Long non-coding RNA HOXA-AS3 facilitates the malignancy in colorectal cancer by miR-4319/SPNS2 axis.

Growing evidence has shown the oncogenic role of long non-coding RNA HOXA-AS3 in the progression of several types of cancers, while the effect of HOXA-AS3 on colorectal cancer (CRC) remains unclear. In this study, HOXA-AS3 was significantly over-expressed in CRC clinical samples and human CRC cell lines (SW480, SW620, HCT116, COLO205, and LOVO). HOXA-AS3 knockdown was further achieved by specific siRNAs in COLO205 and LOVO cell lines. The depletion of HOXA-AS3 remarkably inhibited cell proliferation, induced cell cycle arrest, and promoted cell apoptosis in CRC cell lines. Additionally, HOXA-AS3 knockdown was determined to facilitate miR-4319 expression and reduce expression level of sphingolipid transporter 2 (SPNS2) in CRC cell lines. The dual luciferase reporter assay suggested that HOXA-AS3 acted as a sponge of miR-4319, and miR-4319 further directly targeted SPNS2 for expression regulation. Besides, HOXA-AS3 was determined to mediate CRC cell proliferation and apoptosis via miR-4319/SPNS2 axis. Moreover, tumorigenesis experiment validated that HOXA-AS3 promoted CRC progression in vivo by regulating miR-4319, SPNS2, and protein kinase B (AKT) signaling. In summary, this study reveals the novel role of HOXA-AS3 in pathogenesis of CRC and provides a candidate for CRC therapeutic target.

A standardized pathological proposal for evaluating microvascular invasion of hepatocellular carcinoma: a multicenter study by LCPGC.

BACKGROUND AND AIMS: Microvascular invasion (MVI) is a key pathological factor that severely affects the postoperative prognosis of patients with hepatocellular carcinoma (HCC). However, no MVI classification schemes based on standardized gross sampling protocols of HCC are available at present. METHODS: 119 HCC specimens were sampled at multiple sites (3-, 7-, and 13 points) for the optimum MVI detection rate. 16,144 resected HCCs were graded as M0, M1 or M2 by adopting three-tiered MVI grading (MVI-TTG) scheme based on the seven-point sampling protocol (SPSP). Survival analyses were performed on 2573 patients to explore the advantages of MVI-TTG. RESULTS: The MVI detection rate determined by SPSP was significantly higher than that determined by the 3-point sampling method (34.5% vs. 47.1%, p = 0.048), but was similar to that determined by the 13-point sampling method (47.1% vs. 51.3%, p = 0.517). Among 16,144 resected HCCs, the proportions of M0, M1 and M2 specimens according to SPSP were 53.4%, 26.2% and 20.4%, respectively. Postoperative survival analysis in 2573 HCC patients showed that the 3-year recurrence rates in M0, M1 and M2 MVI groups were 62.5%, 71.6% and 86.1%, respectively (p < 0.001), and the corresponding 3-year overall survival (OS) rates were 94.1%, 87.5% and 67.0%, respectively (p < 0.001). M1 grade was associated with early recurrence, while M2 grade was associated with both early and late recurrence. MVI-TTG had a larger area under the curve and net benefit rate than the two-tiered MVI grading scheme for predicting time to recurrence and OS. CONCLUSIONS: SPSP is a practical method to balance the efficacy of sampling numbers and MVI detection rates. MVI-TTG based on SPSP is a better prognostic predictor than the two-tiered MVI scheme. The combined use of SPSP and MVI-TTG is recommended for the routine pathological diagnosis of HCC.

Association of p16 as Prognostic Factors for Oropharyngeal Cancer: Evaluation of p16 in 1470 Patients for a 16 Year Study in Northeast China.

