The present invention relates to kits and methods for diagnosing bladder cancer by detecting the altered DNA methylation pattern of the specific sequences in the promoter CpG island of genes in urine sediments from individuals with bladder cancer (including pre-neoplastic stages) as compared to that from the normal individuals (or individuals without bladder cancer).
Having the genetic blueprint for human and increasing number of model organisms available has ushered in a new era for the genetic makeup and functional elucidation in development and disease states, which chiefly concerns analysis and annotation of the epigenetic information that inheritable through cell division without changes in DNA sequence. The epigenetics consists of DNA methylation (cytosine [CpG] methylation), non-coding RNA, histone modification, and chromatin remodeling. This interface sits between the genetic blueprints stored in genomic DNA sequences and phenotypes dictated by the pattern of gene expression. It more readily responds to the changing environment than its sequence based genetic counterparts [1]. Addition of the methyl group at cytosine ring within 5′-CpG-3′ sequence (
Cancers are extremely complex diseases with extensive genetic and epigenetic defects. The defects vary with both types of cancer and individual patients[3]. DNA methylation based on the enzymatic process to add the methyl group at the fifth carbon of cytosines within the palindromic dinucleotide 5′-CpG-3′ sequence (DNA methylation)(
Over 85% CpG dinucleotides are spread out in the repetitive sequences with the transcription-dependent transposition potential. They are heavily hypermethylated/transcription-silenced, a state required for the genome integrity. The extensive hypomethylated state of genome in cancer cells leads to the transcription of the repetitive sequences and enhancement of transposition activity [2,4], which, subsequently, increases genomic instability and transcription of proto-oncogenes [5,6]. The remaining CpG are clustered within the short DNA regions (approximately, 0.2 to 1 kb in length), known as “CpG island”. Approximately 40-50% of the genes have CpG island within or around the promoter, indicating that transcription of these genes can be regulated by DNA methylation-mediated mechanism. Although mostly unmethylated in normal cells, some of them are often hypermethylated and the transcriptional silencing, including the tumor suppressor genes, DNA repairing genes, cell cycle control genes, anti-apoptotic genes, and the like.
The critical role of the epigenetic abnormality at the early stage of carcinogenesis can be presented as loss of genetic imprinting (LOI). For example, overexpression of the genetic imprinting gene IGF2 can promote cell proliferation, and LOI of which was found in normal-appearing colonic epithelium of patients with colorectal cancer, and LOI of this gene in circulating leucocytes is a crucial feature of subjects susceptible to colon cancer[7]. The hypermethylation/transcription silencing of the tumor suppressor and DNA repairing genes was common at the pre-neoplastic stage[8,9]. For instance, the hypermethylated p16ink4A (tumor suppressor gene) and MGMT (DNA repairing gene) were found in the sputum DNA[8]. Abnormal epigenetic state can also result in abnormal proliferation of stem cells, promoting carcinogenesis. The association of H. pyrio infection with the aberrant DNA methylation of a given set of genes suggests detection of DNA methylation provide a pre-warning [10]. Therefore, the tumor warning value of analysis of the DNA methylation of the peripheral DNA (serum, stool, sputum, and urine sediments as the sample sources) from the population at high risk for cancer has been also seriously considered.
In terms of incidence, Bladder cancer is the fourth most common cancer in men and the eighth most common cancer in women in the United States[11]. Its incidence increases dramatically in industrializing China[12]. Although over 70% patients suffering from the superficial lesions could be cured surgically, still 50-70% of those patients will return with more severe conditions and poor prognosis. The bladder cancers at similar pathologic grades and stages have variable clinical behaviors[15], illustrating the substantial deficiency of the exsting system. The gold standard for bladder cancer diagnosis is cystoscopy along with biopsy, but the misdiagnosis rate can be up to 10-40% [16-18]. Urine cytology is a non-invasive detection method with high specificity, but suffered from the low sensitivity for Ta, G1, and T1 bladder cancers [19]. The attempt of use of genetic detection of cellular DNA in urine sediments in diagnosing bladder cancer has involved TP53 gene mutations, loss of heterozygosity, microsatellite instability, and E-cadherin promoter polymorphism (51) [20,21]. A method of seeking for chromosomatic abnormality by in situ cell hybridization in urine sediments is reported to detect 68.6% bladder cancer with 77.7% specificity (http://www.urovysion.com). Many attempts using protein marker were reported [22,23]. Although the assay for protein MNP22 in urine seems more sensitive than the urine cytology, it suffered from a substantial deficiency of the high level of the said protein in patients with benign urinogenital diseases such as hematuria, urocystitis, renal calculi, or urinary tract infections[24]. Therefore, there is still a need for developing a more sensitive and specific method for diagnosing bladder cancer and other types of urinogenital cancers, especially at the early stage thereof.
