Effects of combination therapy with a luteinizing hormone-releasing hormone agonist and chlormadinone acetate on rat prostate weight and plasma testosterone levels

We investigated whether the combination of chlormadinone acetate (CMA) and a luteinizing hormone releasing hormone (LH-RH) agonist, leuprorelin acetate (leuprorelin), more markedly decreased ventral prostate and seminal vesicle weights and plasma sex hormone levels in male rats. Four weeks after administration of 0.28, 0.84 or 2.8 mg/kg of leuprorelin, ventral prostate weights significantly decreased (53.8, 54.4 and 64.1%) and the plasma testosterone levels significantly lowered, but not dose-dependently. After repetitive administrations of 3 and 30 mg/kg/day of CMA, the rates of ventral prostatic atrophy were 37.1 and 65.9%, respectively. Although there was no change in the plasma testosterone level at 3 mg/kg, 30 mg/kg of CMA significantly decreased the level. A combination of leuprorelin (0.28 mg/kg) and CMA (3 or 30 mg/kg) more potently induced ventral prostatic and seminal vesicle atrophy than leuprorelin alone. Furthermore, a combination of leuprorelin and CMA (30 mg/kg) more markedly decreased the plasma testosterone level. According to the pharmacokinetic data for CMA in male rats, the doses of CMA correspond to the clinical dose. These findings suggest that combination therapy with an LH-RH agonist and CMA is more useful than therapy with the agonist alone in the treatment of prostate cancer.

Zeeman levels with exotic field dependence in the high field phase of an S=1 Heisenberg antiferromagnetic chain

We have performed electron spin resonance measurements over a wide frequency and magnetic field range on a single crystal of the S=1 quasi-one-dimensional Heisenberg antiferromagnet Ni(C5H14N2)2N3(PF6). We observed gapped excitation branches above the critical field H(c) where the Haldane gap closes. These branches are analyzed by a phenomenological field theory using the complex-field phi(4) model. A satisfactory agreement between experiment and theory is obtained.

Identification of a novel kinesin-related protein, KRMP1, as a target for mitotic peptidyl-prolyl isomerase Pin1

Mitosis utilizes a number of kinesin-related proteins (KRPs). Here we report the identification of a novel KRP termed KRMP1, which has a deduced 1780-amino acid sequence composed of ternary domains. The amino-terminal head domain is most similar to the kinesin motor domain of the MKLP-1 subfamily and has an intrinsic ATPase activity that is diminished by substituting the consensus Lys-168 with Arg. The central stalk domain is predicted to form a long alpha-helical coiled-coil, and can interact with each other in vivo. An in vivo labeling experiment revealed that KRMP1 is phosphorylated, and we also found that the region within the tail domain containing Thr-1604 as the cdc2 kinase phosphorylation site differs from the bimC box conserved in the bimC subfamily of KRPs. Immunofluorescence analysis showed that endogenous KRMP1 was localized predominantly to the cytoplasm during interphase and dispersed throughout the cell during mitosis. Consistent with this finding, overexpressed KRMP1 was detected in a complicated nuclear or cytoplasmic pattern reflecting multiple nuclear localization/export signals. Furthermore, KRMP1 interacted with the mitotic peptidyl-prolyl isomerase Pin1 in vivo, and an in vitro interaction was detected between the tail domain of KRMP1 and the WW domain of Pin1. Overexpression of KRMP1 caused COS-7 cells to arrest at G(2)-M, and co-expression of Pin1 reversed this effect, indicating their physiological interaction. Together, our results suggest that KRMP1 is a mitotic target regulated by Pin1 and vice versa.

