Patent Description:
Human hair is formed in hair follicles. There are papillae in the hair follicles, small blood vessels are distributed in the papillae to supply nutrients necessary for hair growth, and sebaceous glands are distributed on the upper ends of side surfaces of the papillae to secrete sebum to protect the hair. The dermal papilla regulates hair growth and is the site where male hormones act in male-pattern hair loss. The hair matrix is a site where cell division occurs under the control of the dermal papilla and hair grows.

The main factor of male hair loss is due to the effect of abnormal hormones. At puberty, sex hormones are actively secreted and the secondary sexual character appears. These changes are caused by sex hormones, i.e., androgens (male hormones) and estrogens (female hormones). Androgens develop body hair under the eyebrows, and estrogen mainly promotes hair growth. For men, hair loss is due to excessive secretion of androgens which results in inhibition of the action of estrogen by the excessively secreted androgens.

Specifically, steroid <NUM>-alpha reductase is involved in the male hair loss mechanism by male hormones, and steroid <NUM>-alpha reductase is a main enzyme that reduces testosterone, which is a male hormone, to DHT (dihydrotestosterone). The resulting DHT is known to bind to an androgen receptor to thereby regulate hair growth in the hair follicles and be involved in the proliferation of sebaceous glands.

The androgen receptor is a male hormone (androgen) receptor and is known to be capable of binding to both testosterone and DHT, but have a stronger binding affinity with DHT. It is known that the inhibition of steroid <NUM>-alpha reductase and an androgen receptor increases hair growth factors and induces hair growth, whereas the activation of steroid <NUM>-alpha reductase and an androgen receptor inhibits hair growth, resulting in the occurrence of hair loss (<NPL>; <NPL>; <NPL>).

There are two types of steroid <NUM>-alpha reductase: type <NUM> and type <NUM>. Steroid <NUM>-alpha reductase type <NUM> is mainly distributed throughout the skin, especially in the sebaceous glands, and steroid <NUM>-alpha reductase type <NUM> is mainly distributed around the dermal papilla of the hair follicles and in the outer root sheath. In the early stage of drug development, hair loss therapeutic agents targeting only steroid <NUM>-alpha reductase type <NUM> have mainly been developed, but therapeutic agents for inhibiting both steroid <NUM>-alpha reductase type <NUM> and type <NUM> have recently been developed since the type <NUM> also has been found to affect hair growth.

Among these, finasteride may be used as a drug for inhibiting steroid <NUM>-alpha reductase type <NUM>. Finasteride was originally developed as a therapeutic agent for benign prostatic hypertrophy, it has been approved by the FDA and the Korean Food and Drug Administration as a male pattern hair loss therapeutic agent since finasteride was confirmed to promote hair growth in patients administered. Dutasteride is known to be a therapeutic ingredient that inhibits both steroid <NUM>-alpha reductase type <NUM> and type <NUM>. Drugs which bind to the androgen receptor and thus acts as an antagonist that hinders the binding between the androgen receptor and DHT are called anti-androgen drugs, and as these anti-androgen drugs, Cimetidine, Spironolactone, Flutamide, Cyproterone acetate, and the like are known.

However, these therapeutic ingredients have problems such as sexual dysfunction, fatigue appeal, and the like, and the use thereof is limited in women of childbearing age. These may cause fetal malformations when exposed to pregnant women. Therefore, there is a need to develop a therapeutic agent for hair loss without such side effects.

Under these technical backgrounds, the inventors of the present invention confirmed that a novel RNAi drug with minimal side effects developed using siRNA for inhibiting the expression of the androgen receptor (AR) gene was able to exhibit a desired effect of preventing or treating hair loss, and thus completed the present invention.

<CIT> discloses several asymmetric siRNAs specifically binding to mRNA of the human androgen receptor encoding gene. In particular, siRNAs AR-<NUM> to AR-<NUM> consist of a sense strand having a length of <NUM> nucleotides which comprises SEQ ID NO:<NUM> of the present application and an antisense strand having a length of <NUM> nucleotides which comprises SEQ ID NO:<NUM> of the present application, wherein the <NUM>'-terminus of the sense strand and the <NUM>'-terminus of the antisense strand form a blunt end. Said siRNAs inhibit expression of the human androgen receptor mRNA.

It is an object of the present invention to provide asymmetric shorter duplex siRNA (asiRNA) specifically binding to an AR-encoding gene.

It is another object of the present invention to provide a composition for preventing or treating hair loss which comprises the asiRNA, or a method of preventing or treating hair loss.

