Elsevier

Life Sciences

Volume 188, 1 November 2017, Pages 37-44
Life Sciences

Down regulation of the long non-coding RNA PCAT-1 induced growth arrest and apoptosis of colorectal cancer cells

https://doi.org/10.1016/j.lfs.2017.08.024Get rights and content

Abstract

Aims

The long non-coding RNA (lncRNA) was reported to be involved in the progress of various cancers, however, its effect in colorectal cancer (CRC) remains unknown. The goal of the present study is to investigate the function role of lncRNA PCAT-1 in colorectal cancer.

Main methods

The expression of lncRNA PCAT-1 in four CRC cell lines was measured by real-time PCR, and two lncRNA PCAT-1 high expression cell lines were selected. LncRNA PCAT-1 in these two CRC cell lines was down-regulated by shRNA, and the stable transfected cells were established. Functional involvement of lncRNA PCAT-1 in proliferation and apoptosis of the two CRC cells were evaluated in vitro. Mover, the effect of lncRNA PCAT-1 in tumor proliferation was also evaluated in CRC cell xenograft.

Key findings

The results showed that down-regulation of lncRNA PCAT-1 in CRC cells inhibited proliferation, blocked cell cycle transition, and suppressed the expression of cyclins and c-myc. The apoptosis cell proportion was elevated with increased expression of pro-apoptotic proteins and decreased anti-apoptotic proteins in lncRNA PCAT-1 knock down cells. Forced over-expression of c-myc in PCAT-1 down-regulated CRC cells increased the level of cyclins. The xenograft growth in lncRNA PCAT-1 down-regulated cells was significantly inhibited along with the reduced proliferative cells.

Significance

Our study revealed a tumorigenic effect of lncRNA PCAT-1 in CRC cells, and this effect is partly dependent on the inhibition of c-myc.

Introduction

Colorectal cancer (CRC) is the second most commonly cancer, that there are approximately 1.4 million new cases every year [1]. The mortality rate of CRC has declined over the past 20 years due to the development of screening techniques and improvement in treatments. However, there are still 693,900 people die from CRC every year [1]. Traditional therapies such as surgery, chemotherapy and radiotherapy have limited curative effect on these metastatic malignancies [2]. Therefore, further investigating the underlying pathogenesis and searching for high specificity and sensitivity target of CRC will contribute to decreasing the morbidity and mortality.

Long non-coding RNAs (lncRNAs) are non-protein coding transcripts that over 200 nucleotides in length. Increasingly evidences showed that lncRNAs are involved in diverse biological processes by regulating gene activation and inactivation [3], [4], [5]. The new identified lncRNA, PCAT-1, has been reported to contribute to the progress of prostate cancer [6], [7], esophageal squamous carcinoma [8], bladder cancer [9], hepatocellular carcinoma [10], [11], non-small cell lung cancer cells [12], glioblastoma cells [13], and so on. In addition, Ge et al. [14] found that lncRNA PCAT-1 is frequently up-regulated in colorectal cancer tissues compared to the adjacent normal tissues in colorectal cancer patients, the high expression of lncRNA PCAT-1 was observably related to a poor prognosis. However, the precise role of lncRNA PCAT-1 in the progress of CRC remains unknown.

In the present study, the expression of lncRNA PCAT-1 in four colorectal carcinoma cell lines was determined, and two highly expressed cell lines were selected. The expression of lncRNA PCAT-1 in these two cell lines was down-regulated by shRNA, then, the effects of lncRNA PCAT-1 on the progress of CRC was studied in vitro and in vivo. The potential molecular mechanism was also studied.

Section snippets

Cell lines

The colorectal cancer cell lines HT-29, SW480 and Caco-2 cells were purchased from Type Culture Collection Center of Chinese Academy of Science, Shanghai, China. HTC-116 cell was purchased from Zhong Qiao Xin Zhou Biotechnology Co., Ltd. (Shanghai, China). Cells were maintained in Dulbecco's Modified Eagle Medium (DMEM, Gibco, Grand Island, NY, USA) supplemented with 10% fetal bovine serum (FBS, HyClone, Logan, UT, USA), 100 U/ml penicillin and 100 μg/ml streptomycin in an incubator at 37 °C, 5% CO

Stable down-regulation of lncRNA PCAT-1 in CRC cell lines

Firstly, the expression of lncRNA PCAT-1 in four CRC cell lines was detected, as shown in Fig. 1a, the level of PCAT-1 in Caco-2 and HT-29 cell lines was higher than that in the other two cells, thus, Caco-2 and HT-29 cell lines were selected for further study. To explore the role of lncRNA PCAT-1 in the development and progress of CRC, the expression of PCAT-1 in HT-29 and Caco-2 cells were down-regulated by shRNA and the stable transfected cell lines was selected with G418. As shown in Fig. 1

Discussion

The role of lncRNA PCAT-1 in colorectal cells remains unknown. In the present study, the expression of lncRNA PCAT-1 in HT-29 and Caco-2 cell lines was stably down-regulated by shRNA, and the effect of lncRNA PCAT-1 on the progress of colorectal carcinoma was determined. The results showed that, down-regulation of lncRNA PCAT-1 significantly suppressed the proliferation of colorectal cancer cells, that accompanied by the cell cycle arrest. In addition, inhibition of lncRNA PCAT-1 also induced

Conclusion

Taken together, our data suggest that lncRNA PCAT-1 acts as a tumor promotive gene in colorectal carcinoma. Down-regulation of lncRNA PCAT-1 could inhibit proliferation and induce apoptosis of colorectal carcinoma cells, and these effects was partly dependent on the inhibition of c-myc. Our results indicate that lncRNA PCAT-1 may serve as a potential novel therapeutic target for colorectal carcinoma.

The following are the supplementary data related to this article.

. The effect of shRNA2-PCAT-1 on

Conflict of interest statement

The authors declare that there are no conflicts of interest.

Author contributions

Yong Feng and Lei Qiao designed the study. Lei Qiao, Xiangyu Liu, Yichao Tang and Zheng Zhao performed the experiment. Lei Qiao and Jilong Zhang analyzed the data and constructed the figures. Lei Qiao and Yong Feng drafted the manuscript. All authors read and approved the final manuscript.

Acknowledgments

This work was supported by the Science and Technology Plan Project of Shenyang City [grant number F12-277-1-19].

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