[The mechanism of NUMB regulate tumor proliferation].

OBJECTIVE: To study the specific mechanism of NUMB regulate tumor proliferation. METHODS: A stable cell line by knocking down NUMB in Hela was eatablished and the Western blot and qRT-PCR was applied to confirm the knocking out of NUMB. The effect on tumor proliferation in the absence of NUMB was investigated by observing tumor growth in nude mice. The effect on the cell cycle in the absence of NUMB was detected by flow cytometry and Brdu assay. Finally, differential expression profiles of various cell cycle regulatory proteins was detected by using Western blot analysis. RESULTS: Western blot and qRT-PCR results indicated that NUMB was specifically and efficiently knocked down in the Hela stable cell line. Tumor growth experiments demonstrated that NUMB depletion significantly promoted the tumor proliferation. Flow cytometry and Brdu assay indicated that NUMB depletion significantly promoted the G1/S transition and enhanced the cell proliferation. Western blot results demonstrated that Cyclin-E protein level was increased in NUMB depletion cell, whereas expression of P27 protein was decreased. CONCLUSION: NUMB might be involved in cell cycle process by regulating Cyclin-E and P27 protein level and thereby has an effect on tumor proliferation.

Liposomal honokiol inhibits VEGF-D-induced lymphangiogenesis and metastasis in xenograft tumor model.

Lymph nodes metastasis of tumor could be a crucial early step in the metastatic process. Induction of tumor lymphangiogenesis by vascular endothelial growth factor-D may play an important role in promoting tumor metastasis to regional lymph nodes and these processes can be inhibited by inactivation of the VEGFR-3 signaling pathway. Honokiol has been reported to possess potent antiangiogenesis and antitumor properties in several cell lines and xenograft tumor models. However, its role in tumor-associated lymphangiogenesis and lymphatic metastasis remains unclear. Here, we established lymph node metastasis models by injecting overexpressing VEGF-D Lewis lung carcinoma cells into C57BL/6 mice to explore the effect of honokiol on tumor-associated lymphangiogenesis and related lymph node metastasis. The underlying mechanisms were systematically investigated in vitro and in vivo. In in vivo study, liposomal honokiol significantly inhibited the tumor-associated lymphangiogenesis and metastasis in Lewis lung carcinoma model. A remarkable delay of tumor growth and prolonged life span were also observed. In in vitro study, honokiol inhibited VEGF-D-induced survival, proliferation and tube-formation of both human umbilical vein endothelial cells (HUVECs) and lymphatic vascular endothelial cells (HLECs). Western blotting analysis showed that liposomal honokiol-inhibited Akt and MAPK phosphorylation in 2 endothelial cells, and downregulated expressions of VEGFR-2 of human vascular endothelial cells and VEGFR-3 of lymphatic endothelial cells. Thus, we identified for the first time that honokiol provided therapeutic benefit not only by direct effects on tumor cells and antiangiogenesis but also by inhibiting lymphangiogenesis and metastasis via the VEGFR-3 pathway. The present findings may be of importance to investigate the molecular mechanisms underlying the spread of cancer via the lymphatics and explore the therapeutical strategy of honokiol on antilymphangiogenesis and antimetastasis.