Implementation of literature case study in clinical epidemiology teaching reformation for medical students of the eight-year medical education program / 基础医学与临床

In order to improve the teaching quality of clinical epidemiology for medical students engaged in eight-year curriculum of Peking Union Medical College, and foster the practice of evidence-based medicine and clinical research in Peking Union Medical College Hospital (PUMCH), the Clinical Epidemiology Unit of PUMCH(PUMCH-CEU) utilized successful experience from institutions abroad and conducted a teaching reform. In addition to theory teaching, PUMCH-CEU incorporated literature case study and assignments into the course, so as to improve students' understanding about the design, measurement, and evaluation of clinical research. The execution of a well-designed reformation plan has led to a great success of this course, as well as fruitful achievements.

Application of combined telomerase activity analysis and immunocytochemistry in cytopathologic diagnosis / 中华病理学杂志

<p><b>OBJECTIVE</b>To evaluate the application of traditional cytomorphology, telomerase activity analysis and immunocytochemistry in cytopathologic diagnosis of pleural effusion and bronchoalveolar lavage samples.</p><p><b>METHODS</b>A total of 123 agar-paraffin double-embedded pleural effusion and bronchoalveolar lavage fluid samples were enrolled into study. The cytomorphologic features were reviewed and correlated with immunocytochemical findings and telomerase activity.</p><p><b>RESULTS</b>Telomerase activity was detected in 53 specimens using the real-time telomeric repeat amplification protocol. Amongst the cases studied, 39 samples (31.7%) contained overtly malignant cells while 20 cases (16.0%) were equivocal by conventional cytology. After verification by immunocytochemistry and clinical follow-up data, the diagnostic accuracy of telomerase activity and cytology was 87.0% and 82.1%, respectively. The sensitivity (97.6%) and specificity (100.0%) of cytology examination, when combined with telomerase activity analysis, were greater than those of cytology examination or telomerase activity analysis alone.</p><p><b>CONCLUSIONS</b>Telomerase activity analysis can be used as an adjunctive investigative tool in cytology assessment of pleural effusion and bronchoalveolar lavage samples. The diagnostic accuracy can be further improved with the application of immunocytochemistry on agar-paraffin double-embedded cell block tissues.</p>

Over expression of hyperplasia suppressor gene inhibits the malignant phenotype of breast cancer cell / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the effect of over expression of human hyperplasia suppressor gene (HSG) on proliferation, invasion, apoptosis and cell cycle of human breast cancer cells and to determine the relationship between HSG and Ras-dependent signaling pathway.</p><p><b>METHODS</b>Full length HSG coding sequences were cloned into plasmid pcDNA3.0. The recombinant plasmids were transfected into MDA-MB-231, a highly malignant breast cancer cell line. Vacant pcDNA3.0 was used as the control. MTT, Matrigel transwell assay and flow cytometric analysis were used to test for proliferation, invasion, cell cycle distribution and apoptosis of tumor cells after transient transfection of HSG.GST-pulldown and Western blotting assays were performed to investigate the activity of Ras protein.</p><p><b>RESULTS</b>HSG transfection inhibited proliferation of MDA-MB-231 cells, and significantly decreased the number of invading cells in Matrigel transwell assay compared with the vector/231 group (78.5 +/- 5.8 vs. 131.1 +/- 14.5) cells. FACS analyses demonstrated that compared with the vector/231 group, up-regulation of HSG promoted breast cancer cell apoptosis [(35.8 +/- 4.8)% vs. (25.6 +/- 3.5%)] and induced G(0)/G(1) phase arrest [(56.3 +/- 2.3)% vs. (50.4 +/- 1.9%)] after transfection for 18 hours. Furthermore, GST-pulldown assay showed that over-expression of HSG remarkably decreased the activity of Ras (about 65% lower than control).</p><p><b>CONCLUSIONS</b>HSG exibits multiple anticancer functions in breast cancer cells including inhibition of proliferation and in vitro invasion, G(0)/G(1) arrest and promotion of apoptosis. Besides, inhibition of Ras-dependent signaling pathway may be involved in these processes.</p>

