Small molecule inhibitor SB203580 enhances the antitumor effect of gefitinib in PC-9 and A549 lung cancer cell lines / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To detect the inhibitory effect of a p38MAPK inhibitor SB203580 in combination with gefitinib on lung adenocarcinoma cell line PC-9 cells and A549 cells, and its cellular and molecular mechanisms of action.</p><p><b>METHODS</b>MTT test was used to detect the growth inhibition of PC-9 and A549 cells by SB203580 alone and in combination with gefitinib. Cell apoptosis and cell cycles were determined by flow cytometry. The expressions of p38 and phosphorylated -p38 proteins in the two cell lines were analyzed by immunofluorescence microscopy. The associated protein expression was determined by Western-blot.</p><p><b>RESULTS</b>Compared with the SB203580 group and gefitinib group, the growth inhibition and cell apoptosis of PC-9 cells in the SB203580 + gefitinib group were significantly increased (P < 0.05). The inhibition rate of PC-9 cells of 2 µmol/L SB203580 + 0.01 µmol/L gefitinib group was (46.6 ± 2.4)%, significantly higher than that induced by 0.01 µmol/L gefitinib (12.7 ± 1.5%) (P < 0.05). Immunofluorescence microscopy showed a low expression of phosphorylated-p38 protein in A549 cells and high expression in PC-9 cells. Flow cytometry showed that PC-9 cells in the SB203580 + gefitinib group were (77.35 ± 2.83)% at G0/G1 phase, (3.38 ± 0.84)% at S phase, and (19.56 ± 1.99)% at G2/M phase. Western-blotting showed that compared with the control group, the expression of phosphorylated Akt and phospho-p38 proteins in PC-9 cells of the SB203580 + gefitinib group was almost completely suppressed.</p><p><b>CONCLUSIONS</b>The results indicate that the small molecular inhibitor SB203580 can effectively enhance the inhibitory effect of gefitinib on lung adenocarcinoma PC-9 cells. The enhanced inhibitory effect of SB203580 may be correlated with the blockage of p38MAPK signal transduction pathway.</p>

Effect of Wnt signaling suppression on gefitinib in non small cell lung cancer cell lines / 中华病理学杂志

<p><b>OBJECTIVE</b>To explore the effect of Wnt signaling suppression on proliferation of non small cell lung cancer to gefitinib, and its related mechanisms.</p><p><b>METHODS</b>PC9 and PC9/AB2 cells of both gefitinib sensitive and resistant were treated with different concentrations of gefitinib, and the proliferation index was measured using CCK8 kit. The members of Wnt signaling pathway were detected by Western blot. Dual luciferase reportor gene assay (TOP Flash) was used to document the transcriptional level of β-catenin. β-catenin siRNA was transfected into PC9/AB2 cells to suppress the Wnt signaling transcription, followed by treatment with different concentrations of gefitinib. Western blot was then used to detect the expression of EGFR and its downstream signaling after inhibit the expression of β-catenin.</p><p><b>RESULTS</b>Treating with different concentrations of gefitinib, the resistance of PC9/AB2 cells to gefitinib was significantly increased (P < 0.05). The members of Wnt signaling expressed at higher level in PC9/AB2 cells than in PC9 cells (t = 24.590, P = 0.000). TOP Flash examination showed that the endogenous transcriptional activity of Wnt signaling was higher in PC9/AB2 cell than that in PC9 cell (t = 4.983, P = 0.008). Compared with the negative control group, apoptotic rate and sensitivity to gefitinib significantly increased in interfered group (P < 0.05). The expression of p-ERK1/2 significantly decreased after Wnt signaling suppression, although other proteins showed no significant alterations.</p><p><b>CONCLUSION</b>Suppressing the activity of Wnt signaling can partly reverse the celluar resistance to gefitinib in non small cell lung cancer.</p>