Human papillomavirus (HPV) is an etiological risk factor for oropharyngeal squamous cell carcinomas (OPSCC). Our study investigates the prevalence, prognostic, and clinicopathologic features of HPV-related oropharyngeal cancer in Northeast China and elucidates the involvement of p16 in the tumorigenesis and progression of OPSCC. Specimens from 1470 OPSCC patients collected from 2000 to 2016 were analyzed using the status of HPV by polymerase chain reaction (PCR) and p16 immunohistochemistry. Overexpression of p16 was observed in 81 (5.51%) of the 1470 cases, and HPV positive was present in 78 cases (5.31%) of the 1470 cases. HPV positive and p16 overexpression have a good concordance. However, we found that the etiological fraction of HPV in cancers of the OPSCCs was obviously lower in Northeast China than other cohorts previously reported. Interestingly, nearly 89% of patients with p16 expression were smokers, and nearly 70% of patients with p16 expression had a history of alcohol. Our study also demonstrates that p16 expression is significantly associated with early stage primary OPSCCs and the patients with p16 expression tend to show better survival following surgery and radiotherapy.

Human epidermal growth factor receptor 2 status of gastric cancer patients in Asia: results from a large, multicountry study.

AIM: Current estimates of the human epidermal growth factor receptor 2 (HER2)-positivity rate in gastric cancer vary widely in the literature, and there are limited data from countries in Asia. The primary aim of this study was to conduct a clinical audit of laboratories across seven countries in Asia to determine the incidence of HER2-positive gastric cancer in this region. METHODS: Pathologists were asked to collect data on patient gender, age, cancer site, specimen type, tumor spread, type and grade, HER2 test results, including protein and/or gene copy enumeration, and final HER2 status on consecutive gastric cancer cases tested for HER2 in their laboratory over a 2-year period. RESULTS: HER2 results from 5,301 gastric cancers were submitted by 50 laboratories. The overall HER2-positivity rate was 9.7% which, after the exclusion of China, increased to 18.1%. The rate between countries ranged from 0% to 23.1%, and from 0% to 50.0% between laboratories. An equivocal HER2 result was recorded in 19.5% of cases. CONCLUSION: Despite the lack of centralized testing to confirm the accuracy of HER2 diagnoses, the incidence of HER2-positive gastric cancer observed here was comparable to that reported in the literature. Nevertheless, rates were highly variable between countries and laboratories, which suggests a lack of HER2 testing expertise in gastric cancer. Given that the mortality rates for gastric cancer in Eastern Asia are the highest in the world, efforts should focus on improving HER2 testing expertise in the region so that patients receive the appropriate treatment early in their disease.

Human epidermal growth factor receptor 2 status of breast cancer patients in Asia: Results from a large, multicountry study.

AIM: Current estimates of the human epidermal growth factor receptor 2 (HER2)-positivity rate in breast cancer are largely based on studies from the United States, Europe and Australia, and might not reflect the rate among breast cancer patients in Asia. The primary aim of this study was to conduct a clinical audit of laboratories across eight countries in Asia to determine the incidence of HER2-positive breast cancer in this region. METHODS: Pathology laboratories submitted data on breast cancers consecutively tested for HER2 over a two-year period. The proportion of HER2-positive, -equivocal and -negative tumors was determined for each country and overall. HER2-positivity rate by age and histological grade was also determined. RESULTS: HER2 results from 30 179 breast cancers were submitted by 96 laboratories. The overall HER2-positivity rate was 23.5%; the rate between countries ranged from 19.7% to 44.2%, and from 4.4% to 51.6% between laboratories. An equivocal HER2 result was recorded in 18.2% of cases. Discrepancies between laboratories suggest that testing expertise contributes to variations seen in HER2 status across laboratories, as well as the generally higher rate of HER2-positivity that was recorded. CONCLUSION: In this study, the incidence of HER2-positive breast cancer diagnosed in Asian women was higher than published studies on women from Western countries. In addition, the study found that women in Asian countries presented with breast cancer at an earlier age, with a higher histological grade. This study serves to highlight the challenges with HER2 testing and data collection in a large multicenter Asian cohort.