DNA methylation analysis methods generally rely on methylation modification of the original genomic DNA before any amplification step, comprising using the methylation-sensitive restriction enzyme digestion and bisulphite treatment [25]. The latter one exploited the sharp difference in the sensitivity to the bisulphite-mediated deamination (C to U conversion) between cytosine and methylated cytosine residues, which enable detection of as few as 1-10 tumor cells among 104 normal cells[25]. Attempts of assaying methylation patterns of genes in bodily fluids, including bronchoalveolar lavage fluid, stool, serum, or plasma and urine sediments, for in vitro detection of cancer have been intensively reported. Other methods of detecting DNA methylation pattern include methylation-specific enzyme digestion, methylation-sensitive single nucleotide primer extension (MS-SnuPE) [26], restriction landmark genomic scanning (RLGS) [27], differential methylation hybridization (DMH) [28], BeadArray platform technology (Illumina, USA)[29], and base-specific cleavage and mass spectrometry (Sequenom, USA)[30], as well as those under development or to be developed.
To achieve the above purpose, the present inventor has carried out extensive research and firstly discloses the difference of DNA methylation patterns between subjects with bladder cancer and those without bladder cancer, and detection of which may be used to determine bladder cancer in a subject. The method comprises the following steps:
(a) providing urine sediment sample from said subject;
(b) determining methylation pattern of one or more genes in the urine sediments, wherein said genes are selected from a group consisting of ABCC13, ABCC6, ABCC8, ALX4, APC, BCAR3, BCL2, BMP3B, BNIP3, BRCA1, BRCA2, CBR1, CBR3, CCNA1, CDH1, CDH13, CDKN1C, CFTR, COX2, DAPK1, DRG1, DRM, EDNRB, FADD, GALC, GSTP1, HNF3B, HPP1, HTERT, ICAM1, ITGA4, LAMA3, LITAF, MAGEAI, MDR1, MGMT, MINT1, MINT2, MT1GMT, MINT1, MINT2, MT1A, MTSS1, MYOD1, OCLN, p14ARF, p16INK4a RASSF1A, RPRM, RUNX3, SALL3, SERPINB5, SLC29A1, STAT1, TMS1, TNFRSF10A, TNFRSF10C, TNFRSF10D, TNFRSF21, and WVVOX;
(c) comparing methylation pattern of said genes in the urine sediment sample from said subject with that from normal subject, wherein the hypermethylation of one or more of genes indicates that said subject is suffering from bladder cancer.
The present invention further provides the procedures and standards for methylation pattern analysis and determining bladder cancer in a subject. The methods and standards will be used in diagnosing, prognosing, and monitoring the recurrence, and determining whether the tumors have been surgically removed. Other advantages and features of the present invention have been further disclosed in the following specific embodiments with reference to the accompanied figures.
This figure shows the electrophoretogram of MSP data of the representative methylation state and its sequencing verification. The number above each lane is the Identification Number of patient, cell lines (5637, T24, and SCaBER). M Sss1 indicates the result of normal liver tissue DNA modified by methylation by M Sss1 methyl transferase in a tube used as positive control. Gene names are listed above each panel. The wild-type sequences and the sequences of representative PCR products cloned from T vectors are aligned.
Note: Ur: urine sediment, T: tumor tissue, G XX: No. of clinical samples, BJ, bisulphate-treated DNA derived from a normal fibroblast cell line, used as control of non-methylated DNA template. H2O: control without DNA template. M. Sss I: positive control of methylated template of methylated DNA derived from normal liver tissue in a tube.
Y axis: the percentage of methylation targets in a subgroup. T/Ur: commonly methylated in both tumor tissues and urine sediments; T; only methylated in tissues, and Ur: only methylated in urine sediments. The number of events and (percentage) are shown at the top of each column.
