[1, 2-Bis(2, 6-difluoro-3-hydroxyphenyl)ethylene-diamine]platinum(II) complexes, compounds for the endocrine therapy of breast cancer - mode of action II: contribution of drug inactivation, cellular drug uptake and sterical factors in the drug-target interaction to the antitumor activity.

The marked activity of [meso-1, 2-bis(2, 6-difluoro-3-hydroxyphenyl)ethylenediamine]platinum(II) (meso-3-PtLL', L, L' = Cl(2) or L = OH(2), L' = OSO(3)) on the hormone-sensitive MXT-M-3, 2 breast cancer implanted in mice is most probably due to a mechanism based on the reduction of the endogenous estrogen level. Cytotoxic effects which are poorly pronounced in experiments on several breast cancer cell lines (e.g. MCF-7), do not significantly contribute to the anti-breast cancer activity of this compound. In contrast to this, the standard cisplatin and the structurally related comparison compound [meso-1, 2-bis(4-fluorophenyl)ethylenediamine]platinum(II) (meso-4-PtLL', L, L' = Cl(2) or L = OH(2), L' = OSO(3)) are strongly active in vivo as well as in vitro. Both effects entail programmed cell death, which is responsible for the inhibition of the tumor growth. The minor cytotoxicity of meso-3-PtLL' in breast cancer cell cultures is caused neither by an inappropriate rate of reaction with bionucleophiles (e.g. by a too fast inactivation by plasma proteins) nor solely by the observed poor absorption by the tumor cells resulting in an insufficient drug concentration at the DNA. Additionally, an impeded reaction with biologically important, guanine-rich sequences of DNA (owing to the 2, 6-standing F atoms which hinder the drug-target inter action) must be assumed as cause of its marginal cytotoxicity.

[1, 2-Bis(2, 6-difluoro-3-hydroxyphenyl)ethylene-diamine]platinum(II) complexes, compounds for the endocrine therapy of breast cancer - mode of action I: antitumor activity due to the reduction of the endogenous estrogen level.

Aqua[meso-1, 2-bis(2, 6-difluoro-3-hydroxyphenyl)ethylenediamine]sulfatoplatinum(II) (meso-3-PtSO(4)) and its racemate (rac-3-PtSO(4)) are highly active on the hormone-sensitive MXT-M-3, 2 breast cancer of the mouse. In vitro, on the MXT(+) cell culture derived from this tumor, however, they are inactive (meso-3-PtSO(4)) or moderately active (rac-3-PtSO(4)) in concentrations corresponding to levels of these drugs in animal experiments. The in vivo effect is mainly caused by a reduction of the endogenous estrogen level in the host animals due to an interference with the ovarian steroid biosynthesis as demonstrated for meso-3-PtSO(4). Therefore, a reversal of the breast cancer inhibiting effect of meso-3-PtSO(4) can be achieved by simultaneous estrone administration. Histological results on ovaries, uterus, and tumor of meso-3-PtSO(4)-treated mice also favor such a mode of action. However, especially for rac-3-PtSO(4) cytotoxic effects contributing to the anti-breast cancer activity cannot be excluded. Considerations on the mode of action of Pt-complexes which inhibit breast cancer by interference with estrogen receptor mediated processes of growth control and with DNA replication are presented.

Chronic human parvovirus B19 infection in rheumatic disease of childhood and adolescence.

Parvovirus B19 causes erythema infectiosum in children, but the virus is associated with an increasing range of different diseases. About 20% of infections are associated with delayed virus elimination and viremia persisting over several months or years. These persistent B19-infections are characterised by the presence of IgG against the non-structural protein NS1. This study aimed to find further evidence for an association of parvovirus B19 persistence with VP1/2- and NS1-specific IgG-antibodies in children suffering from rheumatic diseases of childhood. Forty-eight children and adolescents with joint complaints lasting longer than 1 year including patients with juvenile systemic sclerosis and juvenile dermatomyositis showed antibodies against the viral NS1-protein. Laboratory markers of inflammation, humoral immune response against parvovirus B19 proteins and the presence of viral genomes in patients' sera as well as in 124 healthy children were investigated. Almost 50% of the patients showed laboratory signs of chronic inflammation. B19-DNA was amplified in 31% of patients' sera and 7% of the controls (P<0.0001). VP2-specific IgM was detectable in 50% of the patients' and 6% of control sera. NS1-specific immune reactions were linked to persistent B19-infection as indicated by the presence of viral genomes in the peripheral blood and of VP2-specific IgM years after disease onset. To estimate the severity of the disease and the clinical course, the number of affected and functionally impaired joints were noted and compared with the records from patients' initial visit in the hospital. Disease related complications were registered. Impairment of activities of daily living was assessed by Childhood Health Assessment Questionnaire (CHAQ)- and Munich Quality of Life Questionnaire (KINDL)-tests. During observation the clinical state of four patients worsened, 27 improved, the others remained stable. Twenty-four children were restricted in their daily activities.

