Small cell lung cancer stem cells display mesenchymal properties and exploit immune checkpoint pathways in activated cytotoxic T lymphocytes

Small cell lung cancer (SCLC) is an aggressive tumor type with early dissemination and distant metastasis capacity. Even though optimal chemotherapy responses are observed initially in many patients, therapy resistance is almost inevitable. Accordingly, SCLC has been regarded as an archetype for cancer stem cell (CSC) dynamics. To determine the immune-modulatory influence of CSC in SCLC, this study focused on the characterization of CD44(+)CD90(+) CSC-like subpopulations in SCLC. These cells displayed mesenchymal properties, differentiated into different lineages and further contributed to CD8(+) cytotoxic T lymphocytes (CTL) responses. The interaction between CD44(+)CD90(+) CSC-like cells and T cells led to the upregulation of checkpoint molecules PD-1, CTLA-4, TIM-3, and LAG3. In the patient-derived lymph nodes, CD44(+) SCLC metastases were also observed with T cells expressing PD-1, TIM-3, or LAG3. Proliferation and IFN-γ expression capacity of TIM-3 and LAG3 co-expressing CTLs are adversely affected over long-time co-culture with CD44(+)CD90(+) CSC-like cells. Moreover, especially through IFN-γ secreted by the T cells, the CSC-like SCLC cells highly expressed PD-L1 and PD-L2. Upon a second encounter with immune-experienced, IFN-γ-stimulated CSC-like SCLC cells, both cytotoxic and proliferation capacities of T cells were hampered. In conclusion, our data provide evidence for the superior potential of the SCLC cells with stem-like and mesenchymal properties to gain immune regulatory capacities and cope with cytotoxic T cell responses. With their high metastatic and immune-modulatory assets, the CSC subpopulation in SCLC may serve as a preferential target for checkpoint blockade immunotherapy

Liver resection modulates hepatic chemokine levels in breast cancer

BACKGROUND: Resection of metastatic hepatic tumors of breast cancer may result in the acceleration of hepatic and extrahepatic tumor progression due to the microenvironmental circulation of chemokines. This study aimed to investigate the effect of hepatectomy on a large panel of chemokines, liver regeneration, and myeloid cell levels in an experimental breast cancer model. METHODS: The 4T1 breast cancer cells were inoculated, and 30% to 40% hepatectomy was performed. Mice without tumors or only laparotomy (no hepatectomy) served as control groups. After 14 days (short-term) and 21 days (long-term), tissue samples were obtained from the regions near and distant from the resection site. Chemokine levels were evaluated by enzyme-linked immunosorbent assay arrays. Myeloid infiltration in the liver and the primary tumor and hepatic regeneration status were also histopathologically evaluated. RESULTS: The levels of pro-tumorigenic chemokines such as CCL2, CCL3, CCL4, and CCL5 were elevated in hepatectomized tumor-bearing animals. This observation was consistent with the presence of hepatic metastases. Liver regeneration and myeloid cell infiltration showed significant differences between the tumor-bearing hepatectomized groups followed in the short and long term. CONCLUSION: Our study showed elevation and variations in chemokines after hepatectomy, with a prominent increase in pro-tumorigenic chemokines. These results can be associated with the acceleration of metastasis after liver resection. However, further prospective studies are required to better define the impact of resection, which may transform the liver into a favorable site for metastasis