Artesunate induces apoptosis and inhibits growth of Eca109 and Ec9706 human esophageal cancer cell lines in vitro and in vivo.

Esophageal cancer is a common malignant tumor worldwide with a high incidence rate in China and it is a great threat to human health. Combined modality therapy is used for chemotherapeutic treatment of esophageal cancer; however, drug resistance and side effects of the drugs is a major barrier to the success of chemotherapy. As chemotherapy with common drugs is far from providing satisfactory clinical outcomes for patients with esophageal cancer, more efficient drugs are urgently required. Artesunate (Art) is the first-line treatment option for malaria; however, it was recently revealed that Art has remarkable anti-tumor activity, making it a novel candidate for cancer chemotherapy. Although the anti-cancer effects of Art have been well documented, its potential against esophageal cancer has rarely been explored. The present study aimed to investigate the significance and mechanism of the anti-proliferative activity of Art on esophageal cancer cells in vitro and in vivo. In the in vitro experiments, Art inhibited the growth as well as induced cell apoptosis and cell cycle arrest of esophageal cancer cell lines (Eca109 and Ec9706) in a concentration-dependent manner. Furthermore, downregulation of mitochondrial membrane potential, B-cell lymphoma-2 (BCL-2) and CDC25A, as well as upregulation of BCL-2­associated X protein (Bax) and caspase-3 expression in Art-treated cells were identified. In addition, an in vivo study showed that Art produced a dose-dependent tumor regression in nude mice, while side effects were low. The anti-tumor activity of 200 mg/kg Art was similar to that of 3 mg/kg cisplatin. In conclusion, Art exerted concentration-dependent inhibitory activity against esophageal cancer in vivo and in vitro by inducing cell apoptosis and cell cycle arrest through affecting mitochondrial membrane potential, BCL-2, Bax, caspase-3 and CDC25A.

Nimesulide inhibits the growth of human esophageal carcinoma cells by inactivating the JAK2/STAT3 pathway.

Although selective COX-2 inhibitors have cancer-preventive effects and induce apoptosis, the mechanisms underlying these effects are not fully understood. This study investigated the effects of nimesulide, a selective COX-2 inhibitor, on apoptosis and on the JAK/STAT signaling pathway in Eca-109 human esophageal squamous carcinoma cells. The effects and mechanisms of nimesulide on Eca-109 cell growth were studied in culture and in nude mice with Eca-109 xenografts. Cells were cultured with or without nimesulide and/or the JAK2 inhibitor AG490. Cell proliferation was evaluated using the MTT assay, and apoptosis was investigated. COX-2 mRNA expression was measured using reverse transcription polymerase chain reaction, and protein expression was detected by Western blot analysis, immunohistochemistry, and flow cytometry. Nimesulide significantly inhibited Eca-109 cell viability in vitro in a dose- and time-dependent manner (P<0.05). Nimesulide also induced apoptosis, which was accompanied by a significant decrease in the expression of COX-2 and survivin and an increase in caspase-3 expression. Nimesulide downregulated the phosphorylation levels of JAK2 and STAT3, and JAK2 inhibition by AG490 significantly augmented both nimesulide-induced apoptosis and the downregulation of COX-2 and survivin (P<0.05). In vivo, nimesulide inhibited the growth of Eca-109 tumors and the expression of p-JAK2 and p-STAT3. Thus, nimesulide downregulates COX-2 and survivin expression and upregulates caspase-3 expression in Eca-109 cells, by inactivating the JAK2/STAT3 pathway. These effects may mediate nimesulide-induced apoptosis and growth inhibition in Eca-109 cells in vitro and in vivo.

The PTEN/PI3K/Akt signaling pathway mediates HMGB1-induced cell proliferation by regulating the NF-κB/cyclin D1 pathway in mouse mesangial cells.

