Construction and application of a new prokaryotic expression vector derivative of pBV220 / 生物工程学报

A single-stranded oligonucleotides containing a 6 histidine sequence, a hydroxylamine cleavage site, a thrombin cleavage site, and stop codon TAA were inserted into the polylinker's downstream of prokaryotic expression vector pBV220 between BamHI and PstI. The resultant vector is named pBV223. Proteins expressed in this vector will have a 6 histidine tail as affinity handy fused to their C terminus and can be quickly purified by one step immobilized metal affinity chromatography (IMAC). This plasmid is verified by restriction map and DNA sequencing. Subsequently, the metastasis suppressor gene nm23-H1 cDNA (without the stop codon) was cloned into vector PBV223 in frame with the 6-histidine sequence, hydroxylamine and thrombin cleavage sites. The soluble nm23-H1 fusion protein was successfully induced in the bacterial DH5a and easily purified with Ni chromatograph. These results indicated that the strategy to clone the single-stranded oligonucleotides directly into the restriction sties between BamH I and Pst I in the pBV220 vector is the simplest and cost-effective method.

Construction of human nm23-H1 mutant and EGFP fusion genes using site-directed mutagenesis / 中国肺癌杂志

<p><b>BACKGROUND</b>Previous researches have proven that nm23-H1 gene is a tumor metastatic suppressor gene, however, it is still unknown about its exact molecular mechanisms. Site-directed mutagenesis can correctly change the base sequence and get mutant proteins. The aim of this study is to construct nm23-H1 mutant and EGFP fusion genes by site-directed mutagenesis, and to provide basement for studying the functional and biochemical mechanisms of nm23-H1 gene.</p><p><b>METHODS</b>Site-directed mutagenesis of nm23-H1 gene was performed by modified QuikChange™ Site-directed Mutagenesis Kit method. Pure plasmid containing fusion gene of nm23-H1 and EGFP (PLXSN-nm23-H1-EGFP) was mini-prepared. Four pairs of mutagenic primers were synthesized in vitro and the desired five mutations, S44A, P96S, H118F, S120G and P96S-S120G were introduced into nm23-H1-EGFP fusion gene by PCR.</p><p><b>RESULTS</b>Five nm23-H1 mutant and EGFP fusion genes, nm23-H1(S44A)-EGFP, nm23-H1(P96S)-EGFP, nm23-H1 (H118F)-EGFP, nm23-H1(S120G)-EGFP and nm23-H1(P96S-S120G)-EGFP, were successfully constructed. The results of DNA sequencing confirmed that the base sequences of the mutant fusion genes were completely concordant with experiment design.</p><p><b>CONCLUSIONS</b>Five nm23-H1 mutant and EGFP fusion genes are successfully constructed, which can be used in further studies. QuikChange™ site-directed mutagenesis is a simple, rapid and efficient method.</p>

A study on the deletion and mutation of Rb gene in lung cancer / 国际检验医学杂志

Objective To investigate the deletion and mutation of Rb gene in human lung cancer.Methods Polymerace chain reaction (PCR ) and restriction enzyme analytic techniques were used to detect the exon 14-16 and 22-23 regions of Rb gene in 20 human lung cancer DNA samples and 3 normal human lung tissue DNA samples.Results Two deletions existed in the exon 14-16 regions of two lung cancer DNA samples.Conclusion Deletion of Rb gene is in existance in human lung cancer, especially in small cell lung cancer. This may be useful for studying the cause of lung cancer.

Experimental study on molecular mechanism of nm23-H1 gene transfection reversing the malignant phenotype of human high-metastatic large cell lung cancer cell line / 中国肺癌杂志

