CN115636868A - Cationic nano-carrier-based polypeptide delivery system and preparation method and application thereof - Google Patents

Abstract

The invention discloses a polypeptide delivery system based on a cationic nano-carrier, which comprises a cationic nano-carrier and a stable polypeptide inhibitor; the sequence of the cationic nano-carrier is Fmoc-RRMEHRMEW, and two Mets are connected through 1, 2-di (bromomethyl) benzene to form cyclic peptide with sulfonium salts at two ends; the amino acid sequence of the stable polypeptide inhibitor is as follows: cyclo (isoD-NS-Dap) -D-W-N-E-P-A-E-E-W-G-N-W-V-D-E. The invention also provides a preparation method of the polypeptide delivery system and application of the polypeptide delivery system in preparing a medicament for interfering formation of an MTDH/SND1 complex and treating triple negative breast cancer. The polypeptide delivery system has good cell penetrability and low toxicity, can effectively target SND1 and interfere the formation of MTDH/SND1 compound in tumor cells after entering the cells, and shows better anti-tumor activity in triple negative breast cancer cells.

Description

Cationic nano-carrier-based polypeptide delivery system and preparation method and application thereof

Technical Field

The invention belongs to the field of pharmaceutical chemistry, and relates to a polypeptide delivery system, in particular to a stable polypeptide delivery system targeting MTDH/SND1 based on a cationic nanocarrier, and a preparation method and application thereof.

Background

The polypeptide is used as an endogenous molecule of an organism, and has high biocompatibility and low cytotoxicity. Meanwhile, the polypeptide molecules are modified by various polypeptide stabilizing methods, so that the biophysical and chemical properties of the linear polypeptide can be improved, and the modified polypeptide molecules can be used as various bioactive materials for cell culture, tissue engineering, drug delivery and the like. The delivery system based on the cationic polypeptide becomes a new non-viral vector, and has the advantages of better biocompatibility, design diversity, easy synthesis, lower immune reaction risk and the like compared with polymer and lipid vectors.

The previous group of subjects rationally designed a 9 amino acid sulfonium salt polypeptide wpc carrier, where electropositivity resulting from sulfonium modification at the side chain of the polypeptide Met enhances the electrostatic interaction between the polypeptide and the nucleic acid molecule, and where elimination of electropositivity at high GSH concentrations facilitates release of the nucleic acid molecule for nucleic acid delivery.

A series of researches show that the wpc polypeptide carrier and siRNA are copolymerized to form nanoparticles, the nanoparticles have certain inhibition effect on growth and proliferation of HeLa cells, the HeLa cells are blocked in a G2 phase, and the transfection efficiency is similar to that of commercial transfection reagents Lipo-2000 and Oligo. And the wpc polypeptide carrier-siRNA copolymerized nanoparticles also have a certain proliferation inhibition effect on HeLa xenograft tumors on a nude mouse level, and have no obvious biological toxicity on each organ tissue of mice during administration. In addition to delivering nucleic acids, wpc vectors hold great potential for use in the delivery of polypeptides and proteins.

MTDH and SND1 can interact to form a functional complex, mediating the development of cancer. Tryptophan residues 394 and 401 of MTDH can extend into two hydrophobic pockets of SND1 protein, and the binding of these two pockets also plays a crucial role in the binding of MTDH to SND 1.

Based on the two pockets, the original sequence is mutated (mutation of Ala at position 396 into Glu further enhances the binding with the SND1 protein), and the original sequence is subjected to cyclization modification by a cross-linking and loop-closing method based on terminal aspartic acid so as to maintain the binding conformation of the original sequence in a complex system, thereby improving the physicochemical properties of the polypeptide, such as binding, cellular uptake, serum stability and the like.

Since the developed stable polypeptide contains more negative amino acids, it is hoped that the stable polypeptide is assisted by a cationic carrier to enter cells for playing a role, a 9-amino acid sulfonium salt polypeptide wpc carrier developed by the subject group is introduced, and the wpc carrier is positively charged as a whole and has the application potential of carrying negative nucleic acid proteins or polypeptides to enter cells for playing a role. Based on the previous wpc, good curative effect is achieved on siRNA delivery, so that the cell uptake capacity of the polypeptide is improved by using a vector with positive electricity of the wpc, the administration concentration of the polypeptide is reduced, and the anti-tumor activity of the polypeptide in triple negative breast cancer cells is researched.