To achieve the above object, the present invention provides siRNA specifically binding to mRNA of an androgen receptor (AR)-encoding gene having SEQ ID NO: <NUM> and comprising a sense strand consisting of the sequence of SEQ ID NO: <NUM> and an antisense strand complementary to the sense strand and consisting of the sequence of SEQ ID NO: <NUM>, wherein a <NUM>'-terminus of the sense strand and a <NUM>'-terminus of the antisense strand form a blunt end.

The present invention also provides a composition for use in a therapeutic method of preventing or treating hair loss which comprises the siRNA as defined above.

The present invention also provides a non-therapeutic use of a composition comprising the siRNA as defined above for preventing or treating hair loss.

Unless otherwise defined, all technical and scientific terms as used herein have the same meanings as those commonly understood by one of ordinary skill in the art to which the present invention pertains. Generally, the nomenclature used herein is well known and commonly used in the art.

Accordingly, the present invention relates to siRNA specifically binding to mRNA of an androgen receptor (AR)-encoding gene having SEQ ID NO: <NUM> and comprising a sense strand consisting of the sequence of SEQ ID NO: <NUM> and an antisense strand complementary to the sense strand and consisting of the sequence of SEQ ID NO: <NUM>, wherein the <NUM>'-terminus of the sense strand and the <NUM>'-terminus of the antisense strand form a blunt end.

The AR-encoding gene has mRNA Accession Number: NM_001011645. <NUM> and includes a sequence having SEQ ID NO: <NUM>.

In the present invention, siRNA is a concept including all substances having a general RNA interference (RNAi) action. RNAi is an intracellular mechanism for gene regulation that was first found in Caenorhabditis elegans in <NUM>, and as for the mechanism action, it is known that the antisense strand of a double-stranded RNA introduced into a cell complementarily binds to mRNA of a target gene to thereby induce the degradation of the target gene. In this regard, small interfering RNA (siRNA) is one of the methods of inhibiting gene expression in vitro. siRNAs of <NUM>-<NUM> bp in length are theoretically capable of performing selective inhibition against almost all genes, and thus can be developed as therapeutic agents for various gene-related diseases such as cancer, viral infection, and the like, and is the new candidate drug development technology that has recently drawn the most attention. The first attempt to perform in vivo treatment using siRNA in mammals was in mid-<NUM>, and since then, there have been numerous reports of in vivo treatment thanks to many attempts for application studies.

However, contrary to the possibility of in vivo treatment, side effects and disadvantages of siRNA have continually been reported. To develop an RNAi-based therapeutic agent, challenges such as: <NUM>) the absence of an effective delivery system; <NUM>) the off-target effect; <NUM>) the induction of immune responses; and <NUM>) intracellular RNAi mechanism saturation need to be overcome. Although siRNAs are an effective method of directly regulating target gene expression, it is difficult to develop a therapeutic agent using such siRNAs due to the above-described problems. With regard thereto, the applicant of the present invention has developed an asymmetric shorter duplex siRNA (asiRNA) structure-related technology (<CIT>). asiRNA is an asymmetric RNAi-inducing structure having a shorter double helix length than the <NUM>+<NUM> structure of existing siRNAs. asiRNA is a technology that has overcome known problems with the existing siRNA structure technology, such as the off-target effect, RNAi mechanism saturation, immune responses by TLR3, and the like, and accordingly is used for the development of a new RNAi drug with minimal side effects.

Based on this, the present invention provides asymmetric siRNA including a sense strand having a length of <NUM>-<NUM> nt and an antisense strand complementary to the sense strand and having a length of <NUM> nt or more, as defined in the claims and thus the siRNA according to the present invention may stably maintain high delivery efficiency without incurring problems such as the off-target effect, RNAi mechanism saturation, immune responses by TLR3, and the like, and may inhibit the expression of an androgen receptor target gene.

In the present invention, the term "sense strand" refers to a polynucleotide having the same nucleic acid sequence as that of the AR-encoding gene, and has a length of <NUM>-<NUM> nt. The sense strand is as defined in claim <NUM>.

The inventors of the present application selected, as target gene, an androgen receptor, which plays a major role in inhibiting the synthesis of proteins required for hair follicle growth in male pattern hair loss and inducing hair loss by reducing the dermal papilla. As a result of screening <NUM> or more siRNAs targeting each target gene and selecting siRNAs with excellent inhibitory efficiency from among the same, it was confirmed that siRNA comprising a sense strand having SEQ ID NO: <NUM> and an antisense strand complementary to the sense strand and consisting of SEQ ID NO: <NUM>, effectively reduced the expression of mRNA of the AR-encoding gene.