<p><b>BACKGROUND</b>nm23-H1 gene is a well-known tumor metastasis suppression gene. Our previous study has found that transfection of wild type nm23-H1 gene can significantly downregulate the ERK1/2 activity of human high-metastatic large cell lung cancer cell line L9981. The aim of this study is to investigate the influence of nm23-H1 and exogenous ERK1/2 pathway inhibitor U0126 on the extracellular signal-regulated kinase (ERK1/2) of human high-metastatic large cell lung cancer cell line L9981 and its malignant biological behaviors.</p><p><b>METHODS</b>The expressive levels of total-ERK1/2, dually phosphorylated ERK1/2 and ERK1/2 relative activity of the human high-metastatic large cell lung cancer cell lines, L9981 (parent cell line with nm23-H1 gene hetero-deletion), L9981-nm23-H1 (transfected with nm23-H1 gene ) and L9981-PLXSN (transfected with vector) were detected by Western blot and immunoprecipitation technique after treating with U0126 (40μmol/L for 20 minutes). The in vitro proliferative and invasive abilities among the above three lung cancer cell lines were determined by MTT and improved Boyden chamber methods.</p><p><b>RESULTS</b>The phosphorylated ERK1/2 expression level and relative activity in L9981-nm23-H1 lung cancer cell line were remarkably lower than those in L9981 and L9981-PLXSN lung cancer cell lines after being treated with U0126 (P < 0.01), but there was no significant difference between L9981 and L9981-PLXSN lung cancer cell lines. No significant difference of total ERK1/2 expression level was observed among the three lung cancer cell lines (P > 0.05) after being treated with U0126. The in vitro proliferation and invasion of L9981-nm-23H1 lung cancer cell line were remarkably lower than those of L9981 and L9981-PLXSN lung cancer cell lines (P < 0.01 ), but no significant difference was found between L9981 and L9981-PLXSN lung cancer cell lines (P > 0.05 ); U0126 could significantly down-regulate the in vitro proliferation and invasion of L9981 lung cancer cell line (P < 0.01).</p><p><b>CONCLUSIONS</b>Blocking the activity of ERK1/2 in L9981 lung cancer cell line and transfecting the nm23-H1 gene into the L9981 lung cancer cell line may produce similar cell biological behavior changes, namely the significant reduction of in vitro proliferation and invasion of L9981 lung cancer cell line. These results indicate that the molecular mechanism which nm23-H1 gene reverses invasion and proliferation of the human high-metastatic large cell lung cancer cell line may be related to its effects of down-regulating the activity of the key kinase ERK1/2 of Ras-to-MAPK signal transduction pathway.</p>

Effects of targeting inhibition of ERK1/2 signal transduction pathway on malignant biological behaviors of human high-metastatic large cell lung cancer cell line L9981 / 中国肺癌杂志

<p><b>BACKGROUND</b>It has been known that oncogenesis and development of lung can- cer is a complex process regulated many genes and involved in multistages. Recent studies have demonstrated that signal transduction abnormality may play a very important role in these procedures. The aim of this study is to investigate the influence of exogenous MEK1/2 pathway inhibitor U0126 on the expression and activity of extracellular signal-regulated kinase (ERK1/2) of human high-metastatic large cell lung cancer cell line L9981 and its malignant biological behaviors.</p><p><b>METHODS</b>The expressive levels of total-ERK1/2, dually phosphorylated ERK1/2 and ERK1/2 relative activity of the human high-metastatic large cell lung cancer cell line L9981 (parent cell line with nm23-H1 gene hetero-deletion ) were detected by Western blot and immuno-precipitation technique after treating with different doses of U0126. The in vitro proliferative and invasive abilities of the lung cancer cell line were determined by MTT and modified Boyden chamber methods.</p><p><b>RESULTS</b>The ERK1/2 relative activity of L9981 gradually decreased accompanied with increase of U0126 doses, and a highly significant difference of phosphorylated ERK1/2 expression level existed among the different concentration groups of U0126 (P < 0.01), but no significant difference of total ERK1/2 expression was found among the different concentration groups of U0126 (P=0.387). After treatment with same concentration of U0126 for different time, the ERK1/2 relative activity of L9981 gradually decreased as the treatment time of U0126 prolonging, and a highly significant difference of phosphorylated ERK1/2 expression level was observed among different treatment time groups (P < 0.01). But no significant difference of total ERK1/2 expression level was found among different time groups (P=0.689). The inhibition of ERK1/2 pathway by MEK1/2 specific inhibitor U0126 targeting the ERK1/2 pathway of L9981 was dose- and time-dependent. After treatment with different concentration of U0126, the proliferation of L9981 gradually decreased accompanied with increase of U0126 concentration and a highly significant difference existed among different groups of U0126 concentration (P < 0.001). The in vitro invasion of L9981 gradually decreased accompanied with increase of U0126 concentration. No significant difference of in vitro invasion of L9981 was found among 0, 10 and 20μmol/l of U0126 (P > 0.05). A highly significant difference was observed when U0126 concentration increased to 40 and 60μmol/l compared with 0, 10 and 20μmol/l of U0126 (P < 0.001).</p><p><b>CONCLUSIONS</b>The inhibition of Ras-to-MAPK pathway by Ras-to-MAPK specific inhibitor U0126 targeting the Ras-to-MAPK pathway of the human high-metastatic large cell lung cancer cell line L9981 is dose-dependent and time-dependent. Suppressing or blocking of Ras-to-MAPK signal transduction pathway can reverse the invasive and metastatic phenotype of the human high-metastatic large cell lung cancer cell line L9981. These results suggest that the key kinase MEK1/2 of the ERK1/2 pathway may be a potent therapeutic target for human lung cancer.</p>