Establishment and characterization of new murine breast cancer cell lines.

The establishment of two new breast cancer cell lines, MXT+ and MXT-, derived from the murine breast cancer models MXT-M-3,2 MC (hormone-sensitive) and MXT-M-3,2 (ovex) MC (hormone-insensitive), is described. Characterization of the cell lines was performed by investigation of morphology, steroid hormone receptor state, growth kinetics, and drug response as well as by cytogenetic analysis. MXT+ contains estrogen receptors (ER; 6.9 fmol/mg protein) as well as progesterone receptors (PgR; 9.2 fmol/mg protein) and therefore is inhibited by tamoxifen (Tam). MXT- proved to be ER- but PgR+ (23.4 fmol/mg protein) and, as expected, resistant against Tam. The sensitivity of MXT+ and MXT- against a pattern of therapeutically established anti-breast cancer drugs (cDDP, cisplatin; JM-8, carboplatin; DX, adriamycin; 5-FU, 5-fluorouracil; MTX, methotrexate; VLB vinblastine) was studied by use of a computerized, kinetic chemosensitivity assay based on quantification of biomass by staining cells with crystal violet. For each compound the inhibition profile reflecting cytostatic, transient cytotoxic, or cytocidal drug effects as well as development of resistance was evaluated. The following order of activity was found: MTX > VLB > or = DX > cDDP > or = 5-FU > JM-8. The test data of 5-FU, VLB, cDDP, and Tam on MXT+ as well as on MXT- were compared with those from studies on ER+ and ER- human breast cancer cell lines (MCF-7, ZR-75-1, T-47-D, and MDA-MB-231, respectively). They revealed comparable inhibition profiles and sensitivities of human and murine breast cancer cell lines, an indication that the results achieved in combined in vitro-/in vivo tests by use of the murine test models MXT+, MXT-, MXT-M-3,2 MC, and MXT-M-3,2(ovex) MC are relevant for therapy in humans.

Parvovirus B19 infection in pregnancy: quantitative viral DNA analysis using a kinetic fluorescence detection system (TaqMan PCR).

Human parvovirus B19 infections are common in the general population, and infection during pregnancy may cause hydrops fetalis and fetal death. To initiate adequate treatment, accurate laboratory diagnosis is essential. The most sensitive tests are nested PCR systems, but these assays provide semiquantitative results at best. A parvovirus B19 DNA assay was developed based on the real time TaqMan PCR. This method was calibrated on the basis of serial plasmid dilutions and tested with an international parvovirus B19 standard. The assay was capable of quantifying parvovirus B19 DNA from one to about 5 x 10(7) genome equivalents per reaction (corresponding to 100 to 5 x 10(9) genome equivalents per ml serum). Samples from 51 pregnant women with suspected acute parvovirus B19 infection were tested, and positive PCR results were obtained in at least one of the materials investigated in 41 cases. The median viral DNA load in maternal blood samples was 1.3 x 10(4) copies/ml (range 7.2 x 10(2)-2.6 x 10(7)). Maternal virus DNA concentration was not associated with the presence of maternal symptoms and/or fetal complications. As the stage of infection was not known in the majority of cases, our data do not exclude an association between peak levels of parvovirus B19 DNA and the development of complications. Maternal sera and corresponding fetal material were available for concurrent testing from 15 DNA-positive cases: in most fetal samples, viral DNA concentrations were several orders of magnitude higher (up to 2.1 x 10(12) copies/ml) compared to the corresponding maternal blood samples.

Establishment and Characterization of New Murine Breast Cancer Cell Lines.

