[Upregulation of PLOD2 promotes invasion and metastasis of osteosarcoma cells].

Objective: To investigate the relationship of procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 (PLOD2) expression and the clinical characteristics of osteosarcoma, and explore the potential mechanism of tumour metastasis promoted by PLOD2. Methods: The expression of PLOD2 in osteosarcoma tissues and paired adjacent tissues were detected by immunohistochemistry and qRT-PCR. Correlation of PLOD2 expression in osteosarcoma with the clinical pathologic features was analyzed by Chi square test and Kaplan-Meier analysis.Fibrillar collagen formation and collagen deposition in the tumor tissues were detected by picrosirius red staining. We transfected U-2OS cells with LV-vector, LV-over/PLOD2, sh-NC and sh-PLOD2. The expression of PLOD2 was detected by qRT-PCR. The impact of POLD2 on U-2OS cell invasion was determined by wound-healing assay and Transwell migration assay. The expressions of PLOD2/FAK/JAK2-STAT3 signal pathway related proteins were detected by western blotting. Results: The high expression level of PLOD2 in osteosarcoma tissues was 72.5%, significantly higher than 0% in paired adjacent noncancerous tissues (P<0.01), the expression of PLOD2 was positively correlated with lymph node metastasis, pulmonary metastasis and poor outcome (P<0.01). The same results were also observed in qRT-PCR assay. The median survival time of patients with high expression of PLOD2 protein was 13 months, significantly shorter than 32 months of patients with low expression of PLOD2 (P<0.05). The result of picrosirius red staining showed that the percentage of collagen fiber deposition in the osteosarcoma tissue with high level of PLOD2 was (74.43+ 9.63)%, significantly higher than (9.67±1.28)% in tissue with low expression of PLOD2 (P<0.001). The result of wound-healing and Transwell migration assay showed that over-expression of PLOD2 markedly promoted the invasion, however, knockdown of PLOD2 suppressed the invasion of U-2OS cells (both P<0.01). The result of western blotting showed that over-expression of PLOD2 significantly increased the expression levels of p-FAK, p-JAK2, p-STAT3, but knockdown PLOD2 decreased the levels of p-FAK, p-JAK2, p-STAT3 in U-2OS cells. Conclusions: Up-regulation of PLOD2 in osteosarcoma is correlated with lymphatic and distant metastasis. PLOD2 promotes invasion and metastasis of osteosarcoma might through FAK/JAK2-STAT3 signal pathway.目的： 分析赖氨酸羟化酶2(PLOD2)的表达水平与骨肉瘤患者临床病理特征和预后的关系，并探讨其调控骨肉瘤细胞侵袭和转移的机制。 方法： 以免疫组化法和实时荧光定量PCR法检测40例骨肉瘤患者肿瘤组织和配对癌旁组织中PLOD2蛋白和mRNA的表达水平，并分析PLOD2蛋白的表达与患者临床病理特征的关系。应用天狼猩红染色检测胶原纤维蛋白沉积。以空载体(LV－vector)、过表达PLOD2(LV－over/PLOD2)、空白对照干扰(sh－NC)和干扰PLOD2表达(sh－PLOD2)的慢病毒载体转染骨肉瘤U－2OS细胞，采用实时荧光定量PCR法检测PLOD2 mRNA的表达情况；采用细胞划痕和侵袭实验检测U－2OS细胞的迁移和侵袭能力；采用Western blot法检测FAK/JAK2－STAT3信号通路相关蛋白的表达情况。 结果： PLOD2蛋白在骨肉瘤组织中的高表达率为72.5%，明显高于其在癌旁组织中的高表达率(0%，P<0.01)，PLOD2 mRNA在骨肉瘤组织和癌旁组织中的表达趋势与PLOD2蛋白的表达一致。PLOD2蛋白在骨肉瘤组织中的表达与骨肉瘤患者的淋巴结状态和远处转移有关(均P<0.01)。PLOD2蛋白高表达患者的中位生存时间为13个月，明显低于低表达组患者(32个月，P<0.05)。天狼猩红染色显示，在PLOD2蛋白高表达的骨肉瘤组织中，胶原纤维沉积百分比为(74.43±9.63)%；在PLOD2蛋白低表达的骨肉瘤组织中，胶原纤维沉积百分比为(9.67±1.28)%，差异有统计学意义(P<0.001)。细胞划痕和侵袭实验结果显示，过表达PLOD2可明显提高U－2OS细胞的迁移和侵袭能力(均P<0.01)，干扰PLOD2的表达后U－2OS细胞的迁移和侵袭能力明显减弱(均P<0.01)。Western blot法检测结果显示，过表达PLOD2可上调FAK/JAK2－STAT3信号通路相关蛋白p－FAK、p－JAK2、p－STAT3的表达；干扰PLOD2的表达后，p－FAK、p－JAK2、p－STAT3的表达明显下调。 结论： PLOD2在骨肉瘤组织中高表达，并与骨肉瘤细胞的迁移和侵袭有关；PLOD2促进骨肉瘤迁移和侵袭的机制可能与激活FAK/JAK2－STAT3信号通路有关。.