Construction of RGD10-NGR9 dual-targeting superparamagnetic iron oxide and its magnetic resonance imaging features in nude mice / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To construct angiogenesis-specific RGD10-NGR9 dual-targeting superparamagnetic iron oxide nanoparticles, and to evaluate its magnetic resonamce imaging (MRI) features in nude mice and potential diagnostic value in tumor MRI.</p><p><b>METHODS</b>Dual-targeting peptides RGD10-NGR9 were designed and synthesized. Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles were synthesized by chemical co-precipitation method and the surface was modified to be hydrophilic by coating with dextran. The dual-targeting peptides RGD10-NGR9 were conjugated to USPIO. Cell binding affinity and up-taking ability of the dual-targeting USPIO nanoparticles to integrin ανβ3-APN positive cells were subsequently tested by Prussian blue staining and phenanthroline colorimetry in vitro. The RGD10-NGR9 conjugated with USPIO was injected intravenously into xenograft mice, which were scanned by MRI at predetermined time points. The MRI and contrast-to-noise ratio (CNR) values were calculated to evaluate the ability of dual-targeting USPIO as a potential contrast agent in nude mice.</p><p><b>RESULTS</b>P-CLN-Dextran-USPIO nanoparticles with stable physical properties were successfully constructed. The average diameter of Fe3O4 nanoparticles was 8-10 nm, that of Dextran-USPIO was about 20 nm and P-CLN-Dextran-USPIO had an average diameter about 30 nm. The in vitro studies showed a better specificity of dual-targeting USPIO nanoparticles on proliferating human umbilical vein endothelia cells (HUVEC). In vivo, RGD10-NGR9-USPIO showed a significantly reduced contrast in signal intensity and 2.83-times increased the CNR in the tumor MRI in xenograft mice.</p><p><b>CONCLUSION</b>This novel synthesized RGD10-NGR9 dual-targeting USPIO is with better specific affinity in vitro and in vivo, and might be used as a molecular contrast agent for tumor angiogenesis MRI.</p>

Mutations in exon 19 of EGFR gene in non-small cell lung cancer from Chinese patients / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the mutations in exon 19 of epidermal growth factor receptor (EGFR) gene in non-small cell lung cancer from Chinese patients.</p><p><b>METHODS</b>Genomic DNA was extracted from 72 lung cancer tissues. Then the exon 19 of EGFR gene was amplified by nested PCR and sequenced.</p><p><b>RESULTS</b>In 13 tumor tissues, multi-nucleotide in-frame deletion mutations at the exon 19 of EGFR gene, had been detected. There were 4 mutation types. The mutation rate was 18.1%. The mutations were all heterozygous. There was association of the exon 19 mutation of EGFR gene with adenocarcinoma, female patients and non-smokers.</p><p><b>CONCLUSION</b>There were multi-nucleotide in-frame deletion mutations in exon 19 of EGFR gene. Mutations of the exon 19 of EGFR gene were higher in female, non-smoking and adenocarcinoma patients.</p>

Sensitivity of two cell lines with acquired resistance to gefitinib to several chemotherapeutic drugs / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the sensitivity of tumor cell lines with acquired resistance to gefitinib to several chemotherapeutic drugs and provide preclinical basis of available chemotherapy regimens after failure of molecular targeted therapy.</p><p><b>METHODS</b>Human lung adenocarcinoma cell lines PC9 and PC9/G with acquired resistance to gefitinib were cultured in vitro. The sensitivity to chemotherapeutic drugs and inhibition rate of cell proliferation was determined by MTT assay. Effects of drugs on apoptosis and expression of P-170 were determined by flow cytometry. Difference of gene expression profile between PC9 and PC9/G cells was analyzed by DNA microarray. Western blot was used to test the expression of Akt, phospho-Akt and integrin beta1.</p><p><b>RESULTS</b>The resistance index of PC9/G cells to cisplatin was about 5.4-fold compared with that of PC9 cells. LY294002 may significantly elevate the sensitivity of PC9/G cells to cisplatin (P < 0.05). PC9/G cells were more sensitive to docetaxel than PC9 cells. No significant difference of sensitivity to pemetrexed was found between these two cell lines. Expression level of P-170 in PC9/G cells was lower than that in PC9 cells. In PC9/G cells, the expression of integrin beta1 and DNA healing gene was high and expression of gene during mitosis was low. The level of expression of Akt, phospho-Akt and integrin beta1 in PC9/G cells was higher than that in PC9 cells.</p><p><b>CONCLUSION</b>In PC9/G cells, a cell line with acquired resistance to gefitinib, over-expression of PI3K, integrin and DNA restoration gene and continuous activation of PI3K is found to be correlated with resistance to cisplatin. Docetaxel or pemetrexed is a more reasonable choice than cisplatin for treatment of NSCLC patients who failed to respond to EGFR-TKI.</p>