In one aspect, the present invention provides a method for detecting bladder cancer in a subject, comprising the following steps:
(a) providing a urine sediment sample from said subject;
(b) determining the methylation pattern of one or more genes in the urine sediments, wherein said genes are selected from a group consisting of ABCC13, ABCC6, ABCC8, ALX4, APC, BCAR3, BCL2, BMP3B, BNIP3, BRCA1, BRCA2, CBR1, CBR3, CCNA1, CDH1, CDH13, CDKNIC, CFTR, COX2, DAPK1, DRG1, DRM, EDNRB, FADD, GALC, GSTP1, HNF3B, HPP1, HTERT, ICAM1, ITGA4, LAMA3, LITAF, MAGEA1, MDR1, MGMT, MINT1, MINT2, MT1GMT, MINT1, MINT2, MT1A, MTSS1, MYOD1, OCLN, p14ARF, p16INK4a, PTCHD2, RASSF1A, RPRM, RUNX3, SALL3, SERPINB5, SLC29A1, STAT1, TIMP3, TMS1, TNFRSF10A, TNFRSF10C, TNFRSF10D, TNFRSF21, and WWOX;
(c) comparing the methylation pattern of one or more genes in the sample from said subject with that in the sample from normal subject, wherein the hypermethylated state in one or more genes indicates that said subject suffered from bladder cancer.
As used herein, the term “sample” in the context of the present invention is defined to include any sample obtained from any individual which is proper to test for DNA methylation, for example, those samples taken from the subjects with urinogenital symptoms. The term “urine sediment” has the meaning well known by a person skilled in the art, which includes the epithelial cells exfoliated from urethra, and etc. The cytological analysis of urine sediment has been used in clinical diagnosis of bladder cancer, since cells from bladder tumors are often exfoliated into urine sediment.
The sample being used in the present invention may also be the established bladder cancer cell lines, such as T24 (ATCC number: HTB-4), SCaBER (HTB-3), and 5637(HTB-9).
The present method is applicable to determine the urinogenital cancer. Said urinogenital cancer may include, for example, bladder cancer, prostate cancer, and kidney cancer. (Other types of cancer whose cells can be present in urine may also be detected by the present method. As a result, the “urinogenital cancers” are also included in the scope of the present invention.
The term “subject” as used herein includes, but not limited to, mammal, such as human.
The term “methylation” and “hypermethylation”, used interchangeably herein, are defined as the presence or high methylation of CpG loci within a gene sequence, most often within the promoter of a gene. When MSP is used, the tested DNA (gene) region can be considered to be hypermethylated if a positive PCR result is obtained from a PCR reaction using methylation-specific primers. Using Real-time Quantitative Methylation-Specific PCR, the hypermethylated state can be determined according to the statistically significant difference in comparison with the relative value of the methylation state of the control sample.
The basis of the present invention lies in that the methylation profiling of CpG sequence (for example, the region within the promoter CpG island of a tumor related gene, known as gene infra) from individuals suffering from bladder cancer is different from normal individuals or those whithout bladder cancer. As a result, the methylation state of one or more of the following genes may be used as an indicator of presence of bladder cancer in the subject. These genes may be selected from a group consisting of ABCC13, ABCC6, ABCC8, ALX4, APC, BCAR3, BCL2, BMP3B, BNIP3, BRCA1, BRCA2, CBR1, CBR3, CCNA1, CDH1, CDH13, CDKNIC, CFTR, COX2, DAPK1, DRG1, DRM, EDNRB, FADD, GALC, GSTP1, HNF3B, HPP1, HTERT, ICAM1, ITGA4, PTCHD2, LAMA3, LITAF, MAGEA1, MDR1, MGMT, MINT1, MINT2, MT1A, MTSS1, MYOD1, OCLN, p14ARF, p16INK4a, PTCHD2, RASSF1A, RPRM, RUNX3, SALL3, SERPINB5, SLC29A1, STAT1, TIMP3, TMS1, TNFRSF10A, TNFRSF10C, TNFRSF10D, TNFRSF21, and WWOX.
