Evaluation of the potential for lymph node metastasis using CRP 1846C>T genetic polymorphism in invasive breast cancer.

Lymph node status is a key indicator of the best approach to treatment of invasive breast cancer. However, the accuracy with which lymph node metastasis is diagnosed is not currently satisfactory. New and more reliable methods that enable one to know who has a greater potential for lymph node metastasis would be highly desirable. We previously reported that lymph node involvement in esophageal and lung cancer may have a genetic component: C-reactive protein (CRP) 1846C>T genetic polymorphism. Here we examined the diagnostic value of CRP 1846C>T polymorphism for assessing the risk of lymph node metastasis in cases of invasive breast cancer. The study participants were 185 women with invasive breast cancer who underwent curative surgery with lymph node dissection. Using DNA from blood samples and polymerase chain reaction-restriction fragment length polymorphism, the utility of CRP genetic 1846C>T polymorphism (rs1205) for assessing the risk of lymph node metastasis was evaluated. Fifty-two (28 %) patients had lymph node metastasis. After the patients were divided into two groups based on their CRP 1846 genotypes (C/C+C/T and T/T), the clinical characteristics did not differ between the groups, but there was a significantly greater incidence of lymph node metastasis among patients in the T/T group. Moreover, the odds ratio for lymph node involvement in patients carrying the 1846 T/T genotype was more than 2.2 in multivariate logistic regression models. CRP genetic polymorphism may be a novel predictor of the risk of lymph node metastasis in invasive breast cancer.

Evaluation of the risk of lymph node metastasis using CRP 1846C>T genetic polymorphism in submucosal thoracic esophageal squamous cell carcinoma.

BACKGROUND: More than 40 % of patients with submucosal esophageal squamous cell carcinoma (ESCC) have lymph node metastasis. Furthermore, the potential presence of undetectable metastasis before treatment prompts surgeons to be aggressive with respect to lymph node dissection. Extending the indication for endoscopic resection, a minimally invasive treatment, to superficial ESCCs will require more accurate and individualized evaluation of lymph node metastasis. METHODS: The study participants were 121 esophageal cancer patients who underwent curative surgery for thoracic submucosal ESCC at three Japanese hospitals. DNA was extracted from blood samples, and the C-reactive protein (CRP) 1846C>T genetic polymorphism (rs1205) was investigated using polymerase chain reaction-restriction fragment length polymorphism. We then evaluated the value of CRP 1846C>T polymorphism for diagnosis of lymph node metastasis. RESULTS: Forty-nine (40 %) patients had lymph node metastasis. The CRP 1846 C/T genotype was C/C in 19 patients, C/T in 57 patients, and T/T in 45 patients. Fisher's exact analysis of the CRP 1846C>T polymorphism showed a significantly higher frequency of lymph node involvement with the T/T genotype. Univariate and multivariate logistic regression models revealed that patients carrying the 1846 T/T genotype had a significantly greater likelihood of developing lymph node metastasis (odds ratio >2.6). Combining the CRP 1846 C/T genotype with clinical diagnosis, mainly using CT, brought a negative predictive value of 80 % to diagnosing lymph node involvement. CONCLUSIONS: CRP genetic polymorphism may be a novel predictor of risk of lymph node metastasis in ESCC, which could enable better evaluation of the necessity for lymph node dissection.

A CRP genetic polymorphism associated with the tumoral expression of CRP in esophageal cancer.

C-reactive protein (CRP) produced locally within esophageal cancer is associated with the prognosis and the rate of recurrence. CRP genetic polymorphisms reportedly affect serum CRP concentrations; however, there are no reports of an association between genetic polymorphisms and tumoral CRP expression. This study enrolled 73 Japanese patients classified with Stage IIA-IV thoracic esophageal squamous cell cancer, and also investigated their CRP genetic polymorphisms using DNA extracted from their peripheral blood. The study then assessed the association between CRP genetic polymorphisms and tumoral CRP expression. The results revealed a significant association between the CRP 1846C>T genetic polymorphism and tumoral CRP expression. This finding suggests that tumoral CRP production controlled by CRP genetics significantly influences tumor behavior.

