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Hypoxia stimulates the EMT of gastric cancer cells through autocrine TGF? signaling.

ABSTRACT: Epithelial mesenchymal transition (EMT) is considered to be correlated with malignancy of cancer cells and responsible for cancer invasion and metastasis. We previously reported that distant metastasis was associated with hypoxia in gastric cancer. We therefore investigated the effect of hypoxic condition on EMT of gastric cancer cells. Gastric cancer cells were cultured in normoxia (21% O2) or hypoxia (1% O2) for 24 h. EMT was evaluated as the percentage of spindle-shaped cells in total cells. Effect of transforming growth factor ?1 (TGF?1) or tyrosine kinase inhibitors on the EMT was evaluated. The expression level of TGF?1 and TGF?R was evaluated by real time RT-PCR. The TGF?1 production from cancer cells was measured by ELISA. Hypoxia stimulated EMT of OCUM-2MD3 and OCUM-12 cells, but not that of OCUM-2M cells. The expression level of TGF?1 mRNA under hypoxia was significantly higher than that under normoxia in all of three cell lines. The expression level of TGF?R mRNA was significantly increased by hypoxia in OCUM-2MD3 cells, but not in OCUM-2M cells. TGF?R inhibitor, SB431542 or Ki26894, significantly suppressed EMT of OCUM-2MD3 and OCUM-12. TGF?1 production from OCUM-2MD3 and OCUM-12 cells was significantly increased under hypoxia in comparison with that under normoxia. These findings might suggest that hypoxia stimulates the EMT of gastric cancer cells via autocrine TGF?/TGF?R signaling.

SUBMITTER: Matsuoka J

PROVIDER: S-EPMC3656884 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Hypoxia stimulates the EMT of gastric cancer cells through autocrine TGFβ signaling.

Matsuoka Junko J Yashiro Masakazu M Doi Yosuke Y Fuyuhiro Yuhiko Y Kato Yukihiro Y Shinto Osamu O Noda Satoru S Kashiwagi Shinichiro S Aomatsu Naoki N Hirakawa Toshiki T Hasegawa Tsuyoshi T Shimizu Kiyoshi K Shimizu Toshiyuki T Miwa Atsushi A Yamada Nobuya N Sawada Tetsuji T Hirakawa Kosei K

PloS one 20130517 5

Epithelial mesenchymal transition (EMT) is considered to be correlated with malignancy of cancer cells and responsible for cancer invasion and metastasis. We previously reported that distant metastasis was associated with hypoxia in gastric cancer. We therefore investigated the effect of hypoxic condition on EMT of gastric cancer cells. Gastric cancer cells were cultured in normoxia (21% O2) or hypoxia (1% O2) for 24 h. EMT was evaluated as the percentage of spindle-shaped cells in total cells. ...[more]

PMID: 23690936

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Project description:BackgroundMost patients with advanced breast cancer develop bone metastases, which cause pain, hypercalcemia, fractures, nerve compression and paralysis. Chemotherapy causes further bone loss, and bone-specific treatments are only palliative. Multiple tumor-secreted factors act on the bone microenvironment to drive a feed-forward cycle of tumor growth. Effective treatment requires inhibiting upstream regulators of groups of prometastatic factors. Two central regulators are hypoxia and transforming growth factor (TGF)- beta. We asked whether hypoxia (via HIF-1alpha) and TGF-beta signaling promote bone metastases independently or synergistically, and we tested molecular versus pharmacological inhibition strategies in an animal model.Methodology/principal findingsWe analyzed interactions between HIF-1alpha and TGF-beta pathways in MDA-MB-231 breast cancer cells. Only vascular endothelial growth factor (VEGF) and the CXC chemokine receptor 4 (CXCR4), of 16 genes tested, were additively increased by both TGF-beta and hypoxia, with effects on the proximal promoters. We inhibited HIF-1alpha and TGF-beta pathways in tumor cells by shRNA and dominant negative receptor approaches. Inhibition of either pathway decreased bone metastasis, with no further effect of double blockade. We tested pharmacologic inhibitors of the pathways, which target both the tumor and the bone microenvironment. Unlike molecular blockade, combined drug treatment decreased bone metastases more than either alone, with effects on bone to decrease osteoclastic bone resorption and increase osteoblast activity, in addition to actions on tumor cells.Conclusions/significanceHypoxia and TGF-beta signaling in parallel drive tumor bone metastases and regulate a common set of tumor genes. In contrast, small molecule inhibitors, by acting on both tumor cells and the bone microenvironment, additively decrease tumor burden, while improving skeletal quality. Our studies suggest that inhibitors of HIF-1alpha and TGF-beta may improve treatment of bone metastases and increase survival.

Dataset Information

Hypoxia stimulates the EMT of gastric cancer cells through autocrine TGF? signaling.

Publications

Hypoxia stimulates the EMT of gastric cancer cells through autocrine TGFβ signaling.

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