Abstract:
A zinc finger-like peptide for treating cancer, a pharmaceutical composition containing the zinc finger-like peptide and a method for treating cancer are disclosed. In the present invention, the zinc finger-like peptide for treating cancer comprises: at least seven amino acids, wherein the sequence of the at least seven amino acids has 85-100% similarity to a sequence represented by SEQ ID NO: 1.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefits of the Taiwan Patent Application Serial Number 100124615, filed on Jul. 12, 2011, the subject matter of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a zinc finger-like peptide for treating cancer, a pharmaceutical composition containing the zinc finger-like peptide and a method for treating cancer. 
         [0004]    2. Description of Related Art 
         [0005]    Foods or food additives, and environmental pollutions have been a source of contention as a cause or catalyst for promoting cancer in recent years. Not coincidentally, the same event is happening as well in the developed countries and around the world, positing as an alarming sign that the incidence rates of cancers are quite high. According to the data published by the American Cancer Society, cancer is being proved to be the most significant threat to public health. 
         [0006]    The general methods for treating cancer include surgery, radiotherapy, chemotherapy and immune therapy. In recent years, the development of several therapeutic agents has lead to cancer treatments through new anti-cancer mechanisms, and it has been proven that the survival rate of patients can be increased by treating them with these therapeutic agents. Generally, the therapeutic agents can treat cancers through inhibition of cell cycle progression, angiogenesis, farnesyl transferase, and tyrosine kinases. 
         [0007]    Although it is known that certain agents exhibit therapeutic effects on cancer, these agents do have their limitations. For example, “Gefitinib” is a drug for inhibiting non-small cell lung cancer, but it fails to cure in most cases. Also, it has no effects on blocking the progression of breast and colorectal cancers. In addition, the therapeutic effects of the anti-cancer drugs also depend on the locations of tumor cells, genetic variations of patients, and the side effects of drugs. Furthermore, cancer cells may become malignant and spread from its original sites to target organs via the lymphatic system or bloodstream, thereby establishing metastatic cancers. 
         [0008]    Since the risk of developing cancer generally increases with age, the occurrence rates of cancer go up as more people live to an old age and as mass lifestyle changes. Hence, there is a long unfulfilled need to provide new agents for cancer treatment and prevention. 
       SUMMARY OF THE INVENTION 
       [0009]    The object of the present invention is to provide a zinc finger-like peptide, a pharmaceutical composition containing the zinc finger-like peptide and a method for treating cancer, which can be used to treat cancer. 
         [0010]    Another object of the present invention is to provide a zinc finger-like peptide expression plasmid, a pharmaceutical composition containing the zinc finger-like peptide and a method for treating cancer, wherein the zinc finger-like peptide expression plasmid can express a zinc finger-like peptide for treating cancer. 
         [0011]    To achieve the object, the zinc finger-like peptide for treating cancer comprises: at least seven amino acids, wherein the sequence of the at least seven amino acids has 85-100% similarity to a sequence represented by SEQ ID NO: 1. 
         [0012]    In addition, the zinc finger-like peptide expression plasmid for treating cancer comprises: a DNA sequence for expressing the aforementioned zinc finger-like peptide. 
         [0013]    To achieve the object, the zinc finger-like peptide for treating cancer comprises: at least seven amino acids, wherein the sequence of the at least seven amino acids has 50-100% similarity to a sequence represented by SEQ ID NO: 1 (RRSSSCK). 
         [0014]    In addition, the zinc finger-like peptide expression plasmid for treating cancer comprises: a DNA sequence for expressing the aforementioned zinc finger-like peptide, which has 70-100% identity to a sequence represented by SEQ ID NO: 3 (agaaggtcgt cttcttgtaa a). 
