PK11195, an isoquinoline carboxamide ligand of the mitochondrial benzodiazepine receptor, increased drug uptake and facilitated drug-induced apoptosis in human multidrug-resistant leukemia cells in vitro

The isoquinoline peripheral benzodiazepine receptor ligand PK11195 increased drug (daunomycin)- and fluorochrome (calcein-AM) uptake and induced apoptosis detected by flow cytometry (FCM) technique, DNA electrophoretic analysis and poly(ADP-ribose) polymerase (PARP) cleavage in human multidrug-resistant myeloid leukemia (BL-60/VCR) and ovarian carcinoma (A2780/ADR) cells in vitro. The position of PK11195 with respect to drug-resistance modulator (DRM) efficiency, compared to the reference DRMs with the aid of FCM technique, was as follows: PSC833 > verapamil > PK11195 > vincristine. Our data show up to now not indicated observation that PK11195 possesses multidrug resistance modulating activity.

PSC 833 modulation of multidrug resistance to paclitaxel in cultured human ovarian carcinoma cells leads to apoptosis

BACKGROUND

Multidrug resistance (MDR) modulator PSC 833 has been shown to modulate multidrug resistance in Pg-p-positive human ovarian carcinoma cells A2780/ADR. Co-treatment of A2780/ADR cells with paclitaxel (PTX) and PSC 833 resulted in the restoration of PTX-sensitivity comparable to that in parental A2780 cells.

RESULTS

The flow cytometry experiments presented here showed PTX-(A2780) and PTX plus PSC 833 (A2780/ADR)-induced cell accumulation in the G2/M-phase of the cell cycle with concomitant appearance of apoptotic cells with sub-G0 (hypodiploid) DNA content. Furthermore, these events were accompanied by the appearance of poly(ADP-ribose) polymerase (PARP) cleavage, up-regulation of Bax, p53 and p21WAF1/CIP1 proteins and internucleosomal DNA fragmentation. Interestingly, we did not detect any significant alterations in Bcl-xL, CD95/Fas and Fas-L protein levels.

CONCLUSION

These results demonstrate the PSC 833 reduced the Pg-p-mediated multidrug resistance in human ovarian carcinoma cells to PTX-induced apoptosis in vitro.

PSC 833 induces apoptosis in drug-sensitive human leukemia cell line and modulates resistance to paclitaxel in its multidrug-resistant variant

BACKGROUND

The non-immunosuppressive cyclosporine analog PSC 833 has been shown to reverse multidrug-resistance of neoplastic cells including the MDR-1 gene coded P-glycoprotein (P-gp)-mediated cells resistant to paclitaxel.

MATERIALS AND METHODS

Apoptosis was demonstrated in drug-sensitive HL-60 and multidrug-resistant human promyelocytic leukemia HL-60/ADR (MRP) and HL-60/VCR (MDR-1) cells in vitro with the aid of flow cytometry, DNA analysis and western blotting.

RESULTS

The techniques used herein determined accumulation of paclitaxel/PSC 833 induced apoptotic cells with sub-G0 (hypodiploid) DNA content and blocked in the G2/M phase of the cell cycle, internucleosomal DNA fragmentation, poly (ADP-ribose) polymerase cleavage, Bcl-2 modulation and Bax up-regulation, without any significant alterations in the levels of Bcl-xL, CD95/Fas or Fas-L proteins.

CONCLUSION

Drug resistance modulator PSC 833 abolished the P-gp-mediated multidrug-resistance to paclitaxel and paclitaxel-induced apoptosis in human myeloid leukemia (HL-60/VCR) cells in vitro. Furthermore, PSC 833 alone induced apoptosis in parental drug-sensitive leukemia cells, but not in both multidrug-resistant sublines studied.

Resistance of human multidrug-resistant neoplastic cell lines to paclitaxel-induced-radiosensitization is reduced by the non-immunosuppressive cyclosporine analog SDZ PSC 833

The non-immunosuppressive cyclosporine analog SDZ PSC 833 abolished the resistance of human multidrug resistant (MDR-1, P-gp) human promyelocyte leukemia HL-60/VCR cells in vitro to paclitaxel-induced cell cycle- and viability alterations, as well as resistance to paclitaxel-induced radiosensitization. Furthermore, SDZ PSC 833 abolished also the resistance of human multidrug-resistant ovarian A2780/ADR cells to paclitaxel-induced cell cycle alterations and reduced its resistance to paclitaxel-induced radiosensitization. In these multidrug-resistant ovarian carcinoma cells the supra-additive interaction between paclitaxel and SDZ PSC 833 pre-exposure and subsequent irradiation appeared at slightly higher paclitaxel concentrations (40-100 nM) compared to those required for a similar interaction in the parental drug sensitive A2780 cells (40-80 nM paclitaxel).

Alterations of cell surface antigens induced by placental isoform of ferritin in human carcinoma cell lines

AIM

the ability of the breast cancer-associated placental acid isoform of ferritin (p43-PLF) to modulate cell surface expression of HLA, CD59 (protectin) and CD66 antigen (adhesion antigen related to CEA) was examined.

METHODS

the expression of these antigens in human breast carcinoma cell lines BT-20, T47D and MDA-MB-468 was determined with the aid of flow cytometry and monoclonal antibodies.