Interleukin-6 -634G>C genetic polymorphism is associated with prognosis following surgery for advanced thoracic esophageal squamous cell carcinoma.

OBJECTIVE: Systemic and/or local interleukin-6 (IL-6) reportedly plays an active role in the progression and prognosis of thoracic esophageal squamous cell carcinoma (TESCC). We assessed the associations between IL-6 and IL-6 receptor (IL-6R) genetic polymorphisms, tumoral IL-6 expression and survival rates following surgery. METHODS: The study participants were 63 Japanese patients treated between 2003 and 2008 for T2-T4 advanced TESCC using curative esophagectomy without neoadjuvant treatment. We investigated IL-6 -634G>C (rs1800796) and IL-6R 48892A>C (rs8192284, Asp358Ala) genetic polymorphisms using DNA from peripheral blood samples. In addition, tumoral IL-6 expression was investigated immunohistochemically in resected specimens, and serum IL-6 was measured using a human IL-6 immunoassay. RESULTS: There was a significant difference in survival between patients with the IL-6 -634G/G+G/C genotype and those with the C/C genotype, such that their 5-year overall survival rates were 42 and 72%, respectively. By contrast, the IL-6R 48892A /C genotype and tumoral IL-6 expression had no significant effect on survival among patients. Univariate and multivariate analyses revealed that IL-6 -634G>C polymorphism was an independent prognostic factor with a hazard ratio of 3. CONCLUSIONS: IL-6 -634G>C genetic polymorphism may be a predictive prognostic factor in patients receiving esophagectomy for TESCC.

Tumoral CRP expression in thoracic esophageal squamous cell cancers is associated with poor outcomes.

PURPOSE: Cancer cells reportedly produce C-reactive protein (CRP) locally within tumors. The aim of this study was to determine whether tumoral CRP is associated with clinical outcome and recurrence in thoracic esophageal squamous cell cancer. METHODS: The subjects included 73 Japanese patients with thoracic esophageal squamous cell cancer (pathological Stage IIA-IV) that had not been treated preoperatively with either chemotherapy or radiotherapy. Tumoral CRP expression in resected specimens of tumor tissue was assessed by immunohistochemistry. The survival rate following surgery, the rates and patterns of recurrence, and the serum CRP levels before treatment and at recurrence were analyzed in patients with and without tumoral CRP expression. RESULTS: Fifty-nine percent of the study participants (43/73) were positive for tumoral CRP expression, and the remaining 41% (30/73) were negative. No significant difference in clinicopathological factors was observed between the tumoral CRP-positive and CRP-negative groups; however, patients expressing tumoral CRP showed significantly poorer survival and recurrence rates. A multivariate analysis showed that tumoral CRP expression was an independent factor contributing to the likelihood of a poor outcome. CONCLUSION: Tumoral CRP is associated with a poor outcome in thoracic esophageal squamous cell cancer. Tumoral CRP could therefore be an important target for the treatment of this disease.

Interleukin-2 -330T>G genetic polymorphism associates with prognosis following surgery for thoracic esophageal squamous cell cancer.

BACKGROUND: Key molecules in the T helper (Th)1 and Th2 pathways underlie differential responses to the progression and surgical treatment of cancer. We investigated the relationship between Th1/Th2 cytokine polymorphism and prognosis in patients with thoracic esophageal squamous cell cancer. MATERIALS AND METHODS: The study participants were 159 Japanese patients treated for thoracic esophageal squamous cell cancer with curative esophagectomy at Akita University Hospital. We determined the associations between prognosis following esophagectomy and genetic polymorphisms in Th1 cytokines (interleukin [IL]-2, Interferon-γ, IL-12ß), and Th2 cytokines (IL-4, IL-10). RESULTS: IL-2 -330T>G genetic polymorphism was significantly associated with prognosis after esophagectomy. Univariate and multivariate analyses using a Cox proportional hazards model revealed that patients carrying the IL-2 -330G/G genotype had a significantly poorer prognosis than those carrying the T/G or T/T genotype. However, IL-2 -330T>G polymorphism was not associated with preoperative serum IL-2 levels. Moreover, interferon-γ, IL-12ß, IL-4, and IL-10 genetic polymorphisms were not associated with prognosis after esophagectomy for thoracic esophageal squamous cell cancer. CONCLUSIONS: It is suggested that IL-2 -330T>G genetic polymorphism may be a predictive factor for prognosis in patients receiving esophagectomy for thoracic esophageal squamous cell cancer.

