International Journal of Biomedical Engineering and Clinical Science 2018; 4(1): 25-29 http://www.sciencepublishinggroup.com/j/ijbecs doi: 10.11648/j.ijbecs.20180401.15 ISSN: 2472-1298 (Print); ISSN: 2472-1301 (Online) Down-Regulation of Long Non-Coding RNA CASC9 Suppresses the Migration and Invasion of Esophageal Cancer Cells Maliha Ghaffar 1, *, † , Sara Khodahemmati 1, † , Jintao Li 1, * , Muhammad Shahzad 3 , Minglian Wang 1 , Yangjunqi Wang 1 , Yi Zeng 1, 2, * 1 Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bio-Engineering, Beijing University of Technology, Beijing, China 2 State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China 3 School of Economics and Management, North China Electric Power University, Beijing, China Email address: * Corresponding author † Maliha Ghaffar and Sara Khodahemmati are co-first authors. To cite this article: Maliha Ghaffar, Sara Khodahemmati, Jintao Li, Muhammad Shahzad, Minglian Wang, Yangjunqi Wang, Yi Zeng. Down-Regulation of Long Non-Coding RNA CASC9 Suppresses the Migration and Invasion of Esophageal Cancer Cells. International Journal of Biomedical Engineering and Clinical Science. Vol. 4, No. 1, 2018, pp. 25-29. doi: 10.11648/j.ijbecs.20180401.15 Received: March 7, 2018; Accepted: March 24, 2018; Published: April 12, 2018 Abstract: The objective of the study was to investigate the role of CASC9 in esophageal cancer cells migration and invasion. Expression of long noncoding RNA (lncRNA) CASC9 was found high in esophageal cancer cells by qRT-PCR. The CASC9 knockdown effects on cell migration and invasion were analyzed in vitro. Expression of lncRNA CASC9 was found markedly high in KYSE-450 cell line as compared to other esophageal cancer cell lines. After the knockdown of CASC9, migration and invasion were significantly decreased as compared to negative control. Increased expression of CASC9 before knockdown and decreased expression after knockdown in esophageal cancer cells, showed that CASC9 may act as a biomarker for esophageal cancer and may help to understand the mechanisms of this lethal disease. Keywords: CASC9, Esophageal Cancer, Cell Migration, Invasion, Long Noncoding RNA 1. Introduction Esophageal cancer (EC) is one of the deadliest malignancies in the world and ranked as the 6 th main cause of cancer deaths [1, 2]. The two main subtypes of EC are esophageal squamous cell carcinoma (ESCC) and esophageal adreno-carcinoma (EAC). Both types are characterized by distinct pathology and etiology but the most prominent histologic type in China is ESSC as its occurrence is more than 90% [1, 3]. EC is diagnosed at late-stage despite the advancement in diagnostic techniques and therapeutics. Overall 5 years survival rate is less than 40% due to the aggressiveness of this lethal malignancy [4, 5]. The mortality rate can be reduced by early diagnosis along with effective therapeutics and novel biological markers with high specificity and sensitivity can help us to achieve this goal. For this purpose, it is the need of time to understand all molecular changes which take place in biological pathways as a result of the disease and will give us a better understanding of the disease. As a result of transcription, a large numbers of protein- coding, as well as non-protein coding RNAs are produced. In 2002, non-coding RNAs were discovered for the first time [6]. Non-coding RNAs are proved to be key regulators of different biological pathways which can cause transformation of normal cells to malignant cells [7, 8]. Long non-coding RNAs (lncRNAs) are non-coding RNA molecules consists of more than 200 nucleotides and protein-coding potential is either absent or limited. Research evidence has proved their