No abstract

The present study aimed to investigate the molecular pharmacodynamic mechanisms of losartan used in the treatment of hypertension. A total of 12 spontaneously hypertensive rats (SHR) were divided randomly into an SHR group treated with saline and LOS group treated with losartan. Six Wistar‑kyoto rats (WKY) were enrolled as the WKY group with saline in the study. The LOS group received 30 mg/kg/day losartan by intragastric injection, while the SHR and WKY were fed the same volume of saline. The dosage was modulated according to the weekly weight. Changes in blood pressure were measured by the indirect tail cuff method. Angiotensin (Ang) II production in the plasma and renal tissue was measured by an immunoradiometric method. Na+/H+ exchanger (NHE)3 and serum and glucocorticoid‑inducible kinase (SGK)1 were assessed by quantitative polymerase chain reaction (qPCR) and western blot analysis. When compared with the WKY group, the blood pressure of the SHR and LOS groups were higher prior to treatment with losartan. Following two weeks, blood pressure was reduced and the trend continued to decrease over the following six weeks. The plasma and renal tissue levels of Ang II in the SHR and LOS groups were significantly higher than those in the WKY group. NHE3 and SGK1 were increased at the mRNA and protein level in the SHR group, and losartan reduced the expression of both of them. The results suggested that in hypertensive rats, the circular and tissue renin angiotensin systems were activated, and the increased Ang II stimulated the expression of NHE3 and SGK1, which was reduced by losartan. Therefore, the effects of losartan in hypertension may be associated with the Ang II‑SGK1‑NHE3 of intra‑renal tissue.

p73 is a member of the p53 tumor suppressor protein family and induces apoptosis in tumor cells that lack functional p53. It has been demonstrated that methylation of CpG islands in the promoter and exon 1 region may result in silencing of the p73 gene. The aim of this study was to investigate the correlation between p73 gene expression and chemosensitivity in non-small cell lung cancer (NSCLC) cell lines. The expression of the p73 transcript in six NSCLC cell lines was investigated by reverse transcription-polymerase chain reaction (RT-PCR). The methylation status in these cell lines was determined by methylation-specific PCR (MSP) analysis. An in vitro demethylation assay was conducted using the DNA methyltransferase inhibitor 5-aza-2-deoxycytidine (5-aza-dC). Restored expression of p73 in the human lung squamous cell carcinoma cell line C57, both at the mRNA and protein level, was investigated by RT-PCR and immunohistochemistry, respectively. A colony formation assay was used to measure the surviving fraction of the C57 cell line. Transcript silencing of the p73 gene in the six NSCLC cell lines was observed and related to aberrant methylation. The expression of the p73 transcript and protein in the C57 cell line was restored by 5-aza-dC. The surviving fraction for colony formation in C57 cells pre-treated with 5-aza-dC was 0.059±0.006, which was significantly different from that of the control group (0.12±0.008; P<0.05). Our data demonstrated a significant correlation between expression of p73 and cellular chemosensitivity in NSCLC.

To investigate the effects of tumor protein p53 (p53 or TP53) α gene on the chemosensitivity of the H1299 human lung adenocarcinoma cell line, the recombinant vector pEGFP-p53α was constructed. The vector pEGFP-p53α was transfected into the cultured p53-null H1299 cells using Lipofectamine 2000. The G418-resistant cells were then selected. The expression of the p53α gene in these cells was examined using reverse transcription-polymerase chain reaction, and TP53 protein expression was examined using western blot analysis and immunocytochemistry. An MTT assay and colony formation assay were used to analyze the response of the transfected cells to cisplatin (CDDP). DAPI staining was used to determine the level of apoptosis of the transfected cells. The transfected H1299 human lung adenocarcinoma cells stably expressed TP53 protein. The MTT assay demonstrated that the 50% inhibitory concentrations for the H1299, H1299/pEGFP-N1 and H1299/pEGFP-p53α cells were 28, 24 and 18 µmol/l, respectively. The survival rate of H1299/pEGFP-p53α cells was significantly reduced compared with that of H1299 and H1299/pEGFP-N1 cells (P<0.05). The colony formation assay and DAPI staining identified that the colony formation rate and the number of apoptotic cells of H1299/pEGFP-p53α were significantly reduced, compared with those of the H1299 and H1299/pEGFP-N1 cells (P<0.05). Therefor, the present study demonstrated that the transfection of H1299 cells with the p53α gene resulted in an increase in sensitivity to CDDP chemotherapy. The combination of CDDP and gene therapy for H1299 lung adenocarcinoma cell line provides an experimental basis for clinical research.

The research evaluated the effect of Δ133p53 on the chemosensitivity of lung adenocarcinoma cell line H1299. By this study, the drug‐resistant molecular marker and a new target for cancer therapy could be provided. Δ133p53 or negative control plasmid were transferred into H1299 cells by lentivirus vector. The expression of Δ133p53 in transfected cells was examined using immunofluorescence. The 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) method and colony formation test were applied to detect drug sensitivity after cisplatin or 5‐fluorouracil (5‐FU) treatment. After cisplatin (CDDP)/FU treatment, MTT assay demonstrated that the inhibition rate of H1299/Δ133p53 cell was reduced compared with that of the H1299 and H1299/NEG cells at the same concentration of drug. The 50% inhibitory concentrations (IC 50) of CDDP and 5‐FU rose by 36.1 and 30.2%, respectively (P < 0.05). The colony formation assay suggested that the cell proliferation ability of H1299/Δ133p53 cell was prominently increased when compared with that of control group H1299 and H1299 /NEG cells (P < 0.05). The present study demonstrated that the transfection of the Δ133p53 gene in H1299 cells led to the reduction of chemosensitivity.