Table 1 Comparison of the newly established MOC1-HPV tumor models with the existing models of HPV-positive OSCC
| Â | MOC1-HPV | MOC2-E6E7 [55] | ||
|---|---|---|---|---|
Method of establishment | Retroviral transduction | Retroviral transduction | Retroviral transduction | Transfection |
Parental cells | MOC1 cell line | Primary mouse pharyngeal cells | MOC2 cell line | AT-84 cell line |
Oncogenes and reporter genes | HPV-16 E6 and E7 | H-Ras, HPV-16 E6 and E7; mEERL firefly luciferase reporter gene | HPV-16 E6 and E7 | HPV-16 E7; AT-84-E7-Luc firefly luciferase reporter gene |
In vitro | ||||
 Confirmation of E6, E7 expression | qRT‒PCR and IF | / | qRT‒PCR | qRT‒PCR, western blot |
 Proliferation | Comparable population doubling times (PrestoBlue™ metabolic assay) | E6 and E7 immortalized pharyngeal cells (reaching more than 25 population doublings), shorter population doubling time in mEER cells | Doubling time of MOC2-E6E7 comparable to MOC2 (cell count and viability) | / |
 Migration | MOC1 and MOC1-HPV K1 comparable migration velocity, MOC1-HPV K3 significantly slower | / | / | / |
 Gene expression analysis in vitro | RNA-sequencing | / | / | / |
 Radiosensitivity | Comparable radiosensitivity (clonogenic assay, 0–12 Gy) | mEER more resistant than wildtype pharyngeal cells (clonogenic assay) | / | / |
In vivo | ||||
 Location | Subcutaneous (flank), orthotopic not tested | Orthotopic (intraoral) and subcutaneous (flank) | Orthotopic (maxillary vestibule of the oral cavity) | Subcutaneous (flank) or orthotopic (tongue) |
 Source mouse strain | C57Bl/6Ncrl | C57Bl/6 | C57Bl/6J | C3H |
 Confirmation of E6, E7 expression | Determined at tumor volume 50 mm3 (qRT‒PCR) | Maintains expression with tumor growth (qRT‒PCR)[55] | Reduced E6 and E7 expression with tumor growth (qRT‒PCR) | Stable E7 expression maintained (qRT‒PCR) |
 Tumor inoculation | 1 × 106 cells (flank) | 5 × 105 cells (tongue), 1 × 106 cells (flank) | 3 × 104 cells | 6 × 105 cells (floor of the mouth), 1 × 105 cells (flank); forms lung metastases |
 Tumor formation rate | 88% in both HPV models (flank) | Orthotopic 83.3%, subcutaneous 80% | / | / |
 HE | Well differentiated SCC, MOC1-HPV K1 more immune cell infiltration; keratin pearls present | Poorly differentiated SCC | Abundant lymphocyte infiltration | Appearance of sarcomatoid carcinoma or spindle cell squamous carcinoma, no keratinization |
 Tumor growth kinetics | Time to grow from 50–60 mm3 to 100 mm3 comparable in all three tumor models | Logarithmic growth | Significantly slower growth rate of MOC2-E6E7 in oral cavity compared to MOC2 in C57Bl/6J WT mice, but similar in Rag1−/− mice | / |
 Tumor microenvironment | Differences in hypoxia and percentage of proliferating cells, blood vessel area comparable (immunofluorescence staining) | / | / | / |
 Immune profile | Comparable infiltration of CD4 and CD8 T lymphocytes in all tumor models (immunofluorescence staining). Trend toward higher CD4/CD8 ratio in MOC1-HPV K1 tumor model | / | T cell inflamed phenotype (nanoString); significantly more CD8 + TILs in MOC2E6E7 tumors compared to MOC2; CD4 + TILs similar in both (flow cytometry) | Approximately 1.5% of CD3+ cells are CD8+; approximately 1% of CD3+ cells are CD4+ (flow cytometry) [91] |
 Gene expression analysis in vivo | / | / | nCounter PanCancer Immune Profiling Panel (NanoString, WA, USA) | / |
 Radiosensitivity | MOC1-HPV K1 significantly longer growth delay after irradiation with a single dose of 15 Gy | 80% of mice with mEER cells complete response after < 20 Gy irradiation [69] | / | Determined only in combination with immune checkpoint inhibitors (anti-PD-L1) [91] |