The CRP 1846T/T genotype is associated with a poor prognosis in patients with non-small cell lung cancer.

C-reactive protein (CRP) is one of the acute-phase proteins produced predominantly by hepatocytes in response to inflammation, and it has been widely reported that CRP genetic polymorphism is a risk factor for cardiovascular disease and ischemic stroke. In addition, we previously showed that the CRP 1846T/T genotype is related to lymph node metastasis in patients with esophageal cancer. In the present study, we investigated the correlation between CRP 1846C>T polymorphism and the clinicopathological characteristics of non-small cell lung cancer (NSCLC). The study participants were 146 Japanese patients who underwent curative surgery for NSCLC. DNA was extracted from tumor samples, and CRP1846C>T polymorphism was investigated using the polymerase chain reaction-restriction fragment length polymorphism method. We then correlated genotype with known clinicopathological factors. Five-year overall survival among patients with the CRP 1846T/T genotype was significantly lower than among those with the 1846C/C or C/T genotype (p = 0.002, p = 0.001; log-rank test). Multivariate Cox proportional hazard analysis revealed age, sex, pathological stage III, and 1846T/T (hazard ratio, 1.76; 95% confidence interval, 1.003-3.16; p = 0.049) to be independent factors affecting 5-year overall survival. These findings suggest the CRP 1846T/T genotype is an independent predictor of a poor prognosis in patients with NSCLC.

Transforming growth factor-ß1 29T>C genetic polymorphism is associated with lymph node metastasis in patients with adenocarcinoma of the lung.

Transforming growth factor-ß1 (TGF-ß1) is known to suppress antitumor immune responses, and its overexpression is closely associated with a poor prognosis in patients with malignant tumors. Moreover, TGF-ß1 29T>C genetic polymorphism is known to affect survival among breast cancer patients. The relationship between TGF-ß1 polymorphism and the clinicopathological characteristics of non-small cell lung cancer remains unknown, however. The study participants were 91 Japanese patients who underwent curative surgery for adenocarcinoma of the lung. DNA was extracted from tumor samples, and TGF-ß1 29T>C genetic polymorphism was investigated using the polymerase chain reaction-restriction fragment length polymorphism method, after which genotype was correlated with clinicopathological factors. There were no differences between the TGF-ß1 29TT and 29TC+CC genotypes with respect to age, sex, histological differentiation grade, tumor size, or pathological stage. However, the frequency of nodal metastasis was significantly greater in the TGF-ß1 29TC+CC group than the TGF-ß1 29TT group. Multivariate logistic regression analysis of lymph node metastasis revealed that male, tumor size, differentiation grade, and TGF-ß1 29TC+CC genotypes (hazard ratio, 5.26; 95% CI, 1.03-40.0; P = 0.045) are factors associated with a significantly greater likelihood of developing lymph node metastasis. TGF-ß1 29T>C genetic polymorphism is an independent factor associated with lymph node metastasis in adenocarcinoma of the lung.

C-reactive protein -717C>T genetic polymorphism associates with esophagectomy-induced stress hyperglycemia.

