Elevated Baseline Serum PD-L1 Level May Predict Poor Outcomes from Breast Cancer in African-American and Hispanic Women

Chemotherapy-elicited extracellular vesicle CXCL1 from dying cells promotes triple-negative breast cancer metastasis by activating TAM/PD-L1 signaling

BACKGROUND

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, and chemotherapy still serves as the cornerstone treatment functioning by inducing cytotoxic cell death. Notably, emerging evidence suggests that dying cell-released signals may induce cancer progression and metastasis by modulating the surrounding microenvironment. However, the underlying molecular mechanisms and targeting strategies are yet to be explored.

METHODS

Apoptotic TNBC cells induced by paclitaxel or adriamycin treatment were sorted and their released extracellular vesicles (EV-dead) were isolated from the cell supernatants. Chemokine array analysis was conducted to identify the crucial molecules in EV-dead. Zebrafish and mouse xenograft models were used to investigate the effect of EV-dead on TNBC progression in vivo.

RESULTS

It was demonstrated that EV-dead were phagocytized by macrophages and induced TNBC metastasis by promoting the infiltration of immunosuppressive PD-L1+ TAMs. Chemokine array identified CXCL1 as a crucial component in EV-dead to activate TAM/PD-L1 signaling. CXCL1 knockdown in EV-dead or macrophage depletion significantly inhibited EV-dead-induced TNBC growth and metastasis. Mechanistic investigations revealed that CXCL1EV-dead enhanced TAM/PD-L1 signaling by transcriptionally activating EED-mediated PD-L1 promoter activity. More importantly, TPCA-1 (2-[(aminocarbonyl) amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide) was screened as a promising inhibitor targeting CXCL1 signals in EVs to enhance paclitaxel chemosensitivity and limit TNBC metastasis without noticeable toxicities.

CONCLUSIONS

Our results highlight CXCL1EV-dead as a novel dying cell-released signal and provide TPCA-1 as a targeting candidate to improve TNBC prognosis.

Prognostic effect of programmed cell death ligand 1/programmed cell death 1 expression in cancer stem cells of human oral squamous cell carcinoma

The relationship between cancer stem cells (CSCs) in oral squamous cell carcinoma (OSCC) and programmed cell death ligand 1 (PD-L1)/programmed cell death 1 (PD-1) remains unclear. Therefore, the present study aimed to clarify the association between the CD44v3high/CD24low immunophenotype of CSCs in OSCC and PD-L1/PD-1 co-expression, and to assess the prognostic effect of CSCs in terms of immune checkpoint molecules. Formalin-fixed, paraffin-embedded tissue samples and clinicopathological data from 168 patients with OSCC were retrospectively retrieved. Immunohistochemical staining and reverse transcription quantitative polymerase chain reaction were applied to a tissue microarray of the invasive front of each case. Semi-automated cell counting was used to assess CD44v3, CD24, PD-L1 and PD-1 expression by immunohistochemistry (IHC) using a digital image analysis program. Associations between immunological markers and clinicopathological variables were estimated. Patients with the CSC immunophenotype CD44v3high/CD24low, and patients with a high PD-L1/PD-1-positive cell density in the tumor parenchyma and stroma had significantly lower survival rates. Furthermore, patients with the CSC immunophenotype (CD44v3high/CD24low) and high PD-L1/PD-1 co-expression had even lower survival rates (P<0.01, log-rank test). Notably, there was a positive correlation between CD44v3 and PD-L1 expression (τ=0.1096, P=0.0366, Kendall rank correlation coefficient) and a negative correlation between CD24 and PD-1 expression (τ=-0.1387, P=0.0089, Kendall rank correlation coefficient). Additionally, the high CD44v3 expression group, as determined by IHC, exhibited significantly decreased expression of U2 small nuclear RNA auxiliary factor 1 (U2AF1) at the mRNA level compared with that in the low CD44v3 expression group (P<0.001, Mann-Whitney U test), and U2AF1 and PD-L1 mRNA expression exhibited a significant negative correlation (τ=-0.3948, P<0.001, Kendall rank correlation coefficient). In conclusion, CSCs in OSCC may evade host immune mechanisms and maintain CSC stemness via PD-L1/PD-1 co-expression, resulting in unfavorable clinical outcomes.

Prognostic value of soluble programmed cell death ligand-1 in patients with non-small-cell lung cancer: a meta-analysis

Background: Previously published data was collected and a meta-analysis was conducted to precisely identify the prognostic and clinicopathological significance of soluble programmed cell death ligand-1 (sPD-L1) in patients with non-small-cell lung cancer (NSCLC). Materials & methods: Combined hazard ratios (HRs), odds ratios and 95% confidence intervals were used to assess the correlation between sPD-L1 expression and prognosis in patients with NSCLC. Results: A total of 11 studies with 976 patients were included in this meta-analysis. High levels of sPD-L1 were associated with poor overall and progression-free survival (HR: 2.65, 95% CI: 2.32-3.02; p < 0.001 vs HR: 2.02, 95% CI: 1.24-3.29; p = 0.005). sPD-L1 level was not significantly correlated with sex, smoking status, age, Eastern Cooperative Oncology Group performance status, subtype or EGFR mutation. Conclusion: High levels of sPD-L1 are a prognostic marker for poor survival in patients with NSCLC.