Human DLG1 and SCRIB Are Distinctly Regulated Independently of HPV-16 during the Progression of Oropharyngeal Squamous Cell Carcinomas: A Preliminary Analysis

Abstract

The major causative agents of head and neck squamous cell carcinomas (HNSCCs) are either environmental factors, such as tobacco and alcohol consumption, or infection with oncogenic human papillomaviruses (HPVs). An important aspect of HPV-induced oncogenesis is the targeting by the E6 oncoprotein of PDZ domain-containing substrates for proteasomal destruction. Tumor suppressors DLG1 and SCRIB are two of the principal PDZ domain-containing E6 targets. Both have been shown to play critical roles in the regulation of cell growth and polarity and in maintaining the structural integrity of the epithelia. We investigated how modifications in the cellular localization and protein expression of DLG1 and SCRIB in HPV16-positive and HPV-negative histologic oropharyngeal squamous cell carcinomas (OPSCC) might reflect disease progression. HPV presence was determined by p16 staining and HPV genotyping. Whilst DLG1 expression levels did not differ markedly between HPV-negative and HPV16-positive OPSCCs, it appeared to be relocated from cell–cell contacts to the cytoplasm in most samples, regardless of HPV16 positivity. This indicates that alterations in DLG1 distribution could contribute to malignant progression in OPSCCs. Interestingly, SCRIB was also relocated from cell–cell contacts to the cytoplasm in the tumor samples in comparison with normal tissue, regardless of HPV16 status, but in addition there was an obvious reduction in SCRIB expression in higher grade tumors. Strikingly, loss of SCRIB was even more pronounced in HPV16-positive OPSCCs. These alterations in SCRIB levels may contribute to transformation and loss of tissue architecture in the process of carcinogenesis and could potentially serve as markers in the development of OPSCCs.

Individual and Co-Expression Patterns of FAM83H and SCRIB at Diagnosis Are Associated with the Survival of Colorectal Carcinoma Patients

“…Furthermore, a higher expression of SCRIB also predicted shorter survival of ovarian carcinoma [ 24 ] and gastric carcinoma [ 7 ]. However, controversially, the expression of SCRIB was decreased compared to normal tissue in oropharyngeal squamous cell carcinoma, breast cancer, uterine cervical cancer, lung cancer, and lymphoma [ 15 , 38 ]. Therefore, although our results suggest that the expression of SCRIB might be used as a prognostic indicator for CRC patients, further study is needed to determine the clinical significance of SCRIB expression.…”

HPV16 Impacts NHERF2 Expression in Oropharyngeal Cancers

“…From each FFPE sample, five to seven slices (10 µm) were used for DNA isolation, utilizing a commercial kit (NucleoSpin ® DNA FFPE XS, Macherey–Nagel, Dueren, Germany) according to the manufacturer’s instructions. The concentration of the isolated DNA was measured using NanoPhotometer ® N60 (Implen GmbH, Munich, Germany), and the quality was validated by PCR using primers generating 99 bp long beta-actin fragments [ 40 , 41 ].…”

“…For HPV DNA detection, PCR was performed using short primers suitable for FFPE tissue samples GP5/6 and SPF 10, generating approximately 142 bp and 65 bp long PCR products, respectively [ 42 , 43 ]. PCR amplification was performed as previously described [ 40 , 44 ] and 10 μL of amplified PCR products were run on 3% agarose gels (Sigma Aldrich, St. Louis, MO, USA). A sample was considered to be HPV+ if either the GP5/6 or SPF10 PCR was positive.…”

“…However, no strict correlation between p16 overexpression, HPV infection, and the progression of cancer has been established. Studies have shown that about 10–20% of OPSCCs that are p16-positive are not HPV infected [ 39 , 40 ]. Thus, we aimed to better understand the process of HPV-driven oncogenesis in the head and neck area by investigating potential changes in the expression patterns and localization of NHERF2 in the presence of HPV16.…”

Viral subversion of the cell polarity regulator Scribble

“…It was shown that E6 dimerises to enable the degradation of p53 via direct interaction with the ubiquitin ligase E6AP [ 26 , 74 ], suggesting that a similar mechanism may apply to PDZ domain containing proteins that bind to the E6 PBM [ 75 , 76 ]. E6 has also been demonstrated to trigger a relocalisation of Scribble and DLG1 from the cellular membrane into the cytoplasm [ 77 ]. This allows E6 to further stabilise, maintain and increase in infected cells, particularly when binding to Scrib [ 78 , 79 ].…”