The <NUM>'-terminus of the sense strand and the <NUM>'-terminus of the antisense strand form a blunt end. For example, the <NUM>'-terminus of the antisense strand may include, for example, an overhang of <NUM> nt, <NUM> nt, <NUM> nt, <NUM> nt, <NUM> nt, <NUM> nt, <NUM> nt, or <NUM> nt.

In some embodiments, the sense strand or antisense strand of the siRNA may include one or more chemical modifications.

General siRNAs are unable to penetrate through the cell membrane due to reasons such as high negative charge, high molecular weight, and the like, and are rapidly degraded and eliminated in the blood, making it difficult to deliver an amount sufficient for RNAi induction to an actual target site. Currently, in the case of in vitro delivery, numerous high-efficiency delivery methods using cationic lipids and cationic polymers have been developed, but in vivo delivery of siRNA as efficient as in vitro delivery thereof is difficult, and siRNA delivery efficiency is reduced by interactions between various proteins present in the living body.

Therefore, the inventors of the present application developed cell penetrating asiRNA (cp-asiRNA) having self-transfer ability that enables effective intracellular delivery without a separate delivery vehicle by introducing a chemical modification into an asymmetric siRNA structure.

The chemical modification in the sense strand or the antisense strand may comprise, for example, at least one selected from the group consisting of:.

In one embodiment, the chemical modification in the sense or antisense strand may be substitution of an -OH group at the <NUM>' carbon position of a sugar structure in a nucleotide with -CH<NUM> (methyl), modification of a nucleotide bond into phosphorothioate, or cholesterol binding. This may enhance the in vivo stability of siRNA.

When the -OH group at the <NUM>' carbon position of a sugar structure is substituted with -CH<NUM> (methyl) or when the nucleotide bond is modified into a phosphorothioate, resistance to nucleases may be increased, and binding to the cell membrane via cholesterol binding may facilitate the intracellular delivery of siRNA.

In particular, the chemical modification may include at least one modification selected from the group consisting of: a modification in which an -OH group at the <NUM>' carbon position of a sugar structure in the <NUM>'- or <NUM>'-terminus nucleotide of the sense strand is substituted with -CH<NUM> (methyl); a modification in which an -OH group at the <NUM>' carbon position of a sugar structure in two or more nucleotides of the sense strand or the antisense strand is substituted with -CH<NUM> (methyl); a modification of <NUM>% or more of nucleotides bonds in the sense or antisense strand to phosphorothioate; and cholesterol binding at the <NUM>'-terminus of the sense strand.

With regard to the modification in which an -OH group at the <NUM>' carbon position of a sugar structure in a nucleotide is substituted with -CH<NUM> (methyl), the -OH group at the <NUM>' carbon position of the sugar structure in a nucleotide positioned at the <NUM>'-terminus of the sense strand may be substituted with - CH<NUM> (methyl). In addition, a <NUM>'-O-methylated nucleoside, in which an -OH group at the <NUM>' carbon position of a sugar structure is substituted with -CH<NUM> (methyl), may be continuously or discontinuously included in a <NUM>'-terminus to <NUM>'-terminus direction of the sense strand. <NUM>'-O-methylated nucleosides and unmodified nucleosides may be alternately included in the sense strand. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> consecutive <NUM>'-O-methylated nucleosides and unmodified nucleosides may be alternately included in the sense strand. For example, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, <NUM> to <NUM>, or <NUM><NUM>'-O-methylated nucleosides may be present in the sense strand.

<NUM>'-O-methylated nucleosides may be continuously or discontinuously included in a <NUM>'-terminus to <NUM>'-terminus of the antisense strand. <NUM>'-O-methylated nucleosides and unmodified nucleotides may be alternately included in the antisense strand. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> consecutive <NUM>'-O-methylated nucleosides and unmodified nucleosides may be alternately included in the antisense strand. For example, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or <NUM>-<NUM><NUM>'-O-methylated nucleosides may be present in the antisense strand.

With regard to the modification of a nucleotide bond to a phosphorothioate, at least <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of bonds between ribonucleotides in the sense strand may be modified into phosphorothioate. In some embodiments, all (<NUM>%) of the bonds between ribonucleotides in the sense strand may be modified into phosphorothioate.

