The role of miRNAs in human papilloma virus (HPV)-associated cancers: bridging between HPV-related head and neck cancer and cervical cancer

Abstract

Background: Although the role of human papilloma virus (HPV) in cervical squamous cell carcinoma (CSCC) is well established, the role in head and neck SCC (HNSCC) is less clear. MicroRNAs (miRNAs) have a role in the cancer development, and HPV status may affect the miRNA expression pattern in HNSCC. To explore the influence of HPV in HNSCC, we made a comparative miRNA profile of HPV-positive (HPV+) and HPV-negative (HPV-) HNSCC against CSCC.

Methods: Fresh frozen and laser microdissected-paraffin-embedded samples obtained from patients with HPV+/HPV- HNSCC, CSCC and controls were used for microarray analysis. Differentially expressed miRNAs in the HPV+ and HPV- HNSCC samples were compared with the differentially expressed miRNAs in the CSCC samples.

Results: Human papilloma virus positive (+) HNSCC had a distinct miRNA profile compared with HPV- HNSCC. Significantly more similarity was seen between HPV+ HNSCC and CSCC than HPV- and CSCC. A set of HPV core miRNAs were identified. Of these especially the miR-15a/miR-16/miR195/miR-497 family, miR-143/miR-145 and the miR-106-363 cluster appear to be important within the known HPV pathogenesis.

Conclusion: This study adds new knowledge to the known pathogenic pathways of HPV and substantiates the oncogenic role of HPV in subsets of HNSCCs.

Figure 1

(A) Principal component analysis (PCA) plot including all variables. Human papilloma virus− TSCC (yellow), HPV+ TSCC (purple) and tonsillar controls (black). (B) Principal component analysis plot, visualising differentially expressed miRNAs in HPV+, HPV− and tonsillar control, subset of variables. (P<0.01, q<0.06). (C) Heat map: three distinct groups were observed. Human papilloma virus− TSCC (yellow), HPV+ TSCC (purple) and tonsillar controls (black). The heatmap and PCA visualisation was performed using the Qlucore Gene Expression Explorer (http://www.qlucore.com).

Figure 2

(A) Principal component analysis plot including all variables. (B) Principal component analysis plot, visualising differentially expressed miRNAs in CSCC compared with cervical controls. (C) Heat map (P<0.01, q<0.05). Cervical squamous cell carcinoma (CSCC) (purple), cervical controls (black).

Figure 3

Venn diagram illustrating the number of miRNAs differentially expressed in the three groups (HPV+ HNSCC, HPV− HNSCC and CSCC) compared with their normal counterpart and how they overlap with each other (P<0.01).

Figure 4

The schematic representation of the relation between HPV-regulated miRNAs and factors involved in malignant transformation caused by the viral oncoproteins E6 and E7. Putative miRNA-regulated proteins and miRNA controlled by transforming factors are indicated in grey and miRNAs are shown in blue boxes. Binding of E7 to pRb leads to degradation of pRb and release of transcription factor E2F, which drives the cell into S-phase and cell division. Interaction between E7 and p21 results in inhibition of the cyclins, which are targeted by miR-15, miR-16, miR-195, miR-497, and this leads to inhibition of cell cycle arrest and contribute to carcinogenesis. Ubiquitination by E6 and ubiquitin ligase E6AP (potentially targeted by miR-139-5p) leads to p53 degradation and subsequently impaired apoptosis following DNA damage. p53 is also potentially targeted by miR-574-5p and miR-381, and p53 in turns regulates transcription of miR-15, miR-16, miR-143, miR-145 and miR-195 By association with E6/E6AP, NFX1 is degraded and results in activation of hTERT, which leades to cellular immortalisation. E6 degrades the tumour supressor PTPN13 and loss of PTPN13 further enhances the oncogenic Ras signalling. Ras further regulates miR-143 and miR-145 transcription by binding to the promoter.