RESULTS

PLF induced a transient up-regulation followed by a down regulation of cell surface protectin (CD59 antigen) on the cell surface of T47D and to a lesser extent, BT-20 human breast carcinoma cell lines. Furthermore, PLF down-regulated cell surface expression of CEA-related CD66 antigen on both these cell lines. No PLF-induced alterations of protectin, CD66 antigen and HLA class I antigen were found on the MDA-MB-468 breast cancer cell line.

CONCLUSIONS

breast cancer-associated p43 induces alterations of the expression of cell surface molecules in breast cancer cells which could have an effect on the modulation of cancer cell adhesive interactions.

The protein kinase C inhibitor H7 blocks phosphorylation of stathmin during TPA-induced growth inhibition of human pre-B leukemia REH6 cells

The human pre-B acute lymphoblastic leukemia cell line REH6 was used to analyze the regulation of a ubiquitous intracellular phosphoprotein stathmin (Mr 19,000, pl = 5.6-6.2). We demonstrated by 32P-labeling that the short (1 h) treatment of the REH6 cells with the tumor promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), resulted in a rapid phosphorylation of at least three (P1, P2 and P3) stathmin isoforms without an alteration of stathmin isoform expression. Furthermore, Western blot analysis with specific antiserum showed that the prolonged period (48 h) of TPA treatment partially reduced protein levels particularly of two (N2 and P2) stathmin isoforms. The potent and relatively specific protein kinase C (PKC) inhibitor, 1,(5-isoquinolinesulphonyl)2methylpiperasine dihydrochloride (H7), partially inhibited these TPA effects, whereas the specific calmodulin inhibitor R24571 (calmidazolium) had no effect upon these events. Our findings suggest that stathmin phosphorylation in REH6 cells could be in part mediated by PKC activation.

Effects of protein kinase C inhibitor, staurosporine derivative CGP 41 251, on cell cycle, DNA synthesis and drug uptake in neoplastic cell lines

The protein kinase C inhibitor, staurosporine derivative CGP 41 251, was more efficient than staurosporine in the reversal of decreased anthracycline uptake in the anthracycline-resistant cell subline (A2780/ADR) of ovarian carcinoma. Staurosporine was more efficient than CGP 41 251 in the induction of cytometrically determined DNA fragmentation (cytofluorometric equivalent of apoptosis) in A2780 parental human ovarian carcinoma cells compared with the drug-resistant A2780/ADR subline and in both human leukemia K-562 cells as well as mouse leukemia L1210 compared with the araC-resistant L1210 cells. Staurosporine was a more potent inhibitor than CGP 41 251 of DNA synthesis in both araC-sensitive and -resistant mouse leukemia L1210 cells. CGP 41 251 was a slightly more efficient inhibitor of thymidine incorporation than staurosporine in human leukemia K-562 cells and its combination with araC had a higher inhibitory effect on the DNA synthesis in this cell line than staurosporine. CGP 41 251 exerted DNA synthesis inhibitory effects on both araC-sensitive and -resistant L1210 cells. Staurosporine-induced DNA synthesis inhibition in both araC-resistant and -sensitive L1210 mouse leukemia cells was decreased after combined administration with araC.

Expression and alterations of CD66 antigen by interferon-gamma in human breast carcinoma cell lines

Monoclonal antibodies of the CD66/67 panel from the 5th Workshop on Leukocyte Antigens bound (as determined by flow cytometry) to the cell surface of human breast carcinoma cell lines BT-20 and MDA-MB-468. The molecular weight of antigenic polypeptides recognized by the CD66 monoclonal antibody F34-187 differed between the two examined breast carcinoma lines as follows: 50kDa, 95 kDa and 130 kDa polypeptides were expressed on both BT-20 and MCF-7 cell lines, while the major 160-180 kDa polypeptide was found only in MDA-MB-468 cells. IFN-gamma, all-trans retinoic acid and phorbol ester (TPA) induced up-regulation of CD66 antigen(s) recognized by the monoclonal antibody F34-187 (as determined by flow cytometry). Different alterations of CD66 antigenic polypeptides recognized by F34-187 monoclonal antibody, induced by interferon-gamma and indentified by immunoblotting, were found on BT-20, MCF-7 and MDA-MB-468 breast carcinoma cell lines.

Modulation of EGF receptor and CD15 (Lewisx) antigen on the cell surface of breast carcinoma cell lines induced by cytokines, retinoic acid, 12-O-tetradecanoylphorbol 13-acetate and 1,25(OH)2-vitamin D3

Interleukin (IL) 1 alpha induced the up-regulation of cell-surfac-expressed epidermal growth factor (EGF) receptor on both MDA-MB-468 and BT-20 breast cancer cell lines. IL-1 beta and tumor necrosis factor alpha (TNF-alpha) increased the EGF receptor surface expression only on BT-20 breast carcinoma cells. 12-O-tetradecanoylphorbol 13-acetate (TPA) induced up-regulation of EGF receptor on MDA-MB-468 cells, and a marginal but significant increase was determined in BT-20 cells and in interferon gamma (IFN-gamma)-treated MDA-MB-468 cells. CD15 (Lewisx) antigen was down-regulated on MDA-MB-468 cells by TNF-alpha, TPA, IL-1 alpha, as well as by IFN-gamma and all-trans-retinoic acid. 1,25(OH)2-vitamin D3 up-regulated the CD15 antigen surface expression on MDA-MB-468 cells.

Partial purification of an extracellular leptospiral lipase

Sequential procedures involving ethanol precipitation, ultracentrifugation, and molecular sieve chromatography in deoxycholate permitted 140-fold purification of a leptospiral lipase.