Cloning of human PRP4 reveals interaction with Clk1

Prp4 is a protein kinase of Schizosaccharomyces pombe identified through its role in pre-mRNA splicing, and belongs to a kinase family including mammalian serine/arginine-rich protein-specific kinases and Clks, whose substrates are serine/arginine-rich proteins. We cloned human PRP4 (hPRP4) full-length cDNA and the antiserum raised against a partial peptide of hPRP4 recognized 170-kDa polypeptide in HeLa S3 cell extracts. Northern blot analysis revealed that hPRP4 mRNA was ubiquitously expressed in multiple tissues. The extended NH(2)-terminal region of hPRP4 contains an arginine/serine-rich domain and putative nuclear localization signals. hPRP4 phosphorylated and interacted with SF2/ASF, one of the essential splicing factors. Indirect immunofluorescence analysis revealed that endogenous hPRP4 was distributed in a nuclear speckled pattern and colocalized with SF2/ASF in HeLa S3 cells. Furthermore, hPRP4 interacted directly with Clk1 on its COOH terminus, and the arginine/serine-rich domain of hPRP4 was phosphorylated by Clk1 in vitro. Overexpression of Clk1 caused redistribution of hPRP4, from the speckled to the diffuse pattern in nucleoplasm, whereas inactive mutant of Clk1 caused no change of hPRP4 localization. These findings suggest that the NH(2)-terminal region of hPRP4 may play regulatory roles under an unidentified signal transduction pathway through Clk1.

Dual roles of RNA helicase A in CREB-dependent transcription

RNA helicase A (RHA) is a member of an ATPase/DNA and RNA helicase family and is a homologue of Drosophila maleless protein (MLE), which regulates X-linked gene expression. RHA is also a component of holo-RNA polymerase II (Pol II) complexes and recruits Pol II to the CREB binding protein (CBP). The ATPase and/or helicase activity of RHA is required for CREB-dependent transcription. To further understand the role of RHA on gene expression, we have identified a 50-amino-acid transactivation domain that interacts with Pol II and termed it the minimal transactivation domain (MTAD). The protein sequence of this region contains six hydrophobic residues and is unique to RHA homologues and well conserved. A mutant with this region deleted from full-length RHA decreased transcriptional activity in CREB-dependent transcription. In addition, mutational analyses revealed that several tryptophan residues in MTAD are important for the interaction with Pol II and transactivation. These mutants had ATP binding and ATPase activities comparable to those of wild-type RHA. A mutant lacking ATP binding activity was still able to interact with Pol II. In CREB-dependent transcription, the transcriptional activity of each of these mutants was less than that of wild-type RHA. The activity of the double mutant lacking both functions was significantly lower than that of each mutant alone, and the double mutant had a dominant negative effect. These results suggest that RHA could independently regulate CREB-dependent transcription either through recruitment of Pol II or by ATP-dependent mechanisms.

Early hilar lung cancer--risk for multiple lung cancers and clinical outcome

In early hilar lung cancer patients, multiple lung cancers frequently develop. The clinical outcome of such patients were studied. A total of 91 patients, 88 men and three women, who were endoscopically diagnosed with early hilar lung cancer were studied retrospectively. Surgery was performed in 46 patients, while organ-sparing treatment, including photodynamic therapy (PDT), Nd-YAG (neodymium-yttrium, argon, garnet) laser vaporization, and radiotherapy, were done for 45 patients. During follow-up, newly developed lung cancers and/or malignancies in other organs were recorded. The average smoking index (cigarettes per day x years) was 1040. Synchronous and/or metachronous multiple lung cancers developed in 26/91 patients (28.6%). Malignancies in other organs were found in 12/91 (13.2%). The smoking index of patients with multiple lung cancers was significantly higher than for other patients. The overall 5 year survival rate was 70.7% in all patients, 76.0% in the surgery group, and 64.4% in the nonsurgery group. The lung cancer-specific 5 year survival rate was 89.8% in all patients, 89.3% in the surgery group, and 90.5% in the nonsurgery group. Early hilar lung cancer frequently accompanies other lung cancers or malignancies in other organs. A favorable prognosis can be obtained with organ-sparing treatment.