Our previous experiment confirmed that high-mobility group box chromosomal protein 1 (HMGB1) was involved in the pathogenesis of Lupus nephritis (LN) by upregulating the proliferation of the mouse mesangial cell line (MMC) through the cyclin D1/CDK4/p16 system, but the precise mechanism is still unknown. Therefore, in the present study, we demonstrated that HMGB1 induced the proliferation of MMC cells in a time- and concentration-dependent manner, downregulated phosphatase and tensin homolog deleted on chromosome ten (PTEN) expression, increased the level of Akt serine 473 phosphorylation, and induced p65 subunit nuclear translocation. The overexpression of PTEN prevented the upregulation of HMGB1-induced proliferation by blocking the activation of Akt. The knockdown of Akt by siRNA technology and blocking the nuclear factor-κB (NF-κB) pathway using pyrrolidine dithiocarbamate (PDTC) and SN50, inhibitors of NF-κB, both attenuated the HMGB1-induced proliferation by counteracting the activation of the cyclin D1. In addition, while sh-Akt partly blocked the nuclear translocation of the p65 subunit, PDTC did not affect the activation of the Akt induced by HMGB1 in MMC cells. These findings indicate that HMGB1 induced the proliferation of MMC cells by activating the PTEN/phosphoinositide-3-kinase (PI3K)/Akt/NF-κB signaling pathway.

ABCG2 gene amplification and expression in esophageal cancer cells with acquired adriamycin resistance.

Resistance to chemotherapeutic agents is the main reason for treatment failure in patients with cancer. The primary mechanism of multidrug resistance (MDR) is the overexpression of drug efflux transporters, including ATP­binding cassette transporter G2 (ABCG2). To the best of our knowledge, the MDR mechanisms of esophageal cancer have not been described. An adriamycin (ADM)-resistant subline, Eca109/ADM, was generated from the Eca109 esophageal cancer cell line by a stepwise selection in ADM from 0.002 to 0.02 ng/µl. The resulting subline, designated Eca109/ADM, revealed a 3.29-fold resistance against ADM compared with the Eca109 cell line. The ABCG2 gene expression in the Eca109/ADM cells was increased compared with that of the Eca109 cells. The cellular properties of the Eca109/ADM cells were detected by reverse transcription polymerase chain reaction (RT-PCR), flow cytometry and western blotting. The ABCG2 expression levels were detected by RT-PCR and flow cytometry, and the drug efflux effect was detected by flow cytometry. The present study detected the correlation between ABCG2 and the multidrug resistance of esophageal cancer. ABCG2 gene expression and the drug efflux effect of the Eca109/ADM cells were increased compared with those of the Eca109 cells. Collectively, the results of this study indicated that the overexpression of ABCG2 in the Eca109/ADM cells resulted in drug efflux, which may be responsible for the development of esophageal cancer MDR.

Reversal of multidrug resistance by the anti-malaria drug artesunate in the esophageal cancer Eca109/ABCG2 cell line.

The overexpression of ATP-binding cassette (ABC) transporters confers multidrug resistance (MDR) to tumor cells. ABCG2 is a member of the ABC superfamily. The present study aimed to investigate the correlation between ABCG2 expression and the MDR of esophageal cancer and to estimate the therapeutic benefit of downregulating ABCG2 expression and reversing chemoresistance in esophageal cells using artesunate (Art). The Eca109/ABCG2 cell line was established by transfecting the ABCG2 gene into Eca109 cells. The Eca109/ABCG2 esophageal cancer cells with ABCG2 gene overexpression were resistant to adriamycin (ADM), daunorubicin (DNR) and mitoxantrone (MIT), which indicated that ABCG2 may be associated with drug resistance in esophageal cancer. Art is a noteworthy antimalarial agent, particularly in severe and drug-resistant cancer cases, as Art is able to reverse drug resistance. In the present study, Art also exerted profound anticancer activity. The mechanism for the reversal of multidrug resistance by Art in esophageal carcinoma was analyzed using cellular experiments, but still remains largely unknown.

PLC-ε1 gene polymorphisms significantly enhance the risk of esophageal squamous cell carcinoma in individuals with a family history of upper gastrointestinal cancers.

BACKGROUND AND AIMS: Phospholipase C epsilon 1 (PLCε1) may regulate cell growth, differentiation, apoptosis and angiogenesis and play an important role in carcinogenesis and the progression of several cancers. This study was designed to validate the association of the PLCε1 rs2274223 single nucleotide polymorphism (SNP) with esophageal squamous cell carcinoma (ESCC) as identified by genome-wide association studies (GWAS) and further assess whether the rs11599672 SNP could affect an individual's susceptibility to ESCC. METHODS: These two SNPs were genotyped by polymerase chain reaction ligase detection reaction (PCR-LDR) in 527 ESCC patients and 527 controls. RESULTS: Compared with the rs2274223 SNP AA genotype, other genotypes or combined genotypes all enhanced the risk of ESCC. Further analyses showed that AG/GG genotype carriers with a family history of upper gastrointestinal cancers (UGIC) had an increased risk of ESCC than those AA genotype carriers without UGIC family history (OR = 2.10, 95% CI = 1.46-3.10). Overall, rs11599672 SNP had no influence on ESCC susceptibility. However, UGIC family history elevated the risk of ESCC for subjects with the TT genotype (OR = 1.59, 95% CI = 1.13-2.24). CONCLUSIONS: These results highlighted the role of a genetic factor in ESCC and suggested that the PLCε1 rs2274223 SNP might be an effective genetic marker to assess the risk of ESCC in individuals with a UGIC family history from a region of high incidence in northern China.

