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MINI 27 - Biology and Other Issues in SCLC (ID 152)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Small Cell Lung Cancer
- Presentations: 1
MINI27.06 - Acquired Resistance Mechanisms in Small Cell Lung Cancer Mediated by the Cancer Stem Cell Marker Calcium Channel α2δ1 Subunit (ID 2473)
16:45 - 18:15 | Author(s): S. Yu
As a subtype of lung cancer, small cell lung cancer (SCLC) remains a severe threat to human health. Although it is initially a chemosensitive disease, development of acquired resistance is a major problem. Studies in recent years revealed that cancer stem cell (CSC) could play a role in this process. However, the CSC specific marker and the detailed signal pathway associated with acquired resistance in SCLC is unknown yet. It was recently reported that the voltage-dependent calcium channel α2δ1 subunit positive cells is a CSC marker in hepatic cell cancer and that 1B50-1 is the specific monoclonal antibody of the α2δ1 subunit. In present study, we attempted to disclose that α2δ1 could play a role in acquired resistance of SCLC. Also we investigated possible molecular mechanism of α2δ1 mediated resistance in SCLC and finally provided the potential strategies overcoming the resistance.
We screened for positive expression of 1B50-1and CD133 in SCLC cell lines and in patient-derived xenograft (PDX) models, and we used flow cytometry to verify the properties of CSCs. We recorded the expression of 1B50-1 before and after chemotherapy in PDXs in chemosensitive and resistant models to determine if α2δ1 subunit-positive cells were related to acquired resistance. We used exome and transcriptome sequencing to explore the expression of genes related to stem cell properties and drug resistance. We used Western blotting to verify the key molecules and pathways in the process of drug resistance. On the basis of these results, we explored the mechanisms of acquired drug resistance that are mediated by the α2δ1 subunit.
We observed a difference in the positive expression levels of 1B50-1 and CD133 in SCLC cell lines (H1048, H69, and H209) and PDX models. Both 1B50-1-positive and CD133-positive cells exhibited stem cell-like properties such as the capacity to self-renew in vitro, tumorigenesis in vivo, the potential for differentiation, and high expression levels of genes related to CSCs and drug resistance. Chemotherapy could induce the enrichment of 1B50-1-positive cells but not CD133-positive cells in PDXs. Also, high rates of 1B50-1-positive cells corresponded to high levels of resistance. Together, these findings indicated that the expression of 1B50-1 is related to chemoresistance. Exome and transcriptome sequencing revealed that the expressions of multiple pathway related genes in pathways, including MAPK, CAMs, TGFβ, and Notch, were increased in 1B50-1-positive H1048 cells. Western blotting revealed the activation of the Erk protein in the MAPK pathway and the over-expression of the Erk protein in 1B50-1-positive H1048 cells. The specific α2δ1 antibody 1B50-1 improved response to chemotherapy and delayed relapse when combined with chemotherapy or used y as maintenance therapy.
The α2δ1 subunit positive SCLC cells (1B50-1+) displayed CSC properties, and were associated with acquired resistance. The Erk protein in the MAPK pathway was highly expressed in the 1B50-1-positive H1048 cell line, and might be the key molecule involved in resistance mediated by the α2δ1 subunit. The α2δ1 subunit-specific antibody 1B50-1 could improve response to chemotherapy and delay relapse when combined with chemotherapy or when used as sequential therapy.
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