ABSTRACT
<p><b>OBJECTIVE</b>To investigate the status of Notch signaling pathway in small cell lung cancer (SCLC).</p><p><b>METHODS</b>Expression plasmids of pEFBOS-NIC-MYC and pEFBOS-neo were transfected into NCI-H446 cells. Stably transfected cell lines were selected and their growth rates were examined by MTT method. Expression of downstream genes along the Notch signaling pathway were studied by RT-PCR. Protein expression of euroendocrine markers of CgA and NSE were detected by Western blot analysis and immunocytochemistry.</p><p><b>RESULTS</b>The expression of HES1 was increased in the pEFBOS-NIC-MYC group, but the expression of hASH in the pEFBOS-NIC-MYC group was decreased significantly. The transfected cells with pEFBOS-NIC-MYC plasmid showed a significantly slower growth rate compared with that of two control groups (P < 0.05, Student's t-test). Immunocytochemistry of NSE showed that PUs in the NIC transfected group, sham group and negative control group were 7.21 ± 0.59, 28.25 ± 1.46, 30.57 ± 1.31 respectively, the former one was smaller than the values of the latter two significantly (P < 0.01). Western blot analysis showed the grave scales of CgA in NIC transfected group and sham group to be 0.54 ± 0.03 and 0.99 ± 0.05 respectively (grave scales of the negative control was set as 1.00), the former one significantly smaller than that of the other two groups (P < 0.01). The grave scales of NSE in the NIC transfected group and sham group were 0.43 ± 0.02 and 1.07 ± 0.09 respectively (grave scales of the negative control was set as 1.00) and the former one was significantly smaller than the other two groups (P < 0.01).</p><p><b>CONCLUSION</b>Notch signaling pathway regulates SCLC cells through its inhibitory effect on hASH1 transcription via HES1 along with an expression inhibition of neuroendocrine markers in SCLC.</p>
Subject(s)
Humans , Basic Helix-Loop-Helix Transcription Factors , Metabolism , Cell Line, Tumor , Cell Proliferation , Chromogranin A , Metabolism , Homeodomain Proteins , Metabolism , Lung Neoplasms , Metabolism , Pathology , Phosphopyruvate Hydratase , Metabolism , Plasmids , Receptor, Notch1 , Metabolism , Physiology , Recombinant Proteins , Metabolism , Signal Transduction , Small Cell Lung Carcinoma , Metabolism , Pathology , Transcription Factor HES-1 , TransfectionABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of Notch1 signal activation on proliferation and neuroendocrine marker expression in small cell lung cancer cells.</p><p><b>METHODS</b>The active form of Notch1 (NIC) was over-expressed in NCI-H446 cells by constitutive transfection and a stable transfected cell line was established. Proliferation of NCI-H446 cells was analysed by MTT assay on 6 successive days. Expression of neuroendocrine markers (CgA, NSE) was observed by immunohistochemistry and Western blot analysis. Statistical analysis was conducted to compare the results in cells with NIC transfected and those in control groups.</p><p><b>RESULTS</b>MTT assay showed that absorbance (A) of cells overexpressing Notch1 was significantly depressed compared with that of the control cells (P<0.05). Immunohistochemistry of CgA showed that PUs in the NIC transfected group, sham group and negative control group were 8.81 +/- 0.77, 38.10 +/- 1.55, 38.97 +/- 0.80, respectively, the former one was significantly smaller than that of the latter two (P<0.01). Immunohistochemistry of NSE showed that PUs in the NIC transfected group, sham group and negative control group were 7.21 +/- 0.59, 28.25 +/- 1.46, 30.57 +/- 1.31, respectively, the former one was significantly smaller than that in the latter two (P<0.01). Western blot analysis showed that the gray scales of CgA in the NIC transfected group and sham group were 0.54 +/- 0.03 and 0.99 +/- 0.05, respectively, (gray scale of the negative control set as 1.00), the former one was significantly smaller than that of the other two groups (P<0.01). The gray scales of NSE in the NIC transfected group and sham group were 0.43 +/- 0.02 and 1.07 +/- 0.09, respectively (gray scale of the negative control set as 1.00), the former one was significantly smaller than that of the other two groups (P<0.01).</p><p><b>CONCLUSION</b>Notch1 may behave as a tumor suppressor in small cell lung cancer. Notch1 signal activation can inhibit the proliferation and neuroendocrine marker expression in small cell lung cancer cells, suggesting that Notch1 gene could be a new target for small cell lung cancer treatment and probable relief of paraneoplastic syndrome.</p>