Disclosure of Invention

The invention provides a polypeptide delivery system based on a cationic nano-carrier, a preparation method and application thereof, and aims to solve the technical problem of poor effect of a medicine for treating triple negative breast cancer in the prior art.

The invention provides a cationic nanocarrier-based polypeptide delivery system (NS-E-cyc/wpc) comprising a strip of cationic nanocarriers (designated as wpc carrier) and a strip of stabilized polypeptide inhibitor (designated as NS-E-cyc polypeptide); the sequence of the cationic nano-carrier is Fmoc-RRMEHRMEW, and two Mets of the cationic nano-carrier are connected through 1, 2-di (bromomethyl) benzene to form cyclic peptide with sulfonium salts at two ends; the amino acid sequence of the stable polypeptide inhibitor is as follows: cyclo (isoD-NS-Dap) -D-W-N-E-P-A-E-E-W-G-N-W-V-D-E.

Further, in the polypeptide delivery system, the concentration of the cationic nano-carrier is

200-240 μ M, and the concentration of the stable polypeptide inhibitor is 20-40 μ M.

Furthermore, the structural formula of the cation nano carrier is shown as follows,

furthermore, the structural formula of the stable polypeptide inhibitor is shown as follows,

r is Ac, H or beta A-FITC.

The invention also provides a preparation method of the cationic nanocarrier-based polypeptide delivery system, which comprises the following steps:

1) A step of preparing a cationic nanocarrier:

a) Preparing oligopeptide solid-phase resin: loading target oligopeptide on MBHA resin by a solid phase synthesis method;

b) Preparation of sulfonium salt cyclopeptide wpc vector: after the methionine-containing linear polypeptide was synthesized on the solid phase, an appropriate amount of the resin was taken in an EP tube, and 1-2mL of TFA/TIPS/H was added ₂ O/EDT shear shakingReaction 1-2h, TFA, TIPS, H ₂ The volume ratio of O to EDT is 94;

c) Then dissolving the polypeptide in acetonitrile/water solution with the volume percentage concentration of 50% to form polypeptide solution with the concentration of 10mM, adding 1% by volume of formic acid into the polypeptide solution for acidification to enable the final pH to be equal to 3, simultaneously weighing 1.2 polypeptide equivalent 1, 2-bis (bromomethyl) benzene, dissolving the 1.2 polypeptide equivalent 1, 2-bis (bromomethyl) benzene by using one tenth of the volume of DMF (dimethyl formamide) as a solvent, adding the solution to the polypeptide solution, placing the solution in a shaking table for reaction, and purifying the solution by high performance liquid chromatography to obtain a wpc carrier;

the course of the above reaction is shown below,

2) A step of preparing a stable polypeptide inhibitor:

a) Preparing oligopeptide solid phase resin: loading target oligopeptide on MBHA resin by a solid phase synthesis method;

b) Preparation of compound I: the step is carried out on resin, and the target oligopeptide is subjected to the deprotection of Alloc and Allyl under the conditions of tetrakis (triphenylphosphine) palladium and N, N-dimethyl barbituric acid to obtain a compound I;

c) Preparation of compound II: performing ring closure reaction on the compound I in benzotriazole-1-yl-oxy tripyrrolidinyl phosphorus hexafluorophosphate, 1-hydroxybenzotriazole and N-methylmorpholine solution to generate a compound II;

d) Preparation of modified polypeptide: removing the Fmoc protecting group of the compound II by morpholine with the volume percentage concentration of 50%, and then directly acetylating or modifying FITC fluorescent dye;

the course of the above reaction is shown below,

3) Mixing a cationic nano-carrier and a stable polypeptide inhibitor in a cell culture medium, wherein the concentration of the cationic nano-carrier is 200-240 mu M, and the concentration of the stable polypeptide inhibitor is 20-40 mu M.

The invention also provides a cationic nano-carrier, the amino acid sequence of which is Fmoc-RRMEHRMEW, and two Mets are connected through 1, 2-di (bromomethyl) benzene to form cyclic peptide with sulfonium salts at two ends.

The invention also provides application of the cationic nano-carrier in preparation of negative electricity polypeptide drugs carrying the targeting MTDH/SND 1.

The invention also provides application of the polypeptide delivery system in preparation of a medicine for interfering formation of an MTDH/SND1 complex.

The invention also provides application of the polypeptide delivery system in preparing a medicament for treating triple negative breast cancer.

