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Targeting AMP-activated kinase impacts hepatocellular cancer stem cells induced by long-term treatment with sorafenib.

ABSTRACT: Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. HCC treatment is hindered by the frequent emergence of chemoresistance to the multikinase inhibitor sorafenib, which has been related to the presence of cancer stem cells (CSCs) that self-renew and often escape therapy. The key metabolic sensor AMP-activated kinase (AMPK) has recently been recognized as a tumour growth regulator. In this study, we aimed to elucidate the role of AMPK in the development of a stem cell phenotype in HCC cells. To this end, we enriched the CSC population in HCC cell lines that showed increased expression of drug resistance (ALDH1A1, ABCB1A) and stem cell (CD133, Nanog, Oct4, alpha fetoprotein) markers and demonstrated their stemness phenotype. These cells were refractory to sorafenib-induced cell death. We report that sorafenib-resistant cells had lower levels of total and phosphorylated AMPK as well as its downstream substrate, ACC, compared with the parental cells. Interestingly, AMPK knockdown with siRNA or inhibition with dorsomorphin increased the expression of stem cell markers in parental cells and blocked sorafenib-induced cell death. Conversely, the upregulation of AMPK, either by transfection or by pharmacological activation with A-769662, decreased the expression of ALDH1A1, ABCB1A, CD133, Nanog, Oct4, and alpha fetoprotein, and restored sensitivity to sorafenib. Analysis of the underlying mechanism points to hypoxia-inducible factor HIF-1? as a regulator of stemness. In vivo studies in a xenograft mouse model demonstrated that stem-like cells have greater tumourigenic capacity. AMPK activation reduced xenograft tumour growth and decreased the expression of stem cell markers. Taken together, these results indicate that AMPK may serve as a novel target to overcome chemoresistance in HCC.

SUBMITTER: Bort A

PROVIDER: S-EPMC6487713 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Targeting AMP-activated kinase impacts hepatocellular cancer stem cells induced by long-term treatment with sorafenib.

Bort Alicia A Sánchez Belén G BG Mateos-Gómez Pedro A PA Vara-Ciruelos Diana D Rodríguez-Henche Nieves N Díaz-Laviada Inés I

Molecular oncology 20190415 5

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. HCC treatment is hindered by the frequent emergence of chemoresistance to the multikinase inhibitor sorafenib, which has been related to the presence of cancer stem cells (CSCs) that self-renew and often escape therapy. The key metabolic sensor AMP-activated kinase (AMPK) has recently been recognized as a tumour growth regulator. In this study, we aimed to elucidate the role of AMPK in the development of a stem ...[more]

PMID: 30959553

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Project description:Background: In chronic hypoxia (CH) and short-term chronic intermittent hypoxia (CIH) exposure, glycemia and insulin levels decrease and insulin sensitivity increases, which can be explained by changes in glucose transport at skeletal muscles involving GLUT1, GLUT4, Akt, and AMPK, as well as GLUT4 translocation to cell membranes. However, during long-term CIH, there is no information regarding whether these changes occur similarly or differently than in other types of hypoxia exposure. This study evaluated the levels of AMPK and Akt and the location of GLUT4 in the soleus muscles of lean rats exposed to long-term CIH, CH, and normoxia (NX) and compared the findings. Methods: Thirty male adult rats were randomly assigned to three groups: a NX (760 Torr) group (n = 10), a CIH group (2 days hypoxia/2 days NX; n = 10) and a CH group (n = 10). Rats were exposed to hypoxia for 30 days in a hypobaric chamber set at 428 Torr (4,600 m). Feeding (10 g daily) and fasting times were accurately controlled. Measurements included food intake (every 4 days), weight, hematocrit, hemoglobin, glycemia, serum insulin (by ELISA), and insulin sensitivity at days 0 and 30. GLUT1, GLUT4, AMPK levels and Akt activation in rat soleus muscles were determined by western blot. GLUT4 translocation was measured with confocal microscopy at day 30. Results: (1) Weight loss and increases in hematocrit and hemoglobin were found in both hypoxic groups (p < 0.05). (2) A moderate decrease in glycemia and plasma insulin was found. (3) Insulin sensitivity was greater in the CIH group (p < 0.05). (4) There were no changes in GLUT1, GLUT4 levels or in Akt activation. (5) The level of activated AMPK was increased only in the CIH group (p < 0.05). (6) Increased GLUT4 translocation to the plasma membrane of soleus muscle cells was observed in the CIH group (p < 0.05). Conclusion: In lean rats experiencing long-term CIH, glycemia and insulin levels decrease and insulin sensitivity increases. Interestingly, there is no increase of GLUT1 or GLUT4 levels or in Akt activation. Therefore, cellular regulation of glucose seems to primarily involve GLUT4 translocation to the cell membrane in response to hypoxia-mediated AMPK activation.

Project description:Background Sorafenib is the standard first-line treatment for advanced hepatocellular carcinoma (HCC), even though acquired resistance to sorafenib has been found in many HCC patients, resulting in poor prognosis. Accumulating evidence demonstrates that liver cancer stem cells (LCSCs) contribute to sorafenib resistance in HCC. The inflammatory factor interleukin 6 (IL-6) plays a role in sorafenib resistance in HCC. However, the mechanism by which IL-6 in LCSCs is involved in the process of HCC sorafenib resistance remains elusive. Methods In this study, the sorafenib-resistant cell line PLC/PRF/5-R was generated by the concentration gradient method, and cell viability was determined by the CCK-8 assay. LCSCs were isolated from the PLC/PRF/5-R cell line by flow cytometry, and tumorigenesis was confirmed in nude mice. Blockade of IL-6 cells was achieved by lentiviral-mediated interference. The protein levels of stem cell markers (EpCAM, CD44), stemness markers (Oct3/4, ?-catenin), and hepatocyte differentiation markers (glucose-6-phosphate, AFP) were measured by Western blotting analysis. Finally, a xenograft model was used to evaluate the function of IL-6 in the sorafenib resistance of HCC. Results The stable sorafenib-resistant HCC cell line PLC/PRF/5-R was established and showed significant epithelial–mesenchymal transition (EMT) characteristics; the isolated resistant LCSCs from PLC/PRF/5-R were more tumorigenic than the control LCSCs. We showed that IL-6, IL-6R, STAT3 and GP130 expression were dramatically increased in resistant LCSCs compared to control LCSCs. Downregulation of IL-6 expression with short hairpin RNA (shRNA) restored sorafenib sensitivity in resistant LCSCs, suggesting the critical roles of IL-6/STAT3 in inducing sorafenib resistance. Furthermore, a xenograft tumor model showed that IL-6 downregulation improved the antitumor effect of sorafenib. Conclusion LCSCs play an important role in sorafenib-resistant HCC, and inhibition of the IL-6/STAT3 signaling pathway improves the antitumor effects of sorafenib against HCC in vitro and in vivo. These findings demonstrate that IL-6 in LCSCs may function as a novel target for combating sorafenib resistance in HCC.

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Targeting AMP-activated kinase impacts hepatocellular cancer stem cells induced by long-term treatment with sorafenib.

Publications

Targeting AMP-activated kinase impacts hepatocellular cancer stem cells induced by long-term treatment with sorafenib.

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