         [0015]    The present invention provides a zinc finger-like peptide, which is a small molecule peptide similar to a zinc finger motif. The amino-acid length of the peptide is not particularly limited, and the peptide can be constituted of 4-200 amino acids. Preferably, the peptide contains 4-100 amino acids. More preferably, the peptide contains 5-70 amino acids. Most preferably, the peptide contains 6-45 amino acids. Particularly preferably, the peptide contains 7-15 amino acids. The zinc finger-like peptide for treating cancer comprises at least seven amino acids, wherein the sequence of the at least seven amino acids may have 50-100% similarity to a sequence represented by SEQ ID NO: 1. Preferably, the sequence of the at least seven amino acids has 70-100% similarity to a sequence represented by SEQ ID NO: 1. More preferably, the sequence of the at least seven amino acids has 85-100% similarity to a sequence represented by SEQ ID NO: 1. In addition, the sequence of the at least seven amino acids may have 50-100% identity to a sequence represented by SEQ ID NO: 1. Preferably, the sequence of the at least seven amino acids has 70-100% identity to a sequence represented by SEQ ID NO: 1. More preferably, the sequence of the at least seven amino acids has 85-100% identity to a sequence represented by SEQ ID NO: 1. Most preferably, the sequence of the zinc finger-like peptide is SEQ ID NO: 1. 
         [0016]    The zinc finger-like peptide of the present invention may have 50-100% similarity to a sequence represented by SEQ ID NO: 2 (MSSRRSSSCKYCEQDFRAHTQKNAATPFLAN). Preferably, the zinc finger-like peptide has 70-100% similarity to a sequence represented by SEQ ID NO: 2. More preferably, the zinc finger-like peptide has 80-100% similarity to a sequence represented by SEQ ID NO: 2. In addition, the zinc finger-like peptide may have 50-100% identity to a sequence represented by SEQ ID NO: 2. Preferably, the zinc finger-like peptide has 70-100% identity to a sequence represented by SEQ ID NO: 2. Most preferably, the zinc finger-like peptide has 80-100% identity to a sequence represented by SEQ ID NO: 2. 
         [0017]    The DNA sequences shown in SEQ ID NOs: 3 and 4 are respectively coded into the amino acid sequences shown in SEQ ID NOs: 1 and 2. The DNA sequences shown in SEQ ID NO 4 is listed as the following: atgagcagca gaaggtcgtc ttcttgtaaa tattgtgaac aggacttccg agcacacaca cagaagaatg cggccacacc cttcctagcc aac. In the present invention, cDNA having DNA sequences shown in SEQ ID NO: 3 or 4 can be inserted into a vector to obtain the zinc finger-like peptide expression plasmid, which can express peptide having amino acid sequence shown in SEQ ID NO: 1 or 2 in vitro or in vivo. 
         [0018]    The sequence of the aforementioned zinc finger-like peptide can be derived from any zinc finger-like peptide of different species. Preferably, the zinc finger-like peptide of the present invention is derived from human or mouse. In addition, the zinc finger-like peptide may be obtained through peptide synthesis, or expression of cDNA of zinc finger-like peptide from human or mouse. In one aspect of the present invention, the zinc finger-like peptide of the present invention is obtained through peptide synthesis. 
         [0019]    The expression plasmid of the present invention can be any plasmid capable of expressing the zinc finger-like peptide of the present invention. Preferably, the expression plasmid used in the present invention is pCR3.1 (available from Invitrogen) or pEGFPC1 (available from Clontech). The host for the zinc finger-like peptide of the present invention is not particularly limited, as long as it can express the cDNA inserted into the vector. Examples of the host may include: bacteria, mammalian cells or tumor cells. Preferably, the zinc finger-like peptide expression plasmid of the present invention is transfected into mammalian cells or tumor cells to express the zinc finger-like peptide. 
         [0020]    In addition, the zinc finger-like peptide of the present invention may have 50-100% similarity to a sequence represented by SEQ ID NO: 8 (MSSRRSSSCKYCEQD). Preferably, the zinc finger-like peptide has 70-100% similarity to a sequence represented by SEQ ID NO: 8. More preferably, the zinc finger-like peptide has 80-100% similarity to a sequence represented by SEQ ID NO: 8. In addition, the zinc finger-like peptide may have 50-100% identity to a sequence represented by SEQ ID NO: 8. Preferably, the zinc finger-like peptide has 70-100% identity to a sequence represented by SEQ ID NO: 8. Most preferably, the zinc finger-like peptide has 80-100% identity to a sequence represented by SEQ ID NO: 8. Most preferably, the sequence of the zinc finger-like peptide is SEQ ID NO: 8. 
         [0021]    Furthermore, the zinc finger-like peptide of the present invention may have 50-100% similarity to a sequence represented by SEQ ID NO: 9 (FRAHTQKNAATPFLAN). Preferably, the zinc finger-like peptide has 70-100% similarity to a sequence represented by SEQ ID NO: 9. More preferably, the zinc finger-like peptide has 80-100% similarity to a sequence represented by SEQ ID NO: 9. In addition, the zinc finger-like peptide may have 50-100% identity to a sequence represented by SEQ ID NO: 9. Preferably, the zinc finger-like peptide has 70-100% identity to a sequence represented by SEQ ID NO: 9. Most preferably, the zinc finger-like peptide has 80-100% identity to a sequence represented by SEQ ID NO: 9. Most preferably, the sequence of the zinc finger-like peptide is SEQ ID NO: 9. 