Overexpression of human tumor metastasis-related gene TMSG-1 suppresses cell proliferation and invasion of a highly metastatic prostate cancer cell line PC-3M-1E8 in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effects of tumor metastasis-related gene TMSG-1 overexpression on the proliferation and invasion of a highly metastatic prostate cancer cell line in vitro.</p><p><b>METHODS</b>The eukaryotic expression plasmids containing full-length TMSG-1 cDNAs were stably transfected into the highly metastatic prostate cancer cell line PC-3M-1E8. Clones highly expressing TMSG-1 were identified by RT-PCR and Western Blot analysis after G418 screening. The cell proliferation was detected by cell growth curve, MTT assay and soft agar colony formation assay. The invasive potential of tumor cells in vitro was tested by Matrigel invasion assay.</p><p><b>RESULTS</b>Three TMSG-1 overexpression clones were selected. Cell growth curve and MTT assay showed that TMSG-1 overexpression clones exhibited a strong inhibition of proliferation compared with that of the parental cells or those transfected with vector alone from the third day of culture (P <0.05). In vitro analysis also showed that the TMSG-1 transfected clones exhibited a decreased clonogenicity in soft agar compared with that of the parental cells or those transfected with vector only (P < 0.05). TMSG-1 expression significantly suppressed cell invasion in vitro of TMSG-1-transfected PC-3M-IE8 cells (P < 0.05).</p><p><b>CONCLUSION</b>The TMSG-1 protein may serve as a tumor metastasis suppressor due to inhibiting cell proliferation and invasion of the highly metastatic prostate cancer cell line PC-3M-1E8.</p>

Overexpression of tumor metastasis suppressor gene 1 suppresses proliferation and invasion, but enhances apoptosis of human breast cancer cells MDA-MB-231 cells / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the effects of tumor metastasis suppressor gene 1 (TMSG-1) overexpression on the proliferation, invasion and apoptosis of breast cancer cells and to determine possible correlations of TMSG-1 and metastasis of breast cancer.</p><p><b>METHODS</b>Full-length human TMSG-1 coding sequences were cloned into plasmid pcDNA3.0-FLAG. The recombinant plasmids constructs were transfeced into MDA-MB-231, a highly malignant breast cancer cell line. Parental, vector-only stable transfectant and TMSG-1 stable transfectant clones were tested by MTT, soft agar colony formation and Boyden chamber assays. At twenty-four hours and forty-eight hours post transient transfection, double staining with Annexin-V-FITC and PI were employed to distinguish apoptotic cells from living cells by flow cytometry analysis.</p><p><b>RESULTS</b>Three TMSG-1 overexpression clones were selected. Compared with the control cells, TMSG-1 overexpression MDA-MB-231 cells showed strong inhibition of proliferation and decreased clonogenicity in soft agar (P<0.05). Transfection of TMSG-1 into MDA-MB-231 cells significantly suppressed the cell invasion ability in vitro (decreased numbers of cells trespassing the matrigel in three experiments: 72.3+/-8.1, 85.0+/-4.2, and 73.5+/-7.8) in comparison with nave cells without transfection (187.5+/-2.1) and cells transfected with the control vector (162.3+/-6.8) (P<0.01). Transient transfection of TMSG-1 into MDA-MB-231 cells could promote cell apoptosis at 24 and 48 hours after transfection (P<0.05).</p><p><b>CONCLUSIONS</b>TMSG-1 protein may have multiple functions in the regulation of proliferation, invasion and apoptosis of metastatic breast cancer cells, likely as a metastasis suppressor gene.</p>

P2Y purinergic receptor activated PI-3K/Akt signaling pathway in regulation of growth and invasion of prostatic cancer / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate P2Y purinergic receptor activated PI-3K/Akt signaling pathway in the regulation of growth and invasion of prostate cancer in vitro.</p><p><b>METHODS</b>Western blot was used to detect phosphorylation of Akt (a downstream target molecule of PI-3K) by P2Y receptor agonist in 1E8 cells (a highly metastatic subclone derived from PC-3 prostatic cancer cell line). Cell counts, flow cytometry, Matrigel invasion assay, wound healing assay and gelatin zymography were used to detect changes of biological behaviors of 1E8 cells after P2Y receptor activation.</p><p><b>RESULTS</b>AMP-PNP, one non-hydrolysis ATP analogue and P2Y receptor agonist, induced significant phosphorylation of Akt in a time- and dose-dependent manner in IE8 cells. LY294002, a specific inhibitor of PI-3K, effectively blocked Akt phosphorylation induced by AMP-PNP. Continuous exposure to AMP-PNP induced significant growth inhibition of 1E8 cells (inhibition rate at 50.2% at the 8th day), and this inhibition was mainly due to an arrest at S phase of the cell cycle (the S phase fraction of AMP-PNP treated cells was 22.3% higher than that of the control). Application of LY294002 did not reverse the growth inhibition effect of AMP-PNP. Matrigel invasion assay showed that AMP-PNP stimulation increased invasive ability of 1E8 cells, and this effect was effectively blocked by LY294002. No significant changes in the activation of MMP-2 and MMP-9 were detected by gelatin zymography, although wound healing assay showed 21.2% increase in cell migration after AMP-PNP treatment.</p><p><b>CONCLUSIONS</b>PI-3K/Akt signaling pathway participates in P2Y receptor-stimulated prostate cancer invasion by enhancing cell motility, rather than up-regulating MMP-2 and MMP-9 activities. PI-3K signaling pathway plays an important role in prostate cancer proliferation, but is not involved in P2Y receptor mediated growth inhibition.</p>

