ObjectiveTo explore the molecular mechanism of the chemo-resistance in NR2F1-mediated dormant ovarian cancer（OC） cells. MethodsThe expression of the NR2F1 molecule in OC patients and its relationship with the overall survival of patients were analyzed using the GEPIA database. Nuclear receptor subfamily 2 group F member 1（NR2F1） overexpressed OC cell and control cell were constructed by lentivirus in vitro transfection. The proliferation of OC cells was analyzed by CCK-8 method. Real-time fluorescent quantitative PCR（qRT-PCR） was used to analyze the mRNA expression of dormancy-related molecular genes in OC cells. Western blot was performed to analyze the protein expression levels of related molecules. The viability of OC cells treated with different chemotherapy drugs was analyzed by trypan blue exclusion method. Annexin V-FITC/PI double-staining assay was used to detect the apoptosis of OC cells treated by different chemotherapy drugs. Transcriptome sequencing technology was used to analyze the differentially expressed genes in NR2F1 overexpressed SKOV3 cell line， and the relevant signaling pathways were screened through KEGG enrichment analysis. qRT-PCR was performed to verified the mRNA expression level of drug resistance-related molecules in OC cells. The GEPIA database was used to further verify the correlation between the expression of NR2F1 and the drug resistance-related genes. ResultsThe NR2F1 expression is low in the tumor tissues and the high expression of NR2F1 correlates with poor overall survival in the OC patients. Compared with the control group， the proliferation ability of the NR2F1 overexpressed OC cell lines was significantly reduced. The expression of dormancy-related molecules， cyclin-dependent kinase inhibitor 1B（p27）， differentiated embryonic cartilage gene-2（DEC2） and transforming growth factor-β2（TGF-β2）， increased significantly in the NR2F1 overexpressed OC cell lines， and anti-apoptotic molecule B-cell lymphoma gene-2（BCL-2） also increased. In contrast， the expression of the proliferation-related molecule KI67 was decreased. In addition， the NR2F1 overexpressed OC cell lines significantly enhanced the resistance to chemotherapy drugs. Transcriptome sequencing and KEGG enrichment analysis showed that the upregulated genes in NR2F1 overexpressed OC cells were enriched in phosphatidylinositol-3-kinase-protein kinase（PI3K-Akt） signaling pathway， focal adhesion pathway， extracellular matrix-receptor interactions and signaling pathways regulating pluripotency of stem cells， and the downregulated genes in NR2F1 overexpressed OC cells were mainly enriched in cell cycle pathway. The results of qRT-PCR verification showed that drug resistance-related molecules kinesin family member 26B（KIF26B）， secreted protein acidic and rich in cysteine（SPARC）， collagen type Ⅵ alpha 1（COL6A1）， collagen type Ⅴ alpha 2 chain（COL5A2）， frizzled homolog 1（FZD1） and inhibin subunit beta A gene（INHBA） were up-regulated in NR2F1 overexpressed OC cells. GEPIA database analysis showed that the expression of NR2F1 in OC tumor tissues was positively correlated with the expression of drug resistance-related genes KIF26B， SPARC， COL6A1， COL5A2， FZD1 and INHBA. ConclusionsThis study shows that upregulation of NR2F1 may induce dormancy in OC cells and enhance their resistance to chemo-drugs. The NR2F1-mediated drug resistance of dormant OC cells might be associated with the PI3K-Akt signaling pathway and signaling pathways regulating pluripotency of stem cells， and closely related to the upregulation of KIF26B， SPARC， COL6A1， COL5A2， FZD1 and INHBA.

Objective To investigate the expression of PD‐L1 in the CD4+CD25hiCD127low/‐ Treg cells in the peripheral blood of colon cancer and the correlation with clinical stage .Methods The expression of PD‐L1 on CD4+CD25hiCD127low/‐Treg cells from 47 samples of the peripheral blood of colon cancer was analyzed by flow cytometry .Results Compared with those from healthy do‐nor ,the proportion of CD4+CD25hiCD127low/‐Treg cells and expression of PD‐L1 on these cells increased significantly (P<0 .01) . Further analysis showed that expression of PD‐L1 increased with the increase of clinical stage of colon cancer (P<0 .01) ,and de‐creased significantly after postoperation (P<0 .05) .Conclusion Increase of proportion of CD4+CD25hiCD127low/‐Treg cells and the expression of PD‐L1 may enhance the suppression of antitumor immunity ,and thereby promote tumor immunoescape .