Assessment of CB1 and CB2 receptors in head and neck Squamous Cell Carcinoma

Presentation: C058
Topic: Pharynx / Larynx Cancer
Type: Poster
Date: Thursday, April 19, 2018
Session: 9:00 AM - 7:00 PM
Authors: Kelly E Daniels, BS, Adam J Luginbuhl, MD, Andrew P South, PhD
Institution(s): Thomas Jefferson University

BACKGROUND: The endocannabinoid signaling system (ESS) is involved in many cellular processes, including those that regulate cell growth and apoptosis through the PI3K/Akt pathway. Many of these pathways are also implicated in squamous cell carcinoma growth and treatment targets. Marijuana users have a known increase in relative risk to develop human papilloma virus (HPV) related head and neck squamous cell carcinoma (HNSCC).

PURPOSE: The ESS has been implicated for its role in the pathogenesis of various cancers. However, there is limited research exploring its activity in HNSCC. This research characterizes the expression of the two primary receptors in this pathway, CB1 and CB2, in HNSCC versus healthy tissue. Further analysis of patient demographics and outcomes will be correlated to receptor expression levels.

METHODS: Frozen cells were obtained and cultured from the HNSCC tissue bank. Cells from three HPV+ SCC, three HPV- SCC, and three normal human keratinocyte (NHK) samples were cultured. Immunofluorescence (IF) and Western blot (WB) were used to characterize the presence, cellular location, and degree of expression of the two receptors. Immunohistochemical (IHC) staining of paraffin-embedded tissue samples from HNSCC patients were used to compare expression levels between cohorts of self-identified marijuana users and non-users.

RESULTS: IF imaging indicated positive expression of CB1 in all HNSCC and NHK cell lines, and minimal to no expression of CB2. Qualitatively, CB2 exhibited greater expression in NHK cells. Expression of CB1 was confirmed by WB where all cell lines yielded a positive band for CB1 at 60kDa. Quantitative density analysis of WB showed that on average, HNSCC exhibited increased expression of CB1 over NHK (n=7). In isogenic pairs of HNSCC and NHK cells, there is a greater than 50% increase in expression of CB1 in HNSCC over NHK. HPV status yielded variable expression of CB1 between cohorts. Qualitative and quantitative analysis of IHC in marijuana users and non-users is pending completion.

CONCLUSION: CB1 is consistently present on HNSCC cells and above the level of expression on NHK from the same patient. IHC images will be assessed and presented looking at qualitative and quantitative parameters to determine differential expression between marijuana users and non-users.