At least <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the bonds between ribonucleotides in the antisense strand may be modified into phosphorothioate. In some embodiments, a total (<NUM>%) of the bonds between ribonucleotides in the antisense strand may be modified into phosphorothioate.

In another aspect, the present invention relates to a composition for the use in a therapeutic method of prevention or treatment of hair loss, which comprises the siRNA or to the non-therapeutic use of a composition comprising the siRNA as defined above for the prevention or treatment of hair loss.

The term "treatment" as used herein means reducing the symptoms of hair loss or the severity of hair loss in a subject to which the composition is administered or preventing the same from being aggravated, and in some cases may include the progression of hair growth. The term "prevention" as used herein means preventing or delaying the initiation of hair loss, or reducing the possibility of developing hair loss.

The composition may further be prepared including one or more pharmaceutically acceptable carriers, in addition to the siRNA as an active ingredient. The pharmaceutically acceptable carrier has to be compatible with the active ingredient of the present invention, and may be one selected from physiological saline, sterile water, Ringer's solution, buffered saline, dextrose solution, maltodextrin solution, glycerol, ethanol, and a mixture of two or more of these components. If necessary, the composition may include other general additives such as an antioxidant, a buffer, a bacteriostatic agent, and the like. In addition, the composition may be formulated into an injectable preparation such as an aqueous solution, a suspension, an emulsion, or the like by further adding a diluent, a dispersing agent, a surfactant, a binder, and a lubricant. In particular, the composition may be formulated into a lyophilized preparation. The lyophilized preparation may be formulated using a method commonly used in the art to which the present invention pertains, and a stabilizer for lyophilization may also be added.

An administration method of the composition for the use of the invention may be determined by one of ordinary skill in the art on the basis of general symptoms of patients and the severity of diseases. In addition, the composition may be formulated into various forms such as powders, tablets, capsules, liquids, injections, ointments, syrups, and the like, and may also be provided in a unit dosage or multiple dosage container, for example, sealed ampoules and vials, and the like.

The composition for the use of the invention may be administered orally or parenterally. The administration route of the composition for the use according to the present invention may be, but is not limited to, for example, oral administration, intravenous administration, intramuscular administration, intraarterial administration, intramedullary administration, intradural administration, intracardiac administration, transdermal administration, subcutaneous administration, intraperitoneal administration, intestinal administration, sublingual administration, or topical administration. The dosage of the composition for the use according to the present invention varies depending on the body weight, age, gender, and health condition of a patient, diet, administration time, administration method, excretion rate, severity of disease, or the like, and may be easily determined by those of ordinary skill in the art. In addition, for clinical administration, the composition for the use of the present invention may be formulated into a suitable form using known techniques.

Configurations included therapeutic or non-therapeutic use in the prevention or treatment method according to the present invention are the same as those included in the aforementioned embodiments, and thus the foregoing description may be equally applied to the prevention or treatment method.

To obtain high-efficiency RNAi-inducing double-stranded nucleic acid molecules targeting AR, the target sequence of the AR gene was selected and then asiRNA was designed. The asiRNA structure is different from that of generally known siRNAs, and thus when the nucleotide sequences of asiRNA are designed using a general siRNA design program, it may be somewhat difficult to design an optimized asiRNA. Therefore, asiRNA was constructed by the following method. An NCBI db search was used to obtain information on the AR gene (mRNA Accession Number: NM_001011645. <NUM>), which is the target gene pertaining to male pattern hair loss (androgenetic hair loss). For subsequent animal experiments, nucleotide sequences with at least <NUM>% homology to that of mice were secured, and then <NUM> asiRNAs were designed according to a design method such as the exclusion of sequences having a GC content of <NUM>-<NUM>% and <NUM> or more G or C consecutive bases, and then synthesized by OliX Inc. The synthesized sense and antisense strand RNA oligonucleotides were annealed at <NUM> for <NUM> minutes through incubation at <NUM> for <NUM> hour, and the asiRNA annealed by <NUM>% polyacrylamide gel electrophoresis (PAGE) was confirmed using a UV transilluminator.

To confirm gene inhibitory efficiency at the mRNA level, the <NUM> selected asiRNAs were transfected into an A549 cell line at a concentration of <NUM>, and qRT-PCR was performed to measure the expression level of AR mRNA.

