What we do:

The laboratory, led by Dr. Palanisamy, focuses on conducting a comprehensive research program encompassing fundamental and applied RNA molecular biology aspects. The primary objective of our research program is to investigate the mechanisms behind post-transcriptional gene regulation in the context of oral cancer development and progression. The main aim of the laboratory is to examine the role of an atypical form of post-transcriptional gene expression in RNA metabolism, as well as the adjustment of RNA turnover and translation and their corresponding proteins in response to this mechanism. The research hypothesis presented in this study builds upon previous discoveries in the field of cellular and molecular mechanisms of RNA-binding proteins and non-coding RNAs in the context of oral cancer. This research aims to apply these findings to develop clinical interventions that effectively inhibit the progression of the disease. mRNA binding proteins significantly impact various essential facets of mRNA metabolism, encompassing nuclear translocation, cytoplasmic exportation, cytoplasmic conveyance, storage, translation, and degradation. RNA-binding proteins are crucial in regulating the cellular response to many stimuli, including stress, proliferative signals, immunological triggers, and developmental cues. Due to the impact of RBP on the modulation of essential regulators, there exists a considerable scholarly interest in investigating the binding of RBPs to both messenger RNAs (mRNAs) and non-coding RNAs, as well as their regulatory mechanisms in the context of inhibitory and knockdown circumstances in mouse models of oral cancer and mucositis. Therefore, our main objective is to investigate the impact of RNA-binding proteins (RBPs) on regulating gene expression related to oral cancer and mucositis. This will be accomplished by using cell culture and mouse models to study RNA metabolism. Our research endeavors will comprehensively explore the unexplored facets of RNA metabolism in normal and oral cancer contexts, facilitating advancements in therapeutic approaches.

Project 1: Intersections of RNA-binding proteins and T-cells in oral epithelial plasticity.

This effort attempts to understand how the RBP Hu antigen-R (HuR, also known as embryonic lethal abnormal vision L1, ELAVL1) affects oral epithelial carcinogenesis. HuR is overexpressed and leads to chemotherapeutic drug resistance in HNSCC, according to our published and preliminary data. We found that an epithelial tissue-specific HuR knockout (HuR-KO) mouse, developed from a HuRflox/flox crossed with Keratin-14Cre, showed small hyperplastic lesions but failed to develop squamous cell carcinoma when stimulated by 4-Nitroquinoline 1-oxide (4NQO). Pharmacological suppression of HuR in epithelial tumor lines and oral tumors with pyrvinium pamoate (PP) reduces tumor growth. We also found that T cells from the spleen of HuR-KO mice had more effector cytokine secretion than WT 4NQO-induced oral tumor-bearing hosts, suggesting that tumor HuR inhibition may alleviate immunosuppression. This shows that epithelial-specific HuR cross-talk with tumor microenvironment suppresses immunity. Our findings show that HuR inhibition in oral epithelial cancers improves anti-tumor activity by reducing tumor-mediated immunosuppression and increasing effector T-cell responsiveness. Based on these data, we predict that targeting HuR in oral epithelium affects tumor metabolism and boosts T-cell immune response to prevent oral carcinogenesis.

Project 2: Post-transcriptional regulation of RNA-binding protein FXR1 in head and neck squamous cell carcinoma.

Post-translational modification (PTM) of proteins has garnered attention since most cancers have high oncoprotein PTM, corresponding with poor patient prognosis. Protein PTM encompasses phosphorylation, methylation, sumoylation, acetylation, and ubiquitylation. Protein PTM is essential for proteome diversity and cancer development. Arginine methylation, an understudied protein change, promotes cancer cell growth and proliferation. The protein family arginine methyltransferases (PRMTs), which write arginine methylation, are promising therapeutic targets for solid and hematological malignancies. PRMTs promote cancer via regulating epigenetic alterations, mRNA processing, DNA damage response, and immune surveillance. PRMTs directly target RNA-binding protein-rich protein domains like RGG and Tudor. For cell development and differentiation, RBPs modulate mRNAs to regulate gene expression. The fragile X mental retardation (FXR) protein family, which includes FMRP and FXR1 and FXR2, is a highly conserved family of RBPs. PRMT-methylated FMRP and FXR1 have canonical RGG and Tudor domains (FXR2 lacks an RGG box). Recently, we found that oral and lung squamous cell carcinomas and other malignancies overexpress RBP FXR1. New oral tumor growth inhibitors can target FXR1 due to its high expression and carcinogenic characteristics. This project aims to prevent PRMTs-mediated FXR1 methylation and understand its involvement in PTR and oral cancer progression. This hypothesis has two goals: 1. Explain how FXR1 methylation affects oral cancer cell RNA turnover and translation. 2. Determine the FXR1's carcinogenic function.

Project 3: RNA-binding protein Supt6-mediated cellular proteome in HNSCC.

Survival rates for advanced head and neck cancer patients are low despite continuous research. In HNSCC, gene expression patterns mediated by Co-transcriptional or post-transcriptional regulation explain tumor heterogeneity. Dysregulated gene expression causes cells to respond to stimuli, reprograming them for proliferation, differentiation, development, and cancer. Multiple disorders, including cancer, are linked to RNA-binding proteins (RBPs), which regulate gene expression and co- and post-transcriptional events1. Over 400 eukaryotic RBPs and RNA-binding motifs have been found. However, their significance in cancer cell proliferation is little understood. Thus, this project's main objective is to establish an integrated transcriptomics and proteomics strategy to investigate and functionally define a novel RBP involved in HNSCC growth and progression. We show that oral cancer growth and proliferation depend on the RBP Suppressor of Ty 6 Homolog (Supt6h alias Spt6). This HNSCC study was the first to investigate Supt6h's role in cancer directly. We offer a novel hypothesis that post-transcriptional gene regulation by Supt6h and its target mRNA transcripts producing oncogenic proteins drives HNSCC growth/proliferation. The following Specific Aims investigate this hypothesis: SA-1. Explain why HNSCC requires the Supt6h-mediated mRNA turnover pathway. SA-2. In HNSCC, determine how Supt6h regulates the proteome and mRNA translation.