Hedgehog signalling mediates drug resistance through targeting TAP1 in hepatocellular carcinoma

Abstract

Multidrug resistance is one of the reasons for low survival of advanced hepatocellular carcinoma (HCC). Our previous studies indicate that the hedgehog signalling is involved in hepatic carcinogenesis, metastasis and chemo-resistance. The present study aims to uncover molecular mechanisms underlying hepatoma chemo-resistance. TAP1 and GLI1/2 gene expression was assessed in both poorly differentiated hepatoma cells and HCC specimens. Potential GLI-binding site in the TAP1 promoter sequence was validated by molecular assays. Approximately 75% HCC specimens exhibited an elevated expression of hedgehog GLI1 transcription factor compared with adjacent liver tissue. Both GLI1/2 and TAP1 protein levels were significantly elevated in poorly differentiated hepatoma cells. Both Huh-7-trans and Huh-7-DN displayed more karyotypic abnormalities and differential gene expression profiles than their native Huh-7 cells. Sensitivity to Sorafenib, doxorubicin and cisplatin was remarkably improved after either GLI1 or TAP1 gene was inhibited by an RNAi approach or by a specific GLI1/2 inhibitor, GANT61. Further experiments confirmed that hedgehog transcription factor GLI1/2 binds to the TAP1 promoter, indicating that TAP1 is one of GLI1/2 target genes. In conclusion, TAP1 is under direct transcriptional control of the hedgehog signalling. Targeting hedgehog signalling confers a novel insight into alleviating drug resistance in the treatment of refractory HCC. K E Y W O R D Schemo-resistance, GANT61, hedgehog signalling, hepatocellular carcinoma, TAP1 | 4299 ZHOU et al.

Downregulation of GLI3 Expression Mediates Chemotherapy Resistance in Acute Myeloid Leukemia

“…The authors could reverse resistance in the multiple drug-resistant HL-60 AML cell line using the SMO inhibitor NVP-LDE225, resulting in decreased protein expression of MRP1, which is a membrane drug transporter protein responsible for drug resistance and a poor prognosis in AML patients [ 35 ]. Furthermore, activated GLI signaling results in the upregulation of several drug transporters, including the ABC transporters ABCB1 , ABCB2 , and ABCG2 , DNA repair mechanisms, and drug-modifying enzymes of the UDP glucuronosyltransferase ( UGT1A ) family [ 22 , 36 , 37 , 38 ]. However, while the role of GLI signaling in drug resistance is well established, the involvement of GLI3 gene expression in the development of chemotherapy resistance has not been investigated.…”

Hedgehog Signaling, a Critical Pathway Governing the Development and Progression of Hepatocellular Carcinoma

“…This discrepancy may be explained by two reasons: (i) polymorphism of ABCB1 and/or ABCG2 determined the clinical response to sorafenib in patients with HCC [ 98 ]; and (ii) expression of the ABC transporters was associated with the differentiation degree of the HCC. ABCB1 and ABCG2 were mainly expressed in well-differentiated hepatoma cells, whereas poorly differentiated hepatoma cells expressed ABCC1 and ABCB2 (TAP1), accompanied by aberrant activation of the Hh signaling [ 17 ]. We have demonstrated that Hh transcription factors GLI1/2 were able to bind to the consensus sequence in the promoter of ABCC1 or ABCB2 to facilitate resistance to sorafenib, doxorubicin and cisplatin in poorly differentiated hepatoma cells.…”

“…We have demonstrated that Hh transcription factors GLI1/2 were able to bind to the consensus sequence in the promoter of ABCC1 or ABCB2 to facilitate resistance to sorafenib, doxorubicin and cisplatin in poorly differentiated hepatoma cells. Suppression of GLI1/2 by RNA interference approaches or GANT61, a GLI inhibitor, resulted in a decrease in expression of ABCC1 or ABCB2, and partially restored the chemosensitivity in these poorly differentiated hepatoma cells [ 16 , 17 ]. Moreover, ATO, another GLI1 inhibitor, improved the survival of a spontaneous mouse model of medulloblastoma with activated Hh pathway signaling [ 99 ].…”

“…At the same time, molecular targeting agents and checkpoint inhibitors are optimal selections for refractory malignancies, such as pulmonary, hepatocellular and breast carcinoma, and primary and induced resistance to these therapeutics prompts basic and clinical investigations on the molecular interplay underlying drug resistance. Hh signaling has been found to be one of key signaling pathways in modulating drug resistance through ATP-binding cassette (ABC) transporters, such as ABCC1 and TAP1, in our previous studies [ 16 , 17 ].…”

Systematic Analysis of the Function and Prognostic Value of RNA-Binding Proteins in Hepatocellular Carcinoma

“…Most HCC patients lose the opportunity to have surgery when they are diagnosed and are mainly treated by trans-arterial chemoembolization (TACE), radiofrequency ablation, cryoablation, molecular targeted therapies, and other adjuvant treatments. However, these therapies have not signi cantly improved the 5-year survival rate of patients with HCCs [3] . Hence, actively searching for molecular markers and therapeutic targets for predicting the prognosis of patients with primary HCC is important for improving prognosis.…”