Based on previous researches, a stable polypeptide inhibitor based on terminal aspartic acid cyclization is obtained by selecting a sequence (DWNAPEAEEWGNWVDE) which is combined with SND1 in MTDH protein as a starting point from a crystal structure of MTDH/SND1 and combining with molecular docking technology, mutation, cyclization and other experimental means.

The invention builds a model based on main combination of polypeptide derived from an MTDH sequence and SND1 protein by an Autodock molecular docking method, and tries to explain a polypeptide-protein combination interface. In the original MTDH sequence, two tryptophans Trp394 and Trp403 can extend into two hydrophobic pockets of the SND1 protein, and play a crucial role in binding with the SND1 protein, and in addition, the C-terminal acidic amino acid also plays an important role. Therefore, the present invention mutates Ala at position 396 to Glu on the basis of Trp394 and Trp403 to enhance electrostatic interaction with SND1 protein to enhance binding. And performing terminal aspartic acid crosslinking cyclization on the basis of the cyclic amino acid sequence so as to maintain the secondary conformation of the polypeptide. Since the stabilized polypeptide developed by the present invention contains more negatively charged amino acids, a 9-amino acid sulfonium salt polypeptide wpc carrier developed by the subject group is introduced, and the whole wpc carrier is positively charged and can carry negatively charged nucleic acid protein or polypeptide into cells to play a role. Previous studies have also found that wpc has achieved good therapeutic effects on siRNA delivery, and therefore the present invention utilizes a vector positively charged with wpc to increase the cellular uptake capacity of a stable polypeptide, thereby reducing the administration concentration of the polypeptide and studying the antitumor activity of the polypeptide in triple negative breast cancer cells. Experiments prove that the polypeptide delivery system can effectively penetrate cells and effectively interfere the interaction of MTDH/SND1 protein. The polypeptide delivery system has low cytotoxicity, can effectively inhibit the growth and migration of triple negative breast cancer, induces G0/G1 cycle block of triple negative breast cancer cells, and brings new possibility for breast cancer treatment.

The invention provides a stable polypeptide delivery system targeting MTDH/SND1 based on a cationic nanocarrier, discloses a polypeptide (NS-E-cyc) with stable conformation through specific chemical modification (TD strategy), and also widens the application range of wpc cationic polypeptide carriers by assisting the polypeptide to enter cells through positively charged wpc nanocarriers (figure 1). A series of biological experiments prove that the stable polypeptide NS-E-cyc can remarkably enhance the cell uptake capacity of tumor cells after being mixed with a carrier, and can effectively target SND1 protein in the cells and interfere the formation of MTDH/SND1 protein complex, thereby inhibiting the growth and migration of triple-negative breast cancer cells and inducing cell cycle arrest. The TD strategy reserves the free amino group at the N end of the polypeptide, can be used for further chemical modification and is further applied to further structure optimization; such polypeptide delivery systems may be potential therapies for the treatment of triple negative breast cancer.

Compared with the prior art, the invention has remarkable technical progress. The existing cationic polypeptide carrier capable of carrying polypeptide or protein is quite limited, the wpc cationic polypeptide carrier has a simpler sequence, is easy to synthesize and modify, has enhanced positive electricity after sulfonium salt modification, and can be well assembled with negatively charged macromolecules so as to improve the cell penetration capacity.

Drawings

FIG. 1 is a schematic diagram of the present invention.

FIG. 2 fluorescence polarization results and binding constants of the polypeptides and SND1 protein are compared.

FIG. 3 shows a simulation of the crystal structure of the polypeptide and SND1 (PDB: 4 QMG).

Figure 4 cellular uptake capacity of polypeptide after mixing vector wpc with polypeptide.

FIG. 5 interference effect of polypeptide complex on intracellular MTDH/SND1 protein.

FIG. 6. Effect of polypeptide complexes on the proliferation, migration and cell cycle of triple negative breast cancer cells.

