T-cell activation promotes tumorigenesis in inflammation-associated cancer

Abstract

Chronic inflammation has long been associated with a wide range of malignancies, is now widely accepted as a risk factor for development of cancer, and has been implicated as a promoter of a variety of cancers including hematopoietic malignancies. We have described a mouse model uniquely suited to examine the link between inflammation and lymphoma in which the Tax oncogene, expressed in activated T and NK cells, perpetuates chronic inflammation that begins as microscopic intraepithelial lesions and develops into inflammatory nodules, subcutaneous tumors, and large granular lymphocytic leukemia. The use of bioluminescent imaging in these mice has expanded our ability to interrogate aspects of inflammation and tumorigenesis non-invasively. Here we demonstrate that bioluminescence induction in these mice correlated with inflammation resulting from wounding, T cell activation, and exposure to chemical agents. In experiments in which long-term effects of inflammation on disease outcome were monitored, the development of lymphoma was promoted by an inflammatory stimulus. Finally we demonstrated that activation of T-cells in T-cell receptor (TCR) transgenic TAX-LUC animals dramatically exacerbated the development of subcutaneous TCR- CD16+ LGL tumors. The role of activated T-cells and acquired immunity in inflammation-associated cancers is broadly applicable to hematopoietic malignancies, and we propose these mice will be of use in dissecting mechanisms by which activated T-cells promote lymphomagenesis in vivo.

Figure 1

Wound induced bioluminescence in TAX-LUC mice. Surgical lesions were experimentally introduced in ear (A) limb (B), and tail tissue (C). The effect of adjuvant on wound associated bioluminescence was also examined (B, C). Treatments include 1) vehicle, 2) CFA, 3) wound, and 4) wound and CFA. Images were obtained 0.5 hrs before treatment, and 0.5, 2, 24, and 48 hrs after treatment. Representative images shown from A) 30 minutes, B) 2 hours, and C) 24 and 48 hours after treatment.

Figure 2

Phorbol myristyl acetate stimulation of bioluminescence in transgenic mice. For each mouse, the left ear was treated with PMA and the right ear with vehicle. A) Representative images obtained 2 hours after treatment are shown for two LTR-LUC mice (left panels) and two TAX-LUC mice (right panels) comparing bioluminescence following administration of D-luciferin (top panels) and Luminol (bottom panel). B) Histology showing edema and inflammatory infiltrate associated with topical application of PMA (48 hours; Bar = 1 mm). C) Aggressive lymphoma in TAX-LUC mice from intravenous administration of con A. D) Histology is H/E stained sections of bioluminescent tumors in the cervical lymph nodes and small intestine of a con A treated TAX-LUC mouse.

Figure 3

Bioluminescence in TAX-LUC mice correlates with inflammatory response. Representative data are shown from groups of 3 mice each inoculated intraperitoneally with saline, con A, CFA, poly (I:C), or LPS. A) FACS histograms for CD16^lo cells (red curve) and CD16^hi cells (black curve) in liver and spleen 6 hrs after treatment. B) Representative BrdU IHC results from the spleen and liver. C) Bioluminescent images obtained 2 hrs after treatment. Bar = 1 mm.

Figure 4

Bioluminescence imaging of T-cell receptor activation in TAX-LUC-DO mice. Image (A) and quantitation (B) of the bioluminescence time-course following injections, indicated by arrows in B. C) BL images taken 1 hour prior to and 7 hours after immunization. All animals were injected with CFA and OA except where indicated. The total tail tumors in each animal during the course of the experiment is enumerated at the bottom of the figure.

Figure 5

T-cell receptor activation stimulates tumorigenesis in TAX-LUC-DO mice. A) Total number of tumors indicated by a single circle for each animal, with closed circles indicating mice immunized with CFA + OA and open circles indicating mice immunized with CFA alone. Red bars indicate the average number of tumors for each group. B) Survival curve for TAX-LUC-DO mice immunized with CFA and OA or CFA alone. C) FACS histograms of TCR expression in tumors that arose on the tail, small intestine, or ear of treated triple transgenics. D) Histology of tumors that infiltrated the spleen, lung, and liver as well as a comparison of gut and tail tumors. E) TCR^ova, CD16, and TAX expression in tail and gut tumors from a TAX-LUC-DO mouse.