         [0022]    In the present invention, the term “similarity” refers to the percentage of the similar amino acid residues between two sequences, which is defined by the chemical similarity of amino acids. For example, alanine, valine, leucine and isoleucine are similar amino acid residues with saturated hydrocarbon groups; phenylalanine, tyrosine, tryptophan and histidine are similar amino acid residues with aromatic groups; aspartic acid, asparagine, glutamic acid and glutamine are similar amino acid residues with carboxyl groups and amide groups; lysine and arginine are similar amino acid residues with amino groups; serine and threonine are similar amino acid residues with alcoholic groups; and methionine and cysteine are similar amino acid residues with thio-groups. In addition, the term “identity” refers to the percentage of the identical amino acid residues between two sequences. 
         [0023]    In the zinc finger-like peptide containing at least seven amino acids of the present invention, the sequence thereof may contain at least two duplicate amino acid residues with similar chemical properties. For example, the sequence thereof may contain at least two duplicate hydrophilic amino acid residues such as aspartic acid, glutamine, serine, threonine, or cysteine; at least two duplicate amino acid residues with alcoholic groups, such as threonine, serine or tyrosine; or at least two duplicate amino acid residues with thio-groups such as cysteine. In the present invention, the zinc finger-like peptide at least contains two cysteine and one histidine to form a zinc finger-like peptide with C2H2 motif. 
         [0024]    In addition, the zinc finger-like peptide expression plasmid of the present invention may further comprise a vector connecting to the DNA sequence for expressing the zinc finger-like peptide of the present invention. The type of the vector is not particularly limited by number, and can be any vector generally used in the art. For example, the vector may be derived from pEGFP or pECFP, which is generally used to transfect into mammalian cells such as human cell lines for expressing inserted cDNAs. 
         [0025]    Furthermore, the zinc finger-like peptide or the expression plasmid of the present invention may be encapsulated into liposome. Preferably, the expression plasmid is co-transfected into hosts with liposome to express the zinc finger-like peptide. 
         [0026]    The zinc finger-like peptide of the present invention has similar structure to zinc-finger motif. In addition, the peptide of the present invention may selectively contain several duplicate amino acid residues with similar chemical properties or several duplicate identical amino acid residues to form a peptide motif with specific bondings. Furthermore, the zinc finger-like peptide can self-polymerize without adding any catalytic agents. The zinc finger-like peptide of the present invention also can bind to proteins related to apoptosis. Hence, it can inhibit the growth of tumor cells, and can be used to treat or prevent cancers. 
         [0027]    The present invention further provides a pharmaceutical composition for treating cancer, which comprises: an effective amount of the aforementioned zinc finger-like peptide or zinc finger-like peptide expression plasmid; and a pharmaceutically acceptable carrier. 
         [0028]    In addition, the present invention also provides a method for treating cancer, which comprises: administering the aforementioned zinc finger-like peptide, the aforementioned zinc finger-like peptide expression plasmid, or the aforementioned pharmaceutical composition to a subject in need thereof. 
         [0029]    The zinc finger-like peptide of the present invention may be applied to various cancers, such as bladder cancer, bone cancer, brain cancer, breast cancer, cervical caner, colon cancer, endometrial cancer, esophageal cancer, leukemia, liver cancer, lymphoma, kidney cancer, osteosarcoma, ovarian cancer, pancreatic cancer, prostate cancer, skin cancer including basal and squamous cell carcinoma and melanoma, small intestine cancer, stomach cancer, thymus cancer and thyroid cancer, but the scope of applicability of the present invention is not limited thereto. Preferably, the zinc finger-like peptide of the present invention is used to treat breast cancer, colon cancer, esophageal cancer, leukemia, lymphoma, liver cancer, lung cancer, ovarian cancer, pancreatic cancer, prostate cancer, skin cancer, stomach cancer or thyroid cancer. More preferably, the zinc finger-like peptide of the present invention is used to treat breast cancer, colon cancer, lung cancer, lymphoma, prostate cancer or skin cancer. Most preferably, the zinc finger-like peptide of the present invention is used to treat brain cancer, breast cancer, prostate cancer or skin cancer. 
         [0030]    The zinc finger-like peptide of the present invention can inhibit proliferation, growth, invasion and metastasis of tumor cells. 