Transcription expression of endostatin mRNA in non-small cell lung cancer tissues / 中国肺癌杂志

<p><b>BACKGROUND</b>It has been proved that tumor development and metastasis are dependent on angiogenesis. Suppression of tumor angiogenesis can inhibit tumor growth and metastasis. Collagen X VIII/endostatin is one of the most effective inhibitors of angiogenesis at present. The aim of this study is to study the relationship between transcription expression of endostatin mRNA and clinical and pathophysiological characteristics in non-small cell lung cancer (NSCLC).</p><p><b>METHODS</b>The transcription expression of endostatin mRNA was detected in 46 lung cancer tissues and paracancerous lung tissues, 14 benign pulmonary lesion tissues as control by RT-PCR method.</p><p><b>RESULTS</b>(1)The transcription expression of endostatin mRNA in lung cancer tissues (0.872±0.071) was significantly higher than that in paracancerous tissues (0.717±0.073) and benign pulmonary lesion tissues (0.611±0.026) (P < 0.001).(2)The transcription expression of endostatin mRNA in lung cancer tissues was closely related to P-TNM stages, distant metastasis, grade of cell differentiation and size of the primary tumors (P < 0.05), but not to location of tumor, lymph node status, histological classification, age and sex of the patients and smoking or not (P > 0.05).</p><p><b>CONCLUSIONS</b>The transcription expression of endostatin mRNA in NSCLC tissues is significantly higher than that in paracancerous tissues and benign pulmonary lesion tissues, and is closely related to P-TNM stages, distant metastasis, grade of cell differentiation and size of the primary tumors, hence it might be helpful to evaluate the biological behavior of lung cancer.</p>

Construction and identification of procaryotic expression vector of human NIT1 gene / 中国肺癌杂志

<p><b>BACKGROUND</b>The human FHIT gene at chromosome 3p14.2 is a tumor suppressor gene, and its abnormality in structure and function is related to carcinogenesis and progression of lung cancer. It is postulated that FHIT and NIT1 likewise collaborate in biochemical or cellular pathway in mammalian cells, but their molecular mechanisms in lung cancer cell are still unknown. The aim of this study is to construct procaryotic expression vector of human NIT1, providing a foundation to explore the expression of human NIT1 protein and to study the interaction of NIT1 and FHIT genes in lung cancer cell lines.</p><p><b>METHODS</b>The NIT1 cDNA was acquired by RT-PCR. EcoRI/NotI digested PCR product was directly cloned into procaryotic expression vector pET-32a.</p><p><b>RESULTS</b>The sequence of NIT1 cDNA clone exactly corresponded with the sequence of NIT1 cDNA in GenBank. The expectant fragments of DNA were obtained after recombinant procaryotic expression vector was digested by EcoRI and NotI.</p><p><b>CONCLUSIONS</b>The procaryotic expression vector of human NIT1 is successfully constructed by RT-PCR and direct clone. It provides an important basis to detect the expression of NIT1 protein and to further explore the relationship between NIT1 and FHIT genes in oncogenesis and development of human lung cancer.</p>

Cloning of human telomerase catalytic subunit gene promoter and studying on its specific transcriptional activities in human lung cancer cells / 中国肺癌杂志