[Expression of EphA2 and EphrinA1 in human renal cell carcinoma and its relationship with angiogenesis].

OBJECTIVE: To investigate the expression of EphA2 and EphrinA1 and its relationship with angiogenesis in renal cell carcinoma and its relevance to clinicopathologic features. METHODS: The expression of the EphA2 and EphrinA1 was detected by immunohistochemistry (IHC) in the tissues samples from 68 renal cell carcinomas and 24 normal kidneys, and quantitatively analyzed. The microvessel density (MVD) was determined by CD34 immunostaining of microvascular endothelial cells. Statistical analysis was performed using the software SPSS (version 13.0). RESULTS: The expression of EphA2, EphrinA1 and MND in the cancerous tissues were significantly higher (P<0.01) than that in the normal ones. Significantly increased expression of EphA2, EphrinA1 and MVD (P<0.01) was detected in cancer tissues with higher grade differentiation, more advanced stage and more lymph node metastasis, respectively (P<0.05 for each group). Expression of the EphA2 and EphrinA1 protein was shown to be positively associated with the MVD assessed by Spearman's correlation and factor analysis (r=0.555, r=0.485, P<0.01). The MVD was also significantly correlated with the diameter of the tumor (P<0.01). CONCLUSION: EphA2 and EphrinA1 are highly expressed in renal cell carcinoma, and positively correlated with histological differentiation, clinical stage and angiogenesis in the cancer.

The regulatory effect of the p38 signaling pathway on valdecoxib-induced apoptosis of the Eca109 cell line.

Valdecoxib is a second generation selective COX-2 inhibitor that can induce cell apoptosis in a variety of cell types, but its precise regulatory mechanism is unknown. Apoptosis of Eca109 cells and p38 mRNA expression were investigted. The expression of p-p38MAPK, Fas and FasL proteins were detected by immunohistochemical staining and FCM. Valdecoxib increased the apoptosis rate of Eca109 cells. Fas and FasL protein expression was up-regulated in the valdecoxib groups, while SB203580 partly inhibited the valdecoxib-induced overexpression. Valdecoxib increased p38MAPK expression, while SB203580 inhibited the overexpression of this protein and the apoptosis rate decreased. The expression of Fas, FasL and p38MAPK protein were positively correlated with the apoptotic rate. In conclusion, valdecoxib activates the p38MAPK pathway, thus up-regulating expression of the Fas and FasL proteins, which may be one of the mechanisms through which valdecoxib induces apoptosis.

[The functional mechanism of CIK cells on ovarian carcinoma cell lines SKOV3/CDDP].

AIM: To investigate the functional mechanism of CIK cells or ovarian carcinoma cell lines SKOV3/CDDP. METHODS: The changes of ultramicrostructure, cell cycle, apoptosis, expression of multidrug resistance-associated protein (MDR1, Topo-IIbeta) and other molecules (hB7-1, hB7-2, MHCIb, HLA-DR) of SKOV3/CDDP cells treated with or without CIK cells were detected by electron microscope, MTT and FCM. The changes of cytokine (IL-2, TNF-alpha, IFN-gamma, GM-CSF) in sera of SCID mice bearing SKOV3/CDDP cells were detected by radioimmunit and ELISA. RESULTS: CIK cells could induce apoptosis of the SKOV3/CDDP cells by electronmicroscopic observations. The apoptosis rate in CIK group was 9.07%, and its cell cycle was arrested at S and G2/M phase (P<0.05). Compared with NS Group, the co-expression of MDR-1 and Topo-IIbeta were decreased significantly in the CIK treated group(P<0.05), and the expression of MHCIb, HLA-DR, hB7-1 and hB7-2 antigen were increased significantly (P<0.01). Compared with NS Group, the contents of IL-2, TNF-alpha, INF-gamma, GM-CSF were increased significantly (P<0.01) in SCID mice of CIK group. CONCLUSION: CIK cells have several important biological effects on the ovarian carcinoma cell line SKOV3/CDDP, which may lay the foundation for further research on anti-tumor therapy.

