Catechol-O-methyltransferase gene polymorphisms in benign prostatic hyperplasia and sporadic prostate cancer.

Various carcinogenic metabolites, including catechol estrogens, play a role in malignant transformation. An enzyme that is capable of neutralizing the genotoxic effects of these compounds is catechol-O-methyltransferase (COMT). A variant form of this enzyme has been shown to reduce its activity by up to 4-fold; thus, we hypothesize that single nucleotide polymorphisms of the COMT gene can be a risk factor for benign prostatic hyperplasia (BPH) and prostate cancer. To test this hypothesis, the genetic distribution of three different COMT polymorphisms at codon 62 (C-->T), codon 72 (G-->T), and codon 158 (G-->A) were analyzed in 131 normal healthy subjects, 134 BPH, and 178 sporadic prostate cancer samples from a Japanese population. Results of these experiments show that the variant genotype at codon 62 (P = 0.060) and codon 158 (P = 0.047) are risk factors for prostate cancer but not BPH when compared with normal controls. Odds ratio (OR) and 95% confidence interval (95% CI) for cancer were 3.24 and 1.38 to 7.61, respectively, for codon 62 T/T genotype when compared with wild type. At codon 158, the A/A variant for cancer had an OR of 3.00 with a 95% CI of 1.38 to 6.54 compared with wild type. Codons 62 and 158 were in linkage disequilibrium (LD), and when compared with the C-G haplotype, other types (C-A, T-G, T-A) were observed to be associated with prostate cancer (P = 0.040) but not BPH. Codon 72 on the other hand, was not in LD with either codon 62 or 158. The homozygous variant on codon 72 was rare in this Japanese population, and the heterozygous G/T at this codon was not associated with either prostate cancer or BPH. When evaluating the risk of COMT polymorphisms with stage or grade of cancer, no associations were observed for any of the genotypes with the exception of a tendency (P = 0.096) for the variant A allele on codon 158 to be correlated with higher stages (> or = T3) of cancer. This is the first report that shows the polymorphisms of COMT to be associated with sporadic prostatic carcinogenesis. These results are important in understanding the role of COMT polymorphisms in the pathogenesis of prostate cancer.     

Basaloid-Squamous Carcinoma of the Esophagus: Report of a Case

(Received for publication on Oct. 27, 1998; accepted on July 13, 1999)     

Endoscopic surgery for lateral cervical cysts

The infection of an intervertebral disk is a serious condition. The diagnosis often is elusive and difficult to make. It is imperative to have appropriate microbiologic specimens before the initiation of treatment. We report the case of a 51-year-old woman with lumbar spondylodiscitis caused by infection after the placement of an epidural catheter for postoperative analgesia. A spinal magnetic resonance imaging (MRI) scan confirmed the diagnosis, but computed tomography (CT)-guided fine-needle biopsy did not yield adequate material for a microbiologic diagnosis. Laparoscopic biopsies of the involved disk provided good specimens and a diagnosis of Propionibacterium acnes infection. We believe that this minimally invasive procedure should be performed when CT-guided fine-needle biopsy fails to yield a microbiologic diagnosis in spondylodiscitis.     

Cellular and biochemical mechanisms of the resistance of human cancer cells to a new anticancer ribo-nucleoside, TAS-106.

