Patent Application
20080108061
The present invention relates to a method of detecting canceration and malignancy of cancer using a specific cancer-associated gene as an index, and also relates to a method of suppressing/treating cancer using a specific cancer-associated gene as essential part.
A mortality rate of cancer is presently the top end in Japan and occupies one third of the total mortality causes. The mortality rate of cancer goes on increasing and is predicted to occupy about 50% in 10 years. It has been elucidated that cancer is caused and aggravated due to accumulation of abnormalities of many genes. It has been reported that acceleration of oncogene expression and deceleration of cancer suppressor gene expression due to deletion are involved in canceration. Furthermore, it is also known that abnormalities of a gene directly involved in cell differentiation and proliferation and a gene involved in a DNA repair system are involved in canceration.
However, studies that have been hitherto conducted are not sufficient to explain the canceration mechanism in cancer patients. A group of genes involved in canceration varies depending upon the type of cancer. Furthermore, since the individual characters of cancers differ even if they belong to the same type, it has been difficult to systematically analyze the abnormality of which gene group causes cancer. Therefore, it cannot be said that a sufficient diagnostic method for the initial state of cancer and a sufficient diagnostic means for checking degree of malignancy of cancer based on genomic analysis of cancer cells have been provided.
An object of the invention is to find a cancer-associated gene to be used as an index for detecting canceration of cells and degree of malignancy of cancer and to provide a method for detecting cancer using the cancer-associated gene as an index. Another object of the present invention is to provide a method of suppressing/treating cancer using the cancer-associated gene as essential part.
Generally, when a chromosomal abnormality takes place, the cell causes apoptosis to death. Therefore, proliferation of an abnormal cell does not occur in mechanism. However, in some cases, a cell having a chromosomal abnormality may happen to initiate proliferation for an unknown reason through a loophole of the biological control mechanism that should be strictly controlled, thus initiating canceration. Therefore, amplification and deletion of a genome at a chromosomal level are critical causes of canceration. In the case of amplification, expression of a gene present in the amplified genomic region is accelerated, whereas, in the case of deletion, the expression level of a gene present in the deleted genomic region is significantly decelerated. When such abnormalities are accumulated, a cell may probably cause unregulated proliferation.
Comparative genomic hybridization (CGH) is a simple and quick method, that is, the best method, for analyzing gene abnormalities associated with genomic amplification and deletion of a plurality of genes. To analyze abnormality of a gene on the genome involved in canceration and malignant alteration of cancer, it is extremely important to select a group of genes to be printed on a CGH microarray.
The present inventors screened a group of highly potential genes that may be involved in canceration from the databases “National Cancer for Biotechnology” and “University of California Santa Cruz Biotechnology.” They further subjected the DNA thus screened to BLAST search to select genes that conceivably play an important role in the onset of cancer. BAC/PAC clones containing these candidate cancer-associated genes are carefully selected and individually amplified (inexhaustibly amplified). Then, about 800 types of clones thus amplified were loaded on a substrate to form a “MCG cancer array” substrate (hereinafter also referred to “MCG cancer array”). The present invention encompasses the MCG cancer array within its technical range.
The present inventors found cancer-associated genes to be used as cancer detection indexes in several types of cancer by use of the MCG cancer array. Based on the finding, they accomplished one of the present inventions.
More specifically, the present invention provides a method of detecting (hereinafter referred to also as “the detection method of the invention”) cancer using a specific cancer-associated gene as an index. Also in the present invention, there is provided a means for suppressing/treating cancer using the cancer-associated gene. More specifically, the present invention provides a means for suppressing/treating cancer by introducing a specific deletion cancer-associated gene into a cancer cell and a means for suppressing/treating cancer by inhibiting the function of the transcriptional product (mRNA) of a specific amplification cancer-associated gene. These means for suppressing/treating cancer will be explained later.