[Expression and clinical significance of COX-2, p-Stat3, and p-Stat5 in esophageal carcinoma].

BACKGROUND & OBJECTIVE: Cyclooxygenase-2 (COX-2) and signal transducers and activators of transcription (STAT) are closely correlated to the genesis of tumors. This study was to investigate the expression and clinical significance of COX-2, p-Stat3 and p-Stat5 (the activated forms of Stat3 and Stat5) in various lesions of esophageal tissues, and to analyze their correlations to clinicopathologic features of esophageal squamous cell carcinoma (ESCC). METHODS: The expression of COX-2, p-Stat3, and p-Stat5 in 59 specimens of ESCC, 24 specimens of squamous dysplasia, and 18 specimens of normal squamous epithelium was examined by SP immunohistochemistry. Their correlations to clinicopathologic features of ESCC were analyzed. RESULTS: The protein level of COX-2 was significantly higher in ESCC and squamous dysplasia than in normal squamous epithelium (2.10+/-1.77 and 1.85+/-1.24 vs. 0.83+/-0.46, P<0.05). The protein level of p-Stat3 was 0 in normal squamous epithelium, 0.76+/-0.59 in squamous dysplasia, and 2.83+/-1.27 in ESCC. The protein level of p-Stat5 was 1.98+/-0.78 in normal squamous epithelium, 3.92+/-0.41 in squamous dysplasia, and 5.02+/-0.34 in ESCC. There were significant differences among the 3 groups (P<0.05). In ESCC, COX-2 expression was correlated to lymph node metastasis and differentiation (P<0.05); p-Stat3 expression was correlated to tumor invasion depth (P<0.05); but p-Stat5 expression had no correlation to clinicopathologic features. COX-2 expression was positively correlated to both p-Stat3 expression and p-Stat5 expression in ESCC. CONCLUSIONS: The up-regulation of COX-2, p-Stat3, and p-Stat5 may be correlated to the carcinogenesis of ESCC. The activation of Stat3 is correlated to the aggressive behavior of ESCC.

[Correlation of Skp2 expression in gastric carcinoma to expression of P27 and PTEN].

BACKGROUND & OBJECTIVE: S-phase kinase-associated protein 2 (Skp2) is a positive regulator of G1-S transition and promotes ubiquitin-mediated proteolysis of cyclin-dependent kinase inhibitor P27. Its overexpression has been involved in cell transformation and tumorigenesis. This study was to investigate the significance of Skp2 expression in human gastric carcinoma and its correlation to expression of both P27 and PTEN. METHODS: The expression of Skp2 in 138 specimens of gastric cancer and their paired adjacent mucosa, 102 specimens of paired metastatic lymph nodes, 30 specimens of dysplasia, 30 specimens of intestinal metaplasia, 10 specimens of chronic superficial gastritis, and 5 specimens of normal gastric mucosa, and the expression of P27 and PTEN in 138 specimens of gastric cancer were detected by immunohistochemistry. RESULTS: Skp2 labeling frequency was significantly higher in intestinal metaplasia [(12.68+/-0.86)%] and adjacent mucosa [(19.32+/-1.22)%] than in chronic superficial gastritis [(0.53+/-0.13)%] and normal gastric mucosa [(0.47+/-0.19)%] (P<0.001), but there was no difference between chronic superficial gastritis and normal gastric mucosa (P>0.05); Skp2 labeling frequency was significantly higher in dysplasia [(16.74+/-0.82)%] than in intestinal metaplasia (P<0.001), significantly higher in primary gastric carcinoma [(31.34+/-2.17)%] than in dysplasia and adjacent mucosa (P<0.001), and significantly higher in metastatic lymph node [(39.76+/-2.00)%] than in primary gastric carcinoma (P=0.037). Skp2 labeling frequency in gastric carcinoma was positively correlated with differentiation grade (rs=0.315, P<0.001), vessel invasion (rs=0.303, P<0.001), and lymph node metastasis (rs=0.254, P=0.001). Skp2 expression was negatively correlated with both P27 expression (rs=-0.451, P<0.001) and PTEN expression (rs=-0.480, P<0.001) in gastric carcinoma. P27 expression was positively correlated with PTEN expression in gastric carcinoma (rs=0.642, P<0.001). CONCLUSION: Skp2 overexpression, which may lead to degradation of P27 and low expression of PTEN, may be a very important reason in carcinogenesis and progression of gastric carcinoma.