BACKGROUND: Stress hyperglycemia refers to the transient hyperglycemia seen during illness and is usually restricted to patients without previous evidence of diabetes. The influence of genetics on surgery-induced hyperglycemia remains only partially understood. METHODS: The study participants were Japanese patients treated for thoracic esophageal cancer with curative esophagectomy at Akita University Hospital between 2003 and 2007. We determined the associations between esophagectomy-induced stress hyperglycemia (> or =30 mg/dl increases in blood glucose during surgery) and genetic polymorphisms for C-reactive protein (CRP), tumor necrosis factor (TNF)-alpha, -beta, interferon-gamma, transforming growth factor-beta1, interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-6 receptors, IL-10, IL-12beta, adiponectin, and peroxisome proliferator-activated receptor-gamma. RESULTS: In 28 (46%) patients, blood glucose levels increased more than 30 mg/dl during surgery. Among the genetic polymorphisms tested, CRP -717C>T was significantly associated with stress hyperglycemia during esophagectomy. Multivariate logistic regression revealed that patients with the CRP -717T/T genotype had a significantly greater risk of developing surgery-induced hyperglycemia than those with the CRP -717C/T genotype. Stress hyperglycemia was also significantly associated with postoperative infectious complications and duration of intensive care unit stay. CONCLUSIONS: It is suggested that CRP -717 C>T genetic polymorphism may be a predictive factor for stress hyperglycemia in patients receiving esophagectomy for thoracic esophageal cancer.

Correlation between R/S enantiomer ratio of lansoprazole and CYP2C19 activity after single oral and enteral administration.

The purpose of this study was to investigate whether CYP2C19 activity can be estimated from plasma concentrations of lansoprazole enantiomers 4 h (C(4h)) after single administration by oral and enteral routes. Sixty-nine subjects, 22 homozygous extensive metabolizers (homEMs), 32 heterozygous EMs (hetEMs), and 15 poor metabolizers (PMs), participated in the study. After a single oral or enteral dose of racemic lansoprazole (30 mg), plasma concentrations of lansoprazole enantiomers were measured 4 h postdose. The R/S ratio of lansoprazole at 4 h differed significantly among the three groups (P < 0.0001) regardless of the administration route. The R/S ratio of lansoprazole in CYP2C19 PMs ranged from 3.0 to 13.7, whereas in homEMs and hetEMs the ratio ranged from 8.6 to 90 and 2.1 to 122, respectively. The relationship between (S)-lansoprazole concentration and R/S ratio of lansoprazole at C(4h) is given by the following formula: log(10) [R/S ratio] = 2.2 - 0.64 x log(10) [C(4h) of (S)-lansoprazole] (r = 0.867, P < 0.0001). Thus, phenotyping CYP2C19 using the R/S enantiomer ratio of lansoprazole seems unlikely. However, to obtain a pharmacological effect similar to that in CYP2C19 PMs, we can presume that lansoprazole has a sufficient effect in the patient with an R/S enantiomer ratio at 4 h < or = 13.70 and (S)-lansoprazole concentration at 4 h > or = 50 ng/ml.

Influence of CYP2C19 and ABCB1 polymorphisms on plasma concentrations of lansoprazole enantiomers after enteral administration.

An intraoral annihilation enteric-coated preparation of lansoprazole is often administered via intestinal fistula. The purpose of this study was to determine the plasma concentrations of lansoprazole enantiomers after enteral administration in subjects with cytochrome P4502C19 (CYP2C19) and ABCB1 C3435T genotypes. Fifty-one patients who underwent a curative oesophagectomy for oesophageal cancer were enrolled in this study. After a single enteral dose of racemic lansoprazole (30 mg), plasma concentrations of lansoprazole enantiomers were measured 4 h post-dose (C(4h)). There were significant differences in the C(4h) of (R)- and (S)-lansoprazole and the R/S-enantiomer ratio for three CYP2C19 genotype groups (*1/*1, *1/*2 ± *1/*3, and *2/*2 ± *2/*3 ± *3/*3 (poor metabolizers (PMs)), but not the ABCB1 C3435T genotypes. In a stepwise forward selection multiple regression analysis, the C(4h) of (R)- and (S)-lansoprazole were associated with CYP2C19 PMs (p = 0.0005 and < 0.0001 respectively) and age (p = 0.0040 and 0.0121 respectively), while the R/S-enantiomer ratio was associated with CYP2C19*1/*1 (p = 0.0191) and CYP2C19 PMs (p = 0.0426). Direct administration to the jejunum is unaffected by residence time in the stomach and the gastric emptying rate. With enteral administration, CYP2C19 phenotyping of patients using the lansoprazole R/S enantiomer index at C(4h) could be possible.

