Silibinin Overcomes EMT-Driven Lung Cancer Resistance to New-Generation ALK Inhibitors

Sara Verdura; Jose Antonio Encinar; Eduard Teixidor; Antonio Segura-Carretero; Vicente Micol; Elisabet Cuyàs; Joaquim Bosch-Barrera; Javier A Menendez

doi:10.3390/cancers14246101

Silibinin Overcomes EMT-Driven Lung Cancer Resistance to New-Generation ALK Inhibitors

Cancers (Basel). 2022 Dec 11;14(24):6101. doi: 10.3390/cancers14246101.

Authors

Sara Verdura^{1

2}, Jose Antonio Encinar³, Eduard Teixidor^{2

4}, Antonio Segura-Carretero⁵, Vicente Micol^{3

6}, Elisabet Cuyàs^{1

2}, Joaquim Bosch-Barrera^{2

4

7}, Javier A Menendez^{1

2}

Affiliations

¹ Metabolism and Cancer Group, Program Against Cancer Therapeutic Resistance (ProCURE), Catalan Institute of Oncology, 17005 Girona, Spain.
² Girona Biomedical Research Institute, Salt, 17190 Girona, Spain.
³ Institute of Research, Development and Innovation in Biotechnology of Elche (IDiBE) and Molecular and Cell Biology Institute (IBMC), Miguel Hernández University (UMH), 03202 Elche, Spain.
⁴ Medical Oncology, Catalan Institute of Oncology, 17007 Girona, Spain.
⁵ Department of Analytical Chemistry, University of Granada, 18071 Granada, Spain.
⁶ CIBEROBN (Physiopathology of Obesity and Nutrition CB12/03/30038) Carlos III Health Institute, 28029 Madrid, Spain.
⁷ Department of Medical Sciences, Medical School University of Girona, 17071 Girona, Spain.

Abstract

Epithelial-to-mesenchymal transition (EMT) may drive the escape of ALK-rearranged non-small-cell lung cancer (NSCLC) tumors from ALK-tyrosine kinase inhibitors (TKIs). We investigated whether first-generation ALK-TKI therapy-induced EMT promotes cross-resistance to new-generation ALK-TKIs and whether this could be circumvented by the flavonolignan silibinin, an EMT inhibitor. ALK-rearranged NSCLC cells acquiring a bona fide EMT phenotype upon chronic exposure to the first-generation ALK-TKI crizotinib exhibited increased resistance to second-generation brigatinib and were fully refractory to third-generation lorlatinib. Such cross-resistance to new-generation ALK-TKIs, which was partially recapitulated upon chronic TGFβ stimulation, was less pronounced in ALK-rearranged NSCLC cells solely acquiring a partial/hybrid E/M transition state. Silibinin overcame EMT-induced resistance to brigatinib and lorlatinib and restored their efficacy involving the transforming growth factor-beta (TGFβ)/SMAD signaling pathway. Silibinin deactivated TGFβ-regulated SMAD2/3 phosphorylation and suppressed the transcriptional activation of genes under the control of SMAD binding elements. Computational modeling studies and kinase binding assays predicted a targeted inhibitory binding of silibinin to the ATP-binding pocket of TGFβ type-1 receptor 1 (TGFBR1) and TGFBR2 but solely at the two-digit micromolar range. A secretome profiling confirmed the ability of silibinin to normalize the augmented release of TGFβ into the extracellular fluid of ALK-TKIs-resistant NSCLC cells and reduce constitutive and inducible SMAD2/3 phosphorylation occurring in the presence of ALK-TKIs. In summary, the ab initio plasticity along the EMT spectrum may explain the propensity of ALK-rearranged NSCLC cells to acquire resistance to new-generation ALK-TKIs, a phenomenon that could be abrogated by the silibinin-driven attenuation of the TGFβ/SMAD signaling axis in mesenchymal ALK-rearranged NSCLC cells.

Keywords: ALK; EMT; TGFβ; brigatinib; crizotinib; lorlatinib; lung cancer; silibinin.

Abstract

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