Effects of Taxotere on invasive potential and multidrug resistance phenotype in pancreatic carcinoma cell line SUIT-2

FTY720, a synthetic compound from Isaria sinclairii, inhibits proliferation and induces apoptosis in pancreatic cancer cells

FTY720, a synthetic compound produced by modification of a metabolite from Isaria sinclairii, is known as a unique immunosuppressive agent that exerts its activity by inducing apoptosis of lymphocytes [S. Suzuki, FTY720: Mechanisms of action and its effect on organ transplantation, Transplant. Proc. 31 (1999) 2779-2782]. Additionally, it has been found that FTY720 has inhibitory effects on various cancer growth and metastasis [J.D. Wang, S. Takahara, N. Nonomura, Early induction of apoptosis in androgen-independent prostate cancer cell line by FTY720 requires caspase-3 activation, Prostate 40 (1999) 50-55]. To investigate its effect on the growth and metastasis of pancreatic cancer, FTY720 was used to treat three pancreatic cancer cell lines (BxPC-3, AsPC-1, and PANC-1). The MTT assay and flow cytometry were used to evaluate the cell death after FTY720 treatment; the wound closure assay, three-dimensional (3D) Matrigel assay, and invasive assay were used to evaluate the migration, colony formation and invasion abilities after FTY720 treatment, respectively. Protein expression in BxPC-3, AsPC-1, and PANC-1 cells after FTY720 treatment was detected by Western blotting. The MTT assay indicated that the growth of pancreatic cancer cells could be inhibited by FTY720 at various concentrations between 0 and 17 microM in a dose-dependent manner, which was also confirmed by flow cytometry. The wound closure assay, 3D Matrigel assay and cell invasion assay all showed that FTY720 significantly suppressed migration, colony formation and invasion ability of cancer cells at concentrations from 5 to 17 microM. After FTY720 treatment, the phospho-Akt, Bcl-2, pro-caspase-3 expression were down-regulated while the caspase-9 protein expression was increased. In conclusion, FTY720 can inhibit the growth, migration and invasion of pancreatic cancer cells. Our study provides a preclinical support for chemotherapeutic approach with FTY720 for the treatment of pancreatic cancer.

Tumor-stroma interaction of human pancreatic cancer: acquired resistance to anticancer drugs and proliferation regulation is dependent on extracellular matrix proteins

INTRODUCTION

Pancreatic cancer is one of the major causes of cancer-related deaths in industrialized countries. It is known that pancreatic cancer is resistant to chemotherapy and that cancer cells are surrounded by extracellular matrix (ECM) proteins including collagen I, collagen IV, fibronectin, and laminin.

AIMS

To examine the role of ECM proteins in acquired resistance to anticancer drugs and proliferation regulation in pancreatic cancers.

METHODOLOGY AND RESULTS

We used an in vitro model of ECM-induced chemoresistance and cell proliferation of cancer cell lines (MIA PaCa-2, PANC-1, and Capan-1) with 3 different malignancy grades and found that resistance to cytotoxic drugs and proliferation regulation was dependent on ECM proteins. Pancreatic cancer cell lines, especially MIA PaCa-2 cells, adhering to any of the ECM proteins showed decreased cytotoxicity of anticancer drugs, except for gemcitabine. PANC-1 and Capan-1 cells adhering to fibronectin, collagen I, and collagen IV proliferated more than the controls.

CONCLUSION

ECM proteins have important roles in acquired resistance to anticancer drugs and cell proliferation regulation of pancreatic cancer cells. Therefore, the expression of ECM proteins in pancreatic cancer specimens could provide valuable information to aid anticancer drug cytotoxicity, and gemcitabine would be useful for treatment of patients with pancreatic cancer.

Inhibitory effects of docetaxel on expression of VEGF, bFGF and MMPs of LS174T cell

AIM: To study the effects of non-cytotoxic concentrations of docetaxel on some important angiogenic factors of LS174T Cells.

METHODS: The non-cytotoxic concentration of docetaxel and the activity of gelatinase were determined with MTT and gelatin zymography respectively, the expression of VEGF (vascular endothelial growth factor), bFGF (basic fibroblast growth factor), MMP (matrix metalloproteinase) 2 and MMP 9 was investigated with RT-PCR and Western blot.

