Long non-coding RNA LOC100133669 promotes cell proliferation in oesophageal squamous cell carcinoma

Objectives LOC100133669 is a lncRNA whose function during tumorigenesis remains unclear now. Thus, we aimed to explore its clinical significance and function in oesophageal squamous cell carcinoma (ESCC). Materials and Methods ISH was used to detect LOC100133669 expression in ESCC tissues. The full-length LOC100133669 was identified by using RACE assay. Subcellular distribution of LOC100133669 was examined by nuclear/cytoplasmic RNA fractionation and qPCR. The role of LOC100133669 in ESCC cell growth was determined by colony formation, MTT and flow cytometry experiments in vitro, as well as xenograft tumour experiment in vivo. RNA pull-down assay was performed to find LOC100133669-interacted protein, which was further examined by RIP, IP, Western blot and rescue experiments. Results LOC100133669 was upregulated in ESCC tissues compared with adjacent non-tumour tissues. High LOC100133669 expression was associated with poor prognosis of patients with ESCC. We defined LOC100133669 to be 831 nt in length and mainly localized in the cytoplasm of ESCC cells. Knockdown of LOC100133669 inhibited ESCC cell proliferation and cell cycle progression, while overexpression of LOC100133669 showed the opposite effects. Furthermore, LOC100133669 could bind to Tim50 and upregulated its protein level through inhibiting ubiquitination. Overexpression of Tim50 in part abolished the LOC100133669 depletion-caused inhibitory effect on ESCC cell proliferation. Conclusions LOC100133669 plays an oncogenic role in ESCC and may serve as a promising diagnostic marker and therapeutic target for ESCC patients.