The establishment of two new breast cancer cell lines, MXT(+) and MXT(-), derived from the murine breast cancer models MXT-M-3, 2 MC (hormone-sensitive) and MXT-M-3, 2 (ovex) MC (hormone-insensitive), is described. Characterization of the cell lines was performed by investigation of morphology, steroid hormone receptor state, growth kinetics, and drug response as well as by cytogenetic analysis. MXT(+) contains estrogen receptors (ER; 6.9 fmol/mg protein) as well as progesterone receptors (PgR; 9.2 fmol/mg protein) and therefore is inhibited by tamoxifen (Tam). MXT(-) proved to be ER(-) but PgR(+) (23.4 fmol/mg protein) and, as expected, resistant against Tam.The sensitivity of MXT(+) and MXT(-) against a pattern of therapeutically established anti-breast cancer drugs (cDDP, cisplatin; JM-8, carboplatin; DX, adriamycin; 5-FU, 5-fluorouracil; MTX, methotrexate; VLB vinblastine) was studied by use of a computerized, kinetic chemosensitivity assay based on quantification of biomass by staining cells with crystal violet. For each compound the inhibition profile reflecting cytostatic, transient cytotoxic, or cytocidal drug effects as well as development of resistance was evaluated. The following order of activity was found: MTX >, VLB >/= DX > cDDP >/= 5-FU > JM-8. The test data of 5-FU, VLB, cDDP, and Tam on MXT(+) as well as on MXT(-) were compared with those from studies on ER(+) and ER(-) human breast cancer cell lines (MCF-7, ZR-75-1, T-47-D, and MDA-MB-231, respectively). They revealed comparable inhibition profiles and sensitivities of human and murine breast cancer cell lines, an indication that the results achieved in combined in vitro-/in vivo tests by use of the murine test models MXT(+), MXT(-), MXT-M-3, 2 MC, and MXT-M-3, 2(ovex) MC are relevant for therapy in humans.

NS1 protein of parvovirus B19 interacts directly with DNA sequences of the p6 promoter and with the cellular transcription factors Sp1/Sp3.

The nonstructural proteins of parvovirus exert a variety of disparate functions during viral infection ranging from promoter regulation, involvement in DNA replication, and induction of apoptosis. Our interest was focused on the possible mechanism by which the NS1 protein mediates its effects on the p6 promoter of parvovirus B19. It is known that the p6 promoter is highly active in different cell lines and interaction with the viral NS1 protein results in a further increase of the activity. The protein may function by binding directly to the viral DNA or via an indirect binding through interaction with cellular transcription factors bound to the promoter. We examined the interaction of the NS1 protein with cellular transcription factors which are involved in regulating the promoter activity. After purified baculovirus-expressed NS1 protein in gel retardation assays was added, an altered complex formation was observed, indicating that NS1 protein interacts with Sp1/Sp3 transcription factors. Enzyme-linked immunosorbent assays verified these findings. The direct interaction of NS1 protein with p6 promoter elements was analyzed by a coprecipitation assay whereby labeled oligonucleotides spanning the entire promoter region were incubated with NS1 protein followed by an immunoprecipitation with NS1-specific antibodies. An eight-nucleotide-long, almost palindromic sequence (AGGGCGGA) was found as potential NS1-binding motif. Footprint analysis with oligonucleotides containing this DNA motif confirmed this result. Thus, transcriptional regulation by the NS1 protein may involve both the interaction with Sp1/Sp3 that binds to the promoter region and direct binding of NS1 to the promoter DNA.

Cellular transcription factors that interact with p6 promoter elements of parvovirus B19.

All transcripts of the human parvovirus B19 identified so far are regulated by a single promoter at map unit 6 of the viral genome, the so-called p6 promoter. This promoter is active in a wide variety of different cells. In order to identify cellular transcription factors involved in regulating promoter activity, we performed gel-retardation and supershift assays using the parts of the p6 promoter sequence shown previously to be protected in footprint experiments. Thereby, binding was demonstrated of the Oct-1 protein to an octamer motif within the p6 promoter and of the transcription factor Sp1 to three GC boxes. A specific preferential interaction of the factor Sp3 with one of these boxes was observed, indicating that the ratio Sp1:Sp3 may be involved in the regulation of promoter activity. Consensus sites for the regulatory protein YY1 are located close to the GC boxes and the octamer motif, to which this factor binds efficiently.