Synergistic Effect of Metformin and Vemurufenib (PLX4032) as a Molecular Targeted Therapy in Anaplastic Thyroid Cancer – An In Vitro Study

Abstract

Survival rate of patients with anaplastic thyroid carcinoma (ATC) is less than 5% with current treatment. Deregulated cell signaling pathways such as BRAF/MAPK/ERK pathway and AMPK pathway along with suppression of iodine metabolising genes including NIS and TSHR are seen in ATC. In ATC, BRAFV600E mutation is the major mutation occurring in ATC that constitutively activate MAPK/ERK signaling and result in the transformation of normal cells in to undifferentiated cancer cells. Although Vemurufenib is a selective oral drug for the BRAFV600E mutant kinase with a response rate of nearly 50% in metastatic melanoma, our study on ATC has showed resistance to Vemurafenib. Metformin, a diabetic drug is an AMPK activator and has recently proved to be involved in preventing or treating several types of cancer. Using iGEMDock software, a protein-ligand interaction was successful between Metformin and TSHR in our study and demonstrated that combination of Vemurufenib with metformin has synergistic anti-cancer effects and provide the evidence that the combination of drugs suppressed the progression of ATC cells growth by inducing significant apoptosis through downregulation of ERK signaling, upregulation of AMPK pathway and by reversing epithelial-mesenchymal transition (EMT) markers - E-cadherin and Vimentin expression. Our results suggest that Metformin act as a demethylating agent in anaplastic thyroid cancer cells by inducing the expression of NIS and TSHR. cAMP signaling has been studied in ATC for the first time through our study wherein cAMP signaling is downregulated due to decrease in intracellular cAMP level upon metformin treatment. To conclude, our findings demonstrate novel therapeutic targets and treatment strategies for undifferentiated ATC.

Drug repositioning in thyroid cancer treatment: the intriguing case of anti-diabetic drugs

“…Indeed, undifferentiated TC cells express low levels of sodium/iodinesymporter (NIS), a protein membrane crucial for iodine uptake by thyrocites and consequently essential for the efficacy of RAI, the most effective therapy for TC in case of not complete surgical removal. A recent study in ATC cells showed that metformin increased NIS mRNA and protein expression (as well as mRNA of thyroglobulin, TSHR, and NKX2.1) acting also as a demethylating agent (Durai et al, 2021).…”

“…Interesting findings emerged also from studies in vitro on different types of thyroid cells (human anaplastic, differentiated cancer cells, as well as human normal and cancer thyroid primary cell cultures, TC stem cells and rat follicular thyroid cells). These studies highlighted several anti-cancer effects exerted by metformin on TC cells including: i) induction of cell death, ii) reduction of cell growth, iii) inhibition of the metastatic potential iv) modulation of chemokines in the tumor microenvironment, v) de-differentiating effects (increase in iodine up-take) (Chen et al, 2012;Klubo-Gwiezdzinska et al, 2013;Cho et al, 2014;Moon and Mantzoros, 2014;Rotondi et al, 2015;Kim et al, 2018a;Klubo-Gwiezdzinska et al, 2012;Han et al, 2015;Kheder et al, 2017;Nozhat et al, 2018;Ye et al;Sloot et al, 2019;Durai et al, 2021;Morale et al, 2022). The reduction of cell growth and viability showed in TC cells were due to the regulation by metformin of the AMPK-mTOR pathway, inhibiting cell cycle progression and inducing apoptosis (Klubo-Gwiezdzinska et al, 2012;Klubo-Gwiezdzinska et al, 2013;Thakur et al, 2019).…”

“…Finally, some studies also showed that metformin could synergize with other drugs increasing their anti-cancer effects. Indeed metformin showed synergic effects with Sorafenib (a multikinase inhibitor) (Chen et al, 2015), with vemurafenib (a selective inhibitor of BRAFV600E), with gemigliptin (dipeptidyl peptidase-IV inhibitor) (Kim et al, 2018a) and pioglitazone (a TDZ) (Kim et al, 2018a;Ozdemir Kutbay et al, 2020) in several TC models (Hanly et al, 2015;Durai et al, 2021).…”