Robust oscillations within the interlocked feedback model of Drosophila circadian rhythm

A mechanism for generating circadian rhythms has been of major interest in recent years. After the discovery of per and tim, a model with a simple feedback loop involving per and tim has been proposed. However, it is recognized that the simple feedback model cannot account for phenotypes generated by various mutants. A recent report by Glossop, Lyons & Hardin [Science286, 766 (1999)] on Drosophila suggests involvement of another feedback loop by dClk that is interlocked with per-tim feedback loop. In order to examine whether interlocked feedback loops can be a basic mechanism for circadian rhythms, a mathematical model was created and examined. Through extensive simulation and mathematical analysis, it was revealed that the interlocked feedback model accounts for the observations that are not explained by the simple feedback model. Moreover, the interlocked feedback model has robust properties in oscillations.

Primary leiomyosarcoma of the heart subsequent to double carcinomas of the thyroid and lung

A 63-year-old woman underwent surgical operations for left lower lung cancer and for thyroid cancer. Nine months later, a third cancer developed in her heart and this tumor was removed by open heart surgery. A pathologic study revealed that the tumor was primary leiomyosarcoma of the heart and thus independent from the previous lung and thyroid carcinomas. This case was regarded as a triple carcinoma including a primary leiomyosarcoma arising from the left atrium. Reports in the literature on primary malignant tumors of the heart are reviewed briefly.

Regulatory Domain of Protein Stability of Human P51/TAP63, a P53 Homologue

The amino terminal of human P51/TAp63, a P53 homologue, possesses a transactivation domain involved in the activation of its target genes by binding to DNA elements responsive to the p53 protein family. Using a series of amino terminal deletions, the transactivation domain was mapped between amino acid residues 50 to 69. This domain also regulates protein stability in a proteasome-dependent manner, and Ser51 and Ser68 were found to be essential for this stability. Our results suggest that P51 activity is greatly affected by protein stability.

Endoscopic evaluation of centrally located early squamous cell carcinoma of the lung

BACKGROUND

Lung-sparing treatment recently has become a choice in the treatment of patients with early hilar lung carcinoma. To select the method of treatment, it is important to evaluate the histologic extent of the tumor using endoscopy.

METHODS

A total of 46 patients who underwent surgery for an endoscopically evaluated early lung carcinoma of the tracheobronchial tree were analyzed. Initial surgery was performed in 16 patients and in 30 patients surgery was performed after preoperative laser therapy. The endoscopic findings were classified into three types: superficial, nodular, and polypoid. In the resected lung, the greatest tumor dimension, the depth of mural invasion, the presence of microscopic blood and lymph vessel invasion, and metastases to the dissected lymph nodes were examined.

RESULTS

The mean greatest tumor dimensions were 14.6 +/- 7.3 mm (mean +/- standard deviation) in the nodular group, 23.3 +/- 12.8 mm in the superficial group, and 19.0 +/- 9.2 mm in the polypoid group. The greatest tumor dimension in the superficial group was significantly larger than that in the nodular group (P < 0.01). Preoperative endoscopic diagnosis of early hilar lung carcinoma was correct histologically in 34 of 46 cases (74.0%). Hilar lymph node metastases (N1), extrabronchial invasion, and extension to the peripheral bronchus were recognized in 12 cases. Complete disappearance of the tumor due to preoperative laser therapy was confirmed in eight patients. Lymph node metastasis was not found when the greatest tumor dimension measured < 8 mm. The overall absolute 5-year survival rate was 76.0% for all patients, 87.1% for the surgery alone group, and 70.0% for the surgery after preoperative laser therapy group.

CONCLUSIONS

Curative treatment of early hilar lung carcinoma is possible using photodynamic therapy alone when the tumor size is < or = 8 mm and the lesion does not extend to the peripheral bronchus.