CRP genetic polymorphism is associated with lymph node metastasis in thoracic esophageal squamous cell cancer.

BACKGROUND: Lymph node involvement is the most important prognostic factor in thoracic esophageal cancer. A more accurate molecular technique for diagnosing lymph node metastasis and a better understanding of the molecular mechanisms governing lymph node metastasis would be highly desirable. The purpose of this study is to examine the association between inflammation-related genetic polymorphisms and lymph node metastasis. METHODS: The study participants were 113 Japanese patients undergoing curative surgery for thoracic esophageal squamous cell cancer. DNA was extracted from blood samples and genetic polymorphisms in C-reactive protein (CRP), tumor necrosis factor (TNF)-alpha and -beta, interferon (IFN)-gamma, transforming growth factor (TGF)- beta, interleukin (IL)-1beta, IL-1 receptor antagonist, IL-2, IL-4, IL-6, IL-6 receptor, IL-10, and IL-12beta were investigated using the polymerase chain reaction-restriction fragment length polymorphism method. We then assessed the association between inflammation-related genes and lymph node metastasis. RESULTS: For CRP 1846C>T polymorphism, the frequency of the 1846T/T genotype was significantly higher in patients with lymph node metastasis (P = 0.0043), and the odds ratio (3.040) derived from logistic regression models indicated that the 1846T/T genotype significantly increases the likelihood of lymph node metastasis. In submucosal cancer, the utility of CRP 1846C>T polymorphism for predicting lymph node involvement was superior to usual methods (computed tomography and ultrasonography), with positive and negative predictive values of 69% and 75%, respectively. CONCLUSIONS: These findings suggest that CRP polymorphism is a potentially effective predictor of lymph node metastasis and may thus be useful for deciding on treatment strategy.

[Evaluation of infection control activities in health care facilities in Akita Prefecture].

OBJECTIVE: Infection control is essential for health care facilities. Aiming at improving the activity for infection control, increasing number of health care facilities has settled infection control team (ICT) in this decade. However, the quality of infection control activity has not been evaluated. METHOD: The quality of infection control was investigated in 49 hospitals and 55 welfare institutions for the aged in Akita prefecture using a questionnaire. RESULT: All the hospitals with more than 400 beds or more had ICT; however, less than 50% of the hospitals with 399 beds or less had ICT. The coverage of full-time specialist for infection control remained at a low level. Collection and analysis of information such as the prevalence of multi-drug resistant microorganisms and the consumption of antibiotics remained at a low level. More than 88% of the facilities hoped for a regional infection control network system to improve infection control activities. Reciprocal help in case of outbreak, education, lectures, sharing rules on infection control, making guidelines and teaching materials for infection control, analysis of infection control-related epidemiological data and getting suggestions and recommendations from authorized infection control specialists were included in the strongly required functions of the network.

Three novel single nucleotide polymorphisms (SNPs) of the CYP2B6 gene in Japanese individuals.

