scholarly journals L-Type Amino Acid Transporter 1 Regulates Cancer Stemness and the Expression of Programmed Cell Death 1 Ligand 1 in Lung Cancer Cells

2021 ◽  
Vol 22 (20) ◽  
pp. 10955
Author(s):  
Yi-Heng Liu ◽  
Yu-Ling Li ◽  
Huan-Ting Shen ◽  
Peng-Ju Chien ◽  
Gwo-Tarng Sheu ◽  
...  

The l-type amino acid transporter 1 (LAT1) is a membranous transporter that transports neutral amino acids for cells and is dysregulated in various types of cancer. Here, we first observed increased LAT1 expression in pemetrexed-resistant non-small cell lung cancer (NSCLC) cells with high cancer stem cell (CSC) activity, and its mRNA expression level was associated with shorter overall survival in the lung adenocarcinoma dataset of the Cancer Genome Atlas database. The inhibition of LAT1 by a small molecule inhibitor, JPH203, or by RNA interference led to a significant reduction in tumorsphere formation and the downregulation of several cancer stemness genes in NSCLC cells through decreased AKT serine/threonine kinase (AKT)/mammalian target of rapamycin (mTOR) activation. The treatment of the cell-permeable leucine derivative promoted AKT/mTOR phosphorylation and reversed the inhibitory effect of JPH203 in the reduction of CSC activity in pemetrexed-resistant lung cancer cells. Furthermore, we observed that LAT1 silencing caused the downregulation of programmed cell death 1 ligand 1 (PD-L1) on lung cancer cells. The PD-L1+/LAT1+ subpopulation of NSCLC cells displayed great CSC activity with increased expression of several cancer stemness genes. These data suggest that LAT1 inhibitors can serve as anti-CSC agents and could be used in combination with immune checkpoint inhibitors in lung cancer therapy.

2020 ◽  
Vol 111 (9) ◽  
pp. 3174-3183
Author(s):  
Rudi Mao ◽  
Xiao Tan ◽  
Ying Xiao ◽  
Xinyu Wang ◽  
Zhixing Wei ◽  
...  

Oncogene ◽  
2004 ◽  
Vol 23 (36) ◽  
pp. 6170-6174 ◽  
Author(s):  
Liang You ◽  
Biao He ◽  
Zhidong Xu ◽  
Kazutsugu Uematsu ◽  
Julien Mazieres ◽  
...  

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Onsurang Wattanathamsan ◽  
Rawikorn Thararattanobon ◽  
Ratchanee Rodsiri ◽  
Pithi Chanvorachote ◽  
Chanida Vinayanuwattikun ◽  
...  

AbstractThe posttranslational modifications (PTMs) of microtubules have been reported to play an important role in cancer aggressiveness, including apoptosis resistance. In this study, we aimed to investigate the biological role of microtubule PTMs in the regulation of paclitaxel responsiveness. The acetylated tubulin (Ace-tub) level was strongly associated with paclitaxel sensitivity, as observed in patient-derived primary lung cancer cells and xenografted immunodeficient mice. We showed that paclitaxel-resistant H460 lung cancer cells, generated by a stepwise increase in paclitaxel, exhibited markedly increased tubulin acetylation and consequently acquired paclitaxel resistance. Upregulation of tubulin acetylation by overexpression of α-tubulin acetyltransferase 1 wild-type (αTAT1wt), an enzyme required for acetylation, or by treatment with trichostatin A (TSA), a histone deacetylase 6 (HDAC6) inhibitor, significantly attenuated paclitaxel-induced apoptosis. Investigation of the underlying mechanism revealed that the levels of antiapoptotic Mcl-1 appeared to increase in αTAT1wt-overexpressing and TSA-treated cells compared to control cells, whereas the levels of other antiapoptotic regulatory proteins were unchanged. On the other hand, decreased tubulin acetylation by αTAT1 RNA interference downregulated Mcl-1 expression in patient-derived primary lung cancer and paclitaxel-resistant lung cancer cells. A microtubule sedimentation assay demonstrated that Mcl-1 binds to microtubules preferentially at Ace-type, which prolongs the Mcl-1 half-life (T1/2). Furthermore, immunoprecipitation analysis revealed that polyubiquitination of Mcl-1 was extensively decreased in response to TSA treatment. These data indicate that tubulin acetylation enhances the resistance to paclitaxel-induced cell death by stabilizing Mcl-1 and protecting it from ubiquitin–proteasome-mediated degradation.


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