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Additional file 1: Fig. S1. Body weight changes in mice receiving radiation or pregabalin. Body weight changes in mice after 14 days of continuous injection of pregabalin (PGB) or saline solution (Con) in RIBI mice. For days 1–4 post-treatment, n = 14–23 mice per group. For days 5–8 post-treatment, n = 10–15 mice per group. For days 9–14 post-treatment, n = 4–9 mice per group. Fig. S2. Microglial body size and CD68 expression changes after radiation in vivo. A Representative confocal images of IBA1 and CD68 co-labeling in the cortex of mice 3, 7, or 14 days after radiation. Red: IBA1, green: CD68. B-C Quantification of the body size of IBA1+ cells and the proportion of CD68+ area / IBA1+ area in the cortex. Data were analyzed by one-way ANOVA followed by the Student’s t-test analysis. All other groups were compared with the control group. n = 4 mice per group and 2–3 slices per mouse for immunofluorescence staining. Data were presented as mean ± SEM, *p < 0.05, **p < 0.01, and ***p < 0.001. Fig. S3. Pregabalin inhibited microglia activation in the cortex of RIBI mice. A Representative images of IBA1 and CD68 co-labeling in the cortex of mice 3 days after radiation. Red: IBA1, green: CD68. B Quantification of the proportion of CD68+ area / IBA1+ area in the cortex of mice 3 days after radiation. C Representative images of IBA1 and CD68 co-labeling in the cortex of mice 7 days after radiation. D Quantification of the proportion of CD68+ area / IBA1+ area in the cortex of mice 7 days after radiation. Data were analyzed by one-way ANOVA followed by the Student’s t-test analysis. All other groups were compared with the indicated group. n = 4 mice per group and 2–3 slices per mouse for immunofluorescence staining. Data were presented as mean ± SEM, *p < 0.05, **p < 0.01, and ***p < 0.001. Fig. S4. Pregabalin inhibited microglia activation in the hippocampus of RIBI mice. A-B Representative confocal images of IBA1 and CD68 co-labeling in the hippocampal CA1 (A) and DG (B) regions of RIBI mice 14 days after pregabalin treatment. Red: IBA1, green: CD68, and blue: DAPI. n = 4 mice per group and 2–3 slices per mouse for immunofluorescence staining. See Fig. 1I-J for statistical data in the main text. Fig. S5. Effect of pregabalin on microglial inflammatory response induced by radiation in vitro. A-D Q-PCR analysis the effects of pregabalin, with different concentration (1 µM, 6.25 µM, 12.5 µM, 25 µM, and 50 µM), on the mRNA levels of inflammatory factors Il-1β, Tnf-α, Cox-2, and iNos in BV2 cells after a single dose of 10 Gy radiation. Data were analyzed by one-way ANOVA followed by the Student’s t-test analysis. All other groups were compared with the indicated group. n = 3 per group for Q-PCR analysis in vitro. Data were presented as mean ± SEM, ns = not significant, **p < 0.01, and ***p < 0.001. Fig. S6. Effect of pregabalin on IL-6 and TNF-α expressions in microglia after radiation. A Representative immunofluorescent images of IL-6 and β-tubulin in BV2 cells among the different groups. Staining with β-tubulin to visualize cytoskeleton and staining with DAPI to visualize nucleus. B The fluorescence intensity data of IL-6 were recorded by confocal microscopy. C Representative immunofluorescent images of TNF-α and β-tubulin in BV2 cells among the different groups. D The fluorescence intensity data of TNF-α were recorded by confocal microscopy. Data were analyzed by one-way ANOVA followed by the Student’s t-test analysis. All other groups were compared with the indicated group. n = 3 per group for immunofluorescence staining in vitro. Data were presented as mean ± SEM, ns = not significant and **p < 0.01. Fig. S7. Pregabalin inhibited microglial inflammatory response not by acting on astrocyte in vitro. A Schematic diagram of BV2 cells incubated with the culture supernatant from astrocyte after different treatment. B-E Q-PCR analysis of Il-1β, Tnf-α, iNos, and Icam-1 mRNA levels in BV2 cells after incubated with the supernatant from pregabalin-treated astrocyte. Data were