Anti-HIF1A monoclonal antibody, clone nhd4

Tumor suppressor protein p53 aggregates in the hypoxic core of solid tumors. C terminus of Hsc70-interacting protein (CHIP) displays chaperone as well as E3 ligase activities in both stabilizing and degrading wild-type and mutant p53. In this study, we have discovered that CHIP selectively degrades aggregating mutant p53 under both normal and hypoxic conditions. Silencing of CHIP alleviates degradation of aggregating mutant p53 in both normoxia and hypoxia, but has no significant effect on the level of nonaggregating mutant p53. Although both U-box and TPR domains of CHIP are responsible for p53 degradation, the U-box domain selectively binds to aggregating mutant p53, whereas the TPR domain interacts with nonaggregating mutant p53. The degradation of mutant p53 by CHIP is shown to be via autophagy through K63-linked polyubiquitination. Both in normoxia and under physiological hypoxia, the level of aggregating mutant p53 in the presence of CHIP was reduced threefold, whereas under serum starvation, it was reduced fivefold. Interestingly, both wild-type and mutant p53 interact with and stabilize CHIP at the post-translational level, suggesting a chaperone synergy between p53 and CHIP. This finding may have strong therapeutic significance via selective degradation of oncogenic mutant p53 in regressing hypoxic tumors.

Ameloblastic carcinoma (AC) is defined as a rare primary epithelial odontogenic malignant neoplasm and the malignant counterpart of benign epithelial odontogenic tumor of ameloblastoma (AB) by the WHO classification. AC develops pulmonary metastasis in about one third of the patients and reveals a poor prognosis. However, the mechanisms of AC oncogenesis remain unclear. In this report, we aimed to clarify the mechanisms of malignant transformation of AB or AC carcinogenesis. The relatively important genes in the malignant transformation of AB were screened by DNA microarray analysis, and the expression and localization of related proteins were examined by immunohistochemistry using samples of AB and secondary AC. Two genes of hypoxia-inducible factor 1 alpha subunit (HIF1A) and zinc finger E-box-binding homeobox 1 (ZEB1) were significantly and relatively upregulated in AC than in AB. Both genes were closely related in hypoxia and epithelial-mesenchymal transition (EMT). In addition, expressions of HIF-1 alpha and ZEB1 proteins were significantly stronger in AC than in AB. In the cell assays using ameloblastoma cell line, AM-1, hypoxia condition upregulated the expression of transforming growth factor-beta (TGF-beta) and induced EMT. Furthermore, the hypoxia-induced morphological change and cell migration ability were inhibited by an antiallergic medicine tranilast. Finally, we concluded that hypoxia-induced HIF-1 alpha and ZEB1 were critical for the malignant transformation of AB via TGF-beta-dependent EMT. Then, both HIF-1 alpha and ZEB1 could be potential biomarkers to predict the malignant transformation of AB.