[The effects of pcDNA3.1-IL-15 transfection on the surface molecules and immune function of murine bone marrow-derived dendritic cells].

AIM: To explore the effects of pcDNA3.1-IL-15 transfected on co-stimulatory molecule expression and immune function on murine bone marrow-derived dendritic cells (DCs). METHODS: Recombinant plasmid pcDNA3.1-IL-15 was constructed and used to transfect DCs. The expression of CD40, CD80 and CD86 on the transfected DCs was analyzed by flow cytometry. Murine splenocytes were stimulated with the transfected DCs. CD4+ and CD8+ T cell subsets in the splenocytes were analyzed by flow cytometry. The proliferation of splenocytes was detected by MTT colorimetry. The IFN-gamma in the culture supernatant of the splenocytes was detected by ELISA. RESULTS: pcDNA3.1-IL-15-transfected DCs expressed higher level of CD40, CD80 and CD86, and induced proliferation of CD4+ T cells and CD8+ T cells in the splenocytes. But the ratio of CD4+/CD8+ T cells was lower than that in the spleen cells stimulated by untransfected DCs or DCs transfected with pcDNA3.1. CONCLUSION: pcDNA3.1-IL-15 can improve the expression of co-stimulatory molecules on DCs and enhance their immune function.

[Effects of ginsenoside Rh2(GS-Rh2) on cell cycle of Eca-109 esophageal carcinoma cell line].

OBJECTIVE: To investigate the effects of ginsenoside Rh2 (GS-Rh2) on growth inhibition and cell cycle of Eca-109 esophageal carcinoma cell line in culture. METHOD: The effects of GS-Rh2 on cell growth inhibition was detected by MTT assay. Cell cycle was analyzed by flow cytometry (FCM). Cell morphology was observed by a light microscope after HE staining. The protein expression of cell cycle components (cyclinE, CDK2, p21WAF1) were examined by immunocytochemistry and Western blot. The mRNA expression were examined by semiquantitative RT-PCR. RESULT: GS-Rh2 inhibited the proliferation of Eca-109 cells in dose and time-dependent manners. The inhibition rate was about 50% after 1-day treatment with 20 microg x mL(-1) GS-Rh2 x 20 microg x mL(-1) GS-Rh2 induced the mature differentiation and morphological reversion. With increasing dose of GS-Rh2 treatment, the cell number of G0/G1 phase was increased, whereas it decreased at S and G2/M phase. There was significant difference between 10, 20 microg x mL(-1) GS-Rh2 groups and the corresponding group without GS-Rh2 treatement. After treating cells by 20 microg x mL(-1) GS-Rh2 for 1, 2, 3 days individually, the protein and mRNA expression of both cyclinE and CDK2 reduced, while the expression of p21WAF1 enhanced gradually. CONCLUSION: GS-Rh2 could arrest Eca-109 cells at G0/G1 phase and induce cell differentiation tending to normal. Furthermore, GS-Rh2 had an effect on expression of cell cycle components (cyclinE, CDK2 and p21WAF1) to inhibit Eca-109 cell proliferation.

Relation of overexpression of S phase kinase-associated protein 2 with reduced expression of p27 and PTEN in human gastric carcinoma.

AIM: To investigate the significance of S phase kinase-associated protein 2 (Skp2) expression in human gastric carcinoma and the relation between expressions of Skp2, p27 and PTEN. METHODS: Immunohistochemical analysis was performed on 138 gastric carcinoma specimens, their paired adjacent mucosa specimens, 102 paired lymphatic metastatic carcinoma tissue specimens, 30 dysplasia specimens, 30 intestinal metaplasia specimens, 10 chronic superficial gastritis specimens and 5 normal gastric mucosa specimens for Skp2 expression and on 138 gastric carcinoma specimens for p27 and PTEN expression. RESULTS: Skp2 labeling frequency was significantly higher in intestinal metaplasia (12.68+/-0.86) and adjacent mucosa (19.32+/-1.22) than in normal gastric mucosa (0.53+/-0.13) and chronic superficial gastritis (0.47+/-0.19) (P = 0.000); in dysplasia (16.74+/-0.82) than in intestinal metaplasia (P = 0.000); in gastric primary carcinoma (31.34+/-2.17) than in dysplasia and adjacent mucosa (P = 0.000); in metastasis gastric carcinoma in lymph nodes (39.76+/-2.00) than in primary gastric carcinoma (P = 0.037), respectively. Skp2 labeling frequency was positively associated with differentiation degree (rho = 0.315, P = 0.000), vessel invasion (rho = 0.303, P = 0.000) and lymph node metastasis (rho = 0.254, P = 0.000) of gastric cancer. Expression of Skp2 was negatively associated with p27 (rho = -0.451, P = 0.000) and PTEN (rho = -0.480, P = 0.000) expression in gastric carcinoma. p27 expression was positively associated with PTEN expression in gastric carcinoma (rho = 0.642, P = 0.000). CONCLUSION: Skp2 overexpression may be involved in carcinogenesis and progression of human gastric carcinoma in vivo, possibly via p27 proteolysis. PTEN may regulate the expression of p27 by negatively regulating Skp2 expression.

