Integrative Quantitative Proteomics and Phosphoproteomics Reveal the Regulatory Role of ZNF322A in Lung Cancer A549 Cells

ZNF322A is a transcription factor that belongs to C2H2-type zinc finger protein family. Recent study revealed that ZNF322A is a potential oncogene in lung cancer patients. However, the network regulated by ZNF322A was still unknown. In this study, we integrated quantitative phosphoproteomic and proteomic analyses for ZNF322A-silencing lung cancer A549 cells. Hydroxy acid-modified metal oxide chromatography (HAMMOC) phosphopeptide enrichment method, and isobaric tag for relative and absolute quantitation (iTRAQ) coupled with LC-MS/MS were applied. We identified 2754 phosphosites corresponding to 1822 phosphopeptides and 976 phosphoproteins, among these, 53 phosphosites were upregulated and 85 were downregulated in siZNF322A treated cells. Quantitative iTRAQ LC-MS/MS proteomics reveals the proteome profile in ZNF322A-silencing A549 cells, and 1108 proteins were identified. By bioinformatics approaches including functional enrichment, network and phosphorylation motif analyses, the results indicated that ZNF322A might regulate several biological processes, such as RNA processing and cell cycle. Phosphorylation of HSP27 Ser82 and IRS1 Ser1101 were significantly upregulated upon ZNF322A-silencing and participate in the regulation of unfolded protein response and glucose uptake. Our study provides a new insight for further investigation of protein phosphorylation status in ZNF322A-mediated lung cancer cells.