Progressive and sufficient decrease of hepatitis B core antibody can predict the disappearance of hepatitis B virus DNA in Japanese patients with hepatitis B surface antigen clearance

The aim of this study was to elucidate the relationships among serum levels of hepatitis B virus (HBV) DNA, periods after hepatitis B surface (HBs) antigen clearance, and the titer of hepatitis B core (HBc) antibody in 200-fold diluted serum. Twelve patients who had clearance of HBs antigen from serum were studied. Five patients had not received any treatment (group A), and seven had received prednisolone withdrawal therapy. The patients in groups A and B were followed up for 86 months and 108 months (median), respectively. Serum HBV was measured by the nested polymerase chain reaction method. In both groups, serum HBV tended to become gradually undetectable after HBs antigen clearance. The positive rate of HBV in the sera 5 years or more after HBs antigen clearance was significantly lower than that in the sera at less than 5 years, both in group A (P = 0.004) and group B (P = 0.010). In both groups, the titer of HBs tended to decline every year after HBs antigen clearance. HBV was still detectable in the sera of some patients for a long period of time after they showed seroconversion to HBs antibody. The results suggest that detection of HBV was difficult in sera with an HBc titer of 30% or lower and at more than 5 years after HBs antigen clearance in both groups. It is important to note that HBV DNA rarely exists in the serum, even when HBs antigen and HBc are both negative.

Evidence for the singlet-dimer ground state in an S = 1 antiferromagnetic bond alternating chain

Susceptibility, ESR, and magnetization measurements have been performed on single crystals of an S = 1 bond alternating chain compound: [Ni(333-tet) (mu-NO2)] (ClO4) (333-tet = N,N'-bis(3-aminopropyl)propane-1,3-diamine) and the compound doped with a small amount of Zn. We observed an anomalous angular dependence in the Zn-doped sample. These results are well explained by the model based on the valence-bond solid picture for the singlet-dimer phase. The picture implies that the free spins of S = 1 with a positive uniaxial single-ion anisotropy are induced at the edges of the chains without forming the singlet dimer.

The cycle of the seminiferous epithelium in the greater Japanese shrew mole, Urotrichus talpoides

Spermatogenesis and acrosomal formation in the greater Japanese shrew mole, Urotrichus talpoides, were studied by light microscopy. On the basis of acrosomal changes, morphology of spermatid head, nuclear shape, appearance of meiotic figures, location of spermatid and period of spermiation, the cycle of the seminiferous epithelium was classified into 12 stages, and developing spermatids could be divided into 15 steps. The mean relative frequencies of stages from I to XII were 10.9, 8.7, 9.8, 7.3, 8.5, 10.3, 12.5, 8.7, 5.8, 5.4, 5.1 and 7.1%, respectively. Similar to the case in the musk shrew, the spermatid nucleus of the greater Japanese shrew mole remained in the middle region of the seminiferous epithelium and only the acrosome extended towards the basement membrane. The elongation of the acrosome, however, was not prominent. The proacrosomal vesicle first appeared in stage II and then one large and round granule was seen in stage III. The acrosomal vesicle became flattened on the surface of the nucleus in stage IV. Spreading of the acrosomic system has been recognized from stage VII. In stage VII, spermiation occurred. In stage IX, the spermatid nucleus began to elongate. Elongation and condensation of the nucleus were clearly observed in stage X. In stage XII, pachytene spermatocytes divided into diplotene spermatocytes. In stage XII, meiotic figures and secondary spermatocytes were observed.

SPK-1, a C. elegans SR protein kinase homologue, is essential for embryogenesis and required for germline development

SR-protein kinases (SRPKs) and their substrates, serine/arginine-rich pre-mRNA splicing factors, are key components of splicing machinery and are well conserved across phyla. Despite extensive biochemical investigation, the physiological functions of SRPKs remain unclear. In the present study, cDNAs for SPK-1, a C. elegans SRPK homologue, and CeSF2, an SPK-1 substrate, were cloned. SPK-1 binds directly to and phosphorylates the RS domain of CeSF2 in vitro. Both spk-1 and CeSF2 are predominantly expressed in germlines. RNA interference (RNAi) experiments revealed that spk-1 and CeSF2 play an essential role at the embryonic stage of C. elegans. Furthermore, RNAi studies demonstrated that spk-1 is required for germline development in C. elegans. We provide evidence that RNAi, achieved by the soaking of L1 larvae, is beneficial in the study of gene function in post-embryonic germline development.

