Dataset Information

Biological effects of prostaglandin E2-EP4 antagonist (AAT-008) in murine colon cancer in vivo: enhancement of immune response to radiotherapy and potential as a radiosensitizer.

ABSTRACT:

Background

Prostaglandin E2 (PGE2) promotes tumor growth and metastasis by acting on a family of four receptors (EP1-4). We investigated the radiosensitizing effects of a newly developed antagonist of PGE2-EP4 (AAT-008) in mouse colon cancer cells in vivo and explored the mechanism using flow cytometry (FCM).

Methods

CT26WT cells grown in Balb/c mice were used. AAT-008 at doses of 0, 3, 10, and 30 mg/kg/day was orally administered once or twice daily for up to 19 days. On day 3, the tumors were irradiated at 9 Gy in the radiotherapy (RT) group. Tumor sizes were measured every other day. For the first FCM series, AAT-008 (10 mg/kg/day) was administered from day 0 to 18 and RT (9 Gy) was given on day 3. The population of effector T cells (Teff), defined as CD45⁺CD8⁺CD69⁺, in the tumors was investigated on day 19. For the second FCM series, AAT-008 (30 mg/kg/day) was administered from day 0 to 12. The populations of Teff and regulatory T cells (Treg), and the ratio of Teff/Treg were investigated on day 13.

Results

The growth delay effect of AAT-008 administered alone (3-30 mg/kg/day) appeared minimal. In the first growth delay experiment where AAT-008 was administered once daily, the combined effect of AAT-008 (30 mg/kg/day) and RT appeared additive. In the second growth delay experiment where AAT-008 was administered twice daily, the combined effect appeared additive at 3 and 10 mg/kg/day and supra-additive at 30 mg/kg/day. In the first FCM series, the mean Teff proportions in the tumors were 43% and 31% in the 10 mg + RT and 0 mg + RT groups, respectively. Notably, 67% Teff was observed in responsive mice in the 10 mg + RT group. In the second FCM series, the mean Treg proportion and Teff/Treg ratio in the 0 mg + RT and 30 mg + RT groups were 4.0% and 1.5%, respectively (P=0.04) and 10 and 22, respectively (P=0.04).

Conclusions

AAT-008 potentially enhances the radiosensitivity of colon cancer cells, apparently by stimulating the immune system against the cancer cells.

SUBMITTER: Manabe Y

PROVIDER: S-EPMC10007874 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature

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Publications

Biological effects of prostaglandin E2-EP4 antagonist (AAT-008) in murine colon cancer <i>in vivo</i>: enhancement of immune response to radiotherapy and potential as a radiosensitizer.

Manabe Yoshihiko Y Takahashi Yutaka Y Sugie Chikao C Wang Zhen Z Katsuki Shohei S Kondo Takuhito T Murai Taro T Nakashima Masahiro M Takaoka Taiki T Ogawa Kazuhiko K Shibamoto Yuta Y

Translational cancer research 20230129 2

<h4>Background</h4>Prostaglandin E2 (PGE2) promotes tumor growth and metastasis by acting on a family of four receptors (EP1-4). We investigated the radiosensitizing effects of a newly developed antagonist of PGE2-EP4 (AAT-008) in mouse colon cancer cells <i>in vivo</i> and explored the mechanism using flow cytometry (FCM).<h4>Methods</h4>CT26WT cells grown in Balb/c mice were used. AAT-008 at doses of 0, 3, 10, and 30 mg/kg/day was orally administered once or twice daily for up to 19 days. On d ...[more]

PMID: 36915594

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