The present invention provides a method for detecting malignant glioma, wherein canceration of a specimen is detected based on an index of not less than 1.5 fold amplification of at least one gene selected from the group consisting of
EIF4G gene, ETV5 gene, CDC10 gene, IGFBP1 gene, TCRG gene, MYCLK1 gene, TAX1BP1 gene, IL6 gene, PMS2 gene, MUC3 gene, MET gene, SMOH gene, BRAF gene, CDK5 gene, AR gene, CUL4B gene, MCF2 gene, MAGEA2 gene, CTAG gene, ALX gene, MUC1 gene, ARHGEF2 gene, PMF1 gene, NTRK1 gene, ERV5 gene, MUC4 gene, IGFBP7 gene, PC4 gene, SKP2 gene, DAB2 gene, CDH10 gene, CDH12 gene, TERT gene, E2F3 gene, TPMT gene, TFAP2A gene, EEF1E1 gene, RREB1 gene, CDK6 gene, PRIM1 gene, GLI gene, FUS gene, CYLD gene, and GRB2 gene; in comparison with a normal cell.
The present invention further provides a method for detecting malignant glioma as mentioned above, wherein canceration of a specimen is detected based on an index of not less than 4 fold amplification of at least one gene selected from the group consisting of ALX gene, MUC1 gene, ARHGEF2 gene, PMF1 gene, NTRK1 gene, ERV5 gene, MUC4 gene, IGFBP7 gene, PC4 gene, SKP2 gene, DAB2 gene, CDH10 gene, CDH12 gene, TERT gene, E2F3 gene, TPMT gene, TFAP2A gene, EEF1E1 gene, RREB1 gene, EGFR gene, PMS2 gene, CDK6 gene, PRIM1 gene, GLI gene, FUS gene, CYLD gene, and, GRB2 gene; in comparison with a normal cell.
The present invention further provides a method for detecting neuroblastoma, wherein canceration of a specimen is detected based on an index of not less than 1.5 fold amplification of at least one gene selected from the group consisting of MYCL1, CDH10 and MYC genes in comparison with a normal cell.
The present invention further provides a method for detecting neuroblastoma, wherein canceration of a specimen is detected based on an index of amplification of at least one gene selected from the group consisting of MYCN, CDK4 and PPM1D genes.
The present invention further provides a method for detecting rhabdomyosarcoma, wherein canceration of a specimen is detected based on an index of not less than 1.5 fold amplification of at least one gene selected from the group consisting of
The present invention further provides a method for detecting rhabdomyosarcoma, wherein canceration of a specimen is detected based on an index of not less than 4 fold amplification of a CDK4 gene in comparison with a normal cell.
The present invention further provides a method for detecting malignant glioma, wherein canceration of a specimen is detected based on an index of a heterozygous deletion of at least one gene selected from the group consisting of
The present invention further provides a method for detecting malignant glioma, wherein canceration of a specimen is detected based on an index of a homozygous deletion of MTAP gene and/or CDKN2A(p16) gene.
Preferably in the above, the detection is performed by a CGH method, DNA chip method, quantitative PCR method or real time RT-PCR method.
Preferably in the above, detection is performed by a CGH method or DNA chip method and a plurality of types of DNA fragments to be fixed onto the detection substrate are genomic DNA, cDNA or synthetic oligonucleotides.
Preferably in the above, the detection is performed by a CGH method, and a plurality of types of DNA fragments to be fixed onto the detection substrate are genomic DNA, and the genomic DNA is a gene amplification product of BAC DNA, YAC DNA or PAC DNA.
The present invention further provides a method for suppressing a malignant glioma cell, which comprises introducing a gene, whose deletion is involved in canceration of a malignant glioma cell, into a malignant glioma cell.
The present invention further provides a method for suppressing a malignant glioma, which comprises introducing MTAP gene and/or CDKN2A(p16) gene into a malignant glioma.
The present invention further provides a method of suppressing a malignant glioma cell, which comprises applying, to a malignant glioma cell, a nucleic acid antagonizing a transcriptional product of a gene whose amplification is involved in canceration of the malignant glioma cell.