Novel RING finger proteins, Air1p and Air2p, interact with Hmt1p and inhibit the arginine methylation of Npl3p

Heterogeneous nuclear ribonucleoproteins (hnRNPs) are involved in the mRNA processing and export and are post-translationally modified by methylation at arginine residues in their arginine-glycine-rich (RGG) domains. We screened the factors that can interact with the RGG domain of Npl3p only in the presence of Hmt1p with the two-hybrid system in Saccharomyces cerevisiae. An isolated clone, YIL079, encodes a novel RING finger protein that was not directly bound to Npl3p but associated with the N terminus of Hmt1p. Thus, we designated the gene product Air1p (arginine methyltransferase-interacting RING finger protein). Air1p inhibited the Hmt1p-mediated methylation of Npl3p in vitro. Overexpression of Air1p repressed the Hmt1p-dependent growth of cells. Since homology searches indicate that the YDL175 gene product has significant identity (45%) with Air1p, we designated the gene AIR2. Air2p also has a RING finger domain and was bound to Hmt1p. Although single disruption of either gene gave no effect on the cell growth, cells lacking Air1p and Air2p grew at an extremely slow rate with accumulated poly(A)(+) RNA in the nucleus. Thus, Air1p and Air2p may affect mRNA transport by regulating the arginine methylation state of heterogeneous nuclear ribonucleoproteins.

Clinical outcomes of orbital irradiation combined with or without systemic high-dose or pulsed corticosteroids for Graves' ophthalmopathy

PURPOSE

To evaluate the outcomes of orbital irradiation with or without high-dose or pulsed corticosteroids in patients with Graves' ophthalmopathy (GO).

METHODS AND MATERIALS

One hundred and twenty-one patients with moderate to severe GO who received orbital irradiation from 1987 to 1997 were retrospectively analyzed. A total dose of 20 Gy in 10 fractions was delivered to the bilateral retrobulbar volume. Eighty-six patients were treated in combination with high-dose or pulsed corticosteroids and irradiation. Univariate and multivariate analyses were performed to assess the prognostic variables.

RESULTS

The median follow-up period was 26 months. The overall clinical response was evaluated as excellent in 17 patients (14%), good in 65 (54%), fair in 31 (25%), no response in 7 (6%), and worse in 1 (1%). The best responses were noted for soft-tissue signs, extraocular muscle involvement, and sight loss, while a limited response was noted for proptosis. Multivariate analysis revealed that the use of high-dose corticosteroid or pulsed corticosteroids, female gender, and a shorter duration of ophthalmopathy before radiotherapy were significantly correlated with favorable outcomes. No long-term complications related to radiotherapy were observed.

CONCLUSION

Orbital irradiation combined with high-dose or pulsed corticosteroids is an effective treatment for moderate to severe GO, especially in cases with major manifestations of soft-tissue signs, extraocular muscle impairment, or sight loss.

Content-based image retrieval system using neural networks

An effective image retrieval system is developed based on the use of neural networks (NNs). It takes advantages of association ability of multilayer NNs as matching engines which calculate similarities between a user's drawn sketch and the stored images. The NNs memorize pixel information of every size-reduced image (thumbnail) in the learning phase. In the retrieval phase, pixel information of a user's drawn rough sketch is inputted to the learned NNs and they estimate the candidates. Thus the system can retrieve candidates quickly and correctly by utilizing the parallelism and association ability of NNs. In addition, the system has learning capability: it can automatically extract features of a user's drawn sketch during the retrieval phase and can store them as additional information to improve the performance. The software for querying, including efficient graphical user interfaces, has been implemented and tested. The effectiveness of the proposed system has been investigated through various experimental tests.

Spectrum of autoantibodies against a dynamin-related protein, dymple

OBJECTIVE

To characterize the clinical features of patients with autoantibodies against dymple, a dynamin-related protein.

METHODS

Serum samples from 281 patients with rheumatic diseases were examined. The characteristics of antidymple and antibody-reactive determinants were investigated by immunoblotting with the recombinant dymple antigen, including its deletion mutants, and by immunofluorescence studies with affinity-purified serum.

