breast cancer.

Duplication in the chromosome 8q24 region is a frequent occurrence in carcinomas. The PVT1 oncogene (PVT1), a long non-coding RNA, is found in this locus. PVT1 amplification is a frequent event in cancers, such as in lymphomas, serous ovarian, colorectal and breast cancers. Ectopic PVT1 expression is related with reduced survival duration in cancer patients. in the present study, we proved that PVT1 is markedly augmented in breast cancer tissues compared with adjacent non-tumorous tissues. Thus, PVT1 is an independent prognostic factor for the survival duration of breast cancer patients. Furthermore, PVT1 is pivotal in regulating p21 expression. In addition, we detected PVT1 DNA in serum and found that circulating PVT1 DNA significantly increased in the serum of breast cancer patients. Compared with PVT1 RNA, DNA is the main form of the PVT1-derived segment. These relevant findings collectively demonstrate that PVT1 plays a pivotal role in breast cancer and is a possible target for novel breast cancer therapies. The detection of circulating PVT1 DNA fragments may be a convenient means to predict the prognosis of breast cancer patients.

The interaction between smoking and CYP1A1 MspI polymorphism on lung cancer: a meta-analysis in the Chinese population.

&NA; Many studies have examined the interaction between CYP1A1 MspI gene polymorphism and smoking for the risk of lung cancer risk in Chinese, but their results have been inconsistent. Therefore, a meta‐analysis was performed to ascertain this issue. PubMed, Springer Link, Ovid and other Chinese databases were searched to include all the relevant studies. Smoking status was categorised as ‘smokers’ and ‘non‐smokers.’ The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed or random effect model. Subgroup analyses according to ethnicity, source of control and geographical location were also conducted. This meta‐analysis identified 13 studies containing 2248 lung cases and 3079 controls. Overall, a significant association between lung cancer and the variants of CYP1A1 MspI was found among smokers (type B and type C combined vs. type A: OR = 1.89, 95% CI = 1.15‐3.11, P = 0.000 for heterogeneity), whereas not found among non‐smokers. Similar to the overall results, stratified analyses showed that the increased risk of lung cancer was observed in population‐based studies and north China among smokers (OR = 1.65, 95%CI = 1.03‐2.66; OR = 2.00, 95% CI = 1.14‐3.53). Our meta‐analysis showed that there was an interaction between the CYP1A1 MspI and smoking on the risk of lung cancer in the Chinese population.