Decreased expression of follicular dendritic cell-secreted protein correlates with increased immunoglobulin A production in the tonsils of individuals with immunoglobulin A nephropathy.

Immunoglobulin A nephropathy (IgAN) is characterized by a qualitative abnormality of IgA in the circulation and IgA deposition in the renal mesangium. Recent research has indicated that pathogenic IgA may originate from affected tonsils. Follicular dendritic cell-secreted protein (FDC-SP), a small novel secretory protein that may regulate the induction of B-cell responses, has been suggested to control IgA production. Given this background, this study investigated the expression of FDC-SP and its correlation with IgA production in the tonsils of IgAN patients. Immunohistochemistry and reverse transcription-polymerase chain reaction were used to compare the expression of FDC-SP in the tonsils of IgAN patients with tonsillitis and of non-IgAN patients with chronic tonsillitis. The location of FDC-SP in tonsillar tissue was confirmed by double immunofluorescence. We found that FDC-SP expression significantly decreased and was correlated negatively with enhanced IgA production in the tonsils of IgAN patients. FDC-SP secreted by follicular dendritic cells may act on germinal center B cells and participate in the modulation of IgA generation in the tonsils. Our study demonstrated that FDC-SP may be involved in IgA production in the tonsils of IgAN patients, making this protein an attractive candidate immunomodulator, and highlighting a promising strategy for therapeutic intervention in IgAN.

Astrocyte elevated gene-1 mediates glycolysis and tumorigenesis in colorectal carcinoma cells via AMPK signaling.

To investigate the role of AEG-1 in glycolysis and tumorigenesis, we construct myc-AEG-1 expression vector and demonstrate a novel mechanism that AEG-1 may increase the activity of AMPK by Thr172 phosphorylation. The higher expression levels of AEG-1 in colorectal carcinoma cells were found but showed significant difference in different cell lines. To study the role of AEG-1 in colorectal cells, myc-AEG-1 vector was constructed and transfected into NCM460 colonic epithelial cells. We observed consistent increasing of glucose consumption and lactate production, typical features of anaerobic glycolysis, suggesting that AEG-1 may promote anaerobic glycolysis. Moreover, we noted that AMPK phosphorylation at Thr172 as well as pPFK2 (Ser466) was increased in NCM460 cells overexpressing AEG-1. Compound C may block AMPK and PFK2 phosphorylation in both control and AEG-1-overexpressed cells and decrease the glucose consumption and lactate production. The present findings indicated that reduced AEG-1 protein levels by RNAi may decrease the glucose consumption and lactate production in HCT116 colorectal carcinoma cells. The present identified AEG-1/AMPK/PFK2 glycolysis cascade may be essential to cell proliferation and tumor growth. The present results may provide us with a mechanistic insight into novel targets controlled by AEG-1, and the components in the AEG-1/AMPK/PFK2 glycolysis process may be targeted for the clinical treatment of cancer.

High levels of BCOX1 expression are associated with poor prognosis in patients with invasive ductal carcinomas of the breast.

This study was to examine the breast cancer-overexpressed gene 1 (BCOX1) expression in invasive ductal carcinomas (IDC) of the breast and its value in the prognosis of the disease. The levels of BCOX1 expression in 491 paired IDC and surrounding non-tumor breast tissues as well as 40 paired fresh specimens were evaluated by tissue microarray, immunohistochemistry and quantitative RT-PCR. The potential associations of high BCOX1 expression with clinicopathological variables and the overall survival of these patients were analyzed. The relative levels of BCOX1 mRNA transcripts in the IDC breast tissues were significantly higher than that in the corresponding non-tumor tissues (P = 0.005). The anti-BCOX1 was predominantly stained in the cytoplasm of breast tissue cells and the levels of BCOX1 expression in the majority of breast cancer tissues were obviously higher than that in the corresponding non-tumor breast tissues. High levels of BCOX1 expression were found in 59.5% (292/491) of breast cancer tissues. The high BCOX1 expression was significantly associated with high histological grade (P = 0.037), positive expression of human epidermal growth factor receptor 2 (HER2, P = 0.031) and triple negative breast cancer (P = 0.027). The high BCOX1 expression in breast cancers was significantly associated with a shorter overall survival of these patients (P = 0.023), particularly in patients with triple negative breast cancer (P = 0.005). Therefore, the high BCOX1 expression may serve as a novel marker of poor prognosis and a potential therapeutic target for patients with IDC of the breast.