RESULTS

Five serum samples (2%) were found to have antidymple. All of these patients were male, and 4 of them had interstitial pneumonitis. Their sera were considered to mainly recognize the N-terminus of dymple, which contains GTP-binding motifs.

CONCLUSION

Dymple, which joins the cytoplasmic autoantigens, could be a marker for a newly recognized subset of connective tissue diseases.

Detection of cardiac calcinosis in hemodialysis patients by whole-body scintigraphy with 99m-technetium methylene diphosphonate

A noninvasive method for the diagnosis of cardiac calcinosis, a life-threatening complication in hemodialysis patients with end-stage renal disease (ESRD), has not, as yet, been firmly established. We tested whether whole body scanning with 99m-technetium methylene diphosphonate (MDP) might visualize cardiac calcinosis. In 19 consecutive chronic hemodialysis ESRD patients (13 males and 6 females, aged 40-81, mean 63 +/- 8 years) with cardiovascular disease [mitral annular calcinosis and/or calcified aortic valve (n = 4), hemodialysis cardiomyopathy (n = 1), coronary artery disease (n = 9) and peripheral artery atherosclerotic disease (n = 6)], MDP uptake in the heart was compared to that in 7 non-ESRD controls with hyperparathyroidism due to adenoma. Cardiac and lung field MDP uptake was confirmed in only 3 (16%) and 5 (26%) of the 19 ESRD subjects, respectively, but was absent in controls. Positive cardiac uptake was related to cardiac calcified complications (mobile intracardiac calcinosis, myocardial calcinosis and mitral annular calcification) and the duration of hemodialysis (p = 0.015). While it was statistically insignificant, subjects showing MDP uptake were elder and had higher serum Ca or Ca x P product and lower intact parathyroid hormone levels. These results suggest that cardiac calcinosis in ESRD patients can be detected noninvasively by myocardial scintigraphy with 99m-technetium MDP.

Direct imaging of phosphorylation-dependent conformational change and DNA binding of CREB by electron microscopy

BACKGROUND

The second messenger cAMP stimulates the expression of numerous genes through the PKA-dependent phosphorylation of CREB. The cAMP-regulated transcription factor CREB undergoes conformational change in response to phosphorylation by PKA at Ser 133. The phosphorylation enables interaction between the kinase-inducible domain (KID) of CREB and KIX domain of CREB binding protein (CBP).

RESULTS

To understand the activation mechanism of CREB-mediated gene expression, we performed the electron-microscope imaging of the transcription machinery. We improved the metal shadowing techniques to achieve higher resolution to detect phosphorylation-induced conformation change of the protein. Homodimer formation of CREB and the complex formation of phosphorylated CREB with CBP were observed under the electron microscope. The binding of the CREB dimer to CREs on the somatostatin and tyrosine hydroxylase promoters were also visualized directly and stereoscopically.

CONCLUSIONS

Greatly improved resolution achieved by our modified metal shadowing techniques makes it possible to visualize that the shape of CREB homodimer was changed in phosphorylation-dependent manner and that the promoter DNA strands containing CREs appeared to be bent and twisted slightly by the holding in the crevice of the CREB homodimer. This method may be applicable to visualize transcriptional activation process of nuclear receptors or general transcription machinery.

[A case of biloma caused by early complications of hepatic artery infusion chemotherapy]

We report a 70-year-old male who had biloma as an early complication of hepatic artery infusion chemotherapy. The patient had a history of subtotal gastrectomy for a advanced gastric cancer. Two years after the primary operation on the stomach, a solitary metastatic liver tumor was indicated by follow-up abdominal CT, and a segmental hepatectomy was performed. Soon after the hepatectomy, intraarterial catheter placement was performed via the left subclavian artery for preventive chemotherapy. Infusion chemotherapy of 10.5 g 5-FU and 75 mg CDDP was administered for a month, during which time the patient had liver dysfunction, fever, tenderness, and abdominal fullness. Abdominal CT revealed a large low density mass at a lateral segment of the liver which could not be seen on the previous CT image. Also, extravasation of contrast media was identified by angiography via the reservoir catheter. Using an interventional technique, percutaneous transhepatic drainage for biloma and extubation of the reservoir catheter were performed. The present case is thought to be of an early and rare complication of hepatic artery infusion chemotherapy. The etiology is discussed herein.

