Abstract A028: Cornulin, An epithelial differentiation marker: A novel antitumor protein and prognosticator in patients with Head and Neck Squamous Cell Carcinoma
Authors: Kaur Rajandeep , Saini Krishan Kumar , Chatterjee Debajyoti , Bakshi Jaimanti , Srinivasan Radhika , Ghoshal Sushmita , Datta Dipak , Pal Arnab 
Published: December 2023

Abstract
Background: Cornulin, a relatively unexplored protein, was reported to be downregulated in esophageal carcinoma along with the association of low tissue Cornulin level with disease stage. In our preliminary study, based on TMT-based LC-MS/MS analysis, the salivary Cornulin was also found to be downregulated ~10-fold in Head Neck Squamous Cell Carcinoma (HNSCC) patients. The current study further explored the biomarker potential of salivary Cornulin in HNSCC patients and the anti tumor effects of Cornulin in in vitro as well as in in vivo HNSCC models.
Methods: Sandwich ELISA and immunohistochemistry techniques were utilized to assess the levels of Cornulin in the saliva and tissues of patients diagnosed with HNSCC, respectively. The expression of Cornulin in HNSCC was examined by analyzing the TCGA database using the GEPIA2 tool. To investigate the antitumor effects of Cornulin, its levels were increased through lentiviral transduction in the Cal27 and FaDu, HNSCC cell lines with low Cornulin expression. Subsequently, various cell assays were conducted to examine the antitumor effects of Cornulin upregulation. Additionally, the effects of increased Cornulin expression was also evaluated in an in vivo nude mice model.
Results: The pre-treatment salivary Cornulin levels were significantly low (p=0.0001) in HNSCC patients (n=128,146.4±5.589pg/mL) as well as in oral premalignant disease patients (n=25, 174.6 ± 9.924 pg/mL) with respect to healthy controls (n=84,185.2±7.170pg/mL). Also, the tumor tissue expression of Cornulin (n=113, H-score=12.70±2.396) was significantly downregulated (p&lt;0.0001) in comparison to the tumor-free margin (n=72, H-score=139.6±10.34). The patients showing complete clinical response regained normal salivary within 6 months of completion of treatment (p&lt;0.0001). More importantly, low salivary Cornulin level at diagnosis was associated with poor overall survival (p=0.0282), indicating it to be a potential prognostic marker. On upregulation of Cornulin in low expressing HNSCC cell lines (Cal27 and FaDu), interestingly, the cellular viability, migration, and invasion showed significant decrease. These findings suggest that Cornulin plays a role in inhibiting tumor growth, indicating its potential as an anti-tumor factor. The analysis of RNAseq data of Cornulin overexpressed cell lines and further Gene set enrichment analysis, we found that G2/M checkpoint pathway to be positively enriched in the Cornulin overexpressed cell line. Furthermore, the cell cycle analysis revealed Cornulin overexpression arrests G1/S phase of cell cycle. In nude mice xenograft model, decreased tumor progression as well as tumor volume was documented after Cornulin overexpression. There was increased in differentiation in the xenograft tumors formed by Cornulin overexpressed cells.
Conclusion: Here, we report for the first time intrinsic Cornulin to have a role as a potent anti-tumor and its potential as prognostic marker. However the pathways by which Cornulin shows its antitumor activity needs to be further evaluated.
Citation Format: Rajandeep Kaur, Krishan Kumar Saini, Debajyoti Chatterjee, Jaimanti Bakshi, Radhika Srinivasan, Sushmita Ghoshal, Dipak Datta, Arnab Pal. Cornulin, An epithelial differentiation marker: A novel antitumor protein and prognosticator in patients with Head and Neck Squamous Cell Carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A028.