<p>Silencing of Long Non-Coding RNA Colon Cancer-Associated Transcript 2 Inhibits the Growth and Metastasis of Gastric Cancer Through Blocking mTOR Signaling</p>
Authors: Hongbo Wang
Aiguang Wang
Sen Lin
Wenjuan Yang
Chao Geng
Journal: OncoTargets and Therapy (2020)
Discipline: CLINICAL MEDICINE
Keywords: apoptosis; autophagy; colon cancer-associated transcript 2; gastric cancer; mammalian target of rapamycin.
Affiliations: Department of Gastroenterology, The Second Hospital of Shandong University, Jinan City, Shangdong 250033, People's Republic of China., Department of Nursing, Jinan Central Hospital, Jinan City, Shangdong 250013, People's Republic of China., Department of Oncology, Qianfoshan Hospital of Shandong Province, Jinan City, Shangdong 250014, People's Republic of China., Department of Gastroenterology, Shouguang People's Hospital, Shouguang City, Shangdong 262799, People's Republic of China.

Abstract:  Purpose: This study aimed to evaluate the specific role of colon cancer-associated transcript 2 (CCAT2) on gastric cancer (GC), and reveal the potential regulatory mechanism relating to mammalian target of rapamycin (mTOR) signaling. Methods: The expression of CCAT2 was detected in GC tissues and cells by quantitative real-time PCR (qRT-PCR), and its relation with the pathologic characteristics of GC patients was analyzed. HGC-27 and SGC-7901 cells were transfected with siRNA-CCAT2 to silence CCAT2, and HGC-27 cells were then treated with an mTOR agonist Leucine (Leu) to activate mTOR signaling. The cell proliferation was evaluated by cell viability and colony formation. The cell cycle and apoptosis, and the migration and invasion abilities were detected by Flow cytometry, and Transwell assay, respectively. The expression of PCNA (proliferation marker), Snail, N-cadherin, E-cadherin (invasion markers), P53, Caspase-8, Bcl-2 (apoptosis markers), LC3-II/LC3-I, ATG3, p62 (autophagy makers), phosphorylated mTOR (p-mTOR), p-AKT, and p-p70S6K (mTOR signaling markers) were detected by Western blot. Results: CCAT2 was upregulated in GC tissues and cells, and positively associated with the maximum tumor diameter, lymphatic metastasis, TNM staging, and low overall survival rate (P &lt; 0.05). siRNA-CCAT2 transfection significantly inhibited the viability, colony formation, and migration and invasion abilities, blocked the cell cycle in G0/G1 phase, and promoted the apoptosis and autophagy of SGC-7901 and HGC-27 cells (P &lt; 0.05). In addition, siRNA-CCAT2 transfection significantly upregulated P53, Caspase-8, LC3-II/LC3-I and ATG3, and downregulated PCNA, Bcl-2, p62, p-mTOR, p-AKT and p-p70S6K in SGC-7901 and HGC-27 cells (P &lt; 0.05). siRNA-CCAT2 reversed the tumor-promoting effect of mTOR signaling activation on HGC-27 cells (P &lt; 0.05). Conclusion: Silencing of CCAT2 inhibited the proliferation, migration and invasion, and promoted the apoptosis and autophagy of GC cells through blocking mTOR signaling. 

Retracted: No

PubPeer comments:
 The colony forming assay images show show, throughout the manuscript, an unnaturally even spacing of colonies, which we would not normally expect to see under normal conditions. Moreover, there are some repetitive elements that add to the unlikeliness. I have included an example below.  We see similar indications of  collaging in the flow cytometry plots. I have again included an example.  Add to this the western blots that are, again throughout the paper, completely devoid of background and show signs of heavy image processing. I believe the authors need to show their raw data, if only to convince us that these experiments even took place. ,