The present invention further provides a method of suppressing a malignant glioma, which comprises applying, to a malignant glioma, a nucleic acid antagonizing a transcriptional product of at least one gene selected from the group consisting of ALX gene, ARHGEF2 gene, PC4 gene, SKP2 gene, DAB2 gene, PMF1 gene, NTRK1 gene, ERV5 gene, CDH10 gene, CDH12 gene, TERT gene, MUC4 gene, PDGFRA gene, IGFBP7 gene, E2F3 gene, TPMT gene, TFAP2A gene, EEF1E1 gene, RREB1 gene, EGFR gene, GLI gene, CDK4 gene, FUS gene, PMS2 gene, CDK6 gene, PRIM1 gene, CYLD gene, and GRB2 gene.
Preferably in the above, the nucleic acid antagonizing a transcriptional product of a gene is small interference RNA against a transcriptional product mRNA, or an antisense oligonucleotide of the mRNA.
The detection according to the invention may be carried out by CGH method, DNA chip method, quantitative PCR method, or real time RT-PCR method. To detect amplification or deletion of a gene, the DNA chip method or CGH method is preferably used and the CGH method is particularly preferable. When the expression of a cancer suppressor gene (corresponding to the “deletion gene” mentioned above) is suppressed by another cause except for gene deletion, such as acceleration of methylation of a CpG island of the gene and deceleration of acetylation of a protein associated with the gene, it is preferable to employ a detection means for detecting an transcriptional product of the gene, such as the real time RT-PCR method and the DNA chip method, capable of quantifying the transcribed product of the gene.
The specimen to be subjected to the detection method of the present invention is derived from a subject and corresponds to the type of cancer to be detected. To explain more specifically, a biopsy specimen such as brain is used when a subject is checked for malignant glioma, neuroblastoma, or rhabdomyosarcoma.
As a preferable embodiment of the detection method of the present invention, mention may be made of application of a CGH method to a substrate on which a plurality of types of gene amplification products having a specific genome DNA region obtained from a BAC (bacterial artificial chromosome) DNA, YAC (yeast artificial chromosome) DNA, or PAC (phage artificial chromosome) DNA are individually and separately fixed. In this embodiment, amplification and deletion gene of a genomic DNA can be analyzed by the CGH method.
The amount of the BAC DNA generally obtained is too little to fix onto numerous substrates practically used as genomic DNA fixed substrates. Therefore, the DNA must be obtained as an amplified product of a gene (the amplification process of the gene is also called as “inexhaustible process”). In the inexhaustible process, BAC DNA etc., was digested with a 4-nucleotide recognition enzyme, such as RsaI, DpnI, or HaeIII, and then, an adapter was added to ligate the digested fragments. The adapter is an oligonucleotide formed of 10 to 30 nucleotides and preferably 15 to 25 nucleotides. The double stranded chain has a complementary sequence. After annealing, the 3′ end of the oligonucleotide forming a smooth end must be phosphorylated. Then, using a primer having the same sequence as one of the oligonucleotides serving as the adaptor, amplification is performed by PCR (Polymerase Chain Reaction). In this manner, the inexhaustible process can be carried out. On the other hand, an aminated oligonucleotide having 50 to 70 nucleotides characteristic in each of the BAC DNA and the like may be used as a detection probe.
The inexhaustibly amplified BAC DNA or the like (the same in the embodiment genomic DNA, cDNA or synthetic oligonucleotide is used) is fixed onto a substrate, preferably a solid substrate, to manufacture a desired DNA fixed substrate.
Examples of the solid substrate include glass, plastic, membrane and a three-dimensional array. Preferably a glass substrate such as a slide glass is preferable. The solid substrate formed of such as glass is preferably coated by depositing poly-L-lysine, amino silane, gold, and aluminium thereon and applied by an amino group modified DNA immobilization surface treatment.
The concentration of the inexhaustibly amplified DNA mentioned above (the same in the embodiment genomic DNA, cDNA or synthetic oligonucleotide is used) to be spotted on the substrate is preferably 10 pg/μl to 5 μg/μl, and more preferably, 1 ng/μl to 200 ng/μl. The amount of the spot is preferably 1 nl to 1 μl, and more preferably, 10 nl to 100 nl. The size and shape of individual spots to be fixed on the substrate are not particularly limited; however, for example, may be a diameter of 0.002 to 0.5 mm and a circular to elliptic shape as viewed from the top. The thickness of dry spots is not particularly limited; however, may be 1 to 100 μm. The number of spots are not particularly limited; however, preferably 10 to 50,000, and more preferably 100 to 5,000. Each DNA may be spotted in the range of a singular spot to quadruplicated spots, and preferably duplicated or triplicated spots.
