Effect of silencing colon cancer-associated transcript 2 on the proliferation, apoptosis and autophagy of gastric cancer BGC-823 cells

Abstract

The role of long non-coding RNAs (lncRNAs) in the carcinogenesis and progression of tumors has been receiving increasing attention. Colon cancer-associated transcript 2 (CCAT2), a type of oncogenic lncRNA, is regarded as a novel biomarker of poor prognosis and metastasis in various types of cancer. However, the molecular contributions of CCAT2 to gastric cancer (GC) progression remain largely unclear. The aim of the present study was to demonstrate the effect of silencing CCAT2 on the biological behavior of GC BGC-823 cells and illustrate the potential underlying molecular mechanisms. A short hairpin RNA interference plasmid pRNAT-U6.1-CCAT2 targeting CCAT2 was successfully constructed. At 48 h after transfection with the interference plasmid, the survival rate of BGC-823 cells was significantly decreased, as determined by the MTT assay. In addition, RT-qPCR results revealed that CCAT2 gene expression was effectively suppressed by the transfection, while POU domain class 5 transcription factor 1B (POU5F1B) gene expression was significantly decreased. Terminal deoxynucleotidyl transferase dUTP nick end labeling assay further revealed that the apoptotic index was significantly higher in the interference group. Western blot analysis also demonstrated that the expression of beclin-1 protein was significantly increased, whereas the expression levels of phosphoinositide 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) proteins were downregulated in the interference group. In conclusion, CCAT2 was able to positively regulate the expression of POU5F1B gene. Furthermore, silencing of CCAT2 gene inhibited the proliferation of BGC-823 cells, as well as induced apoptosis and autophagy in BGC-823 cells, by suppression of the PI3K/mTOR signaling pathways.

<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>

“…In addition to the proliferation, a previous study has proved that the apoptotic index of BGC-823 cells is significantly increased by silencing of CCAT2. 11 In consistent with previous study, we found that siRNA-CCAT2 transfection significantly increased the percentage of apoptotic cells. In addition, siRNA-CCAT2 transfection significantly upregulated P53 and Caspase-8, and downregulated Bcl-2 in HGC-27 and SGC-7901 cells.…”

“…This result is just consistent with previous studies that CCAT2 knockdown significantly inhibits the growth ability and survival rate of BGC-823 cells. 10,11 We also found that siRNA-CCAT2 transfection significantly inhibited the colony formation, and downregulated PCNA in HGC-27 and SGC-7901 cells. These results further illustrate that silencing of CCAT2 inhibits the proliferation of GC cells.…”

“…9 In addition, previous studies have found that CCAT2 promotes the proliferation, migration, and invasion of GC cells, while silencing of CCAT2 inhibits the migration and invasion, and promotes the apoptosis of GC cells. 8,10,11 Although the tumor-promoting role of CCAT2 on GC cells has been identified in previous studies, the specific regulatory mechanisms of CCAT2 on GC are not fully revealed.…”

Prognostic model based on autophagy-related lncRNAs in gastric cancer

“…Among them, some lncRNAs were de ned as protective factors while others were risk factors [25,[41][42][43][44]. Furthermore, several studies have proved that lncRNAs participated in the progression, especially malignant progression of GC through regulating autophagy-related mRNAs [24][25][26][27][28][29]45].…”

“…Pieces of evidence showed that lncRNA is vital for the occurrence, prognosis, and chemoresistance of GC by regulating autophagy-related mRNA [24][25][26]. Some studies have demonstrated that silencing of LINC01419 and CCAT2 promotes autophagy through constraining the PI3K/Akt1/mTOR pathway thus inhibiting the invasion and migration of GC cells [27,28]; Another study also revealed that autophagy was associated with the proliferation of GC cells, partially due to the MALAT1 promoted by downregulating miR-204 [29]. However, most of these experiments only explored the role of one or a few lncRNAs in the autophagy of GC, and could not fully explain the relevant mechanisms.…”