We sequenced all exons and exon-intron junctions of the CYP2B6 gene from 200 Japanese individuals. We found three novel single nucleotide polymorphisms (SNPs) (1375A>G, 1427G>A and 1454A>T) causing amino acid substitutions (Met(459)Val, Gly(476)Asp and Gln(485)Leu in exon 9), respectively. The detected SNP was as follows: 1) SNP, 031226Hiratsuka01; GENE NAME, CYP2B6; ACCESSION NUMBER, AC023172; LENGTH, 25 base; 5'-CAGAACTTCTCCA/GTGGCCAGCCCCG-3'. 2) SNP, 031226Hiratsuka02; GENE NAME, CYP2B6; ACCESSION NUMBER, AC023172; LENGTH, 25 base; 5'-CCCAGGAGTGTGG/ATGTGGGCAAAAT-3'. 3) SNP, 031226Hiratsuka03; GENE NAME, CYP2B6; ACCESSION NUMBER, AC023172; LENGTH, 25 base; 5'-CCCCAACATACCA/TGATCCGCTTCCT-3'.

Phase II study of personalized peptide vaccination for previously treated advanced colorectal cancer.

The prognosis of advanced colorectal cancer (aCRC) remains poor, and development of new therapeutic approaches, including immunotherapy, is needed urgently. Herein we report on our phase II study of personalized peptide vaccination (PPV) in 60 previously treated patients with aCRC, who had failed at least one regimen of standard chemotherapy and/or targeted therapy. For PPV, a maximum of four HLA-matched peptides were individually selected from a pool of 31 different peptide candidates based on preexisting host immunity, and administered subcutaneously without severe adverse events. Boosting of IgG and cytotoxic T lymphocyte (CTL) responses specific to the administered peptides was observed in 49% and 63%, respectively, of the patients, who completed the first cycles of six vaccinations. Median overall survival (OS) time was 498 days, with 1- and 2-year survival rates of 53% and 22%, respectively. Multivariate Cox regression analysis of prevaccination factors showed that plasma IL6, IP-10, and BAFF levels were significantly prognostic for OS [hazard ratio (HR), 1.508, P = 0.043; HR, 1.579, P = 0.024; HR, 0.509, P = 0.002, respectively]. In addition, increased peptide-specific CTL responses after vaccination were significantly predictive of favorable OS (HR, 0.231; P = 0.021), suggesting a causal relationship between biologic and clinical efficacy of PPV. On the basis of the safety profile and potential clinical efficacy, we believe that clinical trials of PPV would be warranted for previously treated patients with aCRC.

Interferon-gamma 874A>T genetic polymorphism is associated with infectious complications following surgery in patients with thoracic esophageal cancer.

BACKGROUND: Cytokines play a major role in the organization of orchestrated responses to infections, and there is an emerging consensus that cytokine gene polymorphisms mediate individual variations in cytokine expression. Our aim in this study was to assess whether cytokine polymorphisms were associated with infectious complications following esophagectomy in a Japanese population. METHODS: The study participants were Japanese patients treated with transthoracic esophagectomy without neoadjuvant treatment. DNA was extracted from blood samples, and genetic polymorphisms for interferon (INF)-gamma, tumor necrosis factor-alpha and -beta, transforming growth factor-beta1, interleukin (IL)-1beta, IL-1 receptor antagonist, IL-2, IL-6, IL-6 receptor, IL-10, and IL-12beta were investigated using the polymerase chain reaction-restriction fragment length polymorphism method. We then assessed the association between gene polymorphisms and postoperative infection. RESULTS: Of the 110 patients studied, 18 (16%) developed a postoperative infection (pneumonia, 14 patients; pyothorax, 5; intraabdominal abscess, 1; neck abscess, 1; sepsis, 2). Although the characteristics of patients who developed postoperative infections did not differ, analysis of the genotypes using the Fisher exact test revealed a significantly (P = .0215) greater incidence of postoperative infections among those carrying the INF-gamma 874 (rs2430561) A/A and A/T genotypes. Moreover, univariate and multivariate logistic regression models showed patients carrying the INF-gamma 874A/T genotype were significantly more likely to develop postoperative infectious complications (odds ratio>3.4). CONCLUSION: Our findings suggest that the IFN-gamma 874A>T polymorphism is potentially predictive of the likelihood that patients undergoing esophagectomy for thoracic esophageal cancer will develop postoperative infections. This polymorphism may therefore have important clinical relevance and should be considered when treatment regimens are designed.