Detailed Description

Example 1 design and optimization of stabilized polypeptide inhibitors

Based on the previous research, the sequence (DWNAAEEWGNWVDE, named MS2D, with Kd about equal to 60 nM) of MTDH protein and SND1 binding is selected as the starting point from MTDH/SND1 crystal structure (PDB: 4 QMG), the mutation of key amino acid and the terminal aspartic acid cyclization modification are carried out on the original sequence, on one hand, the influence of side chains with different lengths on the binding is studied, and on the other hand, the influence of the side chains with different lengths on the conformation of the original linear sequence is studied after the loop is closed. In order to test the binding strength of the stable polypeptide inhibitor and the SND1 protein, the invention synthesizes polypeptides (MS 2D-E and MS 2D-D) with FITC labels according to a polypeptide solid phase synthesis method and expresses and purifies the SND1 protein (16-339).

The binding ability of the polypeptides to SND1 protein (16-339) was then tested using Fluorescence Polarization (FP). It can be seen that both mutated polypeptides have improved binding capacity relative to MS2D, and that MS2D-E with longer side chains has relatively superior binding capacity. (FIGS. 2A and 2B) MS2D-E was then subjected to terminal aspartic acid cross-linking cyclization modification, in order to increase the hydrogen bonding of the cyclopeptide to the wpc carrier, the original-Ala-Ala in the cyclopeptide aminocyclamide loop was mutated to-Asn-Ser, which was named MS2D-E-NS-E-cyc, NS-E-cyc for short. The experimental results found that the loop-closing position was fixed at the N-terminus of MS2D-E and that the sequence was not inserted (Cyclo (isoD NS Dap) DWNEEEWGNWVDE) to maintain the binding ability of the original sequence (Kd approximately equal to 20 nM) (FIGS. 2A and 2B).

It was further found by molecular docking that NS-E-cyc maintains the basic backbone of linear polypeptides, two key tryptophans can extend into the hydrophobic pocket of SND1 protein, and Glu396 can extend into the basic pocket of SND1 protein, thus enhancing the electrostatic interaction with SND1 protein, and the longer the side chain, the closer the side chain is to the basic amino acid, the more favorable the binding to the protein, probably also the reason for the stronger binding of MS2D-E compared to MS2D-D (FIG. 3).

EXAMPLE 2 preparation of polypeptide delivery System

The invention also provides a preparation method of the polypeptide delivery system, which comprises the following steps:

1. preparation of cationic nanocarriers (wpc carrier):

1.1 preparation of oligopeptide solid-phase resin: loading target oligopeptides on MBHA resin by a standard solid phase synthesis method;

1.2 preparation of sulfonium salt cyclopeptide wpc vector: after the methionine-containing linear polypeptide was synthesized on the solid phase, an appropriate amount of resin was taken in an EP tube, and 1-2mL of TFA/TIPS/H was added ₂ O/EDT (94. Then the polypeptide is dissolved in 50% acetonitrile/water to form a polypeptide solution with a concentration of about 10mM, 1% by volume formic acid is added for acidification (pH equal to about 3), 1.2 polypeptide equivalents of 1, 2-bis (bromomethyl) benzene are simultaneously weighed, after dissolution with about one tenth of the solvent volume of DMF, the polypeptide solution is added, the mixture is placed on a shaker for reaction for 24 hours, and High Performance Liquid Chromatography (HPLC) is used for purification to obtain the wpc carrier.

The course of the above reaction is shown below,

2. preparation of a Stable polypeptide inhibitor (NS-E-cyc polypeptide):

2.1 preparation of oligopeptide solid phase resin: loading target oligopeptides on MBHA resin by a standard solid phase synthesis method;

2.2 preparation of Compound I: the step is carried out on resin, and the Alloc and the alyl protecting groups of the target oligopeptide are removed under the conditions of tetrakis (triphenylphosphine) palladium and N, N-dimethyl barbituric acid to obtain a compound I;

2.3 preparation of compound II: performing a ring-closing reaction on the compound I in benzotriazole-1-yl-oxy tripyrrolidinyl phosphorus hexafluorophosphate, 1-hydroxybenzotriazole and N-methylmorpholine solution to generate a compound II;

2.4 preparation of modified polypeptide: removing the Fmoc protecting group of the compound II by morpholine with the volume percentage concentration of 50%, and then directly acetylating or modifying FITC fluorescent dye;

the course of the above reaction is shown below,

3. mixing a cationic nano-carrier and a stable polypeptide inhibitor in a cell culture medium, wherein the concentration of the cationic nano-carrier is 200-240 mu M, and the concentration of the stable polypeptide inhibitor is 20-40 mu M. The polypeptide delivery systems of the following examples were prepared using the methods described above, and the use of cationic nanocarriers and stable polypeptide inhibitors were tested after mixing in cell culture media.