We have established variants of DLD-1 human colon carcinoma and HT-1080 human fibrosarcoma cells resistant to the new anticancer ribo-nucleosides, 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)-cytosine (ECyd, TAS-106) and 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)uracil (EUrd). Both variants were shown to have decreased (3- to 24-fold decrease) uridine-cytidine kinase (UCK) activity, and exhibited cross-resistance to EUrd and TAS-106. Based on the IC(50) values determined by chemosensitivity testing, a 41- to 1102-fold resistance to TAS-106 was observed in the resistant cells. TAS-106 concentration-dependently inhibited RNA synthesis, while its effect on DNA synthesis was negligible. The degree of resistance (14- to 3628-fold resistance) calculated from the inhibition of RNA synthesis tended to be close to the degree of chemoresistance of tested cells to TAS-106. The experiments on the intracellular metabolism of TAS-106 in the parental cells revealed a rapid phosphorylation to its nucleotides, particularly the triphosphate (ECTP), its major active metabolite. The amount of TAS-106 transported into the resistant cells was markedly reduced and the intracellular level of ECTP was decreased from 1/19 to below the limit of detection; however, the unmetabolized TAS-106 as a percentage of the total metabolite level was high as compared with the parental cells. The ratio of the intracellular level of ECTP between parental and resistant cells tended to approximate to the degree of resistance calculated from the inhibitory effect on RNA synthesis. These results indicate that the TAS-106 sensitivity of cells is correlated with the intracellular accumulation of ECTP, which may be affected by both the cellular membrane transport mechanism and UCK activity.     

The mouse rasH2/BHT model as an in vivo rapid assay for lung carcinogens.

We have demonstrated the utility of a 9-week in vivo two-stage assay for lung cancer initiating agents, using transgenic mice carrying the human prototype c-Ha-ras gene (rasH2 mice) and butylhydroxytoluene (BHT) as a potent lung promoter (rasH2/BHT model). In the present study, to ascertain appropriate conditions for BHT administration in this model, the effects of exposure on proliferation of alveolar type II cells in male rasH2 mice were examined. Additionally, use of BHT was validated for promotion of urethane (UR) carcinogenesis in male and female rasH2 mice. In a time-course study of a single intragastric administration of BHT at a dose of 400 mg/kg, increased bromodeoxyuridine-labeling index (LI) reached a maximum 3 days after treatment and was still observed after 7 days. In a dose-response study, effects were dose-dependent, the dose of 400 mg/kg causing eight-fold elevation as compared to the control. With repeated administration, whereas the LI was increased dramatically at first, effects gradually diminished with further exposure, and finally six BHT treatments failed to induce cell proliferation. In a two-stage model using UR as the initiator, although up to five consecutive doses of BHT were able to exert continued enhancing effects in terms of adenoma yield, no increment was evident with further treatments. The data overall indicate that a rasH2/BHT model with five weekly administrations of BHT at a dose of 400 mg/kg is most efficacious.     

Sensitivity of Human Cancer Cells to the New Anticancer Ribo-nucleoside TAS–106 Is Correlated with Expression of Uridine-cytidine Kinase 2

TAS–106 [l–(3– C -ethynyl-β- d - ribo -pentofuranosyl)cytosine] is a new anticancer ribo -nucleoside with promising antitumor activity. We have previously presented evidence suggesting that the TAS–106 sensitivity of cells is correlated with intracellular accumulation of the triphosphate of TAS–106, which may be affected both by cellular membrane transport mechanisms and uridine-cytidine kinase (UCK) activity. Since the presence of a UCK family consisting of two members, UCK1 and UCK2, has recently been reported in human cells, we investigated the relation between expression of UCK1 and UCK2 at both the mRNA and protein levels and UCK activity (TAS–106 phosphorylation activity) in a panel of 10 human cancer cell lines. Measurement of UCK activity in these cell lines revealed that it was well correlated with the cells' sensitivity to TAS–106. In addition, the mRNA or protein expression level of UCK2 was closely correlated with UCK activity in these cell lines, but neither the level of expression of UCK1 mRNA nor that of protein was correlated with enzyme activity. We therefore compared the protein expression level of UCK2 in several human tumor tissues and the corresponding normal tissues. Expression of UCK2 protein was barely detectable in 4 of the 5 human tumor tissues, but tended to be high in the pancreatic tumor tissue. It could not be detected at all in any of the normal tissues. Thus, expression of UCK2 appeared to be correlated with cellular sensitivity to TAS–106, and it may contribute to the tumor-selective cytotoxicity of TAS–106.