Date of Graduation

12-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Biomedical Engineering

Advisor

David A. Zaharoff

Committee Member

Gisela F. Erf

Second Committee Member

Timothy J. Muldoon

Third Committee Member

Narasimhan Rajaram

Keywords

Health and environmental sciences; Autologous tumor cell vaccine; Breast cancer; G-csf

Abstract

Heterogenous cancers such as breast carcinoma, would highly benefit from personalized vaccine approaches such as autologous tumor cell vaccines (ATCVs). By using cancer cells that are isolated from self, this approach has the potential to generate a polyclonal immune response against tumor antigens, that are specific to the individual. However, so far, ATCVs against breast cancers have not had any clinical success due to the poor immunogenicity of the malignant cells.

In this study, for the first time, we determined tumor derived G-CSF to play a major role in affecting immune response against breast cancer ATCVs. By using CRISPR/Cas9 genome editing technology, we found that tumor derived G-CSF results in the accumulation of exceptionally high levels of myeloid derived suppressor cells (MDSCs) in the spleen and lymph nodes of immunized mice. For the first time, we demonstrated that by eliminating G-CSF in ATCVs, the overall efficacy of the vaccine can be significantly improved. Further, for the first time, by using breast cancer cells that naturally produce varying levels of G-CSF, we reestablished the effect of G-CSF on splenic MDSC accumulation.

Additionally, we addressed the MDSC associated immunosuppression, by investigating strategies to facilitate the maturation of immature immune cells. We considered different commercially available toll like receptor (TLR) agonists namely Pam3CSK4 (Pam), Poly (I:C), lipopolysaccharide, FLA-ST, FSL-1 and R848, and compared their effect on MDSC maturation in-vitro. Of all the agonists, we found that only Pam resulted in the complete maturation of MDSCs since it resulted in the upregulation of all four MDSC maturation markers, CD80, CD86, MHCII and F4/80. Additionally, Pam also significantly reduced the number of MDSCs in the treated whole splenocyte cultures.

Future studies that are discussed here will expand our knowledge on the effect of tumor derived G-CSF in clinical cancer burden and metastasis of breast cancer. Further, in-vivo studies with the TLR agonists, would help design an effective adjuvant therapy against aggressive and metastatic breast cancers, with improved survival and reduced rate of recurrence.

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