<p><b>BACKGROUND</b>To clone DNA sequence of human telomerase reverse transcriptase (hTERT) promoter, and study its transcriptional activities in various human lung cancer cells and normal lung cell.</p><p><b>METHODS</b>hTERT promoter of 1.1 kb was amplified with polymerase chain reaction (PCR) method, utilizing DNA of 293 cell as template. After DNA sequencing with correct result, the hTERT promoter was inserted into luci-ferase reporter vectors (pGL3-Basic) to reconstruct a recombinant plasmid named pGL3-hTERTp. Then the reconstructed plasmid was transiently transfected into lung cancer cell lines A549, SPC-A-1, LTEPa-2, NCI-H446, YTMLC, GLC-82, A2 and human embryonic pulmonary fibroblast cell line MRC-5. The transcriptional activities of hTERT promoter in various cells were determined by measuring the luciferase activities after 48 hours of transfection.</p><p><b>RESULTS</b>Electrophoresis demonstrated that cloned hTERT promoter was about 1.1 kb, and DNA sequencing showed a same sequence as registered in GenBank. The cloned hTERT promoter was located between 1 126 bp and 43 bp in upstream of the transcription start site ATG and the length was 1 086 bp. The recombinant plasmid pGL3-hTERTp was confirmed by double digestion and PCR method with correct results. Luciferase assay showed there were different transcriptional activities of hTERTp in various lung cancer cell lines, but not in the MRC-5 cell line.</p><p><b>CONCLUSIONS</b>The hTERT promoter cloned in this study has transcriptional activities in various lung cancer cell lines but not in normal cell. It may act as control element in tumor-targeting gene therapy with hTERT.</p>

Detection of mRNA expression of CK-19 and MUC1 gene for diagnosis of lymph node micrometastasis in NSCLC patients by reverse transcriptase-polymerase chain reaction / 中国肺癌杂志

<p><b>BACKGROUND</b>To investigate gene diagnosis of micrometastasis in lymph nodes in patients with non-small cell lung cancer (NSCLC) and the feasibility of mucin 1 (MUC1) mRNA and cytokeratin 19 (CK19) mRNA as molecular marker to detect micrometastasis of lung cancer.</p><p><b>METHODS</b>Expression of MUC1 mRNA and CK19 mRNA was detected in 119 lymph nodes taken from 31 patients with NSCLC, 35 lymph nodes from 10 patients with pulmonary benign diseases as controls by nested reverse transcriptase-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>In the 119 lymph nodes from lung cancer patients, CK19 mRNA expression was detected in 66 lymph nodes (55.5%) and MUC1 mRNA expression was detected in 65 lymph nodes (54.5%) by RT-PCR. Neither CK19 mRNA nor MUC1 mRNA expression was observed in all the 35 lymph nodes in the benign pulmonary lesion group.</p><p><b>CONCLUSIONS</b>The results suggest that the detection of both MUC1 and CK19 mRNA might be helpful to diagnose NSCLC micrometastasis in lymph nodes. The establishment of this method may lead to an earlier diagnosis of metastasis for lung cancer.</p>

Establishment of a human large cell lung cancer cell line L9981-nm23-H1 / 中国肺癌杂志

<p><b>BACKGROUND</b>To establish a human large cell lung cancer cell line L9981-nm23-H1 transfected with wild type nm23-H1 gene.</p><p><b>METHODS</b>pLXSN-nm23-H1-EGFP was constructed by gene clone technique, and L9981-nm23-H1 was established by infected virus of nm23-H1 gene. The DNA and protein expression of nm23-H1 were detected in the transgene large cell lung cancer cell line by PCR and Western blot.</p><p><b>RESULTS</b>pLXSN-nm23-H1-EGFP was constructed successfully, and the nm23-H1 cDNA was inducted to L9981 cell. The protein of nm23-H1 could be detected in L9981-nm23-H1 cell.</p><p><b>CONCLUSIONS</b>Protein of nm23-H1 is stably, continuously and high efficiently expressed in L9981-nm23-H1 cell.</p>

Regulation of nm23-H1 transfection on expression of integrins in human high-metastasis large cell lung cancer cell line L9981 / 中国肺癌杂志

<p><b>BACKGROUND</b>To study the regulation of nm23-H1 gene on the expression of integrins in human high-metastasis large cell lung cancer cell line L9981 by transfecting nm23-H1 into cell.</p><p><b>METHODS</b>Lipofect was used to transfect nm23-H1 into the L9981 cell line; semi-RT-PCR was used to detect the difference of integrin β1 and integrin β3 mRNA expressions between tranfected and non-transfected cell lines; flow cytometry was used to detect the difference of integrin β1 and integrin β3 protein expressions between transfected and non-transfected cell lines.</p><p><b>RESULTS</b>(1) A transgenic cell line L9981-nm23-H1 was obtained, which could stably and effectively express nm23-H1. The mRNA expressions of integrin β1 and β3 in L9981-nm23-H1 cell line were remarkably lower than those in L9981 cell line. (2) The protein expressions of integrin β1 and β3 in L9981-nm23-H1 cell line were significantly lower than those in L9981 cell line too (P < 0.01).</p><p><b>CONCLUSIONS</b>Transfection of nm23-H1 gene into the L9981 cell line can significantly down-regulate the mRNA and protein expressions of integrin β1 and β3 in this cell line, which indicates that nm23-H1 may reverse the metastasis potential of L9981 cell line through modulation of integrin expression.</p>

