Introduction:
HPV16 is a major risk factor for development of oropharyngeal squamous-cell-carcinoma
(OPSCC). Although HPV+ OPSCC metastasize faster than HPV- tumors, they have a better
prognosis. The molecular and cellular alterations causing these differences remain
elusive. In this study we examined whether expression of HPV16-E6E7 targets the number
of migratory and stationary cancer stem cells (CSC). Furthermore, we wanted to elucidate
if aberrantly expressed miRNAs in migratory CSC may be responible for progression
of OPSCCs and whether they may serve as potential novel biomarkers for increased potential
of metastasis.
Methods:
Retroviral transduction, FACS analysis, qRT-PCR, miRNA microarray, in-situ hybridization.
Results:
HPV16-E6E7 expression leads to an increase in the number of stationary (CD44high/EpCAMhigh)
stem cells in primary keratinocyte cultures. Expression of E6E7 in the cell line H357
increased the migratory (CD44high/EpCAMlow) pool. This increase in migratory CSCs
could also be confirmed in HPV+ OPSCC. Differentially expressed miRNAs from HPV16-E6E7
positive migratory CSCs were validated by RT-qPCR and in situ hybridization on HPV+
OPSCCs. These experiments led to the identification of miR-3194 – 5 p, which is upregulated
in primary HPV16+ OPSCC and matched metastasis. MiR-1281 was found to be highly expressed
in HPV+ and HPV- metastasis. As inhibition of this miRNA led to a reduction of migratory
cells it may prove to be a promising drug target.
Conclusion:
Our findings highlight the capability of HPV16 to modify the phenotype of infected
stem cells and that miR-1281 and miR3194 – 5 p may represent promising therapeutic
targets for metastasized OPSCC.