Expression of E-cadherin, beta-catenin, cathepsin D, gelatinases and their inhibitors in invasive ductal breast carcinomas / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>E-cadherin, beta-catenin, cathepsin D, matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 are all invasion-related proteins. The expression patterns of these proteins in invasive ductal breast carcinomas, and their associations with known clinicopathological parameters, tumor recurrence and expressions of estrogen receptor (ER), progesterone receptor (PR), PS2 and c-erbB2 were not well studied in Chinese patients.</p><p><b>METHODS</b>In a set of 94 invasive ductal breast carcinomas, protein expressions of these molecular markers were investigated by immunohistochemistry, and their associations with known clinicopathological parameters, tumor recurrence and expressions of ER, PR, PS2 and c-erbB2 were also examined. In addition, the interrelationship between the expressions of these proteins were studied.</p><p><b>RESULTS</b>Preserved membrane E-cadherin expression was associated with late tumor stage and tumor recurrence, whereas the reduced junctional beta-catenin associated with positive lymph node status and c-erbB2 overexpression. Positive staining of cathepsin D in tumor stromal cells displayed a significant association with late tumor stage. High expression of MMP-2 in cancer cells was associated with large tumor size and PR positive expression. TIMP-2 expression was positively associated with tumor recurrence. In addition, inter-relationship between the expressions of these biomarkers was also assessed. Cathepsin D staining in cancer cells was inversely correlated with its staining in stromal cells, and also inversely correlated with MMP-2 staining in tumor stromal cells. MMP-2 expression in stromal cells displayed an inverse correlation with TIMP-2 expression. MMP-9 expression displayed parallel associations with TIMP-1 and TIMP-2 expression.</p><p><b>CONCLUSION</b>Evaluation of E-cadherin, beta-catenin, cathepsin D, MMP-2 and TIMP-2 expression may be of some help in more accurately predicting the prognosis of invasive ductal breast carcinomas.</p>

Biological implications of the inhibition of survivin by RNA interference in human androgen-independent prostate carcinoma with highly metastatic potential / 中华病理学杂志

<p><b>OBJECTIVE</b>To determine the expression level of survivin in androgen-independent prostate carcinoma, and to investigate the biological role of survivin in invasion and metastasis of androgen-independent prostate carcinoma.</p><p><b>METHODS</b>Highly metastatic prostatic cancer cell line PC-3M-1E8 was stably transfected with pSilencer plasmid targeting survivin expression by RNA interference. The biological effects were observed, including anchorage-independent growth, in vitro invasion by soft agar colony formation and Boyden chamber assay, and also in vivo tumorigenesis in nude mice. Cell cycle and apoptosis indices were evaluated by flow cytometry and Western blot analysis of bioactive fragments of caspase 3.</p><p><b>RESULTS</b>The expression of survivin in transfected PC-3M-1E8 cells was markedly depressed at both mRNA and protein levels (about 78% to 80%) as compared with control. The growth of tumor cells was retarded by anchorage-independent growth assay. The survivin transfectants formed smaller and fewer colonies (14.33 +/- 3.51) than the negative (52.33 +/- 6.81) and blank controls (54.00 +/- 6.00). Inhibition of survivin expression was correlated with enhanced apoptosis of tumor cells (percentages of apoptotic cells of the negative control, blank control and experimental groups were 5.88 +/- 0.99, 6.97 +/- 1.60, 16.40 +/- 1.95 respectively), along with an increased expression of activated caspase 3, and cell cycle inhibition at G(0)/G(1) phase (the relative number of cells at G(0)/G(1) phase were 43.65 +/- 3.44, 43.59 +/- 1.83 and 52.71 +/- 1.10, respectively). In addition, multinucleated giant cells were observed along with a marked inhibition of invasion as reflected by fewer penetrating cells by Boyden chamber assay (46.07 +/- 9.97, 47.87 +/- 9.58 and 38.67 +/- 6.59, respectively).</p><p><b>CONCLUSIONS</b>Survivin expression is high in androgen-independent prostate cancer cells and likely may be related to the apoptosis, growth and invasion of the tumor cells. Targeting the survivin pathway by RNA interference appears to be a promising approach for clinical treatment of androgen-independent prostate cancer.</p>

