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Mark N Adams
MA 03 - Chemotherapy (ID 651)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Advanced NSCLC
- Presentations: 1
MA 03.11 - Targeting CDCA3 Enhances Sensitivity to Platinum-Based Chemotherapy in Non-Small Cell Lung Cancer (ID 9607)
11:00 - 12:30 | Presenting Author(s): Mark N Adams
Lung cancer is the leading cause of cancer-related mortality worldwide with a 5 year survival rate of 15%. Non-small cell lung cancer (NSCLC) is the most commonly diagnosed form of lung cancer. Cisplatin-based regimens are currently the most effective chemotherapy for NSCLC, however, chemoresistance poses a major therapeutic problem. New and reliable strategies are required to avoid drug resistance in NSCLC. Cell division cycle associated 3 (CDCA3) is a key regulator of the cell cycle. CDCA3 modulates this process by enabling cell entry into mitosis through degradation of the mitosis-inhibitory factor WEE1. Herein, we describe CDCA3 as a novel prognostic target to delay or prevent cisplatin resistance in NSCLC.
CDCA3 expression was investigated using bioinformatic analysis, tissue microarray immunohistochemistry and western blot analysis of matched NSCLC tumour and normal tissue. CDCA3 function in NSCLC was determined using several in vitro assays by siRNA depleting CDCA3 in a panel of three immortalized bronchial epithelial cell lines (HBEC) and seven NSCLC cell lines. To determine strategies to suppress CDCA3 activity the phosphorylation status of CDCA3 was assessed using mass spectrometry analysis. Kinases that phosphorylate CDCA3 were identified using a siRNA screen and high content immunofluorescence and microscopy approaches.
We have previously shown that CDCA3 transcripts and protein levels are elevated in resected NSCLC patient tissue, high mRNA levels being associated with poor survival. CDCA3 depletion markedly impairs proliferation in seven NSCLC cell lines by inducing a G2 cell cycle arrest. Silencing of CDCA3 also greatly sensitises NSCLC cell lines to cisplatin. Consistently, NSCLC patients with elevated CDCA3 levels and treated with cisplatin have a poorer outcome than patients with reduced CDCA3 levels. To aid patient response to cisplatin, we have been looking at strategies to suppress CDCA3 expression in tumour cells. Accordingly, in response to cisplatin, CDCA3 is phosphorylated (S) via casein kinase 2 (CK2) which prevents CDCA3 degradation in NSCLC cells. Moreover, the CK2 inhibitor CX-4945 reduces CDCA3 levels in cisplatin treated cells. CX-4945 increased cisplatin-induced cell death in control cells. The efficacy was further enhanced in CDCA3 depleted NSCLC cells.
Our data highlight CDCA3 as a novel factor in the pathogenesis of NSCLC. We propose that preventing cisplatin-induced CDCA3 phosphorylation by targeting CK2 is a worthwhile and novel strategy in treating NSCLC and may ultimately benefit patient outcome by preventing cisplatin resistance.
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