The dry spots may be prepared by spotting a plurality of spots of BAC DNA and the like (the same in the embodiment genomic DNA, cDNA or synthetic oligonucleotide is used) inexhaustibly amplified on a substrate by means of a spotter, and drying the spots. As the spotter, use may be made of an inkjet printer, pin array printer, and bubble-jet (registered trade mark) printer; however, an inkjet printer may be preferably used. More specifically, use may be made of GENESHOT (NGK insulators Ltd., Nagoya) and high-throughput inkjet delivery system SQ series (manufactured by Cartesian Technologies, USA), etc.
In the manner mentioned above, a desired DNA fixation substrate can be manufactured by fixing BAC DNA and the like (the same in the embodiment genomic DNA, cDNA or synthetic oligonucleotide is used) inexhaustibly amplified on a substrate, and preferably a solid substrate. Hybridization was actually performed using Cy-3 labeled genomic DNA derived from a normal diploid cell, and Cy-5 labeled genomic DNA derived from the same normal diploid cell separately on the MCG cancer array. The results are shown in
In the MCG cancer array shown in
Furthermore, actually, DNA derived from a normal cell was labeled with Cy-5 and DNA derived from a cancer cell was labeled with Cy-3. They were subjected to comparative genomic hybridization. Data were taken in by a GenePix 4000B scanner. Individual pixels were analyzed and the results are shown in
To identify a group of genes present in the chromosomal region amplified and deleted in a cancer cell by use of the MCG cancer array, genomic DNA derived from a healthy person and genomic DNA derived from a lung cancer cell are labeled with mutually different dye, for example, Cy-3 and Cy-5, in accordance with a customary method (for example, a nick translation method using dCTP). The labeling kits using the nick translation method using dCTP are sold by PanVera (Takara Shuzo Co., Ltd., a distributor in Japan) and Invitrogen (CA, USA). When the labeled DNA is hybridized with the DNA printed on the CGH array, it is more preferable to add Cot-1DNA, formamide, dextran sulfate, SSC (150 mM NaCl/15 mM sodium citrate), Yeast t-RNA, and SDS (sodium dodecyl sulfate). Furthermore, it is preferable to add a solution containing labeled DNA after it is denatured with heat. As a container for use in hybridization, a container that can be placed on a platform having a locking function and can bring a small amount of solution uniformly into contact with the array is preferable, and use of e.g., hybriman, is more preferable. The temperature of hybridization is preferably 30 to 70° C. and more preferably 38 to 45° C. The hybridization time is preferably 12 to 200 hours and more preferably 40 to 80 hours. The array can be washed with formamide, SSC solution or the like at room temperature. The washing of the array is an important step to reduce a nonspecific signal as much as possible. More preferably, the array was washed at room temperature, and then, washed with the same washing solution at 40 to 60° C., further washed in a solution containing SSC-SDS at 50° C., allowed to stand in a solution containing phosphate buffer/NP-40, and finally shaken in a solution containing SSC.
Using the MCG cancer array, a chromosomal region amplified and deleted in a malignant glioma was identified, and a group of genes present in the chromosomal region was analyzed. Examples of a gene amplified in the malignant glioma having a Ratio value of 1.32 or more include EIF4G, ETV5, EGFR, CDC10, IGFBP1, TCRG, MYCLK1, TAX1BP1, IL6, PMS2, MUC3, MET, SMOH, BRAF, CDK5, AR, CUL4B, MCF2, MAGEA2, and CTAG. Furthermore, examples of a gene having a Ratio value of 4 or more, that is, having a copy number increased to 4-fold or more than that of a normal cell include ALX, MUC1, ARHGEF2, PMF1, NTRK1, ERV5, MUC4, PDGFRA, IGFBP7, PC4, SKP2, DAB2, CDH10, CDH12, TERT, E2F3, TPMT, TFAP2A, EEF1E1, RREB1, EGFR, PMS2, CDK6, PRIM1, GLI, CDK4, FUS, CYLD, and GRB2.
