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Poster Session (ID 8)
- Event: ACLC 2018
- Type: Poster Session
- Presentations: 2
- Coordinates: 11/07/2018, 00:00 - 00:00, Poster Hall
P028 - A Novel Method for Detecting Surface PD-L1 on Circulating Tumor Cells in Peripheral Blood of Patients with SCLC (ID 135)
00:00 - 00:00 | Author(s): Y. Liu
Previous studies have demonstrated that circulating tumor cell (CTC) might work as an alternative to biopsy tissues in the diagnoses of small cell lung cancer (SCLC). Programmed death ligand 1 (PD-L1) is one of the most commonly used biomarkers in immune targeted therapies. However, the expression of PD-L1 in CTC is still unknown. This study aimed to establish an approach to measure PD-L1 in peripheral CTCs from SCLC patients.
Control cells were screened by monoclonal culture and confirmed by immunohistochemistry (IHC) staining and flow cytometry. PD-L1 expression in CTCs and tumor tissue samples from SCLC patients was measured by CellSearch system while the usage of PD-L1 antibody was optimized.
The purity of PD-L1 positive H446 cells had been improved from 70% to 95% by clonal selection, and PD-L1 negative PC3 cells showed lower than 5% purity. In CellSearch system, positive control cells had 98% PD-L1 expression while negative control had less than 3% expression. In two SCLC patients with CTC positive expression, PD-L1 expression was found with 100% (1/1) and 40% (2/5) positive rate.
CellSearch system was used to establish a novel approach for measuring surface PD-L1 expression on CTC, and showed supporting evidences in SCLC patients, thus providing novel insights for automatic assay of PD-L1 in peripheral samples.
P029 - Circulating MDSCs Derived from Small Cell Lung Cancer Patients Secrete TGF - Beta 1 and Play Roles in Angiogenesis (ID 151)
00:00 - 00:00 | Author(s): Y. Liu
Studies showed that small cell lung cancer (SCLC) induced CD33+cells production in vitro and the CD33+ cells present typical features of myeloid-derived suppressor cells (MDSCs). We previously reported CD33+CD11b+HLA-DR-MDSCs level was elevated in peripheral blood of SCLC patients and has a prognostic value for SCLC patients. In this study we further explored the mechanisms of SCLC-derived MDSCs involved in angiogenesis.
Peripheral blood specimens from SCLC patients and healthy volunteer were collected and CD11b+/CD33+cells were separated using magnetic bead. Giemsa stain was used in morphological identification of the cells. CD11b+/CD33+cells were cultured in vitro for 72 hrs, then TGF-?1 in cell pellets and supernatant was detected using RT-PCR and western blot, or ELISA respectively. Endothelial tube formation was performed through culturing HUVEC cells on Matrigel using the supernatant as medium. The supernatant was added into HUVEC cells cultured on Matrigel to test angiogenesis effects.
RT-PCR data showed that CD33+ and CD11b+MDSCs from SCLC expressed higher level of TGF-?1 than those from healthy control, 0.349 vs 0.174 (P=0.000632) and 0.191 vs 0.105 (P=0.000867), respectively, and the expression of TGF-?1 in CD33+MDSCs was higher than that in CD11b+cells (P=0.0382). In addition, the western blot results showed that CD33+MDSCs from SCLC expressed higher TGF-?1 than that in control (0.391 vs 0.164?P=0.000491), however, the similar effects were not seen in CD11b+ cells. TGF-?1 expression in supernatant was higher in SCLC-derived CD33+ or CD11b+MDSCs than those in healthy control, 0.620 vs 0.324 (P=0.0155) and 0.482 vs 0.307 (P=0.0413), respectively), and the TGF-?1 level was higher in CD33+MDSCs than that in CD11b+MDSCs (P=0.00668). A significant decrease in tube formation and TGF-?1 level was found in SCLC patients after treatment compared to those before treatment.
The TGF-?1 was highly expressed in both CD11b+ or CD33+MDSCs from SCLC in both transcription and translation levels, along with level change after treatment implying TGF-? signaling pathway may participate in MDSC-mediated angiogenesis in SCLC. Moreover, the expression level of TGF-?1 was discrepant in different phenotypes of MDSCs demonstrating the plastic phenotype of MDSCs in SCLC.