Aims
The analgesic effect of ketamine in cancer pain remains controversial. This research investigates the role of ketamine in bone metastasis-induced cancer pain in breast cancer (BC) and its associated molecular network.
Conclusion
This study demonstrates that ketamine alleviates BC cell-induced osteoclastogenesis and tumor bone metastasis by suppressing SRC and restoring the EGR1/CST6 axis.
Methods
BC cell lines MDA-MB-231 and ZR-75-1 were treated with ketamine and malignant behaviors were assessed through CCK-8, colony formation, and Transwell assays. To evaluate the pro-osteoclastic effect in vitro, BC cells were co-cultured with RAW 264.7 cells. Alterations in the expression of SRC proto-oncogene (SRC), early growth response 1 (EGR1), and cystatin E/M (CST6) were induced in BC cells using lentivirus. MDA-MB-231 cells were injected intracardially into nude mice to examine tumor bone metastasis in vivo. Molecular interactions between SRC and EGR1, as well as between EGR1 and CST6 were analyzed via immunoprecipitation and luciferase assays.
Results
Ketamine treatment suppressed viability, proliferation, migration and invasiveness, epithelial-mesenchymal transition, and pro-osteoclastic effect in BC cells. Ketamine also reduced osteoclastogenesis and tumor bone metastasis burden and alleviated pain in nude mice. SRC was identified as a target of ketamine. Overexpression of SRC in BC cells blocked the effects of ketamine. SRC bound to the EGR1 promoter, suppressing EGR1 transcription, whereas EGR1 activated CST6 transcription. Either EGR1 or CST6 overexpression counteracted the function of SRC overexpression and decreased the viability of BC cells and their pro-osteoclastic effect in vitro and in vivo.