Activation of nuclear factor-κB subunit p50/p65 enhances gefitinib resistance of lung adenocarcinoma H1650 cell line / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the intrinsic connection between activation of classical nuclear factor-κB (NF-κB) pathway and gefitinib resistance in human lung adenocarcinoma H1650 cells.</p><p><b>METHODS</b>Human lung adenocarcinoma H1650 cells were exposed to gefitinib continuously for 60 days to obtain resistant H1650 cells. The expressions of P-IκBα, P-p50 and P-p65 in the cytoplasm or nuclei were detected using Western blotting in human lung adenocarcinoma HCC827 cells, parental H1650 cells and gefitinib-resistant H1650 cells. The effects of gefitinib alone or in combination with PDTC on the survival rate and expressions of NF-κB P-p50 and P-p65 were compared among the 3 cell lines.</p><p><b>RESULTS</b>Gefitinib-resistant H1650 cells showed increased cytoplasmic and nuclear P-IκBα expressions. The expressions of P-p50 and P-p65 differed significantly among the 3 cell line, decreasing in the order of resistant H1650 cells, parental H1650 cells, and gefitinib sensitive HCC827 cell lines (P<0.05 or 0.01). Treatment with gefitinib alone resulted in a significantly lower cell inhibition rate in resistant H1650 cells than in the parental H1650 cells (P<0.05) and HCC827 cells (P<0.01). The resistant H1650 cells had a significantly higher expression of P-p50 and P-p65 than other two cell lines (P<0.05). In both the resistant and parental H1650 cells, gefitinib significantly lowered P-p50 and P-p65 expressions (P<0.05 or 0.01), and the combined treatment with gefitinib and PDTC significantly decreased the cell survival rate and further lowered the cytoplasmic and nuclear expressions of P-p50 and P-p65 (P<0.01 or 0.01).</p><p><b>CONCLUSION</b>The activation of classical NF-κB pathway is a key factor contributing to transformation of the parental H1650 cells into gefitinib-resistant cells. Gefitinib combined with PDTC can inhibit P-IκBα production and NF-κB P-p50 and P-p65 activation to suppress the survival of residual H1650 cells and the generation of gefitinib-resistant cells.</p>

Inhibition of proliferation in Jurkat cells transfected with exogenous HCAP1 gene / 中国实验血液学杂志

HCAP1 is a novel hepatic cancer related gene located on human chromosome 17p13.3. The loss of heterozygosity occurred at 17p13.3 in various human cancers. In order to investigate the effects of exogenous HCAP1 gene products on cell proliferation of T lymphoma Jurkat cell line, HCAP1 gene! was transfected into Jurkat cells mediated by liposome, and the cells stably expressing exogenous HCAP1 were screened with G418. The effects of HCAP1 products on cell proliferation were assessed by viable cell count, cell growth curve and colony formation assay in soft agar. The results showed that the HCAP1 transgenic Jurkat cells displayed slow growth rate, extended doubling time and reduced colony formation capability, as compared with the cells transfected with pBK/CMV empty vector (P < 0.01). It is concluded that exogenous HCAP1 gene products could inhibit the proliferation of Jurkat cells.

Expression of novel cloned genes HC56, HC71 and HC90 mapped on human chromosome 17p13.3 in leukemic cells / 中国实验血液学杂志

In order to investigate expression of novel genes HC56, HC70 and HC90 mapped on chromosome 17p13.3 in human leukemic cells, HC56, HC71 and HC90 genes expression was examined in cells from 35 patients with acute leukemias and 4 leukemic cell lines by using semi-quantitative RT-PCR with incorporation of alpha(32)P dATP, betaM2 gene as endogenous control. The results showed that HC90 gene expression level was lower in patients with acute lymphocytic leukemia and T lymphocytic leukemic cell line Jurkat than that in normal control. Low-level HC71 gene expression was detected in acute myeloid leukemia. There was no expression difference in HC56 between leukemic cells and normal blood cells. It was concluded that both HC70 and HC90 genes were aberrantly expressed in human leukemic cells.

p73 Gene and Leukemia / 中国实验血液学杂志

p73 has high homology with the classical tumor suppressor gene p53. When overexpressed, p73 could lead to tumor cells growth arrest and induce apoptosis. Lost of p73 gene expression due to hypermethylation was found in about one third patients with acute lymphoblastic leukemia and Burkitt's lymphoma, but the expression level of p73 was higher in patients with acute myelogenous leukemia than that in normal white blood cells. Further research will be necessary to find out the role of p73 in leukemogensis.