More particularly, the hypermethylation state of any gene selected from a group consisting of SALL3, CFTR, ABCC6, HPR1, RASSF1A, MT1A, RUNX3, ITGA4, BCL2, ALX4, MYOD1, DRM, CDH13, BMP3B, CCNA1, RPRM, MINT1, and BRCA1, in the urine sediment indicates that said subject is suffering from bladder cancer.
The methylation pattern of cellular DNA in the urine sediments may be determined by any techniques that are known (e.g. methylation-specific PCR(MSP) and Real-time Quantitative Methylation-Specific PCR, Metylite) or are under developing and to be developed. After bisulfite treatment, the unmethylated cytosines are converted to uracils, while the methylated cytosines remain unconverted. Subsequently, the DNA methylation state in the subject DNA is determined by amplifying the DNA after bisulfite treatment using primers capable of distinguishing methylated DNA from unmethylated DNA (30). This PCR approach, known as MSP can be used to detect small amount of tumor cells from a clinical sample with many normal cells with the proviso that the methylation state of the indicated DNA region (gene) in normal cells is opposite to that in tumor cells. It is possible to identify 1 tumor cells from 10,000 normal cells by using MSP.
It is preferred to use quantitative methylation-specific PCR (QMSP) in detection of methylation level. This method is based on the continuous optical monitoring of a fluorogenic PCR, which is more sensitive than the MSP method (31). It is a high-throughput technique and avoids analyzing its result by electrophoresis. The methods for designing primers and probes are known to the skilled in the art.
Additional useful techniques include methylation-specific enzyme digestion, bisulfite DNA sequencing, methylation-sensitive single nucleotide primer extension (MS-SnuPE) [26], restriction landmark genomic scanning (RLGS) [27], differential methylation hybridization (DMH) [28], BeadArray platform technology (Illumina, USA) [29], and a base-specific cleavage/mass spectrometry (Sequenom, USA)[30], and etc.
For a large sample analysis (comprising being compared with normal and/or non-cancerous subject), the methylation patterns of multiple tumor related genes are obtained, that is, it is possible to detect bladder cancer or other urinogenital cancer (prostate cancer or kidney cancer) in a subject by measuring methylation state of the gene sets.
The present invention also provides a kit for bladder cancer detection, comprising:
(a) means for measuring methylation pattern of one or more genes in the urine sediments, wherein said genes are selected from a group consisting of ABCC13, ABCC6, ABCC8, ALX4, APC, BCAR3, BCL2, BMP3B, BNIP3, BRCA1, BRCA2, CBR1, CBR3, CCNA1, CDH1, CDH13, CDKNIC, CFTR, COX2, DAPK1, DRG1, DRM, EDNRB, FADD, GALC, GSTP1, HNF3B, HPP1, HTERT, ICAM1, ITGA4, LAMA3, LITAF, MAGEA1, MDR1, MGMT, MINT1, MINT2, MT1GMT, MINT1, MINT2, MT1A, MTSS1, MYOD1, OCLN, p14ARF, p16INK4a, PTCHD2, RASSF1A, RPRM, RUNX3, SALL3, SERPINB5, SLC29A1, STAT1, TIMP3, TMS1, TNFRSF10A, TNFRSFIOC, TNFRSFIOD, TNFRSF21, and WWOX;
(b) providing a criteria for determining the methylation state of one or more genes to detect urinogenital cancer (e.g. bladder cancer) in the subject (specifically and sensitively).
The term “means for measuring methylation pattern of one or more genes in the urine sediments” includes any substantial technical measures, instruments, devices, and reagents that may be useful to measuring methylation pattern of one or more genes in the urine sediments. The specific means depend on the method used.
Since one preferred method of detecting the methylation state of a panel of genes is MSP and/or QMSP. The reagents included in the MSP and/or QMSP kits of this invention are apparent to the skilled in the art: reagents and materials for DNA isolation, polymerase for PCR reaction (such as Taq polymerase), sodium bisulfite, MSP/QMSP specific buffers and the corresponding primers, etc. All the related reagents (primers, among others) are included in the scope of the present invention. Primers comprise DNA, RNA, and synthetic equivalents thereof, depending on the amplification technique employed. For example, a pair of short single-stranded primers are used in standard PCR, and the two primers are localized to both sides of the target gene to be amplified (including CpG sequence, the complementation to CpG is directed to methylated region, and the complementation to TpG is directed to unmethylated gene region). The nucleic acid amplification techniques are well-known to the skilled in the art.