RESULTS: The maximum non-cytotoxic concentration of docetaxel on LS174T Cells was 1.0 ng/mL. Compared with the solvent control group, 0.1, 0.5, 1.0 ng/mL of docetaxel could downregulate the expression of VEGF, bFGF, MMP 2 and MMP 9 and suppress the activity of gelatinase.

CONCLUSION: Our study suggests that the non-cytotoxic concentrations of docetaxel have strong antiangiogenic activity on LS174T Cells, which suggests docetaxel may be a promising antiangiogenic agent.

Correlation of CT enhancement, tumor angiogenesis and pathologic grading of pancreatic carcinoma

AIM: To study the correlation between pancreatic phase CT enhancement, intratumor microvessel density (MVD) and pathologic grading of pancreatic carcinoma and to evaluate the relationship between the degrees of CT enhancement and malignancy of pancreatic carcinoma.

METHODS: Thirty four patients with pancreatic carcinoma underwent CT scanning before resection. The enhancement degrees and forms of tumor were observed in pancreatic phase. The operative sample was stained with HE and CD34 marked by immunohistochemistry. MVD and histopathological grades of pancreatic carcinoma were examined. CT enhancement of the tumor, MVD counting in hot spot areas of neoplastic parenchymal cells and pathological grades of pancreatic carcinoma were comparatively analyzed.

RESULTS: Highly differentiated pancreatic adenocarcinoma was identified in 16 patients, moderately-differentiated tumor in 7 and poorly-differentiated in 11. Isodensity CT enhancement was demonstrated in 13 cases, slightly low density enhancement in 9, slightly low density enhancement with small cystic lesions in 9 and slightly low density enhancement with large cystic lesions in 3. The counting of MVD with CD34 marked by immunohistochemistry in hot spot areas of neoplastic parenchyma cells was small in 10 cases, medium in 16 and large in 8. The pathological grades correlated well with CT enhancement of the tumor (r = 0.7857, P < 0.001) and with MVD counting of tumor (r = 0.3613, P < 0.05). The CT enhancement of tumor correlated with MVD(r = 0.6768, P < 0.001).

CONCLUSION: There is an obvious and significant correlation between CT enhancement, pathological grades and MVD number in the hot spot areas of tumor. The extent of CT enhancement is inversely proportional to the malignant degree of pancreatic carcinoma, and to the MVD number in the hot spot areas of neoplastic parenchyma. The MVD in the hot spot areas of neoplastic parenchyma cells can also reflect the prognosis of the patients, and is directly proportional to the malignant degree of pancreatic carcinoma.

Relationship between nuclear morphometry, DNA content and resectability of pancreatic cancer

AIM: To investigate the association of nuclear morphometry and DNA content with resectability of pancreatic cancer.

METHODS: A total of 36 patients with pancreatic adenocarcinoma were divided into resectable group and unresectable group. The nuclear morphometry and DNA contents of tumor cells were analyzed by IBAS autoimagine analyzer from paraffin-embedded materials. Localization size, histological type and grade, and clinical stage of the tumor were evaluated. Factors influencing resectability of pancreatic cancer were investigated using stepwise regression analysis.

RESULTS: Statistical significance was found in nuclear DNA content (integrated optical density, IOD) of tumor cells (1.64 ± 0.41 vs 2.96 ± 0.55), DNA ploidy, ages (46.5 ± 5.3 years vs 58.6 ± 0.7 years) and tumor volumes (298.1 ± 101.5 cm³vs 634.7 ± 512.5 cm³) in both groups (P < 0.05), and no difference was found in the nuclear morphometry (P > 0.05). The rates of diploid/tetraploid and aneuploid were 66.7% and 33.3% in resectable group respectively, and 38.9% and 62.1% in unresectable group, respectively (P < 0.05). IOD (X₁₂), ploidy status (X₁₃) and clinical stage (X₃) were radical resectable indicators with statistical significance. The regression equation for resectability was Y = -9.2053 + 3.5428X₁₂ + 2.5390X₁₃ - 2.3001X₃ (RR = 0.8780, P < 0.01).

