Chemoradiation in Cervical Cancer with Cisplatin and High-Dose Rate Brachytherapy Combined with External Beam Radiotherapy Results of a Phase-II Study

BACKGROUND: In 1999, five randomized studies demonstrated that chemoradiation with cisplatin and low-dose rate (LDR) brachytherapy has a benefit in locally advanced cervical cancer and for surgically treated patients in high-risk situations. We evaluated the safety and efficacy of concomitant chemoradiation with cisplatin and high-dose rate (HDR) brachytherapy in patients with cervical cancer. PATIENTS AND METHODS: 27 patients were included in our phase-II trial: 13 locally advanced cases (group A) and 14 adjuvant-therapy patients in high-risk situations (group B). A definitive radiotherapy was performed with 25 fractions of external beam therapy (1.8 Gy per fraction/middle shielded after eleven fractions). Brachytherapy was delivered at HDR schedules with 7 Gy in point A per fraction (total dose 35 Gy) in FIGO Stages IIB-IIIB. The total dose of external and brachytherapy was 70 Gy in point A and 52-54 Gy in point B. All patients in stage IVA were treated without brachytherapy. Adjuvant radiotherapy was performed with external beam radiotherapy of the pelvis with 1.8 Gy single-dose up to 50.4 Gy. Brachytherapy was delivered at HDR schedules with two fractions of 5 Gy only in patients with tumor-positive margins or tumor involvement of the upper vagina. The chemotherapeutic treatment schedule provided six courses of cisplatin 40 mg/m2 weekly recommended in the randomized studies GOG-120 and -123. RESULTS: A total of 18/27 patients (66.7%) completed all six courses of chemotherapy. Discontinuation of radiotherapy due to therapy-related morbidity was not necessary in the whole study group. G3 leukopenia (29.6%) was the only relevant acute toxicity. There were no differences in toxicity between group A and B. Serious late morbidity occurred in 2/27 patients (7.4%). 12/13 patients (92.3%) with IIB-IVA cervical cancer showed a complete response (CR). 13/14 adjuvant cases (92.8%) are free of recurrence (median follow up: 19.1 months). CONCLUSION: Concomitant chemoradiation with cisplatin 40 mg/m2 weekly x 6 using HDR brachytherapy represents a promising treatment of cervical cancer with an acceptable toxicity.     

Serine hydrolases activate/inactivate trisubstituted nitrosoureas in dependence on intra- and extracellular enzyme location: an SCE study in Chinese hamster V79-E cells

Trisubstituted nitrosoureas are very stable in aqueous systems.But they are potent genotoxins in Chinese hamster V79-E cells,if no exogenous metabolizing system is added, and the mechanismof their genotoxic and carcinogenic activity has been largelyunknown. This investigation shows that the sister-chromatid-exchange(SCE)-inducing capacity of 1,3-dimethyl-3-phenyl-1-nitrosourea(DMPNU) is eliminated by adding dlisopropylfluorophospbate (DFP)or porcine liver carboxylesterase to the incubation system.These effects are caused by two different mechanisms: (i) DFPinhibits endogenous amidases existing in V79-E cells, thus preventingthe intracellular decomposition, which means an activation;and (ii) exogenous carboxylesterase cleaves DMPNU extra cellularly,and the genotoxic decomposition product is obviously too short-livedto reach a critical intracellular target. A second trisubstitutednitrosourea, 3,3-diethyl-1-methyl-1-nitrosourea (DEMNU), whichis mainly activated by monooxygenases, but in the absence ofan exogenous metabolizing system also induces SCEs in V79-Ecells, was studied in the same way. It was found that the ‘direct’genotoxicity of DEMNU may be inhibited by DFP as well, but carboxylesterasedecomposes this trialklynitrosourea with a much lower efficiencythan DMPNU suggesting a low substrate affinity. The SCE-inducingcapacity of both compounds is strongly influenced by the presenceof calf serum in the culture medium. The nature of the serumfactor is still unknown. Pathways for the amidase catalysisof DMPNU and for the activation of DEMNU by monooxygenases andamidases are proposed and discussed with respect to the topicalor systemic carcinogenicity of these agents.     