Status and clinical implication of c-kit and PDGFRA mutations in 165 cases of gastrointestinal stromal tumor (GIST) / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the status of c-kit and PDGFRA mutations of GIST in a the large sample of Chinese patients.</p><p><b>METHOD</b>One hundred and sixty-five cases were evaluated for the presence of c-kit and PDGFRA mutations. Exon 9, 11, 13, 17 of c-kit and exon 12, 18 of PDGFRA were analyzed by PCR amplification and direct sequencing.</p><p><b>RESULTS</b>Immunohistochemical demonstrations of KIT (CD117) were seen in 94% of the cases (155/165). Overall, c-kit mutations were identified in 76.1% (118/155) of CD117 positive cases: 67.1% (104/155) involving exon 11, 7.1% (11/155) involving exon 9, 1.3% (2/155) involving exon 13 and 0.6% (1/155) involving exon 17. The c-kit exon 11 mutations were mostly heterogeneous and clustered in the classic "hot spot" at the 5' end of the exon, including in-frame deletion and point mutation. The second "hot spots" were internal tandem duplications (ITD) at the 3' end of the exon, which were associated with female patient, older age, stomach location and low mitotic counts. The exon 9 mutations correlated with a distinct subset of GISTs involving the small bowel of young male patients. A new point mutation of L641P was identified in exon 13. PDGFRA mutations were present in 50% (5/10) of CD117-negative GISTs, all involving exon 18 with the majority of mutations being D842V. One novel in-frame deletion of IMHD mutation at codon 843 - 846 with S847T was identified. GISTs with PDGFRA mutations were often larger tumors arising from the omentum/mesentery of young male patients with high risk of aggressive behavior.</p><p><b>CONCLUSIONS</b>The vast majority of GISTs in this study harbored c-kit and PDGFRA mutations, there were non-random relations between the gene mutation patterns and the locations of GISTs. It appears that Chinese GIST patients have some unique mutation patterns. It is necessary to evaluate the gene mutations status of GISTs to guide target therapy.</p>

Lung pathology and pathogenesis of severe acute respiratory syndrome: a report of six full autopsies / 中华病理学杂志

<p><b>OBJECTIVE</b>Severe acute respiratory syndrome (SARS) is an emerging infectious disease that first manifested in humans in November 2002. The SARS-associated coronavirus (SARS-CoV) has been identified as the causal agent, but the pathology and pathogenesis are still not quite clear.</p><p><b>METHODS</b>Post-mortem lung samples from six patients who died from SARS from April to July 2003 were studied by light and electron microscopy, Masson trichromal staining and immunohistochemistry. Evidence of infection with the SARS-CoV was determined by reverse-transcription PCR (RT-PCR) , serological examination and electron microscopy.</p><p><b>RESULTS</b>Four of six patients had serological and RT-PCR evidence of recent infection of SARS-CoV. Morphologic changes are summarized as follows: (1) Diffuse and bilateral lung consolidation was seen in all patients (6/6) with increasing lung weight. (2) Diffuse alveolar damage was universal (6/6) with hyaline membrane formation (6/6), intra-alveolar edema/hemorrhage (6/6), fibrin deposition (6/6), pneumocyte desquamation (6/6). A marked disruption in the integrity of the alveolar epithelium was confirmed by immunostaining for the epithelial marker AE1/AE3 (6/6). (3) Type II pneumocytes, with mild hyperplasia, atypia, cytomegaly with granular amphophilic cytoplasm and intracytoplasmic lipid accumulation (5/6). (4) Giant cells in the alveoli were seen in five of 6 patients (5/6) , most of which were positive for the epithelial marker AE1/AE3 (5/6), but some cells were positive for the macrophage marker CD68(2/6). (5) A pronounced increase of macrophages were seen in the alveoli and the interstitium of the lung (6/6), which was confirmed by histological study and immunohistochemistry. (6) Haemophagocytosis was present in five of the 6 patients(5/6). (7) Lung fibrosis was seen in five patients(5/6), with alveolar septa and interstitium thickening(5/6), intraalveolar organizing exudates (6/6) and pleura thickening (4/6). Proliferation of collagen was confirmed by Masson trichromal staining, most of which was type III collagen by immunostaining. The formation of distinctive fibroblast/myofibroblast foci was seen in five patients (5/6) by light microscopy and immunochemistry. (8) Squamous metaplasia of bronchial mucosa was seen in five patients(5/6). (9) Thrombi was seen in all patients(6/6). (10) Accompanying infection was present in two patients, one was bacteria, the other was fungus. In addition, electron microscopy revealed viral particles in the cytoplasm of alveolar epithelial cells and endothelial cells corresponding to coronavirus.</p><p><b>CONCLUSION</b>Direct injury of SARS-CoV on alveolar epithelium, prominent macrophage infiltration and distinctive fibroblast/myofibroblast proliferation may play major roles in the pathogenesis of SARS.</p>

