Pairing a prognostic target with potential therapeutic strategy for head and neck cancer

Mechanism study of lncRNA RMRP regulating esophageal squamous cell carcinoma through miR-580-3p/ATP13A3 axis

OBJECTIVE

It is well-known that lncRNAs regulate energy metabolism in tumors. This study focused on the action of RMRP on esophageal squamous cell carcinoma (ESCC) cell proliferation, apoptosis, and glycolysis.

METHODS

In the resected ESCC tissues and adjacent tissues from patients, RMRP/miR-580-3p/ATP13A3 expressions were evaluated. ESCC cell proliferation rates and apoptotic rates were measured by CCK-8 and flow cytometry, respectively. Apoptosis related markers were examined by Western blot. Moreover, glucose uptake, lactic acid, and ATP were measured by commercial kits, whereas HK2 and PKM2 were evaluated by Western blot to study ESCC cell glycolysis. Finally, the editing program of RMRP/miR-580-3p/ATP13A3 was translated by luciferase reporter assay and RIP analysis.

RESULTS

RMRP and ATP13A3 were induced, while miR-580-3p was reduced in their expression in ESCC tissues. Silencing RMRP reduced proliferation, glycolysis, and anti-apoptosis ability of ESCC cells. RMRP sequestered miR-580-3p to target ATP13A3. Silenced ATP13A3 or overexpressed miR-580-3p rescued overexpressed RMRP-mediated promotion of proliferation, glycolysis, and anti-apoptosis of ESCC cells.

CONCLUSION

RMRP accelerates ESCC progression through the miR-580-3p/ATP13A3 axis, renewing a reference for lncRNA-based therapies for tumors.

P5B-ATPases in the mammalian polyamine transport system and their role in disease

Polyamines (PAs) are physiologically relevant molecules that are ubiquitous in all organisms. The vitality of PAs to the healthy functioning of a cell is due to their polycationic nature causing them to interact with a vast plethora of cellular players and partake in numerous cellular pathways. Naturally, the homeostasis of such essential molecules is tightly regulated in a strictly controlled interplay between intracellular synthesis and degradation, uptake from and secretion to the extracellular compartment, as well as intracellular trafficking. Not surprisingly, dysregulated PA homeostasis and signaling are implicated in multiple disorders, ranging from cancer to neurodegeneration; leading many to propose rectifying the PA balance as a potential therapeutic strategy. Despite being well characterized in bacteria, fungi and plants, the molecular identity and properties of the PA transporters in animals are poorly understood. This review brings together the current knowledge of the cellular function of the mammalian PA transport system (PTS). We will focus on the role of P5B-ATPases ATP13A2-5 which are PA transporters in the endosomal system that have emerged as key players in cellular PA uptake and organelle homeostasis. We will discuss recent breakthroughs on their biochemical and structural properties as well as their implications for disease and therapy.

A chemical genetic screen identifies Aurora kinases as a therapeutic target in EGFR T790M negative, gefitinib-resistant head and neck squamous cell carcinoma (HNSCC)

BACKGROUND

Overexpression of epidermal growth factor receptor (EGFR), and downstream pathway activation appears to be a common oncogenic driver in the majority of head and neck squamous cell cancers (HNSCCs); yet targeting EGFR for the treatment of HNSCC has met with limited success. Apart from the anti-EGFR antibody cetuximab, no small molecule EGFR/tyrosine kinase inhibitors (TKIs) have progressed to routine clinical use. The aim of this study was to determine factors contributing to the lack of response to TKIs and identify alternative therapeutic vulnerabilities.

METHODS

Genomic and transcriptomic sequencing, high-throughput compound screens, overexpression and siRNA knockdown, western blot, in vivo xenograft studies.

FINDINGS

We derived three pairs of isogenic gefitinib (TKI)-sensitive and resistant patient-derived HNSCC cell lines. Genomic sequencing of gefitinib-resistant cell lines identified a lack of activating and resistance-associated EGFR mutations. Instead, transcriptomic sequencing showed upregulated EMT gene signature in the gefitinib-resistant cells with a corresponding increase in their migratory phenotype. Additionally, the resistant cell displayed reduced growth rate. Surprisingly, while gefitinib-resistant cells were independent of EGFR for survival, they nonetheless displayed activation of downstream ERK and AKT signalling. High-throughput screening (HTS) of druggable, small molecule libraries revealed that the gefitinib-resistant cells were particularly sensitive to inhibitors of genes involved in cell cycle and mitosis, such as Aurora kinase inhibitors (AKIs), cyclin-dependent kinase (CDK) inhibitors, and microtubule inhibitors. Notably our results showed that in the EGFR inhibited state, Aurora kinases are essential for cell survival.

INTERPRETATION

Our study demonstrates that in the absence of activating EGFR mutations, HNSCCs may gain resistance to gefitinib through decreased cell proliferation, which makes them exceptionally vulnerable to cell-cycle inhibitors.

FUNDING

Agency for Science, Technology, and Research (A*STAR), National Medical Research Council (NMRC), and the National Institutes of Health (NIH)/National Cancer Institute (NCI).