Means and methods for the generation of mammalian producer cells for the production of recombinant proteins

1. A method for the preparation of a protein production engineered mammalian producer cell capable of increasing production of a protein of interest, the method comprising:

a) providing a mammalian producer cell;

b) increasing the concentration of a combination of miRs selected from the group consisting of miR-15 and miR-34; miR-16 and miR-34; and

miR-15, miR-16, and miR-34 in the mammalian producer cell by transfecting the mammalian producer cell with:

(i) the combination of miRs,

(ii) at least one vector containing a nucleotide sequence encoding the combination of miRs under control of at least one regulatory element allowing overexpression of the miRs, or

(iii) with two or more vectors containing nucleotide sequences encoding individual miRs of the combination of miRs under control of at least one regulatory element allowing overexpression of the combination of miRs,

so as to obtain a protein production engineered mammalian producer cell; and

c) recovering the protein production engineered mammalian producer cell produced in step b), wherein the mammalian producer cell is a CHO cell, a CHO-K1 cell or a CHO-K1 SV cell; and

wherein increasing the concentration of the combination of miRs in accordance with step (b) increases production of the protein of interest in comparison with cells in which the combination of miRs are not increased.

2. The method according to claim 1 , wherein the miR-15 is miR-15a or miR-15b.

3. The method according to claim 1 , wherein the miR-34 is miR-34a, miR-34b or miR-34c.

4. The method according to claim 1 , wherein the combination of miRs comprises mature miRs, precursor miRs, or primary miRs.

5. The method according to claim 1 , wherein the at least one vector encoding the combination of miRs in step b) is transiently or stably transfected.

6. The method according to claim 1 , wherein the mammalian producer cell is transfected with a nucleotide sequence encoding the protein of interest prior to step a) or during step b).

7. The method according to claim 1 , wherein the protein production engineered mammalian producer cell obtained after step b) is transfected with a nucleotide sequence encoding the protein of interest.

8. The method according to claim 1 , wherein the regulatory element allowing the overexpression of the combination of miRs is a promoter.

9. The method according to claim 1 , wherein the protein production engineered mammalian producer cell is a cell exhibiting an increased specific production rate or an increased time integral of viable cell concentration or both.

10. A protein production engineered mammalian producer cell produced according to the method of claim 1 .

11. The method according to claim 1 , wherein the mammalian producer cell comprises an exogenous nucleotide sequence that expresses the protein of interest and wherein the transfecting the mammalian producer cell with the combination of miRs comprises transfecting the mammalian producer cell with nucleotide sequences encoding for stem loops of human pre-miR-15 and pre-miR-34; stem loops of human pre-miR-16 and pre-miR-34; or stem loops of human pre-miR-15, pre-miR-16, and pre-miR-34.

12. The method according to claim 1 , wherein the protein of interest is a chimeric antibody, a heavy chain of an antibody, a light chain of an antibody, a variable region of an antibody, or a constant region of an antibody.

13. The method according to claim 1 , wherein the protein of interest is follicle-stimulating hormone (FSH), factor VIII, thrombopoietin (TPO), erythropoietin (EPO), G-CSF, GM-CSF, tissue-plasminogen activator (TPA), interferon a, interferon 13, interferon y, insulin-like growth factor, or somatotropin.

14. The method according to claim 1 , further comprising;

d) cultivating the protein production engineered mammalian producer cell; and

e) recovering the protein of interest from the protein production engineered mammalian producer cell.