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. Author manuscript; available in PMC: 2016 Jun 15.
Published in final edited form as: Cancer Res. 2015 Apr 23;75(12):2566–2579. doi: 10.1158/0008-5472.CAN-14-2946

Figure 4. STAT3 inhibition sensitizes neuroblastoma to chemotherapy.

Figure 4

(A) Cell viability assay of different NB cell lines (NGP, SH-SY5Y, IMR-32, CHLA-255) were tested by MTS assay in response to etoposide alone and in combination of 0.5 μM and 1.0 μM Stattic treatment for 24 h. Experiments were repeated two times with six replicates for each condition and represented as mean ± SD. (B) Schematic representation of experimental plan to analyze the in vivo effect of STAT3 inhibitor and dual treatment strategy on neuroblastoma. Orthotopic mouse model was used to develop xenografts of NB NGP and SH-SY5Y cell lines and treated with either etoposide (12 mg/kg/day, i.p. injection, three times/week) and Stattic (25 mg/kg/day, i.p. injection, five days/week) alone or combined. Implanted mouse were treated two weeks post-implantation for two weeks. Vehicle (DMSO) was used as control in all experiments. (C) NGP xenografts showing significant decrease in tumor weights in response to Stattic treatment (p=0.03), etoposide treatment and combo treatment (p=0.001) in comparison to controls. Combo treatment also significantly reduced tumor burden in comparison to etoposide alone (p=0.008). (Mann-Whitney test, *p<0.05, **p<0.01, ***p<0.001). The percentage of CD114+ cells determined by flow cytometry analysis on individual tumors showed as mean ± SEM. Human MYCN mRNA was detected by qPCR in bone marrow of xenotransplanted mice. (D) SH-SY5Y xenografts showing significant decrease in tumor weights in response to Stattic treatment (p=0.02), etoposide treatment (p=0.0002) and combo treatment (p=<0.0001) in comparison to controls. Combo treatment also significantly reduced tumor burden in comparison to etoposide (p=0.02) and Stattic alone (p=0.0002). (Mann-Whitney test (*p<0.05, **p<0.01, ***p<0.001). The percentage of CD114+ cells determined by flow cytometry analysis on individual tumors showed as mean ± SEM. Detection of human MYCN mRNA by qPCR in bone marrow of xenotransplanted mice shows trend of reduction of metastasis with Stattic (p=ns).