C-reactive protein 1059G>C genetic polymorphism influences serum C-reactive protein levels after esophagectomy in patients with thoracic esophageal cancer.

BACKGROUND: Little is known about how C-reactive protein (CRP) genetic polymorphisms influence the rise in serum CRP levels seen after surgery. The purpose of this study was to assess the association between CRP polymorphisms and acute-phase serum CRP levels after esophagectomy for thoracic esophageal cancer. STUDY DESIGN: We enrolled 110 patients who underwent curative esophagectomy without neoadjuvant treatment between 2003 and 2008. Using peripheral blood samples collected from the patients, polymorphisms for CRP, tumor necrosis factor, interferon-gamma, tumor growth factor-beta1, interleukin (IL)-1beta, IL-1 receptor antagonist, IL-2, IL-4, IL-6, IL-6 receptor, IL-10, and IL-12beta were all investigated to determine which, if any, affect postoperative serum CRP levels and clinical outcomes. RESULTS: Although preoperative serum CRP levels did not differ, 12 hours after esophagectomy, serum CRP levels were significantly higher in patients carrying the CRP 1059G/G genotype than in those with the 1059G/C genotype (111 +/- 35 mg/L versus 78 +/- 17 mg/L; p = 0.0266), and after 36 hours CRP levels remained higher in those with the 1059G/G genotype (217 +/- 63 mg/L versus 140 +/- 51 mg/L; p = 0.0020). Logistic regression models revealed that patients carrying the CRP 1059G/G genotype had a significantly higher likelihood of a postesophagectomy increase in serum CRP, although the CRP 1059G>C genetic polymorphism had no effect on clinical outcomes. None of the other cytokine genetic polymorphisms influenced postoperative serum CRP levels. CONCLUSIONS: Our findings suggest that the CRP 1059G>C genetic polymorphism is 1 determinant of serum CRP levels after major surgery.

Characterization of human cytochrome p450 enzymes involved in the metabolism of cilostazol.

Cilostazol (OPC-13013; 6-[4-(1-cyclohexl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2(1H)-quinolinone) is widely used as an antiplatelet vasodilator agent. In vitro, the hydroxylation of the quinone moiety of cilostazol to OPC-13326 [6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-4-hydroxy-2(1H)-quinolinone], is the predominant route, and the hydroxylation of the hexane moiety to OPC-13217 is the second most predominant route. This study was carried out to identify and kinetically characterize the human cytochrome P450 (P450) isozymes responsible for the formation of the two major metabolites of cilostazol, namely, OPC-13326 and OPC-13217 [3,4-dihydro-6-[4-[1-(cis-4-hydroxycyclohexyl)-1H-tetrazol-5-yl)butoxy]-2(1H)-quinolinone)]. In in vitro studies using 14 recombinant human P450 isozymes, CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP2J2, CYP3A4, CYP3A5, and CYP4A11, cilostazol was metabolized to OPC-13326 mainly by CYP3A4 (K(m) = 5.26 muM, intrinsic clearance (CL(int)) = 0.34 microl/pmol P450/min), CYP1B1 (K(m) = 11.2 microM, CL(int) = 0.03 microl/pmol P450/min), and CYP3A5 (K(m) = 2.89 microM, CL(int) = 0.05 microl/pmol P450/min) and to OPC-13217 mainly by CYP3A5 (K(m) = 1.60 microM, CL(int) = 0.57 microl/pmol P450/min), CYP2C19 (K(m) = 5.95 microM, CL(int) = 0.16 microl/pmol P450/min), CYP3A4 (K(m) = 5.35 microM, CL(int) = 0.10 microl/pmol P450/min), and CYP2C8 (K(m) = 33.8 microM, CL(int) = 0.009 microl/pmol P450/min). The present study showed that the two major metabolites of cilostazol in vitro, namely, OPC-13326 and OPC-13217, are mainly catalyzed by CYP3A4 and CYP3A5, respectively.