CONCLUSION: There is a high correlation between resectability of pancreatic cancers and their DNA contents, DNA ploidy status and clinical stage.

Effect of ZNRD1 gene antisense RNA on drug resistant gastric cancer cells

AIM: To investigate the expression level of ZNRD1 gene in gastric cancer cells SGC7901 and gastric cancer MDR (multidrug resistant) cells SGC7901/VCR, and to observe the drug sensitizing and proliferation effect of ZNRD1 antisense nucleic acid transduction on SGC7901/VCR cells.

METHODS: Amplification of sequences encoding ZNRD1 from SGC7901/VCR cDNA by PCR. The levels of ZNRD1 mRNA expression were demonstrated using semiquantitative reverse transcription polymerase chain reaction (RT-PCR). Eukaryotic expression vector pcDNA3.1-anti ZNRD1 was constructed and transfected into SGC7901/VCR cells by lipofectamine. Immunochemical method was used to detect the expression of protein in SGC7901/VCR cells and transfectants. The cell cycle alteration and the intracellular adriamycin (ADM) accumulation were observed by FACS. Growth curve and drug sensitization of cells for vincristine (VCR) were analyzed with MTT assay.

RESULTS: We cloned the open reading frame of full-length ZNRD1. The expression of ZNRD1 showed higher in SGC7901/VCR than in SGC7901 cells. The antisense ZNRD1 drug-resistant clones were selected after gene transfection. Immunochemical results showed that the expression level of ZNRD1 protein was lower in anti ZNRD1-SGC7901/VCR cells than that in non-transfectants. Comparing to SGC7901/VCR and pcDNA3.1-SGC7901/VCR, anti ZNRD1-SGC7901/VCR showed gradually accumulated in G₁ phase, with a concomitant decrease of cell population in S phase. FACS also suggested intracellular ADM accumulation increased 2fold in SGC7901/VCR cells after transfected with antisense ZNRD1. MTT assay showed that transfectants cells proliferation was lagged and more sensitive to VCR than non-transfectants.

CONCLUSION: ZNRD1 gene displayed highly expression in VCR resistant gastric cancer cells. Expression of ZNRD1 protein was effectively blocked in anti ZNRD1-SGC7901/VCR cells by gene transfection. ZNRD1 antisense nucleic acid transfection sensitized drug resistant gastric cancer cells to VCR, increased ADM accumulation and inhibited the cells proliferation. ZNRD1 antisense RNA transduction could reverse the MDR of human drug-resistant gastric cancer cell SGC7901/VCR to a degree.

K-ras gene mutation in the diagnosis of ultrasound guided fine-needle biopsy of pancreatic masses

AIM: To investigate the utility of K-ras mutation analysis of ultrasound guided fine-needle aspirate biopsy of pancreatic masses.

METHODS: Sixty-six ultrasound guided fine-needle biopsies were evaluated by cytology, histology and K-ras mutation. The mutation at codon 12 of the K-ras oncogene was detected by artificial restriction fragment length polymorphisms using BstN I approach.

RESULTS: The presence of malignant cells was reported in 40 of 54 pancreatic carcinomas and K-ras mutations were detected in 45 of the 54 FNABs of pancreatic carcinomas. The sensitivity of cytology and K-ras mutation were 74% and 83%, respectively. The speciality of cytology and K-ras mutation were both 100%. The sensitivity and speciality of K-ras mutation combined with cytology were 83% and 100%, respectively.

CONCLUSION: High diagnostic accuracy with acceptable discomfort of FNAB make it useful in diagnosis of pancreatic carcinoma. Ultrasound guided fine-needle biopsy is a safe and feasible method for diagnosing pancreatic cancer. Pancreatic carcinoma has the highest K-ras mutation rate among all solid tumors. The mutation rate of K-ras is about 80%-100%. The usage of mutation of codon 12 of K-ras oncogene combined with cytology is a good alternative for evaluation of pancreatic masses.

Subcellular daunorubicin distribution and its relation to multidrug resistance phenotype in drug-resistant cell line SMMC-7721/R

AIM: To investigate the correlation between subcellular daunorubicin distribution and the multidrug resistance phenotype in drug-resistant cell line SMMC-7721/R.