Panax ginseng polysaccharide induces apoptosis by targeting Twist/AKR1C2/NF-1 pathway in human gastric cancer.

In the present study, we isolated and screened an antitumor polysaccharide (PGP2a) from the roots of Panax ginseng. Chemical composition analysis indicated PGP2a was an acidic protein-polysaccharide. The average molecular weight was estimated to be 3.2 × 10(4)Da. According to gas chromatography (GC) result, PGP2a consisted of galactose, arabinose, glucose and galacturonic acid in the molar ratio of 3.7:1.6:0.5:5.4, respectively. MTT assay showed that PGP2a had a potent inhibitory effect on the growth of HGC-27 cells in a dose-dependent fashion. Furthermore, the number of HGC-27 cells arrested in G2/M phase, and the percentage of apoptotic cells were increased in response to PGP2a treatment along with concentration increasing. Moreover, western blotting analysis showed that protein expressions of Twist and AKR1C2 were suppressed by PGP2a, whereas an increase of NF1 was observed at protein level. Taken together, these findings suggested that PGP2a could be developed as a novel antitumor agent acting on Twist related gene for human gastric cancer therapy.

Astrocyte elevated gene-1: a novel independent prognostic biomarker for metastatic ovarian tumors.

Astrocyte elevated gene-1 (AEG-1), a novel tumor-associated gene, was found overexpressed in many tumors. Therefore, our purpose is to estimate whether AEG-1 overexpression is a novel predictor of prognostic marker in metastatic ovarian tumors. Immunohistochemistry was used to estimate AEG-1 overexpression in metastatic ovarian tumors from 102 samples. The association between AEG-1 expression and prognosis was estimated by univariate and multivariate survival analyses with Cox regression. The log-rank test was used to identify any differences in the prognosis between the two groups. The median overall and progression-free survival rates of patients with tumors from gastrointestinal tract origin were 0.97 and 0.51 years, respectively. Similarly, survival rates of patients with tumors of breast origin were 2.68 and 1.96 years (P < 0.0001). Of 102 patients, 77 had high expression, and AEG-1 overexpression had a significant link of prognosis in metastatic ovarian patients (P < 0.01). On the other hand, medians of overall survival and progression-free survival of patients with tumors of gastrointestinal tract origin were significantly lower than those of patients with tumors of breast origin (P < 0.0001). Patients with metastatic ovarian tumors of breast origin had significantly better prognosis than those with the tumors from gastrointestinal tract primary malignancies. It is suggested that AEG-1 overexpression might be an independent prognostic marker of metastatic ovarian tumors.

Panax ginseng polysaccharide suppresses metastasis via modulating Twist expression in gastric cancer.

It was previously reported that an antitumor polysaccharide (PGPW1) was isolated from the root of Panax ginseng. To extend our study, we investigated here the anti-invasive and metastatic effects of PGPW1 on human gastric cancer cell line HGC-27 and tried to determine its possible mechanism of action. Both scratch wound-healing and Transwell assay identified that PGPW1 dose-dependently inhibited migration and invasiveness of HGC-27 cells. Furthermore, results of western blot showed that protein levels of Twist and AKR1C2 were inhibited by PGPW1, whereas an increase of NF1 was observed. Moreover, down-regulation of Twist expression by PGPW1 blocked epithelial-mesenchymal transition (EMT), characterized by a gain of epithelial cell markers, E-cadherin, and loss of the mesenchymal markers, vimentin and N-cadherin, at protein levels. Collectively, we confirmed that PGPW1 decreased migration and invasion of HGC-27 cells by regulation of Twist, AKR1C2, NF1, E-cadherin, vimentin and N-cadherin expression. In conclusion, PGPW1 may serve as a powerful chemopreventive agent against gastric cancer metastasis.

