Cell proliferation reducing cancer specific PCNA peptides

1. A therapeutic composition for reducing cellular proliferation of malignant cells, the composition comprising a peptide molecule fused or linked to a cell penetrating peptide, wherein the peptide molecule comprises an amino acid sequence selected from the group consisting of LGIPEQEY (SEQ ID NO: 1), LAIPEQEY (SEQ ID NO: 2), LGIAEQEY (SEQ ID NO: 3), LGIPAQEY (SEQ ID NO: 4), LGIPEAEY (SEQ ID NO: 5), LGIPEQAY (SEQ ID NO: 6), LGIAEAEY (SEQ ID NO: 7), LGIPEAAY (SEQ ID NO: 8), LGIAEQAY (SEQ ID NO: 9), and LGIAEAAY (SEQ ID NO: 10), and wherein the cell penetrating peptide comprises an amino acid sequence selected from the group consisting of RRRRRRR (SEQ ID NO: 11), RRRRRRRR (SEQ ID NO: 12), RRRRRRRRR (SEQ ID NO: 13), RRRRRRRRRR (SEQ ID NO: 14), RRRRRRRRRRR (SEQ ID NO: 15), RQIKIWFQNRRMKWKK (SEQ ID NO: 16), GRKKRRQRRRPPQ (SEQ ID NO: 17), GWTLNSAGYLLGKINLKALAALAKKIL (SEQ ID NO: 18), and GRKKRRQRRR (SEQ ID NO: 19).

2. The composition of claim 1 , wherein the amino acid sequence of the cell penetrating peptide comprises one or more amino acid D-isomers.

3. The composition of claim 1 , wherein the cell penetrating peptide is covalently linked or conjugated to the peptide molecule.

4. The composition of claim 1 , wherein the cell penetrating peptide is recombinantly fused with the peptide molecule.

5. The composition of claim 1 , wherein the peptide molecule further comprises a cell surface targeting factor.

6. The composition of claim 1 , further comprising a chemotherapeutic agent.

7. The composition of claim 6 , wherein the chemotherapeutic agent is a DNA damaging agent.

8. The composition of claim 7 , wherein the DNA damaging agent is selected from the group consisting of doxorubicin, irinotecan, cyclophosphamide, chlorambucil, melphalan, methotrexate, cytarabine, fludarabine, 6-mercaptopurine, 5-fluorouracil, capecytabine, cisplatin, carboplatin, oxaliplatin, and a combination thereof.

9. A method In vitro of reducing cellular proliferation or inducing cell death of a cancer cell or a pre-malignant cell expressing cancer-specific proliferating cell nuclear antigen (caPCNA), the method comprising administering a therapeutically effective amount of a composition comprising a peptide molecule fused or linked to a cell penetrating peptide, wherein the peptide molecule comprises an amino acid sequence selected from LGIPEQEY (SEQ ID NO: 1), LAIPEQEY (SEQ ID NO: 2), LGIAEQEY (SEQ ID NO: 3), LGIPAQEY (SEQ ID NO: 4), LGIPEAEY (SEQ ID NO: 5), LGIPEQAY (SEQ ID NO: 6), LGIAEAEY (SEQ ID NO: 7), LGIPEAAY (SEQ ID NO: 8), LGIAEQAY (SEQ ID NO: 9), and LGIAEAAY (SEQ ID NO: 10), and wherein the cell penetrating peptide comprises an amino acid sequence selected from the group consisting of RRRRRRR (SEQ ID NO: 11), RRRRRRRR (SEQ ID NO: 12), RRRRRRRRR (SEQ ID NO: 13), RRRRRRRRRR (SEQ ID NO: 14), RRRRRRRRRRR (SEQ ID NO: 15), RQIKIWFQNRRMKWKK (SEQ ID NO: 16), GRKKRRQRRRPPQ (SEQ ID NO: 17), GWTLNSAGYLLGKINLKALAALAKKIL (SEQ ID NO: 18), and GRKKRRQRRR (SEQ ID NO: 19), to contact the cancer or pre-malignant cell expressing caPCNA.

10. The method of claim 9 , wherein the cancer or premalignant cell has a mutation in a DNA repair protein.

11. The method of claim 10 , wherein the DNA repair protein participates in homologous recombination.

12. The method of claim 11 , wherein the protein is BRCA1.

13. The method of claim 9 , further comprising administering a chemotherapeutic agent.

14. The method of claim 13 , wherein the chemotherapeutic agent is a DNA damaging agent.

15. The method of claim 14 , wherein the DNA damaging agent is selected from the group consisting of doxorubicin, irinotecan, cyclophosphamide, chlorambucil, melphalan, methotrexate, cytarabine, fludarabine, 6-mercaptopurine, 5-fluorouracil, capecytabine, cisplatin, carboplatin, oxaliplatin, and combinations thereof.

16. The method of claim 9 , wherein the cancer or pre-malignant cell is a breast, colon, lung, ovary, prostate, or blood cell.