A Novel Function for KLF4 in Modulating the De-Differentiation of EpCAM−/CD133− nonStem Cells into EpCAM+/CD133+ Liver Cancer Stem Cells in HCC Cell Line HuH7

Abstract

The complex and heterogeneous nature of hepatocellular carcinoma (HCC) hampers the identification of effective therapeutic strategies. Cancer stem cells (CSCs) represent a fraction of cells within tumors with the ability to self-renew and differentiate, and thus significantly contribute to the formation and maintenance of heterogeneous tumor mass. Increasing evidence indicates high plasticity in tumor cells, suggesting that non-CSCs could acquire stem cell properties through de-differentiation or reprogramming processes. In this paper, we reveal KLF4 as a transcription factor that can induce a CSC-like phenotype in non-CSCs through upregulating the EpCAM and E-CAD expression. Our studies indicated that KLF4 could directly bind to the promoter of EpCAM and increase the number of EpCAM+/CD133+ liver cancer stem cells (LCSCs) in the HuH7 HCC cell line. When KLF4 was overexpressed in EpCAM−/CD133− non-stem cells, the expressions of hepatic stem/progenitor cell genes such as CK19, EpCAM and LGR5 were significantly increased. KLF4 overexpressing non-stem cells exhibited greater cell viability upon sorafenib treatment, while the cell migration and invasion capabilities of these cells were suppressed. Importantly, we detected an increased membranous expression and colocalization of β-CAT, E-CAD and EpCAM in the KLF4-overexpressing EpCAM−/CD133− non-stem cells, suggesting that this complex might be required for the cancer stem cell phenotype. Moreover, our in vivo xenograft studies demonstrated that with a KLF4 overexpression, EpCAM−/CD133− non-stem cells attained an in vivo tumor forming ability comparable to EpCAM+/CD133+ LCSCs, and the tumor specimens from KLF4-overexpressing xenografts had increased levels of both the KLF4 and EpCAM proteins. Additionally, we identified a correlation between the KLF4 and EpCAM protein expressions in human HCC tissues independent of the tumor stage and differentiation status. Collectively, our data suggest a novel function for KLF4 in modulating the de-differentiation of tumor cells and the induction of EpCAM+/CD133+ LCSCs in HuH7 HCC cells.

Immunotherapy for targeting cancer stem cells in hepatocellular carcinoma

“…Second, the existence of intertumor, intratumor, and CSC heterogeneity is a daunting challenge in the development of immunotherapy targeting HCC CSCs 23 , 178 . Additionally, several studies have demonstrated that the HCC CSCs are plastic and can be converted from tumor cells without a stem phenotype, which can be induced by virus infection, crosstalk between CSCs and tumor cells, hypoxia stimulation, and conventional therapies 76 , 77 , 106 , 179 , 180 . This plasticity and instability of the CSC phenotype in HCC is a major obstacle for effective immunotherapy targeting CSCs.…”

Tiliroside as a CAXII inhibitor suppresses liver cancer development and modulates E2Fs/Caspase-3 axis

“…High expression of CD133 was positively associated with poor overall survival in HCC patients. CD133 may facilitate CSC characteristics via stabilizing EGFR-Akt or regulating neurotensin/interleukin (IL)-8/CXCL1 pathway 50 , 51 . The results from our 3D formation and CD133, E2F1/3 expression assays indicated that Tiliroside has displayed its anti-stemness ability.…”

Tumorigenic and Immunogenic Properties of Induced Pluripotent Stem Cells: a Promising Cancer Vaccine

“…However, evidence also indicated that Klf4 could promote the expression of cancer stem cell-related markers and mesenchymal markers in colon cancer cells [67]. Similarly, in hepatocellular carcinoma cells, Klf4 can convert regular cancer cells into a cancer stem celllike phenotype by positively regulating the expression of EpCAM and E-CAD [68]. Researchers also confirmed that Klf4 acted as a potent oncogene in breast cancer development via facilitating cell invasion, migration, and the maintenance of stem cell features [69].…”