Date on Master's Thesis/Doctoral Dissertation
Microbiology and Immunology
Cytokines--Therapeutic use; Cancer--Treatment
Tumor infiltrating and tumor associated myeloid cells (TIMs and TAMs) elaborate an array of factors that promote tumor growth and metastasis. IL-12, a potent inflammatory cytokine has been shown to induce regression of many cancers. We hypothesize that IL-12 augments the ability of TIMs and TAMs to respond to inflammatory stimuli providing a window in which these stimuli are more likely to promote tumor destruction. Related to this hypothesis, we asked two questions: (1) Does IL-12 directly change signaling events associated with inflammatory signal transduction? (2) Is IFN? required for the entirety of IL-12 induced enhancement of the response of TIMs to inflammatory stimuli? First, we looked broadly at the in vivo effects of microspheres containing IL-12 on the growth and metastasis of 4T1 tumors. We also did studies with tumor cell-dendritic cell fusion for future examination of the impact of IL-12 and myeloid cells on the efficacy of tumor cell-dendritic cell fusion vaccines in mice. Most of this dissertation focuses on in vitro work using TIMs and TAMs isolated from wild-type BALB/c or IFN? deficient mice bearing the 4T1 mammary carcinoma. TIMs and TAMs were pretreated in vitro with IL-12 followed by LPS. TNFa, IL-6, and IL-10 cytokine and mRNA levels were measured. We also examined the impact of IL-12 on the response 4T1 TIMs to tumor derived products. The phosphorylation of a number molecules involved in inflammatory signaling pathways, including MAPK proteins, were assessed by Western Blot. We found that treatment of TIMs with IL-12 followed by exposure to LPS enhances the amount of IL-6 and TNFa with a reciprocal decrease in IL-10. This observation is associated with increases in the phosphorylation of MAPKs. The presence of IFN? is only partially necessary for these effects. We observed that IL-12 only significantly impacted the production of IL-10 from 4T1 TAMs in response to LPS. IL-12 caused a significant increase in the amount of TNFa and IL-6 in response to tumor derived products without affecting IL-10. Our results provide additional insight into direct changes induced by IL-12 to the functional phenotype of TIMs and TAMs in response to inflammatory stimuli.
Mitchell, Courtney Jetun, "IL-12 induced modulation of tumor derived myeloid cell inflammatory responsiveness." (2014). Electronic Theses and Dissertations. Paper 991.