analyzed by one-way ANOVA followed by the Student’s t-test analysis. All other groups were compared with the indicated group. n = 4 per group for Q-PCR analysis in vitro. Data were presented as mean ± SEM, ns = not significant and *p < 0.05. Fig. S8. Effect of pregabalin on potential chemokines in injured neurons. A-G Q-PCR analysis of Mmp9, Cgrp, Tac1, Cx3cl1, Ccl21, Mmp2, and Ccl2 mRNA levels in neurons after treatment with the different supernatant from BV2 cells. Data were analyzed by one-way ANOVA followed by the Student’s t-test analysis. All other groups were compared with the indicated group. n = 3 per group for Q-PCR analysis in vitro. Data were presented as mean ± SEM, ns = not significant, *p < 0.05, and ***p < 0.001. Fig. S9. Knocking out TLR2/TLR4/RAGE mitigated microglia activation. A-C Schematic diagram of CRISPR/Cas9-mediated TLR2/TLR4/RAGE knockout in BV2 cells and Q-PCR analysis was used to detect the knockout efficiency. D-F Q-PCR analysis of Il-6, Tnf-α, and Cox-2 mRNA levels in activated BV2 cells which were treated with culture supernatant from radiation-injured (activated) or normal (control) neurons for 24 h. Data were analyzed by one-way ANOVA followed by the Student’s t-test analysis. All other groups were compared with the indicated group. n = 3–4 per group for Q-PCR analysis in vitro. Data were presented as mean ± SEM, *p < 0.05, **p < 0.01, and ***p < 0.001. Table S1. List of primers used for RNA analyses. Table S2. List of antibodies used in this study. Table S3. List of gRNA sequences used for CRISPR/Cas9-mediated gene knockout. Table S4. List of oligonucleotide sequences used for plasmid construction. Table S5. List of primers used for the verification of CRISPR/Cas9-mediated gene knockout.

Zhongming Jia,1,* Huamin Zhu,2,* Hongguang Sun,1 Yitong Hua,1 Guoqiang Zhang,1 Jingru Jiang,1 Xiaohong Wang1 1Department of Thyroid and Breast Surgery, Affiliated Hospital of Binzhou Medical University, Binzhou 256603, Shandong, People’s Republic of China; 2Department of Medical Ultrasonics, Affiliated Hospital of Binzhou Medical University, Binzhou 256603, Shandong, People’s Republic of China*These authors contributed equally to this work.Correspondence: Zhongming Jia Tel +86-543-325779Email zhongmingjia522@126.comBackground: Emerging evidence has noted the versatile functions of mesenchymal stem cell-derived exosomes (MSC-Exos) in cancer control. This work aims to probe to function of adipose MSC-Exos (adMSC-Exos) in drug-resistance of breast cancer (BC) cells to cisplatin (DDP) and the molecules involved.Methods: Parental and DDP-resistant BC cell lines MCF-7 and MDA-MB-231 were used. All cells were pre-treated with adMSC-Exos. Then, the viability and apoptosis of cells after DDP treatment were determined. Differentially expressed miRNAs after adMSC-exo treatment were screened out. Rescue experiments were conducted by pre-transfecting miR-1236 inhibitor into adMSCs, and the role of miR-1236 in DDP sensitivity was determined. Targeting mRNAs of miR-1236 were predicted by bioinformatics analysis. Altered SLC9A1 expression was administrated to evaluate its function in DDP resistance.Results: The adMSC-Exos notably increased the sensitivity of either parental or DDP-resistant BC cells to DDP. SLC9A1 was notably highly expressed in DDP-resistant cells but inhibited following adMSC-exo administration. Importantly, miR-1236, which could directly bind to SLC9A1 and suppress its expression, was confirmed as an enriched miRNA in adMSC-Exos. Either inhibition of miR-1236 or upregulation of SLC9A1 blocked the pro-sensitize roles of adMSC-Exos. In addition, the Wnt/β-catenin pathway activity was suppressed by adMSC-Exos but recovered by SLC9A1.Conclusion: This study evidenced that adMSC-Exos carry miR-1236 to increase sensitivity of BC cells to DDP with the involvement of SLC9A1 downregulation and Wnt/β-catenin inactivation. This finding may offer novel insights into treatment for drug-resistant BC.Keywords: breast cancer, cisplatin, resistance, adipose mesenchymal stem cell-derived exosomes, microRNA-1236, SLC9A1