SHP2 and MKP5 in P2Y purinergic receptor-mediated prostate cancer invasion / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the effects of protein tyrosine phosphatase-SHP2 and dual-specificity MAPK phosphatase-MKP5 on the activation of MAPKs and cell invasion induced by P2Y purinergic receptor in human prostate cancer cell lines with different metastatic potentials.</p><p><b>METHODS</b>The wide type (-wt) SHP2, mutant type (-cs) SHP2 and wide type (-wt) MKP5 cDNA expression vectors were constructed and stably transfected into 1E8 cells (highly metastatic) and/or 2B4 cells (non-metastatic). The tyrosine phosphorylation of SHP2 was examined by immunoprecipitation. The activation of ERK1/2 and p38 induced by P2Y receptor agonist ATP was analyzed by Western blot with phospho-specific antibodies against the dually phosphorylated, active forms of ERK1/2 and p38. The in-vitro invasive ability through Matrigel was measured by boyden-chamber assay.</p><p><b>RESULTS</b>ATP induced significant SHP2 phosphorylation, which was stronger and lasted longer in 1E8 than in 2B4. SHP2-wt enhanced the ERK1/2 activation induced by ATP in 2B4 cells, while SHP2-cs delayed and decreased this effect in 1E8 cells. Both SHP2-wt and SHP2-cs had no obvious influence on p38 activation. ATP stimulated cell invasion of both 1E8 and 2B4, while transfection of SHP2-wt into 2B4 cells further increased the invasive-stimulating ability of ATP (18.7% increase compared with ATP treatment alone). Transfection of SHP2-cs into 1E8 cells, however, antagonized the invasive-stimulating ability of ATP (40.9% decrease compared with ATP treated group). Up-regulation of MKP5-wt inhibited phosphorylation of p38 by ATP and reduced cell invasion stimulated by ATP (22.4% and 28.7% decrease compared with ATP treated group of 1E8 and 2B4, respectively).</p><p><b>CONCLUSIONS</b>Both SHP2 and MKP5 play some roles in P2Y receptor-mediated activation of MEK/ERK, p38 signaling pathways and prostate cancer invasion. SHP2 positively regulates ERK activation and prostate cancer invasion, whereas MKP5 inhibits the invasion by suppressing p38 activation.</p>

The prognostic value of human neuroendocrine clone on colorectal carcinoma / 中华外科杂志

<p><b>OBJECTIVE</b>To demonstrate the prognostic value of neuroendocrine clone on colorectal carcinoma.</p><p><b>METHODS</b>The immunochemistry methods were used to investigate the percent of neuroendocrine carcinoma in 73 human colorectal carcinoma. Retrospective analysis and follow-up were carried out in all patients.</p><p><b>RESULTS</b>In all 73 cases of colorectal carcinoma, the total percentage of neuroendocrine carcinoma was 17.8%. Neuroendocrine carcinoma included 11 synapse positive, 6 chromogranin positive and 4 both positive. The major factors related to the prevalence of neuroendocrine carcinoma were sex, age, tumor location and Dukes' stage. And the 1-year survival rate of the patients who suffered from neuroendocrine carcinoma is obviously lower than that of other colorectal carcinoma.</p><p><b>CONCLUSIONS</b>The neuroendocrine carcinoma is a special kind of human colorectal carcinoma, and neuroendocrine clone may be a new marker of the malignant potency. The neuroendocrine clone has its prognostic value and may be a novel therapeutic target.</p>