Different mechanisms of mitotic instability in cancer cell lines

Chromosomes of human malignant tumours display not only structural recombinations but also a wide variety of mostly non-random numerical aberrations. However, only little is known about the mechanisms leading to recurrent aneuploidies. We therefore investigated whether the malsegregation of specific chromosomes is due to a defect of the mitotic spindle apparatus. We analyzed mitoses of cell lines of six gliomas and of one breast carcinoma by combined immunohistochemistry and fluorescence in situ hybridization for non-disjunction of chromosomes 7, 8, 10, 12, 17, and 18 and observed three different phenomena. i) Five of six glioma cell lines showed a bipolar spindle but displayed a chromosome-specific malsegregation of all chromosomes studied with high but significantly different frequencies. Chromosomes 7 and 8 showed non-disjunction in about 75 and 50%, respectively. Although chromosomes 10, 12, 17, and 18 displayed equal separation during mitosis in 72, 86, 73, and 78%, respectively, a relevant percentage of an average of 24% of dividing cells showed even malsegregation of these chromosomes. ii) Only one of the glioma cell lines displayed multipolar spindles in one-third of the investigated cells resulting in non-specific aneuploidy. iii) The breast cancer cell line MCF7 displayed a bipolar spindle, but high frequencies of non-disjunction of all six investigated chromosomes but without preferential loss or gain of specific chromosomes indicating a different mechanism of chromosome malsegregation. In a small percentage of mitoses the chromatids of both homologous chromosomes were not separated mimicking the mechanism in the first meiotic division. This mechanism of double non-disjunction, not detectable by conventional cytogenetic analysis, procreates cell clones with genomic separation for particular chromosomes resulting in homozygosity for mutations which had been present heterozygously in the initial tumour cells.     

Comparative studies on thein vitro andin vivo morphology of clones of experimental CNS tumours in the rat

Summary Two sarcomas, one neurosarcoma and one polymorphous tumour of uncertain classification of the central nervous system of the rat induced by N-nitrosomethylurea or ethylnitrosourea were the source of 14 clones. The cytomorphology and the aggregation pattern of the clonesin vitro are described. The malignancy and histology were checked by homologous transplantation. All the clones formed sarcoma-like structuresin vivo, but it was difficult to decide whether these neoplasias were real sarcomas or very dedifferentiated glial tumours. The differences in cytology observedin vitro were greater than the histological differencesin vivo.     

Biological effects of TrkA and TrkB receptor signaling in neuroblastoma

The Trk family consists of three receptor tyrosine kinases, each of which can be activated by one or more of four neurotrophins-NGF, BDNF, NT3 and NT4. Neurotrophins mediate their multiple effects through a number of distinct intracellular signaling cascades regulating such diverse biological responses as cell survival, proliferation and differentiation in normal and neoplastic neuronal cells. Expression of Trk receptors also plays an important role in the biology and clinical behavior of neuroblastomas. High expression of TrkA is present in neuroblastomas with favorable biological features and highly correlated with patient survival, whereas TrkB is mainly expressed on unfavorable, aggressive neuroblastomas. This short review discusses recent data on the biological roles of TrkA and TrkB signaling in neuroblastoma.     

The human papillomavirus type 16 E7 oncoprotein targets Myc-interacting zinc-finger protein-1

We demonstrate that HPV-16 E7 forms a complex with Miz-1. UV-induced expression of the CDK-inhibitor p21^Cip1 and subsequent cell cycle arrest depends upon endogenous Miz-1 in HPV-negative C33A cervical cancer cells containing mutated p53. Transient expression of E7 in C33A inhibits UV-induced expression of p21^Cip1 and overcomes Miz-1-induced G1-phase arrest. The C-terminal E7Δ79LEDLL83-mutant with reduced Miz-1-binding capacity was impaired in its capability to repress p21^Cip1 expression; whereas the pRB-binding-deficient E7C24G-mutant inhibited p21^Cip1 expression similar to wild-type E7. Using ChIP, we demonstrate that endogenous E7 is bound to the endogenous p21^Cip1 core-promoter in CaSki cells and RNAi-mediated knock down of Miz-1 abrogates E7-binding to the p21^Cip1 promoter. Co-expression of E7 with Miz-1 inhibited Miz-1-induced p21^Cip1 expression from the minimal-promoter via Miz-1 DNA-binding sites. Co-expression of E7Δ79LEDLL83 did not inhibit Miz-1-induced p21^Cip1 expression. E7C24G retained E7-wild-type capability to inhibit Miz-1-dependent transactivation. These findings suggest that HPV-16 E7 can repress Miz-1-induced p21^Cip1 gene expression.     

α-Actinin 4 and BAT1 interaction with the Cytochrome c promoter upon skeletal muscle differentiation

To identify common regulatory features of nuclear genes encoding mitochondrial proteins we searched for regulatory elements in the Cytochrome c promoter during skeletal muscle differentiation in cell culture. A consensus element with the sequence GCTGCCGCAC-(N4-20)-GGSCGYGGG was found in both rat Cyt c and coxIV promoters. This new sequence element with yet undescribed function, but high abundance in promoters of nuclear genes encoding mitochondrial proteins available from the databases, showed a striking change in protein binding in electromobility shift assays when myoblasts were compared to myotubes. Proteins involved in the observed protein-DNA complexes were isolated from myotubes and identified by MALDI-TOF as BAT1, a DEAD-box protein of yet unknown function, heat shock protein HSP84, and α-actinin 4, a non-muscle isoform of the structural protein α-actinin. α-actinin 4 was found to be preferentially localized in the nucleus upon induction of myogenesis, suggesting a signaling function during muscle differentiation. In conclusion, the analyzed sequence motif may be a new candidate for common regulatory elements specific for nuclear encoded mitochondrial genes, and α-actinin 4 may be involved in their regulation. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.