Impact of Wee1 inhibition on the hypoxia-induced DNA damage response

Abstract

Tumor hypoxia is a common feature associated with resistance to current anticancer therapies, such as radiotherapy and chemotherapy. Wee1 is a tyrosine kinase regarded as a gatekeeper of the G 2 /M cell cycle transition. Wee1 has recently been highlighted as a therapeutic target in cells with a deficient G 1 checkpoint, since they are more reliant on the G 2 phase for repair of damage and survival. Here, we have assessed the impact of Wee1 inhibition on hypoxic cells and its therapeutic potential as a single agent under these conditions or in combination with radiation. The p53 null non-small cell lung carcinoma cell line H1299 was used to assess Wee1 phosphorylation and signaling in a range of hypoxic conditions. Inhibition of Wee1 decreased the G 2 population in cells exposed to normoxia (21% O 2 ) or moderate hypoxia (1% O 2 ) but did not effect the cell cycle of cells exposed to levels of hypoxia associated with greatest radio-resistance (<0.1% O 2 ). In addition, DNA damage was induced in response to Wee1 inhibition although this was less significant in cells exposed to <0.1% O 2 . Wee1 inhibitors were then tested as single agents in a 2D and 3D model or in combination with radiation treatment, by clonogenic assay. Following continuous treatment, MK-1775 was shown to sensitize the H1299 cell line to different O 2 tensions. However, in combination with radiation, although MK-1775 had significant efficacy in normoxia, disappointing results were seen when these studies were carried out in hypoxia.

Insights on the Radiation-Induced Adaptive Response at the Cellular Level and Its Implications in Cancer Therapy

“…The metabolic reprogramming associated with CDK4, CDK6, and EGFR is responsible for ROS and is reportedly targeted by abemaciclib and cetuximab [101,102]. Inhibiting genomic stability via targeting ATM by fenofibrate and enhancing cell death by inhibiting CHK1 by WEE1 and kinases-PI3K by alpelisib can decrease radioresistance [103,104].…”

Targeting lung cancer through inhibition of checkpoint kinases

“…Of note, a recent report demonstrated decreased viability of hypoxic A549, H1299, and H1975 lung cancer cell lines after treatment with a hypoxia-activated Chk1 inhibitor (the CH-01 prodrug; Cazares-Korner et al, 2013 ), indicating that hypoxic lung tumors may be sensitive to Chk1 inhibitors. In contrast, a single study suggested that hypoxia does not sensitize H1299 lung cancer cells to the Wee1 inhibitor MK1775 ( O’Brien et al, 2013 ).…”