Effects of P2Y receptor activation on prostatic cancer cells requiring ERK1/2 or p38 cascade / 中华病理学杂志

<p><b>OBJECTIVE</b>To determine the role of extracellular signal-regulated kinase (ERK1/2) and p38 cascades in P2Y receptor-evoked effects on prostatic cancer cells.</p><p><b>METHODS</b>Highly metastatic prostatic cancer cells 1E8 were transfected with dominant-negative MAPK kinase 1 (KA-MEK1). The activation of ERK1/2 was determined by Western blot technique. The role of ERK1/2 and p38 cascades in P2Y receptor-evoked effects on in vitro growth, colony formation and in vitro invasion was detected by cell count, soft agar colony formation assay and in vitro invasion assay. The effect of ATP on apoptosis was detected by flow cytometry.</p><p><b>RESULTS</b>ERK1/2 activity in 1E8-KA-MEK1 transfectants was significantly suppressed by dominant-negative MEK1 transfection. After culture of 6 days, 1E8-KA-MEK1 transfectants exhibited a growth inhibition of 71% as compared with 1E8-pcDNA3 control. Moreover, after continuous treatment with 100 micro mol/L ATP for 6 days, the growth of 1E8-KA-MEK1 transfectants was further inhibited by an additional 17.2%. Pretreatment with 10 micro mol/L p38 inhibitor SB203580 antagonized the effect of ATP-induced additional growth inhibition, suggesting that ERK1/2 and p38 pathways play an important role in ATP-induced growth inhibition. In soft agar assay, 1E8-KA-MEK1 transfectants formed smaller colonies and exhibited a 75% decrease in colony formation (as compared with control). Further treatment with ATP or SB203580 plus ATP did not show significant effect on colony formation of 1E8-KA-MEK1 cells, implying a potential role of ERK1/2, instead of p38, in P2Y receptor-mediated inhibitory effect on colony formation. In in vitro invasion assay, 1E8-KA-MEK1 cells showed a 41% decrease in passing through matrigel-coated membranes, as compared with control. Treatment with ATP could restore their invasive ability, and this effect by ATP could be blocked by pretreatment with SB203580, indicating the involvement of both ERK1/2 and p38 pathways in invasive ability of prostatic cancer cells.</p><p><b>CONCLUSIONS</b>The effects of ATP on in vitro growth, invasion and colony formation of prostatic cancer cells depend on the status of P2Y receptor activation by different treatment protocols. Continuous activation of P2Y receptor results in growth inhibition and transient activation of P2Y receptor stimulates in vitro invasion of prostatic cancer cells. Both ERK1/2 and p38 pathways are responsible for these effects; but only the ERK1/2 pathway is involved in regulation of colony formation of prostatic cancer cells.</p>

Down-regulation of metastatic phenotype in human melanoma cells by controlled expression of anti-sense matrix metalloproteinase 9 / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the correlation between matrix metalloproteinase 9 (MMP-9) expression and tumor invasion and metastasis as well, and to explore the potential application of controlled expression of target gene in tumor gene therapy.</p><p><b>METHODS</b>One self-contained tetracycline-regulated retroviral vector containing anti-sense cDNA of MMP-9 was constructed and transfected into a metastatic human melanoma cell line WM451 which expressed a high level of MMP-9. Techniques such as growth rate measurment, MTT assay, (3)H-thymidine incorporation, colony forming ability in soft agar, invasion assay in Boyden chamber, as well as zymography and Western blot were applied to analyze the expression of MMPs and behaviors of tumor cells in vitro before and after gene transfection. Tumorigenecity and spontaneous metastasis were tested in nude mice.</p><p><b>RESULTS</b>In the presence of exogenous tetracycline, the transfected antisense MMP-9 did not affect the endogenous level of MMP-9 in WM451 cells, and showed no significant changes in cell behaviors in comparison with that of the vector-transfected control cells. Nevertheless, withdrawal of tetracycline from the medium caused a significant down-regulation of expression and activity of MMP-9. The capacity of cell growth in vitro, colony forming ability in soft agar, invasion through Matrigel all were inhibited remarkably when compared with the controls. Spontaneous metastasis in nude mice was significantly inhibited.</p><p><b>CONCLUSIONS</b>Transfection of anti-sense MMP-9 can down-regulate the invasion and metastasis of melanoma cells both in vitro and in vivo, further clarifying the important role of MMP-9 in tumor progression.</p>