IADR Abstract Archives
Characterization of MOC-2-E6E7, A Novel Preclinical Model of HPV-Associated HNSCC
Objectives: To determine the metastatic potential and mechanism of immune escape for MOC-2-E6E7, a novel orthotopic murine model of human papillomavirus (HPV)-related head and neck squamous cell carcinoma (HNSCC) developed to test promising new cancer immunotherapies.
Methods: C57BL/6 mice were injected with either GFP-expressing (MOC-2-E6E7-GFP) or non-GFP-expressing (MOC-2-E6E7) tumor cells into the maxillary oral vestibule and tissues were harvested at multiple weekly timepoints over a 1-month period. Flow cytometry was performed to record the percentage of live GFP+ cells or profile immune cell infiltration. qRT-PCR was utilized to determine expression of HPV oncogenes E6 and E7 over time.
Results: GFP+ cells were undetectable in all tissues by day 21. Only 1% of cells within the tumor inoculation site were GFP-positive by day 7. In contrast, using cytokeratin 8 and 18 as a tumor-specific marker, between 20-43% of cells at the tumor inoculation site at Day 26 were cytokeratin 8/18 positive. 30-50% of cells were cytokeratin 8/18 negative but CD45+ positive, implying a significant immune cell population within tumors. An approximate 100-fold reduction in E6 and E7 expression was observed by Day 26 in MOC-2-E6E7 tumors, with no significant difference in E6 expression for tumors depleted of CD45+ cells. Ipsilateral cervical lymph nodes had almost undetectable levels of E6 and E7 at that same time point.
Conclusions: GFP appears to play an immunogenic role resulting in immune destruction of tumor cells and no detectable metastases in the MOC2-E6E7-GFP in vivo model. The ability of the non-GFP MOC2-E6E7 in vivo model to develop tumors indicates a tumor microenvironment which resists immune control, despite an abundant infiltrate of immune cells. The significant decrease in E6 and E7 mRNA expression within the tumor population by Day 26 (which was not affected by CD45 cell depletion), suggests immunoediting as a mechanism of tumor escape.
Methods: C57BL/6 mice were injected with either GFP-expressing (MOC-2-E6E7-GFP) or non-GFP-expressing (MOC-2-E6E7) tumor cells into the maxillary oral vestibule and tissues were harvested at multiple weekly timepoints over a 1-month period. Flow cytometry was performed to record the percentage of live GFP+ cells or profile immune cell infiltration. qRT-PCR was utilized to determine expression of HPV oncogenes E6 and E7 over time.
Results: GFP+ cells were undetectable in all tissues by day 21. Only 1% of cells within the tumor inoculation site were GFP-positive by day 7. In contrast, using cytokeratin 8 and 18 as a tumor-specific marker, between 20-43% of cells at the tumor inoculation site at Day 26 were cytokeratin 8/18 positive. 30-50% of cells were cytokeratin 8/18 negative but CD45+ positive, implying a significant immune cell population within tumors. An approximate 100-fold reduction in E6 and E7 expression was observed by Day 26 in MOC-2-E6E7 tumors, with no significant difference in E6 expression for tumors depleted of CD45+ cells. Ipsilateral cervical lymph nodes had almost undetectable levels of E6 and E7 at that same time point.
Conclusions: GFP appears to play an immunogenic role resulting in immune destruction of tumor cells and no detectable metastases in the MOC2-E6E7-GFP in vivo model. The ability of the non-GFP MOC2-E6E7 in vivo model to develop tumors indicates a tumor microenvironment which resists immune control, despite an abundant infiltrate of immune cells. The significant decrease in E6 and E7 mRNA expression within the tumor population by Day 26 (which was not affected by CD45 cell depletion), suggests immunoediting as a mechanism of tumor escape.