Restoration of type 1 iodothyronine deiodinase expression in renal cancer cells downregulates oncoproteins and affects key metabolic pathways as well as anti-oxidative system.

Piotr Popławski,Keith Richards,Agnieszka Piekiełko-Witkowska,Eddy Rijntjes,Josef Köhrle,Jacek R Wiśniewski,Beata Rybicka,Michelina Plateroti

doi:10.1371/journal.pone.0190179

Abstract

Type 1 iodothyronine deiodinase (DIO1) contributes to deiodination of 3,5,3’,5’-tetraiodo-L-thyronine (thyroxine, T4) yielding of 3,5,3’-triiodothyronine (T3), a powerful regulator of cell differentiation, proliferation, and metabolism. Our previous work showed that loss of DIO1 enhances proliferation and migration of renal cancer cells. However, the global effects of DIO1 expression in various tissues affected by cancer remain unknown. Here, the effects of stable DIO1 re-expression were analyzed on the proteome of renal cancer cells, followed by quantitative real-time PCR validation in two renal cancer-derived cell lines. DIO1-induced changes in intracellular concentrations of thyroid hormones were quantified by L-MS/MS and correlations between expression of DIO1 and potential target genes were determined in tissue samples from renal cancer patients. Stable re-expression of DIO1, resulted in 26 downregulated proteins while 59 proteins were overexpressed in renal cancer cells. The ‘downregulated’ group consisted mainly of oncoproteins (e.g. STAT3, ANPEP, TGFBI, TGM2) that promote proliferation, migration and invasion. Furthermore, DIO1 re-expression enhanced concentrations of two subunits of thyroid hormone transporter (SLC7A5, SLC3A2), enzymes of key pathways of cellular energy metabolism (e.g. TKT, NAMPT, IDH2), sex steroid metabolism and anti-oxidative response (AKR1C2, AKR1B10). DIO1 expression resulted in elevated intracellular concentration of T4. Expression of DIO1-affected genes strongly correlated with DIO1 transcript levels in tissue samples from renal cancer patients as well as with their poor survival. This first study addressing effects of deiodinase re-expression on proteome of cancer cells demonstrates that induced DIO1 re-expression in renal cancer robustly downregulates oncoproteins, affects key metabolic pathways, and triggers proteins involved in anti-oxidative protection. This data supports the notion that suppressed DIO1 expression and changes in local availability of thyroid hormones might favor a shift from a differentiated to a more proliferation-prone state of cancer tissues and cell lines.

Highlights

Clear cell renal cell carcinoma is the most common subtype of kidney tumors, affecting more than 300,000 people annually worldwide [1]
Proteomic analysis of KIJ265T-DIO1(+) and KIJ265T-DIO1(-) cells identified peptides derived from 4761 proteins (S2 Table)
We show that induction of DIO1 expression in renal cancer cells leads to profound changes in cellular proteome and affects the expression of genes and proteins involved in metabolic regulation, oxidative stress, autophagy and adhesion

Summary

Introduction

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney tumors, affecting more than 300,000 people annually worldwide [1]. Recent findings indicate that tumorous phenotype of ccRCC is largely driven by alterations in cellular metabolism [3,4,5] They include Warburg effect, the universal feature of cancer cells, that is defined as increased consumption of glucose which is largely converted to lactate, even under normoxic conditions, as well as activated pentose phosphate pathway (PPP), suppressed TCA cycle, enhanced lipogenesis and metabolism of amino acids [5,6,7,8]. These changes are interpreted as a metabolic reprogramming that enables efficient production of essential building blocks (nucleotides, lipids, amino acids) required to sustain intensive proliferation of cancer cells. This metabolic shift provides large amounts of metabolites which contribute to cellular buffering system and protection against acidic environment and oxidative stress of tumors [6]

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