Serum levels of endostatin and VEGF in non-small cell lung cancer patients and the relationship with the clinical pathophysiological characteristics / 中国肺癌杂志

<p><b>BACKGROUND</b>To study the relationship between the serum levels of endostatin,VEGF and clinical and pathophysiological characteristics in the non-small cell lung cancer (NSCLC) patients.</p><p><b>METHODS</b>The serum levels of endostatin and VEGF were detected in 46 patients with NSCLC and 14 patients with benign pulmonary diseases as control by ELISA mothod.</p><p><b>RESULTS</b>(1)The preoperative serum level of endostatin [( 20.85 ±4.56) μg/L] and VEGF [(1.75±0.37) μg/L] in lung cancer patients was significantly higher than those in patients with benign pulmonary diseases [(15.68±2.78) μg/L and (1.05±0.32) μg/L). (2)The preoperative serum level of endostatin and VEGF in lung cancer patients was closely related to P-TNM stages, distant metastasis, grade of cell differentiation and the size of the primary tumors ( P < 0.05), but not to the histological classification, type of the tumor, lymph node status, age, sex of the patients and smoking or not ( P > 0.05). (3)The serum level of endostatin in lung cancer patients on the 7th postoperative day [(23.41± 5.12 ) μg/L] was significantly higher than that before operation [(20.85±4.56) μg/L] ( P < 0.05) and on the 1st postoperative day [(18.89±4.67) μg/L] ( P < 0.001). The serum level of VEGF in lung cancer patients on the 7th postoperative day [(3.75±0.71) μg/L] was also significantly higher than that before operation [(1.72±0.46) μg/L] and on the 1st postoperative day [(2.22±0.58) μg/L] ( P < 0.001). (4)The preoperative serum level of endostatin was highly negatively correlated to serum VEGF level in lung cancer patients ( r=-0.380, P < 0.01).</p><p><b>CONCLUSIONS</b>Elevation of serum endostatin and VEGF exists in patients with NSCLC. The serum levels of endostatin and VEGF in patients with NSCLC might be helpful to evaluate the biological behavior of lung cancer.</p>

Transfection of the tumor metastasis suppressor gene nm23-H1 can targetly suppress the activity of extracellular signal-regulated protein kinase (ERK) in human high-metastasis large cell lung cancer cell line L9981 / 中国肺癌杂志

<p><b>BACKGROUND</b>To investigate the influence of the tumor metastasis suppressor gene nm23 H1 on the activity of extracellular signal-regulated protein kinase (ERK) in human high metastasis large cell lung cancer cell line L9981.</p><p><b>METHODS</b>The levels of total ERK1/2 and phospho-pERK1/2 were determined with p44/42 MAP kinase antibody and dually phosphospecific phospho-44/42 MAP kinase antibody in human high-metastasis large cell lung cancer cell lines L9981 (cell line with nm23-H1 gene deletion), L9981-nm23-H1 (cell line with nm23-H1 transfected ) and L9981-PLXSN (cell line with vector transfected) by Western blot method, respectively. The activity of phospho-ERK1/2 was determined with an ERK1/2 assay kit by immunopreciptation and Western blot analysis.</p><p><b>RESULTS</b>The expression levels of phospho-ERK1/2 kinase and the activity of phospho-ERK1/2 in the lung cancer cell line L9981-nm23-H1 were remarkably higher than those of the L9981 cell line and L9981-PLXSN cell line ( P < 0.01), but no significant difference in both the phospho-ERK1/2 expression and phospho-ERK1/2 activity was observed between the L9981 and L9981-PLXSN cell lines ( P > 0.05). There was no significant difference in the total ERK1/2 level among the three cell lines.</p><p><b>CONCLUSIONS</b>nm23-H1 gene can obviously targetly suppress the activity of ERK1/2 in human high metastasis large cell lung cancer cell line L9981. This suggest that the mechanisms of nm23-H1 gene as a tumor metastasis suppressor gene may be related to its suppression to the MAPK/ERK signal transduction pathway.</p>