[Flow cytometric detection and significance of four cyclins in esophageal cancer].

OBJECTIVE: To study the expression and significance of cyclin E, cyclin D1, CDK4 and p27 protein in esophageal squamous cell cancer (ESCC) and their correlation with tumor differentiation and lymph node metastasis. METHODS: Expressions of cyclin E, cyclin D1, CDK4 and p27 protein in 65 patients with ESCC were quantitatively detected by flow cytometry. RESULTS: The expressions of cyclin E, cyclin D1, CDK4 in poorly-differentiated ESCC were higher than those in well-differentiated ESCC (P = 0.0275, 0.0001, 0.0174). The expression of p27 in poorly-differentiated ESCC was lower than that in well-differentiated ESCC (P = 0.0042). There was positive correlation between cyclin E and cyclin D1, cyclin D1 and CDK4, but negative correlation between cyclin D1 and p27. The expressions of all four proteins were not correlated with lymph node metastasis. CONCLUSION: The expressions of cyclin E, cyclin D1, CDK4 and p27 are closely related to tumor differentiation of ESCC. An imbalance between positive and negative control of cell cycling might be critical in the carcinogenesis of esophageal squamous cell cancer.

Flow cytometric analysis of DNA, telomerase content and multi-gene expression in esophageal epithelial dysplasia.

AIM: To investigate the alteration of molecular events and the early carcinogenesis mechanism of esophageal epithelial cells in the high incidence area of esophageal cancer. METHODS: Esophageal epithelial cells of esophageal cancer patients were collected from the high incidence area in China. Content of DNA and telomerase as well as multi-gene expressions such as p53, p21 and cyclin D1 in esophageal precancer cells were quantitatively analysed by flow cytometry (FCM) with indirect immunofluorescence technique and DNA propidium iodide fluorescence staining. RESULTS: FCM analysis results showed the DNA content increased significantly and the heteroploid rate was 87.9% in occurred carcinogenesis. P53 protein accumulation and ras p21 increase were seen in the early carcinogenesis of the esophagus. The positive rate of p53 and ras p21 was 100% (5/5, 4/4 respectively) in the cancer group. Telomerase and oncogene cyclin D1 were over- expressed in all of the cancer patients. CONCLUSION: Increased DNA content and heteroploid rate, accumulation of p53 protein, and over-expression of p21, telomerase and cyclin D1 proteins were early molecular events during the development of esophageal cancer.

Effects of sterigmatocystin, deoxynivalenol and aflatoxin G1 on apoptosis of human peripheral blood lymphocytes in vitro.

OBJECTIVE: To explore the effects of Sterigmatocystin (ST), Deoxynivalenol (DON) and Aflatoxin G1 (AFG1) on apoptosis of human peripheral blood lymphocytes (HPBLs) in vitro and thus to further elucidate the putative roles of these three mycotoxins on human immunosystem. METHODS: The effects of ST, DON and AFG1 on apoptosis of HPBLs were studied with cell culture, flow cytometric (FCM) DNA analysis and DNA agarose gel electrophoresis. RESULTS: DNA agarose gel electrophoresis results showed the characteristic "ladder" pattern of apoptosis in HPBLs treated with ST, DON and AFG1. Flow cytometric DNA analysis revealed that typical subdiploid peaks of apoptosis in DNA histogram could be seen in all groups treated with the three mycotoxins. Significant time-effect and dose-effect relationships were found between the apoptosis rates and treatment time as well as concentrations of the three mycotoxins. CONCLUSION: ST, DON and AFG1 can induce apoptosis of HPBLs in vitro and may have some negative effects on human immunosystem.