As a group of genes deleted in a malignant glioma cell, more specifically a group of genes having a Ratio value of 0.75 or less, that is, having a heterozygous deletion, AFP, EGF5, ABCG2, NFκB, CDKN2A (p16), MTAP, BMI1, PCDH15, PGR, FGF9, ZNF198, FLT1, FLT3, BRCA2, RB1, KLF12, PIBF1, HNF3A, MBIP, and FKHL1 genes were found. Furthermore, as a gene having a Ratio value of 0.25 or less, that is, a gene having a homozygous deletion, MATP gene and CDKN2A(p16) were found.
As a group of genes amplified in a neuroblastoma cell, MYCN gene has an extremely high level amplification (9-97 fold), CDK4 gene has a 25-fold amplification, PPM1D gene has a 9.8 fold amplification, and MYCL1, CDH10 and MYC genes have 2.8 to 4.2 fold amplifications.
Next, a gene amplified in a rhabdomyosarcoma cell was analyzed. As a result, as genes amplified compared to a normal cell, TGFβR3, PAX3, MLL, CDK4, and FKHR genes were found.
By checking amplification and deletion of the chromosomal region of the group of genes thus detected and analyzing the group of genes amplified and deleted, a brain tumor, in particular, malignant glioma, neuroblastoma, and rhabdomyosarcoma can be diagnosed.
As described above, the amplification and deletion of the chromosomal region in cancers such as brain tumor are analyzed by use of the MCG cancer array, and thus a group of genes having amplified and deleted can be identified. Based on the results, it is possible to understand the state of each cancer. To describe more specifically, it is possible to determine whether a tumor is benign, intermediate or malignant. In the case of a malignant tumor, it is possible to provide important findings to determine the grade of the cancer. It is further possible to provide data for efficient chemotherapy performed after a cancerous foci is surgically removed.
It is possible and preferable to simultaneously detect deletion of a chromosome and suppression of expression by monitoring the gene expression by a real time RT-PCR method or a DNA chip method in a deletion cancer gene group.
The suppression/treatment means for a cancer provided by the present invention are roughly divided into two groups. One (1) is a method of suppressing the cancer cell (hereinafter referred to as “suppression/treatment means 1”) by introducing a gene whose deletion is associated with canceration of a cell (called as a deletion cancer gene) into a cancer cell. The other (2) is a method of suppressing the cancer cell (hereinafter referred to as “suppression/treatment means 2”) by applying a nucleic acid antagonizing against a transcriptional product of a gene whose amplification is associated with canceration of a cell (called as an amplification cancer gene) to a cancer cell.
Of the deletion cancer genes mentioned above, many of the genes in the chromosomal region exhibiting a homozygous deletion are detected to fall within the category of a cancer suppressor gene. Of them, a gene suppressing proliferation of target cancer cells or a gene inducing apoptosis of cancer to death can be introduced into a cancer cell by use of a Sendai virus vector or adenovirus vector. In a gene therapy using these virus vectors, as a promoter for the homozygous deletion gene to be expressed, a promoter highly expressed in a cancer tissue but not highly expressed in a normal tissue, such as human CXCR4 promoter (Zhu Z B, Makhija S K, Lu B, Wang M, Kaliberova L, Liu B, Rivera A A, Nettelbeck D M, Mahasreshti P J, Leath C A, Yamaoto M, Alvarez R D, Curiel D T: Transcriptional targeting of adenoviral vector through the CXCR4 tumor-specific promoter, Gene ther., 11, 645-648, 2004) and Survivin promoter are preferably used. Each of these recombinant viruses can be combined with a ribosome to form a composite, which may be introduced into a cancer tissue. Alternatively, it can be introduced in the form of naked DNA into a cancer tissue.
Using a viral vector and a promoter as mentioned above, each cancer therapy can be made by selecting a gene from following candidate genes: MTAP gene and CDKN2A(p16) gene localized in 9p21 for a malignant glioma.
