H(2)S (hydrogen sulfide), regarded as the third gaseous transmitter, is implicated in ulcerative colitis and colorectal cancers. The present study investigates the effects of H(2)S on cell proliferation in human colon cancer HCT 116 cells and SW480 cells. We identified the two key enzymes, CBS and CSE, for H(2)S synthesis in HCT 116 cells. An exogenously administered H(2)S donor NaHS induced cell proliferation in a concentration-dependent manner, with optimal proliferative concentration at 200 micromol/l. NaHS administration increased Akt and ERK phosphorylation. Blockade of Akt and ERK activation attenuated NaHS-induced cell proliferation. Cell-cycle analysis showed that NaHS treatment for 6 h decreased the proportion of cells in G(0)-G(1) phase and increased the proportion of cells in S phase. Protein expressions of Cyclin D1 and PCNA (proliferating cell nuclear antigen) were not altered, but the cyclin-dependent kinase inhibitor p21(Waf1/Cip1) was inhibited significantly by NaHS treatment. NaHS significantly reduced NO metabolite levels. In conclusion, NaHS induced human colon cancer cell proliferation. This effect might be mediated by the increase of Akt and ERK phosphorylation and the decrease of p21(Waf1/Cip1) expression and NO production. The results suggested a role for H(2)S in human colonic cancer development.

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Ink‐free printing based on rewritable paper is an efficient and environmental friendly way to reuse paper, protect resources, and save energy for sustainable development of human society. Among various kinds of rewritable media, light responsive rewritable paper (LRP) is one of the most popular research areas due to its clean and favorable noncontact writing. Visible light is more suitable for LRP for its superior penetration and much less damages to organic molecules than UV light. However, visible‐light‐responsive rewritable paper (VLRP) has only limited successes so far. Herein, a VLRP is newly designed and fabricated based on photoinduced proton transfer (PPT) between photoacid and pH‐sensitive dyes. Success of it is highly benefited from systematical investigation and in‐depth understanding on the key influence factors, such as concentration‐induced undesired isomerization, temperature, humidity, and light intensity, on the PPT and its inverse process. As‐prepared VLRP shows long‐awaited properties, such as, high color contrast and resolution, appropriate legible time of prints, excellent reversibility (>100 cycles), easiness to achieve multicolor prints, and agreeing well with environmental concept of green printing. In addition, study of influence factors on PPT in this work, to some extent, may also help people understand complex photocycle process in biosystem.

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) such as gefitinib and erlotinib have been widely used in treating patients with advanced non-small cell lung cancer (NSCLC). However, acquired resistance to EGFR TKI almost occurs in every patient eventually. To identify its potential mechanism, we established a human NSCLC cell line PC9/AB2 which was 576-fold decrease in gefitinib sensitivity compared with its parental PC9 cell lines. No EGFR-T790M mutation or abnormal expression of c-Met protein was found in PC9/AB2 cells. Over-expression of integrin β1 was found, accompanied with increase of the cells' adhesion and migration. To further confirm the role of integrin β1 in gefitinib acquired resistance, we transferred its siRNA-expressing plasmid and its whole cDNA expressing plasmid into PC9/AB2 and into PC9 cells, respectively. The sensitivity of NSCLC cells to gefitinib was negatively correlated with integrin β1 expression levels. All these data suggest that up-regulation of integrin β1 might be an important factor for gefitinib resistance in NSCLC cell line PC9/AB2.