Nanoparticle conjugates and uses thereof

1. A nanoparticle comprising a charged polymeric dendrimer conjugated to a peptide that specifically binds to IL4Rα expressed on a cell, wherein the peptide that specifically binds to the IL4Rα expressed on myeloid cells is [acetyl]LQRLFRAFR[Abu]LD[Ahx]-C-amide (SEQ ID NO. 1).

2. The nanoparticle of claim 1 , wherein the cell is selected from the group consisting of a myeloid cell, a B cell, a tumor cell and a tumor stromal cell.

3. The nanoparticle of claim 2 , wherein the myeloid cell is a tumor-educated myeloid cell.

4. The nanoparticle of claim 1 , further comprising one or more nucleic acid molecules.

5. The nanoparticle of claim 4 , wherein the one or more nucleic acid molecules is selected from the group consisting of DNA, RNA, shRNA, siRNA, miRNA, an antagomir and RNA sponge.

6. The nanoparticle of claim 5 , wherein the one or more nucleic acid molecule is a shRNA.

7. The nanoparticle of claim 6 , wherein the shRNA is selected from the group consisting of STAT3 shRNA, C-EBPβ shRNA, CCR1 shRNA, CCR2 shRNA and CCR5 shRNA.

8. The nanoparticle of claim 4 , wherein the nucleic acid molecules comprise a combination of STAT3 shRNA and C-EBPβ shRNA, or a combination of CCR1 shRNA, CCR2 shRNA and CCR5 shRNA.

9. The nanoparticle of claim 4 , wherein the nucleic acid molecule comprises miR-142-3p.

10. The nanoparticle of claim 1 , wherein the dendrimer is a PAMAM dendrimer.

11. The nanoparticle of claim 10 , wherein the PAMAM dendrimer is selected from the group consisting of a aG4 dendrimer, G5 dendrimer, a G6 dendrimer and a G7 dendrimer.

12. A method of screening for nucleic acids that modulate the suppressive activity of a myeloid cell comprising

(a) contacting the cell with a nanoparticle comprising

(i) the nanoparticle according to claim 1 ,

(ii) one or more candidate nucleic acids; and

(b) determining whether the suppressive activity of the cell is modulated.