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High Sensitivity of Circulating Tumor Cells Derived from a Colorectal Cancer Patient for Dual Inhibition with AKT and mTOR Inhibitors

1
Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
2
Laboratory of Rare Human Circulating Cells (LCCRH), University Medical Center of Montpellier, 34093 Montpellier, France
3
Molecular Skeletal Biology Laboratory, Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
4
Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
*
Author to whom correspondence should be addressed.
Cells 2020, 9(9), 2129; https://doi.org/10.3390/cells9092129
Received: 14 August 2020 / Revised: 15 September 2020 / Accepted: 18 September 2020 / Published: 20 September 2020
(This article belongs to the Section Cell Signaling)
Circulating tumor cells (CTCs) are cells shed from the primary tumor into the bloodstream. While many studies on solid tumor cells exist, data on CTCs are scarce. The mortality of cancer is mostly associated with metastasis and recent research identified CTCs as initiators of metastasis. The PI3K/AKT/mTOR signaling pathway is an intracellular pathway that regulates essential functions including protein biosynthesis, cell growth, cell cycle control, survival and migration. Importantly, activating oncogenic mutations and amplifications in this pathway are frequently observed in a wide variety of cancer entities, underlining the significance of this signaling pathway. In this study, we analyzed the functional role of the PI3K/AKT/mTOR signaling pathway in the CTC-MCC-41 line, derived from a patient with metastatic colorectal cancer. One striking finding in our study was the strong sensitivity of this CTC line against AKT inhibition using MK2206 and mTOR inhibition using RAD001 within the nanomolar range. This suggests that therapies targeting AKT and mTOR could have been beneficial for the patient from which the CTC line was isolated. Additionally, a dual targeting approach of AKT/mTOR inside the PI3K/AKT/mTOR signaling pathway in the colorectal CTCs showed synergistic effects in vitro. Depending on the phenotypical behavior of CTC-MCC-41 in cell culture (adherent vs. suspension), we identified altered phosphorylation levels inside the PI3K/AKT/mTOR pathway. We observed a downregulation of the PI3K/AKT/mTOR signaling pathway, but not of the RAS/RAF/MAPK pathway, in CTCs growing in suspension in comparison to adherent CTCs. Our results highlight distinct functions of AKT isoforms in CTC-MCC-41 cells with respect to cell proliferation. Knockdown of AKT1 and AKT2 leads to significantly impaired proliferation of CTC-MCC-41 cells in vitro. Therefore, our data demonstrate that the PI3K/AKT/mTOR signaling pathway plays a key role in the proliferation of CTC-MCC-41. View Full-Text
Keywords: circulating tumor cells; CTCs; drug sensitivity assays; PI3K/AKT/mTOR pathway; AKT; MK2206; RAD001; dual targeting; colorectal carcinoma; targeted therapy; personalized medicine circulating tumor cells; CTCs; drug sensitivity assays; PI3K/AKT/mTOR pathway; AKT; MK2206; RAD001; dual targeting; colorectal carcinoma; targeted therapy; personalized medicine
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MDPI and ACS Style

Smit, D.J.; Cayrefourcq, L.; Haider, M.-T.; Hinz, N.; Pantel, K.; Alix-Panabières, C.; Jücker, M. High Sensitivity of Circulating Tumor Cells Derived from a Colorectal Cancer Patient for Dual Inhibition with AKT and mTOR Inhibitors. Cells 2020, 9, 2129. https://doi.org/10.3390/cells9092129

AMA Style

Smit DJ, Cayrefourcq L, Haider M-T, Hinz N, Pantel K, Alix-Panabières C, Jücker M. High Sensitivity of Circulating Tumor Cells Derived from a Colorectal Cancer Patient for Dual Inhibition with AKT and mTOR Inhibitors. Cells. 2020; 9(9):2129. https://doi.org/10.3390/cells9092129

Chicago/Turabian Style

Smit, Daniel J., Laure Cayrefourcq, Marie-Therese Haider, Nico Hinz, Klaus Pantel, Catherine Alix-Panabières, and Manfred Jücker. 2020. "High Sensitivity of Circulating Tumor Cells Derived from a Colorectal Cancer Patient for Dual Inhibition with AKT and mTOR Inhibitors" Cells 9, no. 9: 2129. https://doi.org/10.3390/cells9092129

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