CNTN-1 Enhances Chemoresistance in Human Lung Adenocarcinoma Through Induction of Epithelial-Mesenchymal Transition by Targeting the PI3K/Akt Pathway.

Chemoresistance has been a major obstacle to the effective treatment of lung cancer. Previously, we found that contactin-1 (CNTN-1) is related to cisplatin resistance in lung adenocarcinoma. Here, we aimed to investigate the underlying mechanism behind the role of CNTN-1 in cisplatin resistance in lung adenocarcinoma. EMT-associated phenotypes, including alterations in cellular morphology and marker (E-cadherin, N-cadherin and Vimentin) expression, were compared between A549 cells and A549/DDP cells (a cisplatin-resistant cell line of lung adenocarcinoma with abnormal CNTN-1 expression) by using real-time time PCR and Western blotting. Other methods, including CNTN-1 overexpression in A549 cells and CNTN-1 knockdown in A549/DDP cells, were also used to investigate the role of CNTN-1 in mediating the EMT phenotype and thr resulting cisplatin resistance and malignant progression of cancer cells in vitro and in vivo. A549/DDP cells exhibited an EMT phenotype and aggravated malignant behaviors. CNTN-1 knockdown in A549/DDP cells partly reversed the EMT phenotype, increased drug sensitivity, and attenuated the malignant progression whereas CNTN-1 overexpression in A549 cells resulted in the opposite trend. Furthermore, the PI3K/Akt pathway was involved in the effects of CNTN-1 on EMT progression in A549/DDP cells, verified by the xenograft mouse model. CNTN-1 promotes cisplatin resistance in human cisplatin-resistant lung adenocarcinoma through inducing the EMT process by activating the PI3K/Akt signaling pathway. CNTN-1 may be a potential therapeutic target to reverse chemoresistance in cisplatin-resistant lung adenocarcinoma.

Zhang R ，Sun S ，Ji F ，Liu C ，Lin H ，Xie L ，Yang H ，Tang W ，Zhou Y ，Xu J ，Li P ... -  《-》

miR-206 regulates cisplatin resistance and EMT in human lung adenocarcinoma cells partly by targeting MET.

Chen QY ，Jiao DM ，Wang J ，Hu H ，Tang X ，Chen J ，Mou H ，Lu W ... -  《Oncotarget》

Increased sensitivity of human lung adenocarcinoma cells to cisplatin associated with downregulated contactin-1.

Contactin-1 (CNTN-1), a glycosyl phosphatidylinositol anchor neural cell adhesion molecule (ACAM), is thought to function not only in nervous system development but also in the invasion and metastasis of several tumours. To investigate whether CNTN-1 is involved in multidrug resistance (MDR) in lung adenocarcinoma, CNTN-1 expression was compared between MDR human lung adenocarcinoma A549/cisplatin (A549/DDP) cells and its progenitor A549 cells. The comparison showed that CNTN-1 expression in A549/DDP cells was significantly higher than in A549 cells both at the mRNA level and the protein level. In order to confirm the physiological function of the abnormal expression, lentivirus-mediated short hairpin RNA (shRNA) was used to silence CNTN-1. Cell cytotoxicity assay and cell apoptosis assay revealed that silencing CNTN-1 both in A549 cells and in A549/DDP cells not only rendered cells more sensitive to cisplatin than the negative control, but also increased the cisplatin-induced apoptosis. Metastasis and invasion assays demonstrated that CNTN-1 knockdown reduced metastasis and invasion but did not affect A549 or A549/DDP cell proliferation. To investigate whether the abnormal expression of CNTN-1 is associated with characteristics of patients with non-small cell lung cancer (NSCLC), immunohistochemistry was used to detect CNTN-1 expression in 143 tissue samples from NSCLC patients and the results showed that the degree of CNTN-1 expression positively correlated with lymphatic invasion in patients with lung adenocarcinoma who received adjuvant cisplatin- or carboplatin-based treatment after surgery. Thus, we concluded that CNTN-1 is closely related with MDR of lung adenocarcinoma. Additionally, CNTN-1 is a novel marker to predict chemotherapeutic efficacy of patients with lung adenocarcinoma, especially with regard to cisplatin- or carboplatin-based regimens.

Zhang R ，Yao W ，Qian P ，Li Y ，Jiang C ，Ao Z ，Qian G ，Wang C ，Wu G ，Li J ，Ji F ，Xu J ... -  《-》

Effects of VBMDMP on the reversal of cisplatin resistance in human lung cancer A549/DDP cells.

Wang CK ，Zhang Y ，Zhang ZJ ，Qiu QW ，Cao JG ，He ZM ... -  《-》

Depleted aldehyde dehydrogenase 1A1 (ALDH1A1) reverses cisplatin resistance of human lung adenocarcinoma cell A549/DDP.

Cisplatin is the standard first-line chemotherapeutic agent for the treatment of non-small cell lung cancer (NSCLC). However, resistance to chemotherapy has been a major obstacle in the management of NSCLC. Aldehyde dehydrogenase 1A1 (ALDH1A1) overexpression has been observed in a variety of cancers, including lung cancer. The purpose of this study was to investigate the effect of ALDH1A1 expression on cisplatin resistance and explore the mechanism responsible. Reverse transcriptase-PCR was applied to measure the messenger RNA expression of ALDH1A1, while Western blot assay was employed to evaluate the protein expression of ALDH1A1, B-cell lymphoma 2, Bcl-2-like protein 4, phospho-protein kinase B (p-AKT) and AKT. A short hairpin RNA was used to knockdown ALDH1A1 expression. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the effect of ALDH1A1 decrease on cell viability. The cell apoptotic rate was tested using flow cytometry assay. ALDH1A1 is overexpressed in cisplatin resistant cell line A549/DDP, compared with A549. ALDH1A1 depletion significantly decreased A549/DDP proliferation, increased apoptosis, and reduced cisplatin resistance. In addition, the phosphoinositide 3-kinase (PI3K) / AKT pathway is activated in A549/DDP, and ALDH1A1 knockdown reduced the phosphorylation level of AKT. Moreover, the combination of ALDH1A1-short hairpin RNA and PI3K/AKT pathway inhibitor LY294002 markedly inhibited cell viability, enhanced apoptotic cell death, and increased cisplatin sensitivity. These results suggest that ALDH1A1 depletion could reverse cisplatin resistance in human lung cancer cell line A549/DDP, and may act as a potential target for the treatment of lung cancers resistant to cisplatin.

Wei Y ，Wu S ，Xu W ，Liang Y ，Li Y ，Zhao W ，Wu J ... -  《-》