Long CAG repeat sequence and protein expression of androgen receptor considered as prognostic indicators in male breast carcinoma.

BACKGROUND: The androgen receptor (AR) expression and the CAG repeat length within the AR gene appear to be involved in the carcinogenesis of male breast carcinoma (MBC). Although phenotypic differences have been observed between MBC and normal control group in AR gene, there is lack of correlation analysis between AR expression and CAG repeat length in MBC. The purpose of the study was to investigate the prognostic value of CAG repeat lengths and AR protein expression. METHODS: 81 tumor tissues were used for immunostaining for AR expression and CAG repeat length determination and 80 normal controls were analyzed with CAG repeat length in AR gene. The CAG repeat length and AR expression were analyzed in relation to clinicopathological factors and prognostic indicators. RESULTS: AR gene in many MBCs has long CAG repeat sequence compared with that in control group (P = 0.001) and controls are more likely to exhibit short CAG repeat sequence than MBCs. There was statistically significant difference in long CAG repeat sequence between AR status for MBC patients (P = 0.004). The presence of long CAG repeat sequence and AR-positive expression were associated with shorter survival of MBC patients (CAG repeat: P = 0.050 for 5y-OS; P = 0.035 for 5y-DFS AR status: P = 0.048 for 5y-OS; P = 0.029 for 5y-DFS, respectively). CONCLUSION: The CAG repeat length within the AR gene might be one useful molecular biomarker to identify males at increased risk of breast cancer development. The presence of long CAG repeat sequence and AR protein expression were in relation to survival of MBC patients. The CAG repeat length and AR expression were two independent prognostic indicators in MBC patients.

Metastasis-induction and apoptosis-protection by TWIST in gastric cancer cells.

TWIST, a basic helix-loop-helix transcription factor, has been recently reported to play an important role in tumorigenesis of human cancer through converting the early stage tumors into invasive malignancies. Upregulation of TWIST is often found in cancer patients, especially those with shorter survival period and poor response to chemotherapy. Here we studied the functions of TWIST on regulating migration rate, apoptosis, and gene expression in gastric cancer cells. TWIST expression is elevated in MGC-803 and HGC-27 cells that exhibit high invasive potential; whereas it is reduced in BGC-823 and SGC-7901 cells that possess relatively low invasive content. To evaluate functional consequences of TWIST induction, we examined the effect of TWIST on cell migration and apoptosis. Overexpression of TWIST in BGC-823 cells resulted in increased migration content and decreased sensitivity to the arsenic oxide-induced cell death. Moreover, small interference RNA-mediated TWIST ablation in MGC-803 and HGC-27 cells showed suppressed migration ability, increased induction of apoptosis in response to arsenic oxide, and elevated cell cycle arrest. Furthermore, we found a negative correlation between the TWIST level and p53 level, probably due to transcriptional regulation. Our results have identified TWIST as a critical regulator of gastric cancer cell proliferation and migration, suggesting a potential therapeutic approach to inhibit the growth and metastasis of gastric cancer through inactivation of TWIST.

RUNX3 inhibits cell proliferation and induces apoptosis by TGF-beta-dependent and -independent mechanisms in human colon carcinoma cells.