         [0031]    The zinc finger-like peptide and the pharmaceutical composition for treating cancer of the present invention can be administered via parenteral, inhalation, local, rectal, nasal, sublingual, or vaginal delivery, or implanted reservoir. Herein, the term “parenteral delivery” includes subcutaneous, intradermic, intravenous, intra-articular, intra-arterial, synovial, intrapleural, intrathecal, local, and intracranial injections. 
         [0032]    According to the pharmaceutical composition of the present invention, the term “pharmaceutically acceptable carrier” means that the carrier must be compatible with the active ingredients (and preferably, capable of stabilizing the active ingredients) and not be deleterious to the subject to be treated. The carrier may be at least one selected from the group consisting of active agents, adjuvants, dispersants, wetting agents and suspending agents. The example of the carrier may be microcrystalline cellulose, mannitol, glucose, non-fat milk powder, polyethylene, polyvinylprrolidone, starch or a combination thereof. 
         [0033]    In addition, the term “treating” used in the present invention refers to the application or administration of the zinc finger-like peptide or the pharmaceutical composition containing the zinc finger-like peptide to a subject with symptoms or tendencies of suffering from cancer in order to cure, heal, alleviate, relieve, alter, remedy, ameliorate, improve, prevent or affect the symptoms or tendencies of cancers. Furthermore, “an effective amount” used herein refers to the amount of each active ingredients such as the zinc finger-like peptide required to confer therapeutic effect on the subject. The effective amount may vary according to the route of administration, excipient usage, and co-usage with other active ingredients. 
         [0034]    Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1A  is a curve representing the tumor volumes of mice in the experimental group according to Example 1 of the present invention; 
           [0036]      FIG. 1B  is a curve representing the tumor volumes of mice in the control group according to Example 1 of the present invention; 
           [0037]      FIG. 2  shows curves representing the tumor volumes of mice according to Example 2 of the present invention; 
           [0038]      FIG. 3A  is a curve representing the tumor volumes of mice in the experimental group according to Example 3 of the present invention; 
           [0039]      FIG. 3B  is a curve representing the tumor volumes of mice in the control group according to Example 3 of the present invention; 
           [0040]      FIG. 4  shows curves representing the tumor volumes of mice according to Example 4 of the present invention; 
           [0041]      FIG. 5  shows curves representing the tumor volumes of mice according to Example 5 of the present invention; 
           [0042]      FIG. 6A  is a curve representing the tumor volumes of mice in the experimental group according to Example 6 of the present invention; 
           [0043]      FIG. 6B  is a curve representing the tumor volumes of mice in the control group according to Example 6 of the present invention; 
           [0044]      FIG. 7A  is a curve representing the tumor volumes of mice in the experimental group according to Example 7 of the present invention; 
           [0045]      FIG. 7B  is a curve representing the tumor volumes of mice in the control group according to Example 7 of the present invention; 
           [0046]      FIG. 8  shows curves representing the tumor volumes of mice according to Example 8 of the present invention; 
           [0047]      FIG. 9A  is a curve representing the tumor volumes of mice in the experimental group according to Example 9 of the present invention; 
           [0048]      FIG. 9B  is a curve representing the tumor volumes of mice in the control group according to Example 9 of the present invention; 
           [0049]      FIG. 10A  is a curve representing the tumor volumes of mice in the experimental group according to Example 10 of the present invention; 
           [0050]      FIG. 10B  is a curve representing the tumor volumes of mice in the control group according to Example 10 of the present invention; 
           [0051]      FIG. 11A  is a curve representing the tumor volumes of mice in the control group according to Example 11 of the present invention; 
           [0052]      FIG. 11B  is a curve representing the tumor volumes of mice in the experimental group 1 according to Example 11 of the present invention; and 
           [0053]      FIG. 11C  is a curve representing the tumor volumes of mice in the experimental group 1 according to Example 11 of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0054]    The DNA sequence and the amino acid sequence of the zinc finger-like peptide used in the following examples are listed in the following table 1. 
         [0000]    
       
