Abstract
BackgroundDNA damage response plays critical roles in tumor pathogenesis and radiotherapy resistance. Protein phosphorylation is a critical mechanism in regulation of DNA damage response; however, the key mediators for radiosensitivity in gastric cancer still needs further exploration.MethodsA quick label-free phosphoproteomics using high-resolution mass spectrometry and an open search approach was applied to paired tumor and adjacent tissues from five patients with gastric cancer. The dysregulated phosphoproteins were identified and their associated-pathways analyzed using Gene Set Enrichment Analysis (GSEA). The mostly regulated phosphoproteins and their potential functions were validated by the specific antibodies against the phosphorylation sites. Specific protein phosphorylation was further analyzed by functional and clinical approaches.Results832 gastric cancer-associated unique phosphorylated sites were identified, among which 25 were up- and 52 down-regulated. Markedly, the dysregulated phosphoproteins were primarily enriched in DNA-damage-response-associated pathways. Particularly, the phosphorylation of Bcl-2-associated transcription factor 1 (BCLAF1) at Ser290 was significantly upregulated in tumor. The upregulation of BCLAF1 Ser290 phosphorylation (pBCLAF1 (Ser290)) in tumor was confirmed by tissue microarray studies and further indicated in association with poor prognosis of gastric cancer patients. Eliminating the phosphorylation of BCLAF1 at Ser290 suppressed gastric cancer (GC) cell proliferation. Upregulation of pBCLAF1 (Ser290) was found in association with irradiation-induced γ-H2AX expression in the nucleus, leading to an increased DNA damage repair response, and a marked inhibition of irradiation-induced cancer cell apoptosis.ConclusionsThe phosphorylation of BCLAF1 at Ser290 is involved in the regulation of DNA damage response, indicating an important target for the resistance of radiotherapy.
Highlights
DNA damage response plays critical roles in tumor pathogenesis and radiotherapy resistance
The upregulated protein phosphorylations were predominately involved in the interaction with nucleotides, DNAs, and RNAs (Fig. 1c, e), which were apparently associated with dysregulation of DNA damage repair (DDR), nuclear assembly and genomic instability of gastric cancer (GC)
The mostly down-regulated protein phosphorylations were predominately involved in the regulation of muscle contraction, which reflected the function loss associated with GC (Fig. 1d, f )
Summary
DNA damage response plays critical roles in tumor pathogenesis and radiotherapy resistance. Protein phosphorylation is a critical mechanism in regulation of DNA damage response; the key mediators for radio‐ sensitivity in gastric cancer still needs further exploration. GC is one of the most aggressive and therapy-resistant cancers [1]. The development of molecular targeted therapy has led to a revolutionary breakthrough and become the hope of cancer treatment. The protein phosphorylation is a critical post-translational modification and therapeutic target in regulating different biological processes [7,8,9] important for diagnosis, prognosis and treatment of diseases. A better understanding of GC phosphoproteomics can improve early diagnostic screening and provide effective intervention targets
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
