3714

JAG2

jagged 2;JAG2;jagged 2

protein jagged-2

14q32

protein-coding

BACKGROUND: The Notch signaling pathway is closely related with human organ development and tumorgenisis. Jagged2 is among the most popular topic in Notch studies currently. Recent studies found its vital role in tumor metastasis in breast cancer; however, its expression profile and its prognostic value in urothelial carcinoma of bladder have not been investigated. METHODS: Immunohistochemistry was used to detect the expression of Jagged2 in 120 bladder urothelial carcinoma. Moreover, the expression of Jagged2 was analyzed by Western blot in 60 bladder urothelial carcinoma and 20 normal epithelial tissues. MTT assay and flow cytometry and transwell assay were used to examine the proliferative and invasive ability of bladder cancer cells with the treatment of GSIXX (the inhibitor of Jagged2). Prognostic value of Jagged2 expression and its correlation with tumor metastasis and recurrence were evaluated, and the proliferative and invasive ability and cell cycle process of the bladder cancer cells were detected as well. RESULTS: There was a significantly higher Jagged2 expressions in bladder urothelial carcinoma and highly invasive bladder T24 cells than those in bladder normal tissues and the superficial bladder BIU-87 cells. Jagged2 expression was positively correlated with histological grade, p T stage, recurrence, and metastasis. With the increasing concentration of GSIXX, we found that not only the cell proliferation and invasion activity decreased significantly, but also the cell cycle was blocked at G2/M stage. CONCLUSIONS: Jagged2 expression status was closely correlated with important histopathologic characteristics (grades and stages) and the recurrence and metastasis of bladder urothelial carcinomas. Furthermore, Jagged2 played an important function on the bladder cancer cells' proliferation by regulating the cancer cell cycle from G1/S to G2/M and probably promoted the invasion and metastasis of bladder cancer.

Notch signaling is often and aberrantly activated by hypoxia during tumor progression; however, the exact pathological role of hypoxia-induced Notch signaling in tumor metastasis is as yet poorly understood. In this study, we aimed to define the mechanism of Notch-ligand activation by hypoxia in both primary tumor and bone stromal cells in the metastatic niche and to clarify their roles in tumor progression. We have analyzed the expression profiles of various Notch ligands in 779 breast cancer patients in GEO database and found that the expression of Jagged2 among all five ligands is most significantly correlated with the overall- and metastasis-free survival of breast cancer patients. The results of our immunohistochemical (IHC) analysis for Jagged2 in 61 clinical samples also revealed that both Jagged2 and Notch signaling were strongly upregulated at the hypoxic invasive front. Activation of Jagged2 by hypoxia in tumor cells induced EMT and also promoted cell survival in vitro. Notably, a gamma-secretase inhibitor significantly blocked Notch-mediated invasion and survival under hypoxia by promoting expression of E-cadherin and inhibiting Akt phosphorylation. Importantly, Jagged2 was also found to be upregulated in bone marrow stroma under hypoxia and promoted the growth of cancer stem-like cells by activating their Notch signaling. Therefore, hypoxia-induced Jagged2 activation in both tumor invasive front and normal bone stroma has a critical role in tumor progression and metastasis, and Jagged2 is considered to be a valuable prognostic marker and may serve as a novel therapeutic target for metastatic breast cancer.