Hypoxia Impairs NK Cell Cytotoxicity through SHP-1-Mediated Attenuation of STAT3 and ERK Signaling Pathways

Figure 1

Hypoxic NK cells show lower cytotoxicity against tumor cells. (a, b) Flow cytometric analysis of KHYG-1 cells cytotoxicity against tumor cells. KHYG-1 cells were incubated with K562 (a) or MM.1S (b) tumor cells for 4 h at different ratios after cultivation at normoxic (20% O₂) and hypoxic (1% O₂) conditions for 24 h. Left panel: a representation of results from three experiments; Right panel: statistical analysis showing the percentage of tumor cells killed by NK cells (, ). (c) Western blotting analysis of the effects of hypoxia on the expression of hypoxia marker HIF-1α. NK cells were cultured in 20% or 1% O₂ for 24 h, and then Western blotting analysis was performed. Representative Western blot images are shown in the upper panel; the densitometric analysis is shown in bottom panel (, , ). (d) Flow cytometric analysis of the effects of hypoxia on NK cell viability by performing Annexin V-FITC/7-AAD staining. NK cells were cultured in 20% or 1% O₂ for 24 h, then flow cytometric staining was performed (, ns: no significance).

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