Example 3 introduction of amphiphilic cell-penetrating peptide vectors and cellular uptake of polypeptide complexes

As NS-E-cyc sequences carry more negatively charged amino acids, in order to further increase their cellular uptake capacity, one 9-amino acid sulfonium salt polypeptide (wpc) developed by the previous group of subjects was used as a carrier to deliver NS-E-cyc polypeptides into cells for their effect. The wpc polypeptide sequence contains Fmoc protecting groups and tryptophan hydrophobic parts, as well as basic amino acids such as Arg and His and Glu acidic amino acids, and two Mets are connected through 1, 2-di (bromomethyl) benzene to form cyclic peptides of two-end sulfonium salts. The wpc is positively charged as a whole, and can carry negatively charged nucleic acid such as siRNA into cells, and after entering the cells, the compound wrapped by the wpc is subjected to reduction under the action of GSH (glutathione) with high concentration in a tumor microenvironment at two ends so as to open rings, and release nucleic acid or other negatively charged drugs to play a role. The cytotoxicity of wpc vector was first evaluated, and different concentrations of wpc polypeptide were incubated with MDA-MB-231 cells for 72h, as a result of cck8 experiment, it was found that the cell survival rate of wpc polypeptide was about 75% at 320. Mu.M, and still more than 85% at 240. Mu.M, so that the concentration of vector was preferably not more than 240. Mu.M in order to avoid cytotoxicity caused by too high concentration of vector (FIG. 4A).

The polypeptide NS-E-cyc was then mixed with wpc vector and incubated with MDA-MB-231 cells for 6 hours, and the cellular uptake of the mixed polypeptide complex was examined by flow cytometry. The results of the experiments show that the cell uptake capacity of the mixed NS-E-cyc/wpc polypeptide complex is significantly improved compared to the NS-E-cyc polypeptide itself (FIG. 4B). Laser confocal experiments also demonstrated that the NS-E-cyc/wpc polypeptide complex efficiently entered cells and co-localized with lysosome (FIG. 4C), indicating to some extent that the NS-E-cyc/wpc polypeptide complex entered cells by endocytosis.

Further experiments found that better co-localization of the polypeptide with SND1 was observed at 24h, suggesting that the polypeptide complex can release the polypeptide NS-E-cyc within 24h and then bind to the target (FIG. 4D).

EXAMPLE 4 interference Effect of polypeptide complexes on intracellular MTDH/SND1

To further investigate whether entry of wpc vector-carrying polypeptides into cells can interfere with formation of the MTDH/SND1 complex, co-immunoprecipitation (Co-IP) experiments were used herein to study the binding of MTDH to SND1 protein before and after dosing. As shown in FIG. 4, the MTDH/SND1 interfering effect was more significant in the drug-added group after the NS-E-cyc/wpc polypeptide complex treatment than in the NS-E-cyc polypeptide alone treatment group, and the inhibitory effect was observed only at 20. Mu.M for the NS-E-cyc polypeptide in the complex. The binding of MTDH to SND1 was significantly reduced without affecting the normal expression of MTDH protein, suggesting that wpc vectors can carry polypeptides efficiently into cells targeting SND1 protein, thereby inhibiting the formation of MTDH/SND1 complex (fig. 5).

EXAMPLE 5 Effect of polypeptide complexes on the proliferation, migration and cell cycle of triple negative breast cancer cells

Two triple negative breast cancer cells (human MDA-MB-231 cells and murine 4T1 cells) were used herein to assess the proliferation and migration effects of the polypeptide complex on tumor cells. As shown in FIG. 6A, NS-E-cyc/wpc polypeptide complex (20. Mu.M: 240. Mu.M) treatment resulted in approximately 50% and 40% inhibition of MDA-MB-231 cell and 4T1 proliferation. The scratch test also shows that NS-E-cyc and NS-E-cyc/wpc polypeptide complex (20 muM: 240 muM) can effectively inhibit the migration of tumor cells (FIG. 6B), and the effect of the polypeptide complex is more obvious, which further indicates that the wpc vector can effectively deliver the polypeptide NS-E-cyc to cells, interfere the formation of MTDH/SND1 complex and further inhibit the proliferation and migration of triple-negative breast cancer cells. The final flow-through results showed that the polypeptide complex induced G0/G1 cell cycle arrest in triple negative breast cancer cells, similar to the mechanism of action of previously developed stable polypeptide inhibitors (FIG. 6C).

