Hydrogen peroxide (H2O2) is originally an endogenous small molecule which is reduced into water in cells. In order to know the H2O2-induced oxidative stress in RAW 264.7 cells, first of all, the optimum concentration of exogenous H2O2 which show reactive cellular responses was determined as 40 μM by MTT assay, and followed by 40 μM H2O2 application in RAW 264.7 cells for 30 min, 1, or 2 hours. The expressional changes of essential proteins for cellular proliferation, epigenetic modification, inflammation, apoptosis, survival, and protection were assessed by immunoprecipitation high performance liquid chromatography (IP-HPLC) using 51 antisera. 40 μM H2O2 treatment down-regulated proliferation-related proteins, Ki-67, PCNA, CDK4, cyclin D2, cMyc, and PLK4, induced histone methylation/ deacetylation and DNA methylation by increasing levels of HDAC10 and DMAP1 and by decreasing levels of DNMT1 and KDM4D, activated inflammatory reaction by increasing levels of MCP-1, COX-2, CD68, LTA4H, CXCR4, and lysozyme, and dramatically up-regulated cellular apoptosis-, survival-, and protection-related proteins, AIF, PARP-1, caspase 9, c-caspase 9, pAKT1/2/3, SOD-1, HO-1, NF-kB, NRF2, and GSTO1 in RAW 264.7 cells. These observations suggest exogenous 40 μM H2O2-induced oxidative stresses which resulted global cellular responses including not only antioxidant, inflammation, and apoptosis but also proliferation and epigenetic modification. Particularly, 40 μM H2O2-induced apoptosis was mainly derived from PARP-1/AIF signaling leading parthanatos, and 40 μM H2O2-induced suppression of cMyc/MAX/MAD network was relevant to reduction of RAW 264.7 cell proliferation. Accordingly, H2O2 appears to affect RAW 264.7 macrophages in several ways eliciting not only oxidative stresses but also genome-wide DNA damage.

In order to know the characteristic roles of salivary protein complex (SPC) the gel-filtration chromatography was performed using the unstimulated and the stimulated whole saliva separately. The first and second dominant SPC peaks were fractionated and analyzed by immunoprecipitation HPLC (IP-HPLC) using antibodies against the essential salivary proteins including α-amylase, mucin-1, proline rich proteins (PRPs), histatin, cystatin, LL-37, lysozyme, lactoferrin, -defensin-1, -2, -3, IgA, transglutaminase 4 (TGase 4), mucocidin, α1-antitrypsin, cathepsin G. In the gel-filtration chromatography the stimulated whole saliva showed much reduced amount of SPCs than the unstimulated whole saliva, but the proportional patterns of both whole saliva were almost similar each other. Through IP-HPLC analysis both of the first and second dominant SPCs were variably positive for the essential salivary proteins, however, α-amylase, mucin-1, PRPs, lysozyme, and cathepsin G were predominant in the first dominant SPC, while cystatin, lactoferrin, β-defensin-1, -2,-3, IgA, mucocidin, TGase 4, and α1-antitrypsin were predominant in the second dominant SPC. And more, the α1-antitrypsin and cathepsin G which were mostly derived from gingival crevicular fluid were also consistently found in the SPCs. These data may suggest that the first dominant SPC, rich in α-amylase, mucin-1, PRPs, lysozyme, and cathepsin G, may play a role in food digestion, protein degradation, and mucosa lubrication, while the second dominant SPC, rich in cystatin, lactoferrin, β-defensin-1, -2, -3, mucocidin, IgA, TGase 4, and α1-antitrypsin, may play a role in the mucosa protection and antimicrobial defense.

Immunoprecipitation-based high performance liquid chromatography (IP-HPLC) is a type of modified enzyme-linked immunosorbent assay (ELISA) that uses protein A/G (or antibody)-conjugated beads instead of the antibody-conjugated wells used in ELISA. In order to determine the fidelity of IP-HPLC, the author used 83 antisera to identify protein expression changes caused by cisplatin treatment in KB human oral cancer cells. KB cells were cultured for 12 or 24 hours with 10 ug/mL cisplatin. The results obtained by IP-HPLC were comparable with published cisplatin data, although ELISA was not conducted in the present study. Cisplatin dominantly reduced the levels of proteins associated with cell proliferation, transcription factors, growth factors, cytoskeletal proteins, and cellular differentiating factors, but on the other hand, apoptosis-related factors, oncogenes, and protective proteins were usually up-regulated, presumably to address cisplatin-induced DNA damage. In particular, cisplatin directly inactivated genomic DNA by down-regulating histone H1 and demethylase and by up-regulating deacetylase. Cisplatin also rapidly induced p53 overexpression and mitochondria-mediated endogenous apoptosis occurred after 12 hours of cisplatin treatment, although this was almost completely replaced by FASL/FAS-mediated exogenous apoptosis after 24 hours. This preliminary study was conducted to investigate the anticancer effect of cisplatin on the KB human oral cancer cells and to determine the fidelity of IP-HPLC data. It was concluded that IP-HPLC is useful for identifying profile changes of genome wide essential proteins and signaling changes of major molecular pathways.