METHODS: The multidrug resistant cell line SMMC-7721/R, a human hepatocellular carcinoma cell line, was established. Antisense oligonucleotides (AS-ODN) were used to obtain different multidrug resistance phenotypes by inhibiting the expression of mdr1 gene and/or multidrug resistance-related protein gene (mrp) using Lipofectamine as delivery agent. Expression of mdr1 and mrp genes was evaluated by RT-PCR and Western blotting. Intracellular daunorubicin (DNR) concentration was measured by flow cytometry. Subcellular DNR distribution was analyzed by confocal laser scanning microscopy. Adriamycin (ADM) and DNR sensitivity was examined by MTT method.

RESULTS: Low level expression of mdr1 and mrp mRNAs and no expression of P-Glycoprotein (P-gp) and multidrug resistance-related protein (P₁₉₀) were detected in parental sensitive cells SMMC-7721/S, but over-expression of these two genes was observed in drug-resistant cell SMMC-7721/R. The expression of mdr1 and mrp genes in SMMC-7721/R cells was down-regulated to the level in the SMMC-7721/S cells by AS-ODN. Intracellular DNR concentration in SMMC-7721/S cells was 10 times higher than that in SMMC-7721/R cells. In SMMC7721/S cells intracellular DNR distributed evenly in the nucleus and cytoplasm, while in SMMC-7721/R cells DNR distributed in a punctate pattern in the cytoplasm and was reduced in the nucleus. DNR concentration in SMMC-7721/R cells co-transfected with AS-ODNs targeting to mdr1 and mrp mRNAs recovered to 25 percent of that in SMMC7721/S cells. Intracellular DNR distribution pattern in drug-resistant cells treated by AS-ODN was similar to drug-sensitive cell, and the cells resistance index (RI) to DNR and ADM decreased at most from 88.0 and 116.0 to 4.0 and 2.3, respectively. Co-Transfection of two AS-ODNs showed a stronger synergistic effect than separate transfection.

CONCLUSIONS: P-gp and P₁₉₀ are two members mediating MDR in cell line SMMC7721/R. Intracellular drug concentration increase and subcellular distribution change are two important factors in multidrug resistance (MDR) formation. The second factor, drugs transport by P-gp and P₁₉₀ from cell nucleus to organell in cytoplasm, may play a more important role.

Expression and function of classical protein kinase C isoenzymes in gastric cancer cell line and its drug-resistant sublines

AIM: To investigate the expression and function of classical protein kinase C (PKC) isoenzymes in inducing MDR phenotype in gastric cancer cells.

METHODS: Two cell lines were used in the study: gastric cancer cell SGC7901 and its drug-resistant cell SGC7901/VCR stepwise-selected by vincristine 0.3, 0.7 and 1.0 mg·L^-1, respectively. The expression of classical PKC (cPKC) isoenzymes in SGC7901 cells and SGC7901/VCR cells were detected using immunofluorescent cytochemistry, laser confocal scanning microscope and Western blot. The effects of anti-PKC isoenzymes antibody on adriamycin accumulation in SGC7901/VCR cells were determined using flow cytometric analysis.

RESULTS: (1) SGC7901 cells exhibited positive staining of PKC-α. SGC7901/VCR cells exhibited stronger staining of PKC-α than SGC7901 cells. The higher dosage vincristine selected, the much stronger staining of PKC-α was observed on SGC7901/VCR cells. (2) Both SGC7901 and SGC7901/VCR cells exhibited positive staining of PKC-β I and PKC-β II with no significant difference. (3) Compared with SGC7901, SGC7901/VCR cells had decreased adriamycin accumulation and retention. Accumulation of adriamycin in SGC7901 was 5.21 ± 2.56 mg·L^-1, in SGC7901/VCR 0.3 was 0.85 ± 0.29 mg·L^-1, in SGC7901/VCR 0.7 was 0.81 ± 0.32 mg·L^-1, and in SGC7901/VCR 1.0 was 0.80 ± 0.33 mg·L^-1; Retention of adriamycin in SGC7901 was 2.51 ± 1.23 mg·L^-1, in SGC7901/VCR 0.3 was 0.47 ± 0.14 mg·L^-1, in SGC7901/VCR 0.7 was 0.44 ± 0.15 mg·L^-1, and in SGC7901/VCR 1.0 was 0.41 ± 0.11 mg·L^-1. (4) Fluorescence intensity presented adriamycin accumulation in SGC7901/VCR cells was increased from 1.14 ± 0.36 to 2.71 ± 0.94 when cells were co-incubated with anti-PKC-α but not with anti-PKC-β I, PKC-α II and PKCγ antibodies.

