Chemokine receptor CXCR4 activates the RhoA/ROCK2 pathway in spinal neurons that induces bone cancer pain

Abstract

Background Chemokine receptor CXCR4 has been found to be associated with spinal neuron and glial cell activation during bone cancer pain. However, the underlying mechanism remains unknown. Furthermore, the RhoA/ROCK2 pathway serves as a downstream pathway activated by CXCR4 during bone cancer pain. We first validated the increase in the expressions of CXCR4, p-RhoA, and p-ROCK2 in the spinal dorsal horn of a well-characterized tumor cell implantation-induced cancer pain rat model and how these expressions contributed to the pain behavior in tumor cell implantation rats. We hypothesized that spinal blockade of the CXCR4-RhoA/ROCK2 pathway is a potential analgesic therapy for cancer pain management. Methods Adult female Sprague–Dawley rats (body weight of 180–220 g) and six- to seven-week old female Sprague–Dawley rats (body weight of 80–90 g) were taken. Ascitic cancer cells were extracted from the rats (body weight of 80–90 g) with intraperitoneally implanted Walker 256 mammary gland carcinoma cells. Walker 256 rat mammary gland carcinoma cells were then injected (tumor cell implantation) into the intramedullary space of the tibia to establish a rat model of bone cancer pain. Results We found increased expressions of CXCR4, p-RhoA, and p-ROCK2 in the neurons in the spinal cord. p-RhoA and p-ROCK2 were co-expressed in the neurons and promoted by overexpressed CXCR4. Intrathecal delivery of CXCR4 inhibitor Plerixafor (AMD3100) or ROCK2 inhibitor Fasudil abrogated tumor cell implantation-induced pain hypersensitivity and tumor cell implantation-induced increase in p-RhoA and p-ROCK2 expressions. Intrathecal injection of stromal-derived factor-1, the principal ligand for CXCR4, accelerated p-RhoA expression in naive rats, which was prevented by postadministration of CXCR4 inhibitor Plerixafor (AMD3100) or ROCK2 inhibitor Fasudil. Conclusions Collectively, the spinal RhoA/ROCK2 pathway could be a critical downstream target for CXCR4-mediated neuronal sensitization and pain hypersensitivity in bone cancer pain, and it may serve as a potent therapeutic target for pain treatment.

Recent Advances in CXCL12/CXCR4 Antagonists and Nano-Based Drug Delivery Systems for Cancer Therapy

“…In gastric cancer cells, CXCL12/CXCR4 signaling can activate NF-kB; this upregulates the expression of serine protease inhibitor branch B member 3 (SERPINB3), thus promoting the metastasis of tumor cells [ 49 ]. In bone cancer, CXCR4 mediates pain hypersensitivity by activating the downstream RhoA/ROCK2 pathway [ 50 ]. In pancreatic ductal adenocarcinoma (PDAC), the CXCL12/CXCR4 axis mediates the desmoplastic reaction; this changes the tumor mechanical microenvironment and promotes drug resistance [ 51 ].…”

CXCR1 participates in bone cancer pain induced by Walker 256 breast cancer cells in female rats

“…Chemokine receptors are associated with activation of spinal neurons and glial cells during BCP. 24 To determine whether the upregulation of CXCR1 in the spinal dorsal horn was implicated in BCP, we tested whether the downregulation of CXCR1 by siRNA can alleviate hyperalgesia. In PC12 cells, CXCR1 siRNA significantly downregulated the expression of CXCR1 mRNA without affecting CXCR2 expression ( Figure 5(a) and (b) ).…”

Behavioural Voluntary and Social Bioassays Enabling Identification of Complex and Sex-Dependent Pain- (-Related) Phenotypes in Rats with Bone Cancer

“…These results are consistent with other studies, although there are contradictory results on body weight, depending on methodological aspects such as cell concentration, species, strain, sex, housing conditions, and observation duration, as well ( Currie et al, 2013; Shenoy et al, 2016; Shenoy et al, 2017; Viana et al, 2021 ). Additionally, there are sex-dependent contradictory results for heat hypersensitivity ( Bao et al, 2014; Shenoy et al, 2016; Xu et al, 2020 ). We did not detect heat hypersensitivity in male rats but females’ late tumor progression phase.…”