         
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 SEQ ID NO: 
                 DNA/amino acid sequence 
               
               
                   
               
             
             
               
                 SEQ ID NO: 1 
                 RRSSSCK 
               
               
                   
               
               
                 SEQ ID NO: 2 
                 MSSRRSSSCKYCEQDFRAHTQKNAATPFLAN 
               
               
                   
               
               
                 SEQ ID NO: 3 
                 agaaggtcgt cttcttgtaa a 
               
               
                   
               
               
                 SEQ ID NO: 4 
                 atgagcagca gaaggtcgtc ttcttgtaaa tattgtgaac aggacttccg 
               
               
                   
                 agcacacaca cagaagaatg cggccacacc cttcctagcc aac 
               
               
                   
               
               
                 SEQ ID NO: 5 
                 MSSRRSS G CKYCEQD (serine mutation) 
               
               
                   
               
               
                 SEQ ID NO: 6 
                 RSSSCK (cysteine deletion) 
               
               
                   
               
               
                 SEQ ID NO: 7 
                 atgagcagca gaaggtcgtc tggctgtaaa tattgtgaac aggacttccg 
               
               
                   
                 agcacacaca cagaagaatg cggccacacc cttcctagcc aac 
               
               
                   
               
               
                 SEQ ID NO: 8 
                 MSSRRSSSCKYCEQD 
               
               
                   
               
               
                 SEQ ID NO: 9 
                 FRAHTQKNAATPFLAN 
               
               
                   
               
             
          
         
       
     
