RESUMEN
Chemokine signal pathways are important for the regulation of tumour metastasis. Chemokine receptors CXCR4 (C-X-C chemokine receptor type 4) and XCR1 (chemokine XC receptor 1) are involved in the metastasis of breast cancer, while the interaction between them remains unclear. Here we first identified the interaction between CXCR4 and XCR1 based on membrane protein yeast two-hybrid assays. Bioluminescence resonance energy transfer (BRET) showed that XCR1 could competitively bind to CXCR4 to form a heterodimer (P < 0.01). Results of wound healing assays via transient transfection of XCR1 and CXCR4 into HEK293 cells showed that 41.55% of the migration area rate in the co-transformation group was lower than 58.75% in the CXCR4-alone group after adding 30 nmol/L S D F-β. The co-expression of XCR1 inhibited the cellular motility, possibly mediated by the SDF-1β (stromal cell-derived factor 1)/CXCR4 signal pathway (P < 0.05). Furthermore, CXCR4 on the cell surface after co-expression of XCR1 in CXCR4-EGFP transgenic HEK293 cells was detected by flow cytometry. And the result suggested that XCR1 could accelerate the internalization of CXCR4 into the heterodimer induced by 30 nmol/L SDF-1β (P<0.05), which increased the internalization rate from 14.38% to 64.10%. Finally, the phosphorylation of Akt and ERK, which were involved in cell proliferation and migration, respectively, were examined. After 10 minutes of SDF-1β stimulation, ERK phosphorylation in the CXCR4-alone group showed a 3.59-fold increase, whereas the increase of ERK phosphorylation in the co-transfected group was only 2.08-fold. Interestingly, heterodimer formation reduced the phosphorylation level of ERK and shortened the activation time, whereas the phosphorylation level of Akt remained unchanged. Collectively, our findings revealed the hetero-dimerization of CXCR4 and XCR1 and its effects on CXCR4-mediated cellular motility, receptor internalization, and ERK pathway phosphorylation. Therefore, XCR1-targeting drugs could be candidates for cross-desensitization of CXCR4 and might represent a possible option for inhibiting breast cancer metastasis.
RESUMEN
Objective::To observe the clinical efficacy of Duhuo Xuduan Tang for oral administration and iontophoresis in the treatment of knee osteoarthritis (KOA) with liver and kidney deficiency and its effect on stromal cell-derived factor-1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4) signaling pathway. Method::Totally 150 KOA patients with deficiency of liver and kidney diagnosed in the Teaching Hospital of Tianjin University of Traditional Chinese Medicine(TCM) were randomly divided into control group, oral TCM group and iontophoresis group, with 50 cases in each group. The control group was given glucosamine sulfate capsule, 0.5 g/time, twice a day, while the oral TCM group was given Duhuo Xuduan Tang, 150 mL/time, twice a day. In the iontophoresis group, Duhuo Xuduan Tang was administered at Kuangu acupoint, Xiguan acupoint, Xiyan acupoint and Dubi acupoint for iontophoresis for 30 minutes, once a day. All of the three groups were treated for 4 weeks. The swelling degree and the pain degree of knee joint before and after treatment were observed, and the clinical efficacy was recorded. The protein contents of SDF-1, CXCR4, matrix metalloproteinase-3 (MMP-3) and matrix metalloproteinase-13 (MMP-13) in knee joint fluid before and after treatment were detected by enzyme-linked immunosorbent assay (ELISA). Result::The efficacy of oral TCM group was better than that of iontophoresis group and control group, and the recurrence rate was the lowest (P<0.05). Compared with before treatment, the tenderness increased, whereas visual analogue scale(VAS) score, knee swelling score, The Western Ontario and McMaste Universities (WOMAC) score and SDF-1, CXCR4, MMP-3 and MMP-13 protein content in knee joint fluid decreased in oral TCM group after treatment, which were better than those in iontophoresis group and control group (P<0.05). Conclusion::Duhuo Xuduan Tang for oral administration and iontophoresis has an obvious effect on KOA with liver and kidney deficiency, with the best effect through oral administration. Its mechanism may be related to the inhibition of SDF-1/CXCR4 inflammatory signaling pathway and cartilage decomposition.