Claims (9)

1. A cationic nanocarrier-based polypeptide delivery system, comprising: comprising a cationic nanocarrier and a stabilizing polypeptide inhibitor; the sequence of the cationic nano-carrier is Fmoc-RRMEHRMEW, and two Mets of the cationic nano-carrier are connected through 1, 2-di (bromomethyl) benzene to form cyclic peptide with sulfonium salts at two ends; the amino acid sequence of the stable polypeptide inhibitor is as follows:

Cyclo(isoD-NS-Dap)-D-W-N-E-P-A-E-E-W-G-N-W-V-D-E。

2. the cationic nanocarrier-based polypeptide delivery system of claim 1, wherein: in the polypeptide delivery system, the concentration of the cationic nano-carrier is 200-240 mu M, and the concentration of the stable polypeptide inhibitor is 20-40 mu M.

3. The cationic nanocarrier-based polypeptide delivery system of claim 1, wherein: the structural formula of the cation nano carrier is shown as,

4. the cationic nanocarrier-based polypeptide delivery system of claim 1, wherein: the structural formula of the stable polypeptide inhibitor is as follows,

r is Ac, H or beta A-FITC.

5. The method of claim 1 for preparing a cationic nanocarrier-based polypeptide delivery system, comprising the steps of:

1) A step of preparing a cationic nanocarrier:

a) Preparing oligopeptide solid phase resin: loading target oligopeptide on MBHA resin by a solid phase synthesis method;

b) Preparation of sulfonium salt cyclopeptide wpc support: after the methionine-containing linear polypeptide was synthesized on the solid phase, an appropriate amount of resin was taken in an EP tube, and 1-2mL of TFA/TIPS/H was added ₂ Shaking O/EDT shearing liquid for reaction for 1-2h, TFA, TIPS and H ₂ The volume ratio of O to EDT is 94;

c) Dissolving polypeptide in acetonitrile/water solution with volume percentage concentration of 50% to form polypeptide solution with 10mM concentration, adding 1% volume formic acid of the polypeptide solution for acidification to enable the final pH to be equal to 3, simultaneously weighing 1.2 polypeptide equivalent of 1, 2-di (bromomethyl) benzene, dissolving by using one tenth of solvent volume DMF, adding polypeptide solution, placing in a shaking table for reaction, and purifying by high performance liquid chromatography to obtain a wpc carrier;

the course of the above reaction is shown below,

2) A step of preparing a stable polypeptide inhibitor:

a) Preparing oligopeptide solid phase resin: loading target oligopeptide on MBHA resin by a solid phase synthesis method;

b) Preparation of compound I: the step is carried out on resin, and the target oligopeptide is subjected to the deprotection of Alloc and Allyl under the conditions of tetrakis (triphenylphosphine) palladium and N, N-dimethyl barbituric acid to obtain a compound I;

c) Preparation of compound II: performing ring closure reaction on the compound I in benzotriazole-1-yl-oxy tripyrrolidinyl phosphorus hexafluorophosphate, 1-hydroxybenzotriazole and N-methylmorpholine solution to generate a compound II;

d) Preparing modified polypeptide: removing the Fmoc protecting group of the compound II by morpholine with the volume percentage concentration of 50%, and then directly acetylating or modifying FITC fluorescent dye;

the course of the above-described reaction is as follows,

3) And mixing the cationic nano-carrier and the stable polypeptide inhibitor in a cell culture medium to obtain the polypeptide delivery system based on the cationic nano-carrier, wherein the concentration of the cationic nano-carrier is 200-240 mu M, and the concentration of the stable polypeptide inhibitor is 20-40 mu M.

6. A cationic nanocarrier, comprising: the amino acid sequence of the cyclic peptide is Fmoc-RRMEHRMEW, and two Mets are connected through 1, 2-di (bromomethyl) benzene to form cyclic peptide with sulfonium salts at two ends.

7. Use of the cationic nanocarriers of claim 5 in the preparation of a medicament for the delivery of a MTDH/SND 1-targeted negatively charged polypeptide.

8. Use of a polypeptide delivery system according to claim 1 in the manufacture of a medicament for interfering with the formation of the MTDH/SND1 complex.

9. Use of the polypeptide delivery system of claim 1 in the preparation of a medicament for the treatment of triple negative breast cancer.

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