         [0055]    In the following examples, 8-week nude mice were used as host subjects to perform in vivo experiments. The nude mice were placed in room temperature and suitable humidity, and supplied with sterile water and standard food for 2 consecutive weeks before performing experiments. Then, the nude mice were injected with zinc finger-like peptide and tumor cells. The detailed processes for the experiments are described as follows. 
         [0056]    First, manually synthesized zinc finger-like peptide (Genemed Synthesis Inc., San Antonio, Tex., USA) was resuspended in degassed purified water to obtain 1-5 mM of zinc finger-like peptide solution (100 μl). Herein, the solution for suspending the zinc finger-like peptide is not particularly limited. Preferably, the zinc finger-like peptide is resuspended in degassed purified water, in order to prevent the self-polymerization of the zinc finger-like peptide and loss its ability to inhibit tumor cell growth. 
       EXAMPLE 1 
     Experimental Group 
       [0057]    Herein, zinc finger-like peptide with sequence shown in SEQ ID NO: 2 was injected into nude mice. 
         [0058]    In particularly, nude mice were injected with an intravenous injection of peptide (2 mM, 100 μl phosphate-buffered saline or PBS) via tail veins per week for 3 consecutive weeks, followed by inoculating basal cell carcinoma (BCC) cells (2 million cells/100 μl PBS) at both the right and left flanks. The tumor volumes (mm 3 ) were observed daily during the whole experiment. The result is shown in  FIG. 1A , which is a curve representing the tumor volumes of mice. 
       Control Group 
       [0059]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group was substituted with PBS buffer (100 μl) in the present control group. The result is shown in  FIG. 1B , which is a curve representing the tumor volumes of mice. 
         [0060]    As shown in  FIG. 1A  and  FIG. 1B , the zinc finger-like peptide inhibited the growth of skin cancer cell on nude mice when the mice were pre-injected with zinc finger-like peptide (experimental group). However, the tumor volumes of mice without injection of zinc finger-like peptide (control group) were much larger than those of the experimental group. These results indicate that the zinc finger-like peptide is effective on treating and preventing skin basal cell carcinoma. 
       EXAMPLE 2  
     Experimental Group 1  
       [0061]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 1 was injected into nude mice. 
         [0062]    Nude mice were injected with an intravenous injection of peptide (2 mM, 100 μl PBS) via tail veins per week for 3 consecutive weeks, followed by inoculating BCC cells (2 million cells/100 μl PBS) at both the right and left flanks. 2 months later, boost injection of peptide was carried out per week for 3 consecutive weeks. The tumor volumes (mm 3 ) were daily observed during the whole experiment. 
       Experimental Group 2 
       [0063]    The process of the present experimental group was the same as that of the experimental group 1, except that the zinc finger-like peptide with sequence shown in SEQ ID NO: 1 of the experimental group 1 was substituted with zinc finger-like peptide with sequence shown in SEQ ID NO: 5 in the present experimental group. 
       Control Group 
       [0064]    The process of the present control group was the same as that of the experimental group 1, except that the zinc finger-like peptide of the experimental group 1 was substituted with H 2 O (100 μl) in the present control group. 
         [0065]    The results of the present example are shown in  FIG. 2 , which shows curves representing the tumor volumes of mice of the experimental group 1, the experimental group 2 and the control group of the present example. As shown in  FIG. 2 , the zinc finger-like peptide with sequence shown in SEQ ID NO: 1 (experimental group 1) can prevent and inhibit the growth of cancer cell, and has effect on skin cancer treatment. However, when the fifth amino acid, serine of SEQ ID NO: 1 is replaced with glycine (i.e. the zinc finger-like peptide with sequence shown in SEQ ID NO: 5), the therapeutic effect of the zinc finger-like peptide is decreased. However, the zinc finger-like peptide used in the experimental group 2 still has better treatment effect than H 2 O used in the control group. 
       EXAMPLE 3  
     Experimental Group 
       [0066]    Herein, zinc finger-like peptide with sequence shown in SEQ ID NO: 1 is injected into nude mice. 
         [0067]    With this experimental group, nude mice received an intravenous injection of peptide (2 mM, 100 μl sterile water) via tail veins per week for 3 consecutive weeks, followed by inoculation of malignant melanoma B16F10 (2 million cells/100 μl PBS) at both the right and left flanks. The tumor volumes (mm 3 ) were observed daily during the whole experiment. Shown in  FIG. 3A  is the result representing the tumor volumes of mice of the present experimental group. 
       Control Group 
       [0068]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group was substituted with H 2 O (100 μl) in the present control group. The result is shown in  FIG. 3B , which is a curve representing the tumor volumes of mice of the present control group. 
         [0069]    As shown in  FIG. 3A  and  FIG. 3B , the zinc finger-like peptide can inhibit the growth of skin melanoma on nude mice when the mice were pre-injected with zinc finger-like peptide (experimental group). However, the tumor volumes of mice without injection of zinc finger-like peptide (control group) were much larger than those of the experimental group. These results indicate that the zinc finger-like peptide exhibit dramatic effects on treating and preventing malignant melanoma. 
       EXAMPLE 4  
       [0070]    Nude mice received an intravenous injection of peptide (2 mM, 100 μl) via tail veins per week for 2 consecutive weeks, followed by inoculating malignant melanoma B 16F10 (2 million cells/100 μl PBS) at both the right and left flanks. The tumor volumes (mm 3 ) were observed daily during the whole experiment. 
       Experimental Group 1 
       [0071]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 1 was injected into nude mice. 
       Experimental Group 2 
       [0072]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 1, in which the fifth amino acid, serine was phosphorylated, and injected into nude mice. 
       Experimental Group 3  
       [0073]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 6 was injected into nude mice. 