CDKN2A(p16) gene is a cyclin dependent kinase inhibitor located in a chromosome 9p21 and considered as a cancer suppressor gene. P16 protein, when it binds to CDK4 kinase, is suppressed in its activity, thereby suppressing cell cycle progression. The CDKN2A(p16) gene is deleted in a wide variety of cancers such as acellular esophageal carcinoma, malignant glioma, gastric carcinoma, pancreatic carcinoma and thyroid carcinoma. MTAP is a gene encoding 5′-methylthioadenosinephosphorylase, which is the first enzyme of a methionine salvage pathway and considered as a cancer suppressor gene. The product of the methionine salvage pathway inhibits the activity of ornithine decarboxylase highly expressed in cancer. RIZ is a gene encoding an RB interacting Zinc Finger protein found in leukemia and belongs to Nuclear protein methyltransferase superfamily. DBCCR1 is found as a gene deleted in chromosome 1 of the bladder carcinoma and considered as a cancer suppressor gene. TEK is an angiopoietin-1 receptor, which is otherwise designated as Tie-2. When TEK is phosphorylated by tyrosine kinase, angiogenesis is induced. CDH23 is cadherin related 23 gene, belongs in the cadherin superfamily, and is a glycoprotein associated with calcium dependent cell adhesion. CXADR gene encodes receptors of coxsachie virus and adenovirus. cIAP1 gene encodes an apoptosis inhibitor. FLI1 gene is classified into an ETS transcription factor. TSPY gene is present in human Y chromosome and encodes a testis specific protein. LRP1B is abbreviation of lipoprotein receptor-related protein 1B, which is a cellular membrane receptor using urokinase and a plasminogen activator, etc., as a ligand, and is considered as a cancer suppressor gene. DEC1 refers to “deleted in esophageal cancer 1” and loss of heterozygosity is frequently detected in esophageal carcinoma and squamous cell carcinoma of the bladder, lung and head and neck portion. MMP1 and MMP7 are matrix metalloproteinase and enzymes involved in vascularization. SMAD4 gene is a cancer suppressor gene whose deletion is found in pancreatic carcinoma and encodes a protein that is activated by a receptor and transferred to a nucleus to derive a transcriptional activation activity. ETS1 is a transcription factor and derives angiopoietin-2 gene, etc. RB1 is a retinoblastoma gene and a cancer suppressor gene.
A virus vector is prepared by integrating a gene as mentioned above downstream of a promoter highly expressed in a cancer tissue, and is then introduced into the cancer tissue of a cancer patient. The gene is allowed to express, thereby reducing cancer in size and inhibiting metastasis. In this way, recurrence of cancer after cancer is excised out can be prevented.
Of the amplification cancer genes found above, a group of genes present in the chromosome, amplified 4-fold or more than that of a normal cell, are shown in Table 1.
When these groups of genes are compared to those of a normal cell, the number of genome copies in chromosomes 1 to 22 increases to 8 or more, and that in X and Y chromosomes increases 4 or more. The transcriptional product of a highly expressed gene is decomposed by adding the small interference RNA corresponding to the transcriptional product (mRNA) in accordance with an RNAi (RNA interference) method. In this manner, cancer can be treated. Design and synthesis of siRNA and the transfection of siRNA to a cell, confirmation of the effect of RNAi can be performed by conventional methods with reference to, for example, Takara Bio RNAi Book, “Experimentation protocol” (published by Takara Bio Inc., Shiga prefecture). Examples of siRNA to be used herein include Hairpin siRNA, which can be expressed by using an siRNA oligonucleotide and a pSilencer vector (manufactured by Funakoshi Co., Ltd., Tokyo).
On the other hand, mRNA of a cancer gene amplified and excessively expressed in a cancer can be knocked out by use of an antisense oligonucleotide. In this case, s-oligonucleotide is preferably used to inhibit amplification of a cancer cell since it has a good intracellular stability compared to a general oligonucleotide. SiRNA, Hairpin siRNA and s-oligonucleotide, which are found to be effective by use of a cancer cell, can be evaluated in a nude mouse having a cancer cell transplanted therein.
In this case, it is preferable to construct a delivery system such that these RNA can be accumulated in a cancer tissue.