The present invention provided, for example, a list of verified gene primers (Table 2). However, the scope of the invention is not limited to these examples.
The present invention may also comprises methylation information of corresponding genes in urine sediments (or tissues) obtained from normal and/or non-cancerous subject.
The invention will be further understood with reference to the following examples. It should be noted that all these examples are for purpose of illustration only rather than for limitation of the scope of the invention. Unless otherwise indicated, all the techniques therein are obvious to those having basic knowledge in molecular biochemistry and relevant fields.
Collection of Tissues and Urine Sediments, and DNA Isolation.
With the informed consent of all patients and approval of the ethics committee, 15 samples of bladder cancer tissues were collected in Guangxi Province, China. Three normal bladder tissues were obtained from healthy organ donator. The void morning urine samples were also collected from the bladder cancer patients, diagnosed by the existing methods and standards, known in the clinical arena, at Guangxi Hospital (40) and Zhongshan Hospital, Shanghai, China (92). 79 post-surgical urine samples were also obtained at Zhongshan Hospital, Shanghai, China. The control group included 23 patients with non-cancerous urinogenital diseases (cystitis glandularis: 8, prostatic hyperplasia: 4, vesical calculus: 3, renal calculus: 5, and adrenal nodule: 3), 6 with neurological disease, and 7 healthy volunteers. The urine cytological analysis, and the tumor-node-metastasis (TNM) staging and classification are indicators according to the WHO classification and American Joint Committee on Cancer guidelines.
Bisulfite Treatment and Methylation-Specific PCR Analysis
Primer pairs for PCR detection of 59 methylated and unmethylated alleles were 1, directly from the published information, or 2. designed with software for identification of the CpG islands (http://www.ebi.ac.uk/emboss/cpgplot/index.html) and the primer design software (http://micro-gen.ouhsc.edu/cgi-bin/primer3_www.cgi) (Table 2).
Desalting the DNA samples treated by bisulfite was carried out by a home-made agarose based gel filtration system[31, 32]. The PCR products were cloned and verified by sequencing (
Statistics
The significance analysis of the relation between methylation state of genes and each clinical pathological parameter was carried out by z relevant software (http://www.Rproject.org). The significance of methylation state of each gene as a bladder cancer specific marker is presented as 95% confidence interval (R package Hmisc http://cran.r-project.org/src/contrib/Descriptions/Hmisc.html). The significance of the methylation frequency of each gene in urine sediments from patients with bladder cancer (132 cases) in comparison with that from patients with non-cancerous urinogenital diseases (23 cases) is determined by 2×2 fisher exact test. The receiver operating characteristics (ROC) of both specificity and sensitivity of the gene sets useful in bladder cancer detection were calculated and plotted.
The 59 test genes (table 2) include: 1, those having been investigated in bladder cancer or other types of urinogenital tumors previously, such as CDKN2A, ARF, MGMT, GSTP1, BCL2, DAPK, and HTERT, 2, those being hypermethylated in other types of tumors according to our work [31-43], and 3, those being suggested functionally relate to carcinogenesis by bioinformatics analysis.