       Experimental Group 4 
       [0074]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 6, in which the fourth amino acid serine was phosphorylated, and injected nude mice. 
       Control Group 
       [0075]    In the control group, H 2 O (100 μl) was injected into nude mice. 
         [0076]    The results of the present example are shown in  FIG. 4 , which shows curves representing the tumor volumes of mice of the experimental groups 1-4 and the control group of the present example. As shown in  FIG. 4 , the nude mice of the experimental group 3 died on 31 st  day, and those of the experimental groups 2 and 4 died on 35 th  day. These results indicate that the zinc finger-like peptide with sequence shown in SEQ ID NO: 1 (the experimental group 1) can effectively inhibit the growth of tumor cells. In addition, the skin cancer was completely cured after 115 days, and therefore the zinc finger-like peptide with sequence shown in SEQ ID NO: 1 has effect on skin cancer treatment. Furthermore, according to the results of the experimental groups 2-4, the activities of the zinc finger-like peptide on skin cancer treatment were reduced by phosphorylation of serine or deletion of cyctine of zinc finger-like peptide. 
       EXAMPLE 5  
       [0077]    The cDNA of zinc finger-like peptide was inserted into vector pCR3.1/CMV to form a zinc finger-like peptide expression plasmid, wherein the zinc finger-like peptide was connected to the c-terminal of EGFP. 
       Experimental Group 
       [0078]    In the present experimental group, the zinc finger-like peptide expression plasmid containing DNA sequence for expressing the zinc finger-like peptide (SEQ ID NO: 4) (100 μl) was injected into nude mice via tail veins per week for 2 consecutive weeks, to express zinc finger-like peptide. Then, BCC cells (2 million cells/100 μl medium) were inoculated into nude mice at both the right and left flanks. The tumor volumes (mm 3 ) were observed daily during the whole experiment. 
       Experimental Group 2 
       [0079]    The process of the present experimental group was the same as that of the experimental group 1, except that the DNA sequence shown in SEQ ID NO: 4 was substituted with DNA sequence shown in SEQ ID NO: 7. 
       Control Group 
       [0080]    The process of the present control group was the same as that of the experimental group 1, except that the zinc finger-like peptide expression plasmid was substituted with vector containing EGFP only. 
         [0081]    The results of the present example are shown in  FIG. 5 , which shows curves representing the tumor volumes of mice of the experimental groups 1-2 and the control group of the present example. As shown in  FIG. 5 , the growth of tumor cells can be inhibited and the volume thereof can be reduced, when the zinc finger-like peptide expression plasmid containing DNA sequence shown in SEQ ID NO: 4 (experimental group 1) was injected into nude mice. Hence, the zinc finger-like peptide expression plasmid exhibits ability to treat skin cancer. Although the zinc finger-like peptide expression plasmid containing DNA sequence shown in SEQ ID NO: 7 (experimental group 2) cannot effectively terminate the growth of tumor cells, it can slightly inhibit the growth of the tumor cells. These results indicate that serine in the zinc finger-like peptide plays an important role on the cancer treatment. 
       EXAMPLE 6  
     Experimental Group 
       [0082]    In the present experimental group, zinc finger-like peptide with sequences shown in SEQ ID NO: 8 and 9 was injected into nude mice. 
         [0083]    Nude mice received an intravenous injection of peptide (2 mM, 100 μl ) via tail veins per week for 4 consecutive weeks, followed by inoculating breast adenocarcinoma MDA-MB-231 (2 million cells/100 μl medium) at both the right and left flanks on 40 th  day and 85 th  day. The tumor volumes (mm 3 ) were observed daily during the whole experiment. The result is shown in  FIG. 6A , which is a curve representing the tumor volumes of mice. 
       Control Group 
       [0084]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group was substituted with H 2 O (100 μl) in the present control group. The result is shown in  FIG. 6B , which is a curve representing the tumor volumes of mice. 
         [0085]    As shown in  FIG. 6A , when the nude mice were injected with peptide and followed by inoculating breast tumor cells (experimental group), the growth and proliferation of tumor cells were not observed at both the left and right flanks. However, as shown in  FIG. 6B , the tumor volumes of the nude mice in the control group were increased to 1000 times at both the left and right flanks on the 161st day. These results indicate that the zinc finger-like peptide exhibit effects on treating and preventing breast adenocarcinoma. 
         [0086]    In addition, there are no side effects on the nude mice injected with the zinc finger-like peptide 1.5 years layer. Hence, the zinc finger-like peptide exhibits low side effect and has ability to prevent the growth of breast tumor cells. 
       EXAMPLE 7  
     Experimental Group 
       [0087]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 1 was injected into nude mice. 
         [0088]    Nude mice were injected with an intravenous injection of peptide (3 mM, 100 μl) via tail veins per week for 3 consecutive weeks, followed by inoculating breast carcinoma MDA-MB-468 (2 million cells/100 μl medium) at both the right and left flanks. The tumor volumes (mm 3 ) were observed daily during the whole experiment. The result is shown in  FIG. 7A , which is a curve representing the tumor volumes of mice. 
       Control Group 
       [0089]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group as substituted with H 2 O (100 μl) in the present control group. The result is shown in  FIG. 7B , which is a curve representing the tumor volumes of mice. 
         [0090]    As shown in  FIG. 7A , when the nude mice were injected with peptide and followed by inoculating breast tumor cells (experimental group), the growth and proliferation of tumor cells were not observed at both the left and right flanks. However, as shown in  FIG. 7B , the tumor volumes of the nude mice in the control group were increased to 200-500 times at both the left and right flanks on the 91 st  day. These results indicate that the zinc finger-like peptide exhibit effects on treating and preventing breast carcinoma. 
       EXAMPLE 8  
     Experimental Group 