Cellular immunologic parameters related to age, gender, and stage in lung cancer patients

Several immunologic parameters have been reported to correlate with the clinicopathologic status of lung cancer patients. However, these studies were based on relatively small numbers of patients and often yielded conflicting results. We prospectively studied cellular immunologic parameters related to age, gender, and stage in lung cancer patients. We obtained pretreatment peripheral blood samples from 287 lung cancer patients. Lymphocyte subsets (percentage of lymphocytes positive for CD3, CD4, CD8, HLA-DR, or representing FcgammaR IIIa-positive T cells), natural killer (NK) cell activity, and lymphoblastogenesis (LB) after stimulation by phytohemagglutinin (PHA) were evaluated. Significant decline was seen in older patients in percentages of cells positive for CD3 or CD4, in the CD4/CD8 ratio and in LB. The percentage of FcgR IIIa-positive T cells increased with age. LB as well as CD4 positivity were significantly greater in women than in men. NK cell activity showed the greatest cytotoxic responses in stage IIIA, with significantly less response in stage IV than in IIIA. Node-negative patients showed higher reactivities for LB and lower positivity for HLA-DR than node-positive patients. Patients with no distant metastases had a higher level of NK cell activity than patients with distant metastases. Immune parameters are variously related to age, gender, and the stage in lung cancer patients, some may prove to be useful predictors of survival.

Induction of mammalian cell transformation and genotoxicity by 2-methoxyestradiol, an endogenous metabolite of estrogen

2-methoxyestradiol (2-MeOE(2)) is an endogenous metabolite of 17beta-estradiol and a proposed inhibitor of tumor growth and angiogenesis. However, 2-MeOE(2) is also an inhibitor of microtubule assembly and other microtubule inhibitors, e.g. colcemid and diethylstilbestrol, induce aneuploidy and cell transformation in cultured mammalian cells. To assess the in vitro carcinogenicity and related activity of 2-MeOE(2), the abilities of this metabolite to induce cell transformation and genetic effects were studied simultaneously using Syrian hamster embryo (SHE) fibroblasts. Growth of these cells was reduced by treatment with 2-MeOE(2) at 0.1-1.0 microg/ml in a concentration-dependent manner. Treatment of SHE cells with 2-MeOE(2) at 0.3 or 1.0 microg/ml for 2-48 h also resulted in a concentration- and treatment time-related increase in the mitotic index and the percentage of multinucleated cells. Treatment with 2-MeOE(2) at 0.1-1.0 microg/ml for 48 h induced a statistically significant increase in the frequencies of morphological transformation of SHE cells in a concentration-dependent manner. A statistically significant increase in the frequencies of somatic mutations at the Na(+)/K(+) ATPase or hprt locus was also observed in cells treated with 2-MeOE(2) for 48 h at 0.1 or 0.3 microg/ml, respectively. Treatment of SHE cells with 2-MeOE(2) at 0.3 or 1.0 microg/ml for 24 h induced chromosome aberrations, mainly breaks, exchanges and chromosome pulverization. The incidence of chromosome aberrations was not affected by co-treatment with alpha-naphthoflavone, an inhibitor of 2-hydroxylase that inhibits oxidative conversion of 2-MeOE(2) to 2-hydroxyestradiol, but the incidence was slightly increased by co-treatment with L-ascorbic acid. Numerical chromosomal changes in the near diploid range and in the tetraploid and near tetraploid ranges were also detected in 2-MeOE(2)-treated cells. These findings indicate that 2-MeOE(2) has cell transforming and genotoxic activities in cultured mammalian cells and potential carcinogenic activity.