Based on the search for genome database website of the National Cancer for Biotechnology and University of California, Santa Cruz Biotechnology as well as BLAST search of DNA screened, BAC/PAC clones having an extremely important gene for canceration and amplification of a cancer cell or having a sequence tagged site marker were selected.
BAC and PAC DNA was digested with Dpnl, RsaI, and HaeIII, and thereafter ligated with adaptor DNA. PCR was performed twice using a primer having the sequence of the adaptor. One of the two ends of the primers has the 5′ end aminated. This process is called an inexhaustible process and DNA thus obtained is defined as inexhaustible DNA. The inexhaustible DNA is placed in an ink-jet type spotter (GENESHOT, NGK Insulators, Ltd., Nagoya) and covalently printed, in duplicate, onto an oligo DNA micro array (manufactured by Matsunami Glass, Osaka).
Using the “MCG cancer array,” an amplified and deleted gene was checked in 22 malignant glioma cell lines. The names of the 22 types of cell lines used herein are KNS-42, KNS-60, KNS-81, KNS-89, No.10, No.11, KINGS-1, T98G, GB-1, KS-1, SF126, Marcus, Becker, AM-38, A-172, KALS-1, YH-13, YKG-1, U251MG, NMC-G1, U87MG, and U373MG. A change in genome copy number in malignant glioma cell lines was analyzed. As a result, as genes having a Ratio value of 1.32 or more where amplification was detected, EIF4G, ETV5, EGFR, CDC10, IGFBP1, TCRG, MYCLK1, TAX1BP1, IL6, PMS2, MUC3, MET, SMOH, BRAF, CDK5, AR, CUL4B, MCF2, MAGEA2, and CTAG were found (Table 2). Amplification of these genes was found in about half of the glioma cells tested herein.
Furthermore, as a gene having a Ratio value of 4 or more and having a copy number increased to 4-fold or more as large as in a normal cell, ALX, MUC1, ARHGEF2, PMF1, NTRK1, ERV5, MUC4, PDGFRA, IGFBP7, PC4, SKP2, DAB2, CDH10, CDH12, TERT, E2F3, TPMT, TFAP2A, EEF1E1, RREB1, EGFR, PMS2, CDK6, PRIM1, GLI, CDK4, FUS, CYLD, and GRB2 genes were found (Table 3). The number of cells in which high-level amplification was found is 1 to 2 cell lines.
The relationship between the increase of copy numbers in the chromosome and expression level was analyzed with respect to SKP2 gene. As a result, both were correlated (
With respect to a normal cell and small-lung cancer cells (S-2, SBC-5, ACC-LC-5, ACC-LC-172, ACC-LC-80, ACC-LC-173, Lu-143, Lu-24, Lu-130, Lu-134A, Lu-138), the amplification of SKP2, PC4, CDH6 genes was analyzed by the Southern blot method and the expression levels of SKP2 mRNA and PC4 mRNA were analyzed by the Northern blot method. The results are shown in
Furthermore, invasion and migration of P-10 cells were inhibited by adding a SKP2 antisense oligonucleotide to a culture solution of PC-10 cells. This supports that the acceleration of SKP2 gene expression is highly potentially involved in acquisition of a malignant trait of glioma.
On the other hand, as a gene having a Ratio value of 0.75 or less in a malignant glioma cell, that is, a gene in which a heterozygous deletion was detected, AFP, EGF5, ABCG2, NFκB, p16, MTAP, BMI1, PCDH15, PGR, FGF9, ZNF198, FLT1, FLT3, BRCA2, RB1, KLF12, PIBF1, HNF3A, MBIP, and FKHL1 genes were found (Table 4). The heterozygote detection of a gene was found in about a half of the glioma cell lines tested herein.
Furthermore, as a gene having a Ratio value of 0.25 or less, that is, a gene in which a homozygous deletion was detected, MTAP gene and CDKN2A (p16) gene were found (Table 5). A group of genes having heterozygote and homozygote significantly decreases in expression level, which may possibly be a cause of cancer.
In particular, a gene having a homozygous deletion is a cancer suppressor gene. The deletion taking place in these group of genes plays an important role in inducing canceration.
