Figure 6.

Knockdown of ARNT/HIF‐1β sensitizes MM cells to bortezomib and abrogates the cytoprotective effect of hypoxia. A, U266 cells were stably transfected with pGreenpuro‐shRNA constructs encoding shRNA targeted ARNT (shARNT) or scramble sequence as negative control (shNC), in which expression of HIF‐1β was examined by Western blot analysis to validate knockdown of ARNT expression. (B,C) Cells were then exposed to 2‐3 nmol/L bortezomib (Btz) for 24 h (B) or preincubated with lactic acid (LA) for 8 h, followed by treatment with Btz for additional 24 h (C). After treatment, percentage of apoptotic cells (in rectangle, including Annexin V single positive and Annexin V/7AAD double positive) was determined by flow cytometry. For B and C, representative data of at least 3 independent experiments were shown