Aberrant activation of Janus kinase (JAK) / signal transducer and activator of transcription (STAT) 3 pathway has been implicated in tumor initiation, progression and metastasis which make it a potential therapeutic target in human malignancies. In vitro STAT3 inhibition exhibited anti-tumor effect in medulloblastoma (MB) cell lines; however, little has been reported about the mechanisms of STAT3 activation in medulloblastoma (MB). We found that STAT3 was constitutively activated in both medulloblastoma patient samples and 3 mice models that were clinically classified as SHH subgroup, Group 3 and Group 4 in pediatric MB patients. By using PCR arrays we investigated the early expression profile of local cytokines in host cerebellum during MB pathogenesis and found increased IL17B, IL6 and TNFα in the microenvironment of MB mice models. In vitro cytokine stimulation assay indicated that IL6 was the major activator of STAT3 in D283 MB cells. Confocal immunofluorescence staining of different cell components in the cerebellum in D283 xenografts showed that the endothelial cells and Purkinje cells were the two major sources of IL6 secretion. Our data provides molecular and cellular clue for the activation of STAT3 signaling during MB tumorigenesis and might help to develop more effective therapeutic targets for STAT3 blockade in MB.

Citation Format: Shuang Yan, Sampurna Chatterjee, Trupti Vardam, Shuji Kitahara, Tai Hato, Sylvie Roberge, Vasileios Askoxylakis, Mark Duquette, Dai Fukumura, Lei Xu, Rakesh Jain. Microenvironmental Interleukin-6 induced activation of STAT3 signaling in medulloblastoma: Implications for molecular pathology and therapy. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Pediatric Cancer Research: From Mechanisms and Models to Treatment and Survivorship; 2015 Nov 9-12; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(5 Suppl):Abstract nr A12.