BACKGROUND: Genes involved in the TGF-beta signaling pathway are often altered in several types of cancers. The TGF-beta-resistant human colon cancer cell line HT-29 has inactivated TbetaRII and deficient expression of RUNX3 and Smad4, which are involved in the TGF-beta signaling pathway. METHODS: Western blot and immunocytochemistry were performed to confirm gene expression, the MTT assay to detect cell growth, flow cytometry to investigate the cell cycle and the TUNEL to detect cell apoptosis. RESULTS: In the absence of TGF-beta, Bim was upregulated, cell growth was inhibited and apoptosis was induced. TGF-beta treatment did not affect RUNX3 expression; however, the increase in Bim expression was significant and time dependent. Interestingly, Smad4 but not Smad2/3 was also upregulated upon exposure to TGF-beta. This was not the case after TGF-beta treatment of parent HT-29 cells. As expected, TGF-beta further inhibited cell growth and induced apoptosis in HT-29/RUNX3+ cells. CONCLUSION: Our data demonstrate that RUNX3 is involved in TGF-beta-dependent and -independent cell growth inhibition and apoptosis induction pathways.

Reduced expression and novel splice variants of ING4 in human gastric adenocarcinoma.

ING4, a new member of the ING (inhibitor of growth) family of tumour suppressor genes, has been found to be deleted or down-regulated in gliomas, breast tumours, and head and neck squamous cell carcinomas. The goal of the present study was to investigate whether the expression and alternative splicing of ING4 transcripts are involved in the initiation and progression of stomach adenocarcinoma. ING4 mRNA and protein expression was examined in gastric adenocarcinoma tissues and human gastric adenocarcinoma cell lines by RT-PCR, real-time RT-PCR, tissue microarray immunohistochemistry, and western blot analysis. Alterations in ING4 transcripts were determined through sequence analysis of ING4 cDNA. Our data showed that ING4 mRNA and protein were dramatically reduced in stomach adenocarcinoma cell lines and tissues, and significantly less in female than in male patients. We also found that reduced ING4 mRNA expression correlated with the stage of the tumour. Interestingly, by sequence analysis, we discovered five novel aberrantly spliced variant forms of ING4_v1 and ING4_v2. These variants cause a codon frame-shift and, eventually, deletion of the NLS or PHD domain contributing to the mislocalization of p53 and/or HAT/HDAC complexes and, subsequently, altered gene expression in gastric adenocarcinoma. These results suggest that attenuated and aberrant ING4 expression may be involved in the initiation and progression of stomach adenocarcinoma.

Gene expression profiling in TWIST-depleted gastric cancer cells.

TWIST is an important transcription factor during embryonic development and has recently been found to promote the epithelial-mesenchymal transition (EMT) phenomenon seen during the initial steps of tumor metastasis. To further investigate the potential targets and interacting genes of TWIST in human gastric cancer, we performed microarray analysis to compare the gene expression profiles in HGC-27 cells, with or without small interfering RNA (siRNA)-mediated depletion of TWIST. Our results showed that NF1, RAP1A, SRPX, RBL2, PFDN4, ILK, F2R, ERBB3, and MYB were up-regulated, whereas AKR1C2, FOS, GDF15, NR2F1, ATM, and CTPS were down-regulated after TWIST depletion. Moreover, TWIST-depleted HGC-27 cells showed a reversal of the morphologic and molecular changes associated with EMT. These results provide evidence that TWIST regulates the expression of several genes involved in the differentiation, adhesion, and proliferation of gastric cancer cells. The role of TWIST in the development of certain types of gastric cancer is discussed.

Elevated serum level and gene polymorphisms of TGF-beta1 in gastric cancer.