The A549 cell line was cultured in Dulbecco's Modified Eagle's Medium (DMEM, Gibco) containing <NUM>% fetal bovine serum (FBS, Gibco) and <NUM> units/ml of penicillin <NUM>µg/ml of streptomycin. A549 cells were seeded in a <NUM>-well plate at a density of <NUM> x <NUM><NUM> cells/well, and a transfection experiment was conducted using asiRNA (<NUM>, OliX Pharmaceuticals Inc. ) and RNAiMAX (<NUM>µl/ml, Invitrogen Inc. ) in Opti-MEM (a total volume of <NUM>µl) in accordance with Invitrogen's protocol. After <NUM> hours, RNA purification and cDNA synthesis were performed in accordance with a basic protocol provided by TOYOBO SuperPrep, the expression level of the AR gene was examined with an AR TaqMan probe (T) using a Bio-Rad CFX-<NUM> machine. First, <NUM> kinds of asiRNA from among the <NUM> kinds of asiRNA were subjected to an asiRNA screening experiment and the <NUM> top-ranked asiRNAs (in Table <NUM>, No. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) were selected on the basis of inhibitory efficacy against the expression of the target gene, and the <NUM> selected asiRNAs and the <NUM> remaining asiRNAs (in Table <NUM>, Nos. <NUM> to <NUM>) were subjected to a secondary asiRNA screening experiment (see <FIG>).

The <NUM> top-ranked asiRNAs (in Table <NUM>, No. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) having gone through secondary asiRNA screening were selected on the basis of inhibitory efficacy against the expression of the target gene, and an experiment for confirming the inhibitory effect of the <NUM> selected asiRNAs against AR expression at the protein level was performed. A549 cells were seeded in a <NUM>-well plate at a density of <NUM> x <NUM><NUM> cells/well, and then a transfection experiment was conducted using asiRNA (<NUM>, OliX Pharmaceuticals Inc. ) and RNAiMAX (<NUM>µl/ml, Invitrogen Inc. ) in Opti-MEM (a total volume of <NUM>) in accordance with Invitrogen's protocol. After <NUM> hours, the cells were lysed using a mammalian protein extraction buffer (GE healthcare), and then proteins were quantified using a Bradford assay. <NUM>µg of the protein of each sample was electrophoresed using <NUM>% SDS-PAGE at <NUM> V for <NUM> minutes and at <NUM> V for <NUM> hour, and then transferred onto a PVDE membrane (Bio-Rad) at <NUM> mA for <NUM> hour. After transfer, the membrane was blocked in <NUM>% skim milk for <NUM> hour and allowed to react with AR antibody (ABcam, ab133273) at a ratio of <NUM>:<NUM> for <NUM> hours. The next day, the resulting membrane was allowed to react with anti-Rabbit HRP (Santa Cruz) at a ratio of <NUM>:<NUM> for <NUM> hour, and then the expression levels of the AR protein were compared with each other using ChemiDoc (Bio-Rad). From the results, the <NUM> top-ranked asiRNAs (No. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) capable of more effectively inhibiting AR protein expression were selected (see <FIG>).

The <NUM> top-ranked asiRNA candidates (in Table <NUM>, No. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) having gone through asiRNA screening were selected on the basis of inhibitory efficacy against the expression of the target gene, and an experiment for confirming the inhibitory effects of the <NUM> selected asiRNA candidates against AR expression at the mRNA and protein levels and a lower concentration (<NUM>) was conducted. A549 cells were seeded in a <NUM>-well plate at a density of <NUM> x <NUM><NUM> cells/well, and a transfection experiment was conducted using asiRNA and RNAiMAX (<NUM>µl/ml, Invitrogen Inc. ) in Opti-MEM (a total volume of <NUM>) in accordance with Invitrogen's protocol. After <NUM> hours, total RNA was extracted using TRIzol (TaKaPa), and then cDNA was synthesized using a high-capacity cDNA reverse transcription kit (Applied Biosystems), and the expression level of the AR gene was examined using power SYBR green PCR master Mix (Applied Biosystems), the primers shown in Table <NUM> below, and a StepOne real-time PCR system.

