Analysis of CpG promotor methylation status of the AKR1C3 gene in HPV16 positive and negative oropharyngeal squamous cell carcinoma

Introduction:

At least two subgroups of OPSCC (Oropharyngeal Squamous Cell Carcinoma) can be distinguished based on high-risk Human Papillomavirus (HPV) infection, namely HPV16. We showed that upregulation of Aldo-Keto-Reductases (AKR) 1C1 and 1C3 is strongly associated with poor prognosis irrespective of HPV-status. However, our data suggest that expression of these proteins might be induced by independent mechanisms in HPV+ and HPV-tumors.

Methods:

We performed a bioinformatic analysis of the AKR1C1-C4 promotor regions located on Chromosome 10p15 – 14 in a clinical cohort of patients preselected for good clinical response (n = 26) and appearance of local/distant recurrence (n = 26). AKR1C3 expression was confirmed by immunohistochemistry of 52 FFPE tumor samples from primary OPSCC (n = 26 HPV+, n = 26 HPV-) with additional n = 16 samples from corresponding lymph node metastases. Tumor regions were microdissected for DNA extraction and pyrosequencing was performed to determine methylation status of CpG islands in the promoter region of AKR1C3. Results were correlated with clinical and histopathological data.

Results:

The analysis revealed two promising CpG islands upstream of AKR1C3 correlating with potential C/EBP and SP-1 transcription factor binding sites. Upregulation of AKR1C3 showed poor prognosis for those tumors with unfavorable clinical response (p = 0.0024). CpG methylation analysis correlated with induction of AKR1C3 expression in HPV- but not HPV+ tumor samples.

Conclusions:

Our findings show that HPV-tumors presenting AKR1C3 expression correlated with methylation status of the identified CpG islands, whereas HPV-tumors without AKR1C3 expression did not. Protein expression in HPV+tumors might be regulated by an independent mechanism subject of ongoing analysis.

Publication History

Publication Date:
23 April 2019 (online)