CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims, under 35 U.S.C. § 119, the priority of Korean Patent Application No. 10-2019-0085912 filed on Jul. 16, 2019 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

SEQUENCE LISTING

This application contains a Sequence Listing submitted via EFS-Web and hereby incorporated by reference in its entirety. The Sequence Listing is named SEQCRF-CHIP-156-KIST.txt, created on Nov. 6, 2019, and 12,883 bytes in size.

TECHNICAL FIELD

The present disclosure relates to an immunoregulatory protein-siRNA complex having anticancer activity, more particularly to an immunoregulatory protein-siRNA complex which induces death of cancer cells by inhibiting the immune escape mechanism of the cancer cells, thereby enhancing phagocytosis by macrophages.

BACKGROUND

Cancer has been the number one cause of death over the past few years. A variety of technologies have been developed to treat cancer. For example, anticancer drugs such as doxorubicin or paclitaxel are effective in inhibiting the growth of cancer cells or killing them. However, the anticancer drugs exhibit toxicity to cancer cells and normal cells alike. Therefore, despite their anticancer effects, they are not suitable to be used for treatment due to severe side effects.

In order to solve this problem, development of anticancer drugs using siRNAs is actively ongoing. siRNA is known to interfere with the expression of specific target genes. Therefore, it is expected that a drug having superior anticancer effect with minimized side effect can be developed if the function of siRNA is utilized. In this regard, siRNAs targeting oncogenes, immune cells and various genes such as tumor microenvironment regulators have been developed. However, siRNA is disadvantageous in that it cannot exist stably in vivo on its own and the effect of delivery into cells is very low.

To solve this problem, nanoparticles using various materials such as liposome, chitosan nanoparticle, PLGA (poly(lactic-co-glycolic acid)), etc. have been studied as a carrier for delivering siRNA. Although the nanoparticles can improve stability and delivery as compared to when siRNA is used alone, they may induce toxicity in vivo because the nanoparticles themselves are foreign materials. In addition, they are problematic in that the efficiency of gene transfection is very low because they are degraded by endosomes/lysosomes after being introduced into cells. Accordingly, the recent researches are focused on various substances existing in the body (proteins, exosomes, antibodies, etc.) as carriers in order to effectively deliver siRNA into cancer cells with reduced toxicity. Despite these efforts, commercialization is not achieved yet due to the problems of delivery efficiency and mechanism. For example, the exosome is limited in effectively delivering a drug because it is easily degraded and broken down in vivo, and the antibody has the problem that it cannot effectively deliver siRNA into cells because of relatively large size.

REFERENCES OF THE RELATED ART

Patent Documents

(Patent document 1) Patent document 1. Korean Patent Registration No. 10-1977532.

(Patent document 2) Patent document 2. Korean Patent Publication No. 10-2018-0134424.

SUMMARY

The present disclosure is directed to providing a fusion protein-siRNA complex having superior anticancer activity, which is delivered specifically into cancer cells via cancer cell receptors and enhances phagocytosis by macrophages by doubly inhibiting the immune escape mechanism of the cancer cells.

The present disclosure is also directed to providing a composition for treating or preventing cancer, which contains the fusion protein-siRNA complex as an active ingredient.

The present disclosure provides a fusion protein-siRNA complex, which contains an immunoregulatory fusion protein (A); and a siRNA (B), wherein the immunoregulatory fusion protein (A) is one in which SIPRα protein is bound to a linker peptide cleaved by a lysosomal degradative enzyme.

The SIPR protein may be represented by any one of SEQ ID NOS: 3, 5, 7, 9 and 11, and the linker peptide may be represented by SEQ ID NO: 13.

The immunoregulatory fusion protein (A) may be represented by SEQ ID NO: 1.

The siRNA may be CD47 siRNA.

The siRNA represented by SEQ ID NO: 17 or 18.

The fusion protein-siRNA complex may have an average molecular weight of 20-60 kDa.

The present disclosure also provides a pharmaceutical composition for treating or preventing cancer, which contains the fusion protein-siRNA complex as an active ingredient.

The cancer may be one or more selected from a group consisting of brain tumor, spinal cord tumor, retinoblastoma, oral cancer, nasal cavity cancer, paranasal sinus cancer, pharyngeal cancer, laryngeal cancer, neck cancer, head and neck cancer, melanoma, skin cancer, breast cancer, thyroid cancer, malignant adrenal tumor, endocrine cancer, lung cancer, pleural tumor, respiratory tract cancer, esophageal cancer, stomach cancer, small intestine cancer, colon cancer, anal cancer, liver cancer, biliary tract cancer, pancreatic cancer, kidney cancer, bladder cancer, prostate cancer, testicular cancer, penile cancer, cervical cancer, endometrial cancer, choriocarcinoma, ovarian cancer, blood cancer including acute/chronic leukemia, malignant lymphoma and multiple myeloma, bone tumor, soft tissue tumor, childhood leukemia and childhood cancer.

The present disclosure also provides a method for treating cancer in a human or a non-human animal, comprising administering to a subject in need of such treatment a therapeutically effective amount of a fusion protein-siRNA complex.

The fusion protein-siRNA complex according to the present disclosure is absorbed into cancer cells via receptors specifically overexpressed in the cancer cells, and has maximized anticancer activity by doubly regulating the immune defense function of the cancer cells. In addition, it is advantageous in that it has low cytotoxicity and few side effects due to high delivery efficiency.

Also, it is less risky to the body because it causes the cancer cells to be removed by the autoimmunity (macrophage phagocytosis) of the patient by inhibiting the immunity of the cancer cells, rather than directly inducing the death of the cancer cells.