Construction of adenoviral vector carrying Smad3D or Smad7 / 中国肺癌杂志

<p><b>BACKGROUND</b>To construct recombinant adenoviral vector carrying Smad3D or Smad7 by a simplified means.</p><p><b>METHODS</b>Based on AdEasy System, adenoviral backbone plasmid vector and shuttle vector carrying the gene of interest were transferred into E.coli BJ5183 by chemical transformation methods in special order. The homologous recombination was performed.</p><p><b>RESULTS</b>Recombinant adenoviral vector pAd-Smad3D and pAd-Smad7 were constructed successfully, which were confirmed by restriction enzyme digesting.</p><p><b>CONCLUSIONS</b>Recombinant adenoviral vector may be constructed quickly and efficiently in E.coli by sequential chemical transformation methods.</p>

Establishment and their biological characteristics of clonal cell subpopulations (NL9980 and L9981) from a human lung large cell carcinoma cell line (WCQH-9801) / 中国肺癌杂志

<p><b>BACKGROUND</b>To explore the possibility of separating and establishing clonal cell subpopulations with different metastatic phenotype from a human lung large cell carcinoma cell line (WCQH-9801), to identify the difference of biological and molecular biology between NL9980 and L9981 cell lines.</p><p><b>METHODS</b>Two sub-cell lines (NL9980 and L9981) were isolated and established from a human lung large cell carcinoma cell line (WCQH-9801) by the single cell cloning techniques. The RELP, mRNA and protein transcript expression were detected in NL9980 and L9981 cell lines by Southern blot, RT-PCR and Western blot. The biological characteristics of vivo and vitro were determined in NL9980 and L9981 cell lines by MTT, plate, Boyden chamber methods and animal models.</p><p><b>RESULTS</b>(1)Two sub-cell lines, NL9980 and L9981 which had different metastatic phenotype, were successfully isolated and established from a human lung large cell carcinoma cell line (WCQH-9801). (2)The L9981 cell line had LOH of nm23-H1 gene, deletion of mRNA and protein expression of nm23-H1, but the NL9980 cell line had neither LOH of nm23-H1 nor deletion of mRNA and protein expression of nm23-H1. (3)The proliferation, clone formation and vitro invastion of L9981 cell line were significantly higher than those of NL9980 cell line. (4)The tumorigenicity and lung metastatic rate in nude mouse of L9981 cell line were remarkably higher than those of NL9980. (5) No significant difference of the chromosome number was observed between NL9980 and L9981 cell lines.</p><p><b>CONCLUSIONS</b>(1)NL9980 and L9981 cell lines established from a human lung large cell carcinoma cell line have different biological and molecular characteristics. (2)The high invsaion and metastasis ability of L9981 cell line might be related to the LOH of nm23-H1 gene.</p>

Effects of ectogenous FHIT gene on reversing malignant phenotype of human lung adenocarcinoma cells A549 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the role of fragile histidine triad(FHIT) gene in the proliferation, apoptosis and tumorigenesis of human lung cancer cells.</p><p><b>METHODS</b>FHIT gene packaged with lipofectin was transfected into the cells of a human lung adenocarcinoma cell line (A549), which stably expressed ectogenous FHIT gene. The FHIT mRNA and protein expression of A549-FHIT, A549-vector and A549 cell were detected by reverse transcription-PCR(RT-PCR), Western blot and immunocytochemical methods. The cell cycle pattern and apoptosis were assayed by using flow cytometry.</p><p><b>RESULTS</b>After transfection of FHIT gene, cell growth was obviously inhibited (P<0.01). The apoptosis index of A549-FHIT (8.42%) was significantly higher than that of A549-vector (5.45%) and A549 cells (5.71%)(P<0.01). The clone-formation rate of A549-FHIT cell (21.84%) was significantly lower than that of A549-vector (28.70%) and A549 cells (31.68%, P<0.01). Compared with control cell lines, larger scale of A549-FHIT cells accumulated in G0/G1, presenting that the proportion of the cells in G0/G1 phase was obviously increased from 67.78 % to 82.35 %. Tumorigenicity of the A549 cells in nude mice was greatly inhibited by expression of ectogenous FHIT gene, the weight and volume of A549-FHIT(1.61 g/1.37 cm(3)) were significantly lower than that of A549-vector (2.45 g/1.99cm(3)) and A549 cells (2.77 g/2.27 cm(3))(P<0.05).</p><p><b>CONCLUSION</b>Expression of ectogenous FHIT gene can obviously inhibit the proliferation and tumorigenesis of A549 cells, and can induce A549 cells into programmed cell death. The result of this study suggests that FHIT gene may be a tumor suppressor gene in human lung cancer cells.</p>