Given that the established bladder cancer cell lines are likely to contain deficiencies of clinical bladder cancer at the genetic and epigenetic level, we initially carried out MSP profiling of 59 genes on 3 bladder cancer cell lines: T24 (ATCC number: HTB-4), SCaBER (HTB-3), and 5637 (9). 41 genes were found hypermethylated, at least, in one allele of one cell line (Table 3). Although FADD, LITAF, MGMT and TNFRSF21 are homozygously unmethylated, their hypermethylation states are reported to relate to bladder cancer [44,45]. The following 14 genes have been eliminated in the initial screening: APC, BCAR3, BNIP3, CBR1, CBR3, COX2, DRG1, HNF3B, MDR1, MTSS1, SLC29A1, TIMP3, TNFRFIOA, and VVWOX. In the urine sediments of 11 patients, 21 genes were hypermethylated in 1 to 10 patients (9% to 90%), but not in 3 patients with cystitis glandularis. It is implicated that the hypermethylation states of these genes relate to various degrees of bladder cancer-specificity. The characteristic promoter unmethylation of the MAGEA1 gene and concomitant activation of transcription are frequently found in cancer. However, in the present study of bladder cancer, this phenomenon occurs scarcely (Table 3), the releant study is terminated thereby. This was also the reason to exclude LAMA3, ICAM1, and GALC. We further analyzed 15 cancer tissues and 3 normal bladder tissues for the DNA methylation state of 32 genes. Although 28 genes were unmethylated in the 3 normal bladder tissues, 19 genes among which were hypermethylated in 1-12/15(6.7% to 73.3%) bladder cancer tissues, indicating various degrees of bladder cancer specificity. The other genes: PTCHD2, BRCA1, CDH13, TMS1, CDH1, p14ARF, p16INK4a, FADD, LITAF, MGMT, and TNFRSF2, are also unmethylated. To determine the association of DNA methylation patterns between tumor tissues and cells from urine sediments, we have carried out MSP-profiling of 9 pairs of samples (
Methylation States of 21 Genes in DNA of Urine Sediments from Bladder Cancer Patients and Non-Bladder Cancer Control Group
The test samples are from bladder cancer cohort (132) and 3 control groups, namely, 1), neurological disease (6), 2), healthy volunteers (7), and 3), non-cancerous urinogenital disease (23), including cystitis glandularis: 8, prostatic hyperplasia: 4, vesical calculus: 3, renal calculus: 5 and adrenal nodule: 3. The average age of the bladder cancer cohort was 63.4 (34-88), which matched well to that for the non-cancerous urinogenital disease cohort, i.e. 55.7 (16-83) and the neurological diseases cohort, i.e. 64.1 (46-78).
The 21 genes were unmethylated in the urine sediments from healthy volunteers and patients with the neurological disease. However, 6 hypermethylation events were recorded in four genes: RASSF1a (2/23), MT1A (2/23), RUNX3 (1/23) and ITGA4 (1/23) (
We failed to find the substantial association of the DNA methylation of genes with cancer staging (Table 5) by the statistic test. Comparing with the DNA methylation state in the urine sediments from 79 post-surgical patients, we found that the methylation incidence of MYOD1 and MINT1 turned from 22.2% and 12.9% before surgery to 0% after surgery, respectively, the incidence of methylation of other genes are also substantially reduced (P<0.005)(Table 6). The methylated genes remained in urine sediment were likely caused by the incomplete removal of tumor by the surgical procedure. Therefore, analysis of the DNA methylation pattern in urine sediments from pre- or post-surgical patients can be effective to assess the surgical quality. Additionally, no significance difference was found in the DNA methylation patterns between the primary and recurrent cases of bladder cancer (p>0.05) (Table 7). The methylation of a single gene (SALL3) can be used to detect at most 58.3% of the bladder cancer cases, and detection of multiple genes may improve the detection rate and specificity for bladder cancer. Hypermethylation of 10 genes results in extremely high tumor-specificity (p<0.01), and hypermethylation of 5 additional genes also results in substantial tumor-specificity (p<0.05 (
None of the following four genes: SALL4, CFTR, ABCC6, and HPP1 were false positive in three control groups, the specificity for them, alone or in combination, to detect bladder cancer should be 100% (
The first column indicates the gene sets. The genes in bracket were considered redundant as inclusion thereof did not improve the sensitivity of the set. The second column indicates the number of the true positive (TP=the bladder cancer sample having at least one gene methylated) and false negative (FN=the bladder cancer sample having no gene methylated) events. The third column indicates the number of the false positive (FP=the non-cancerous urinogenital disease sample having at least one gene methylated) and true negative (TN=the non-cancerous urinogenital disease sample having no gene methylated) events. Both Sensitivity=TP/(TP+FN) (%, Column 4) and specificity=TN/(TN+FP) (%, Column 5) of each gene sets were calculated and plotted in
The hypermethylated RASSFIA gene was found in 2 of 23 cases in the non-cancerous urinogenital disease group (2 false positive events and 21 true negative events, Column 3,
Although the aforementioned description relates to particular examples, the spirit and scope of the present invention, and modifications of these information and practical forms according to the established principles are apparent to those skilled in the art. Therefore, such possible modifications should be within the scope of the following claims.
Number | Date | Country | Kind |
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200710044106.1 | Jul 2007 | CN | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CN2008/071725 | 7/23/2008 | WO | 00 | 8/3/2010 |