Using the “MCG cancer array,” amplified genes of 24 neuroblastoma cell lines were analyzed. As a result, a MYCN gene localized in chromosome 2p24 was amplified at a high level (9-97 fold) in 15 cell lines compared to that in a normal cell (Table 6). Furthermore, CDK4 gene localized in chromosome 12q14 was amplified 25 fold and PPM1D gene localized in chromosome 17q23 was amplified 9.8 fold. The possibility that the significant amplification of these genes may be closely involved in canceration and progress of a malignancy degree of cancer is extremely high. MYCL1, CDH10 and MYC genes were amplified 2.8 to 4.2 fold.
Using the “MCG cancer array,” an amplified gene was checked with respect to 7 cell lines of rhabdomyosarcoma (4 embryonal cell lines and 3 alveolar cell lines). As a result, as the genes amplified as compared to those in a normal cell, TGFβR3, PAX3, MLL, CDK4, and FKHR were detected (Table 7). In particular, CDK4 gene is amplified 15 fold in Rh30 cell line and considered to play an important role in this cell line.
CDKN2A (p16) gene was ligated downstream Survivin promoter and integrated into a Sendai virus vector. The resultant viral DNA was packaged to produce a recombinant virus. The recombinant virus was purified by discontinuous iodixanol gradient centrifugation and a heparin agarose column. Squamous cell carcinoma was inoculated in a 96 well tissue culture plate at a concentration of 5×103 cell/well and incubated in a CO2 incubator at 37° C. for one day. Then, 100 moi of purified recombinant Sendai virus was infected per well and incubated for 72 hours. The amplification level of cells was determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay using a commercially available kit (manufactured by Promega, Tokyo) in accordance with the instruction. As a result, in a cell infected with the virus having CDKN2A (p16) gene integrated therein, significant inhibition of proliferation was observed. The cell extraction solution was subjected to Western blot analysis. CDKN2A (p16) protein was not detected in a control Sendai virus infection cell, whereas a clear band of CDKN2A (p16) protein was detected from the cell extraction solution sample. From the results, it was demonstrated that proliferation of carcinoma cells is suppressed by infecting the cells with Sendai virus having CDKN2A (p16) gene integrated therein. This means that Sendai virus having CDKN2A (p16) gene integrated therein can be used for reducing carcinoma or suppressing minute metastasis.
Next, a nude mouse was inoculated with squamous cell carcinoma (cells), and simultaneously, infected with 3×1011 moi of purified recombinant Sendai virus. Inhibition of carcinoma proliferation was monitored while expecting an increase of the life time of the mouse, in other words, an increase of efficiency of the gene therapy according to the present invention.
Based on the results, a clinical trial of gene therapy for a human patient can be planned.
In small cell lung cancer cell, a chromosomal 5p13 region is amplified. Of the small cell lung cancer cell lines, ACC-LC-5 cell line, ACC-LC-172 cell line, Lu-130 cell line, and Lu-134 cell line were investigated. As a result, CDH6, PC4, and SKP2 genes present in the 5p13 region were significantly amplified at a chromosome level by the Southern blot method. When the expression of these genes was analyzed by the Northern blot method, it was found that a significant increase was observed compared to a normal cell (
From cells not treated (untreated), cells treated only with a transfection reagent (oligofectamine), cells transfected with an SKP2 antisense oligonucleotide (AS) and cells transfected with a SKP2 sense oligonucleotide (SC), RNA was prepared, and the expression level of SKP2 mRNA was analyzed by the Northern blot method. The results are shown in
Inhibition of proliferation of small cell lung cancer cells by the SKP2 antisense oligonucleotide was investigated. The results are shown in
Note that
These results demonstrate that the SKP2 antisense oligonucleotide specifically inhibits proliferation of cancer cells. It is therefore apparent that the SKP2 antisense oligonucleotide can be used as a therapeutic agent for cancer.
According to the present invention, a cancer-associated gene to be used as an index for detecting canceration of a cell and degree of malignancy of cancer was found, and a method of detecting cancer using the cancer-associated gene as an index was provided, and furthermore a suppression/therapeutic method of cancer using the cancer-associated gene as essential part was provided.