In addition, A549 cells were seeded in a <NUM>-well plate at a density of <NUM> x <NUM><NUM> cells/well, and a transfection experiment was conducted using asiRNA and RNAiMAX (<NUM>µl/ml, Invitrogen Inc. ) in Opti-MEM (a total volume of <NUM>) in accordance with Invitrogen's protocol. After <NUM> hours, the cells were lysed using a mammalian protein extraction buffer (GE healthcare), and then proteins were quantified using a Bradford assay. <NUM>µg of the protein of each sample was electrophoresed using <NUM>% SDS-PAGE at <NUM> V for <NUM> minutes and at <NUM> V for <NUM> hour, and then transferred onto a PVDE membrane (Bio-Rad) at <NUM> mA for <NUM> hour. After transfer, the membrane was blocked in <NUM>% skim milk for <NUM> hour and allowed to react with AR antibody (ABcam, ab133273) at a ratio of <NUM>:<NUM> for <NUM> hours. The next day, the resulting membrane was allowed to react with anti-Rabbit HRP (Santa Cruz) at a ratio of <NUM>:<NUM> for <NUM> hour, and then the expression levels of the AR protein were compared with each other using ChemiDoc (Bio-Rad). As the result of the experiment for the <NUM> selected asiRNAs, it was confirmed that asiRNA #<NUM>, <NUM>, and <NUM> exhibited gene inhibitory efficiency of <NUM>% or higher efficiently even at a concentration of <NUM> (see <FIG>).

AR cp-asiRNAs (a total of <NUM> kinds) were designed by applying three modification patterns to <NUM> kinds of asiRNA targeting AR according to the number and position of <NUM>'OMe (methyl), phosphorothioate bonds (PS), and cholesterol, and then synthesized by Dharmacon. cp-asiRNA enhances endocytosis efficiency and stability, and thus may penetrate through the cell membrane with high efficiency without the aid of a delivery vehicle to thereby inhibit the expression of the target gene. The synthesized sense and antisense strand RNA oligonucleotides were annealed at <NUM> for <NUM> minutes through incubation at <NUM> for <NUM> hour, and cp-asiRNAs annealed by <NUM>% polyacrylamide gel electrophoresis (PAGE) were confirmed using a UV transilluminator.

The inhibitory effects of the <NUM> kinds of cp-asiRNA shown in Table <NUM> against AR expression were examined. An A549 cell line was incubated with <NUM> or <NUM> of each of the <NUM> cp-asiRNAs in Opti-MEM media for <NUM> hours, and then the media were replaced with Dulbecco's Modified Eagle's Medium (Gibco) containing <NUM>% fetal bovine serum (Gibco) and <NUM> units/ml penicillin <NUM>µg/ml streptomycin, and after <NUM> hours, AR expression was examined at the mRNA level. As the result of repeatedly conducting four experiments, it was confirmed that the <NUM> kinds of AR cp-asiRNA exhibited gene inhibitory efficiency of <NUM>% at a concentration of <NUM> (see <FIG>).

Under the same experimental conditions, the inhibitory effects of the <NUM> kinds of cp-asiRNA against AR expression were examined at the protein level in an A549 cell line. The A549 cell line was incubated with <NUM> or <NUM> of each of the <NUM> cp-asiRNAs in Opti-MEM media for <NUM> hours, and then the media were replaced with Dulbecco's Modified Eagle's Medium (Gibco) containing <NUM>% fetal bovine serum (Gibco) and <NUM> units/ml penicillin <NUM>µg/ml streptomycin, and after <NUM> hours, AR expression was examined at the protein level. Among them, cp-asiRNA #<NUM>(<NUM>,<NUM>) (invention), #<NUM>(<NUM>,<NUM>) (<NUM>,<NUM>) (<NUM>,<NUM>) (referential), and #<NUM>(<NUM>,<NUM>) (<NUM>,<NUM>) (referential) exhibited target gene protein expression inhibitory efficiency of <NUM>% or higher at a concentration of <NUM> on the basis of the band intensity of a no treatment (NT) sample and a <NUM>/<NUM> NT sample (see <FIG>).

An androgen receptor-encoding gene, which plays a major role in inhibiting the synthesis of proteins required for hair follicle growth in male pattern hair loss and inducing hair loss by reducing the size of the dermal papilla, was selected as target genes, and asymmetric siRNA with high inhibitory efficiency against the target gene was selected. siRNA according to the present invention exhibits the ability to inhibit the expression of the target gene for an androgen receptor, and thus may be effectively used as an agent for preventing or treating hair loss.

Claim 1:
siRNA specifically binding to mRNA of an androgen receptor (AR)-encoding gene having SEQ ID NO: <NUM> and comprising a sense strand consisting of the sequence of SEQ ID NO: <NUM> and an antisense strand complementary to the sense strand and consisting of the sequence of SEQ ID NO: <NUM>,
wherein a <NUM>'-terminus of the sense strand and a <NUM>'-terminus of the antisense strand form a blunt end.