CONCLUSION: PKC-α, but not PKC-β I, PKC-β II or PKCγ, may play a role in multidrug resistance of gastric cancer cells SGC7901/VCR.

Differential display of vincristine-resistance-related genes in gastric cancer SGC7901 cell

AIM: To isolate and clone the vincristine-resistine-related genes in gastric cancer SGC7901 cell line and to clarify the multidrug-resistant molecular mechanism of gastric cancer cells.

METHODS: The modified differential-display polymerase chain reaction (DD-PCR) was used to examine the differences in the mRNA composition of Vincristine-resistant gastric cancer SGC 7901 cells (SGC7901/VCR), induced by vincristine sulfate versus SGC7901 cells. The differentially expressed cDNA fragments were confirmed by reverseNorthern analysis, sequencing, BLAST analysis and Northern bolt analysis.

RESULTS: DD-PCR identified that 54 cDNA fragments were preferentially expressed in SGC 7901/VCR cells. When these cDNA fragments were analyzed by reverse Northern blot, 20 were reproducibly expressed at a high level in SGC7901/VCR. Sequencing and BLAST analysis revealed that seven of the genes were known genes: ADP-ribosylation factor 4, Cytochrome oxidase subunit II, Ss-A/Ro ribonucleoprtein autoantigen 60kd subunit, ribosomal protein S13, galaectin-8 gene, oligophrenin 1 mRNA, ribosomal protein L23 mRNA; thirteen of the genes were unknown genes. The length and abundance of the four unknown genes mRNA were further confirmed by Northern blot analysis.

CONCLUSION: The twenty differential known and unknown genes may be related to the vincristine-resistant mechanism in human gastric cancer SGC7901 cell line.

Taxotere resistance in SUIT Taxotere resistance in pancreatic carcinoma cell line SUIT 2 and its sublines

AIM: To investigate the specific mechanisms of intrinsic and acquired resistance to taxotere (TXT) in pancreatic adenocarcinoma (PAC).

METHODS: MTT assay was used to detect the sensitivity of PAC cell line SUIT-2 and its sublines (S-007, S-013, S-020, S-028 and TXT selected SUIT-2 cell line, S2/TXT) to TXT. Mdr1 (P-gp), multidrug resistance associated protein (MRP), lung resistance protein (LRP) and β-tubulin isotype gene expressions were detected by RT-PCR. The functionality of P-gp and MRP was tested using their specific blocker verapamil (Ver) and indomethacin (IMC), respectively. The transporter activity of P-gp was also confirmed by Rhodamine 123 accumulation assay.

RESULTS: S-020 and S2/TXT were found to be significantly resistant to TXT (19 and 9.5-fold to their parental cell line SUIT-2, respectively). RT-PCR demonstrated strong expression of Mdr1 in these two cell lines, but weaker expression or no expression in other cells lines. MRP and LRP expressions were found in most of these cell lines. The TXT-resistance in S2-020 and S2/TXT could be reversed almost completely by Ver, but not by IMC. Flow cytometry showed that Ver increased the accumulation of Rhodamine-123 in these two cell lines. Compared with S-020 and SUIT-2, the levels of β-tubulin isotype II, III expressio ns in S-2/TXT were increased remarkably.

CONCLUSION: The both intrinsic and acquired TXT-related drug resistance in these PAC cell lines is mainly mediated by P-gp, but had no relationship to MRP and LRP express ions. The increases of β-tubulin isotype II, III might be collateral changes that occur when the SUIT-2 cells are treated with TXT.