IL-12 immunotherapy of Braf-induced papillary thyroid cancer in a mouse model

Abstract

Papillary thyroid carcinoma (PTC) accounts for 480% thyroid malignancies, and BRAF V600E mutation is frequently found in 440% PTC. Interleukin-12 (IL-12) is a proinflammatory heterodimeric cytokine with strong antitumor activity. It is not known whether IL-12 immunotherapy is effective against Braf V600E -induced PTC. In the present study, we investigated the effectiveness of IL-12 immunotherapy against Braf V600E -induced PTC in LSL-Braf V600E /TPO-Cre mice. LSL-Braf V600E /TPO-Cre mice were created for thyroid-specific expression of Braf V600E under the endogenous Braf promoter, and spontaneous PTC developed at about 5 weeks of age. The mice were subjected to two treatment regimens: (1) weekly intramuscular injection of 50 μg plasmid DNA expressing a single-chain IL-12 fusion protein (scIL-12/CMVpDNA), (2) daily intraperitoneal injection of mouse recombinant IL-12 protein (mrIL-12, 100 ng per day). The role of T cells, natural killer (NK) cells, and transforming growth factor-β (TGF-β) in IL-12-mediated antitumor effects was determined by a 51 Cr-release cytotoxicity assay. Tumor size and weight were significantly reduced by either weekly intramuscular injection of scIL-12/CMVpDNA or daily intraperitoneal injection of mrIL-12, and tumor became more localized. Survival was significantly increased when treatment started at 1 week of age as compared with that at the 6 weeks of age. Both NK and CD8 + T cells were involved in the cytotoxicity against tumor cells and their antitumor activity was significantly reduced in tumor-bearing mice. TGF-β also inhibited the antitumor activity of NK and CD8 + T cells. The immune suppression was completely reversed by IL-12 treatment and partially recovered by anti-TGF-β antibody. We conclude that both IL-12 gene therapy and recombinant protein therapy are effective against PTC. Given that the immune response is significantly suppressed in tumor-bearing mice and can be restored by IL-12, the current study raises a possibility of the application of IL-12 as an adjuvant therapy for thyroid cancer.

The immune network in thyroid cancer

“…Interestingly, IL-12 improved the cytotoxic activity of CD8 C T cells and NK cells, and increased the infiltration of M1 macrophages compared to alternative M2 macrophages within the tumors. 96 …”

Perspectives for immunotherapy in endocrine cancer

“…Both treatments resulted in significantly lower tumor burden and were mediated by CD8+ and natural killer cells. Suppression of IL-12 abolished these effects indicating that IL-12 might be of interest as adjuvant therapy in advanced BRAF V600E thyroid cancers (Parhar et al 2016).…”

Novel Therapies Against Aggressive Differentiated Thyroid Carcinomas

“…All of this may lead to an immune evasion by cancer cells and progression of the disease [58,59]. There are preclinical and clinical trials at the moment studying therapies targeting tumor-associated macrophages, tumor antigens, T cells, natural killer cells and immune checkpoints [58][59][60]. Also, combination therapy of TKIs with other drugs such as immune checkpoint inhibitors is a matter of special interest [61].…”

“…New multi-TKIs (pyrazolopyrimidines and derivatives of CLM3) and other therapeutic classes such as inhibitors of aurora kinases, proteasome, kinesin spindle protein, cancer stem cells and histone deacetylases, flavonoids, gene and apoptotic cell death-based therapies have already shown promising results in preclinical studies, and may have a role in advanced TC therapy in the future [26][27][58][59][60][64][65][66][67][68][69][70][71]. No writing assistance was utilized in the production of this manuscript.…”