Cl 0353

Fifty-one fresh OS tissues and paired adjacent non-tumor tissues were provided by the Shanxi Province Cancer Hospital. The detailed clinical characteristics of patients are described in Table 1. Upon resection, tissue samples were instantly snap-frozen in liquid nitrogen and stored at −80˚C until use. None of the subjects received any neoadjuvant therapy, such as radiotherapy or chemotherapy before surgery. Approval to conduct the project was obtained from the Ethics Committee of Shanxi Province Cancer Hospital with written informed consent from all sufferers.Table 1

Correlation between circDOCK1 expression and clinicopathological characteristics of OS patients (n = 51).

Clinical feature		circDOCK1
	N = 51	High (26)	Low (25)	P -Value
Age				0.630
≥20	18	10	8
<20	33	16	17
Gender				0.461
Male	30	14	16
Female	21	12	9
Tumour localisation				0.886
Femur	25	13	12
Other	26	13	13
Tumor size				0.065
≥5cm	23	15	8
<5cm	28	11	17
Clinical stage				0.017
I + IIA-B	22	7	15
III	29	19	10
Distant metastasis				0.018
Yes	24	8	16
No	27	18	9

*P < 0.05.

In this study, human OS cell lines: U2OS is p53 and MDM2 normal (CL-0236, Procell, Wuhan, China) and HOS is p53-mutant and CDKN2A (p16)-negative OS (CL-0360, Procell), were cultured in specific mediums (CM-0360, CM-0236, Procell) at 37˚C in 5 % CO₂, respectively. Normal human osteoblast cell line hFOB1.19 (CL-0353, Procell) was routinely incubated in DMEM/F12 with 10 % FBS and 1 % penicillin/streptomycin (Procell) at 34˚C.