Transforming growth factor (TGF)-beta1, as a candidate tumor marker, is currently of interest. In this study, serum TGF-beta1 levels in gastric cancer (GC) patients and healthy volunteers were measured using enzyme-linked immunosorbent assay (ELISA). In addition, single nucleotide polymorphisms (SNPs) of the TGF-beta1 gene at codon 10 and codon 25 were identified by means of amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and sequence analysis. Our results indicated that serum concentrations of TGF-beta1 in GC patients were significantly higher than those in the control, and positively correlated with tumor mass, invasion, metastasis, and clinical stage. The serum TGF-beta1 levels of patients recovering from radical resection were markedly lower than those before surgery. Meanwhile, no deoxyribonucleic acid (DNA) sequence variation at codon 25 of the TGF-beta1 gene was found and a TGF-beta1 gene polymorphism at codon 10 did not show obvious correlations with either TGF-beta1 expression or clinicopathological parameters of GC. Our evidence suggested that serum concentration of TGF-beta1 might be a novel tumor marker for GC and the polymorphisms of TGF-beta1 gene did not play a role as a determinant of serum TGF-beta1 concentration or as a genetic risk factor in the gastric carcinogenesis and progression.

[The effect of As2O3 on induction of apoptosis and inhibition of telomerase activity in colon cancer LS-174T cells].

OBJECTIVE: To study the impact of arsenic trioxide (As2O3) on human colorectal carcinoma LS-174T cells and their activity of telomerase. METHODS: LS-174T cells and xenograft model of nude mice were treated with As2O3. The inhibitory effect of As2O3 on survival of LS-174T cells was determined by MTT assay. Apoptosis was determined by electron microscopy and fluorescence microscopy. Cell cycle was assessed by flow cytometry. Telomerase activity in LS-174T cells was determined by PCR-ELISA kit. RESULTS: With the increasing concentration of As2O3, the ratio of living cells to dead cells decreased significantly, and the IC50 value was 5.23 micromol/L. Apoptosis curve appeared after 24 h and cells turned to apoptosis in a time-dependent manner. As2O3 inhibited the telomerase activity in cell extraction, obviously in a concentration-dependent and time-dependent manner. Inhibitiory effect of As2O3 on xenograft model of nude mice was observed by tumor volume and weight measurement, showing a significant difference between As2O3 and control groups (P < 0.05). CONCLUSION: Both the experiments in vitro and in vivo showed an inhibitory effect of As2O3 on colonrectal cancer S-174T cell growth, probably by induction of apoptosis and inhibition of telomerase activity.

[Diversity of invasiveness and matrix metalloproteinases expression profile of human gastric carcinoma xenografted in different tissue environments].

OBJECTIVE: To study the effect of tissue environment on the invasiveness of carcinoma cells and the implication of expression of matrix metalloproteinases. METHODS: Tissue from a human gastric carcinoma was transplanted and passaged subcutaneously in nude mice. After the 3rd passage, the xenografts were also transplanted into the abdominal cavity of nude mice. The invasiveness of xenografts at the two locations were observed morphologically and the expressions of MMP-2, MMP-7, MMP-9, MMP-13, TM1-MMP, TM2-MMP and TM3-MMP were monitored by immunohistochemistry. RESULTS: The subcutaneous xenografts of human gastric carcinoma in nude mice presented as expanding outgrowths with limited invasion. Except for MMP-7, the other 6 MMPs (MMP-2, MMP-9, MMP-13, TM1-MMP, TM2-MMP, TM3-MMP) were not expressed in the neoplastic cells nor in the tumor stroma. In contrast, the intra-peritoneal xenografts displayed an invasive growth pattern accompanied by more fibrous stroma. All MMPs examined were expressed in the tumor cells at the invasive fronts and in the adjacent stroma. CONCLUSIONS: Invasiveness and expression of MMPs were obviously diverse in human gastric carcinoma cells when grafted at different anatomic locations in nude mice, thus indicating: (1) There exists a close interaction between tumor cells and surrounding stromal cells. The tissue environment may play a definitive role in the tumor phenotype. (2) The expression of MMPs is closely related to the growth pattern and the invasiveness of tumor cells. MMPs produced by the stroma cells at the invasion front may be linked to the invasiveness of neoplastic cells.