       [0091]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 2 was injected subcutaneously into nude mice. 
         [0092]    Nude mice received an injection of breast carcinoma MDA-MB-435s (2 million cells/100 μl PBS) via tail veins at both the right and left flanks on the P t  day, followed by injecting peptide (2 mM, 100 μl) per week for 4 consecutive weeks from the 70 th  day. The tumor volumes (mm 3 ) were observed daily during the whole experiment. 
       Control Group 
       [0093]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group was substituted with PBS buffer (100 μl) in the present control group. 
         [0094]    The results of the present example are shown in  FIG. 8 , which shows curves representing the tumor volumes of mice of the experimental groups 1-2 and the control group of the present example. The tumor volumes in the experimental group were significantly increased from the 89 th  day, and the maximum tumor volumes were observed on the 100 th  day (1000 mm 3 ). Then, the tumor volumes were reduced to 50% on the 113 th  day. However, the tumor volumes in the control group were significantly increased from the 80 th  day, and increased to 4000 times (4000 mm 3 ) on the 105 th  day. Although the tumor volumes in the experimental group were increased, the zinc finger-like peptide used therein can still terminate 75% tumor cell growth compared to the control group. Hence, the zinc finger-like peptide can be used to treat breast cancer. 
       EXAMPLE 9  
     Experimental Group 
       [0095]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 1 was injected into nude mice. 
         [0096]    Nude mice were injected with an intravenous injection of peptide (2 mM, 100 μl) via tail veins per week for 3 consecutive weeks, followed by inoculating malignant prostate cancer DU145 cells (2 million cells/100 μl medium) at both the right and left flanks three months later. The tumor volumes (mm 3 ) were observed daily during the whole experiment. The result is shown in  FIG. 9A , which is a curve representing the tumor volumes of mice. 
       Control Group 
       [0097]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group was substituted with H 2 O (100 μl) in the present control group. The result is shown in  FIG. 9B , which is a curve representing the tumor volumes of mice. 
         [0098]    As shown in  FIG. 9A , when the nude mice were injected with peptide and followed by incoluation of prostate tumor cells (experimental group), the growth and proliferation of tumor cells were not observed at both the left and right flanks. In addition, there is a 3-month resting period after peptide treatment prior to challenge with tumor cells, suggesting that zinc finger-like peptide could provide a long-term protection against cancer. 
         [0099]    However, as shown in  FIG. 9A  and  FIG. 9B , the implanted tumor cells in the control group without peptide injection proliferated at both the right and left flanks, and the tumor volumes of the control group were much lager than those of the experimental group. 
       EXAMPLE 10  
     Experimental Group 
       [0100]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 1 was injected into nude mice. 
         [0101]    Nude mice were injected with an intravenous injection of peptide (2 mM, 100 μl) via tail veins per week for 3 consecutive weeks, followed by inoculating prostatic epithelial cells PZ-HPV-7 (2 million cells/100 μl medium) at both the right and left flanks on the 20 th  day and the 90 th  day. The tumor volumes (mm 3 ) were observed daily during the whole experiment. The result is shown in  FIG. 10A , which is a curve representing the tumor volumes of mice. 
       Control Group 
       [0102]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group was substituted with H 2 O (100 μl) in the present control group. The result is shown in  FIG. 10B , which is a curve representing the tumor volumes of mice. 
         [0103]    As shown in  FIG. 10A , when the nude mice were injected with peptide and followed by inoculating prostate tumor cells (experimental group), the growth and proliferation of tumor cells were not observed at both the left and right flanks However, as shown in  FIG. 10B , the implanted tumor cells in the control group without peptide injection were proliferated at both the right and left flanks. 
         [0104]    Hence, the zinc finger-like peptide can be used to treat prostate cancer, terminate the growth of tumor cells, and obtain the purpose of cancer prevention. 
       EXAMPLE 11  
     Control Group 
       [0105]    The process of the present control group was the same as that of the experimental group, except that the zinc finger-like peptide of the experimental group was substituted with H 2 O (100 μl) in the present control group. The result is shown in  FIG. 11A , which is a curve representing the tumor volumes of mice. 
       Experimental Group 1 
       [0106]    In the present experimental group, zinc finger-like peptide with sequence shown in SEQ ID NO: 1 was injected into nude mice. 
         [0107]    Nude mice were injected with an intravenous injection of peptide (2 mM, 100 μl) via tail veins per week for 3 consecutive weeks, followed by inoculating malignant glioma U87-MG cells (2 million cells/100 μl medium) at both the right and left flanks 1 month later. The tumor volumes (mm 3 ) were observed daily during the whole experiment. The result is shown in  FIG. 11B , which is a curve representing the tumor volumes of mice. 
       Experimental Group 2 
       [0108]    The process of the present control group was the same as that of the experimental group 1, except that the concentration of the zinc finger-like peptide is 4 mM. The result is shown in  FIG. 11C , which is a curve representing the tumor volumes of mice. 
         [0109]    As shown in  FIG. 11A  to  FIG. 11C , when the nude mice were injected with peptide and followed by inoculating brain tumor cells (experimental groups 1 and 2), the growth and proliferation of tumor cells were slower than that observed in the control group. In addition, the suppression on tumor cell growth was getting significant as the concentration of the zinc finger-like peptide increased. 
         [0110]    The aforementioned results indicate that the zinc finger-like peptide or the zinc finger-like peptide expression plasmid can inhibit the growth and the proliferation of tumor cells, and thus has potential for cancer treatment and prevention. 
         [0111]    Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.