SOCS3 deficiency-dependent autophagy repression promotes the survival of early-stage myeloid-derived suppressor cells in breast cancer by activating the Wnt/mTOR pathway.

Early-stage myeloid-derived suppressor cells are a newly defined subset of myeloid-derived suppressor cells in breast cancer tissues and related to poor prognosis in patients with breast cancer. Compared with classical myeloid-derived suppressor cells, early-stage myeloid-derived suppressor cells display exceptional immunosuppressive ability and accumulate in the tumor microenvironment to suppress innate and adaptive immunity. Previously, we demonstrated that early-stage myeloid-derived suppressor cells were SOCS3 deficiency dependent and correlated with differentiation arrest in the myeloid lineage. Autophagy is a major regulator of myeloid differentiation, but the mechanism by which autophagy regulates the development of early-stage myeloid-derived suppressor cells has not been elucidated. Here, we constructed EO771 mammary tumor-bearing conditional myeloid SOCS3 knockout mice (SOCS3MyeKO) characterized by abundant tumor-infiltrating early-stage myeloid-derived suppressor cells and exacerbated immunosuppression in vitro and in vivo. We found that early-stage myeloid-derived suppressor cells isolated from SOCS3MyeKO mice showed differentiation arrest in the myeloid lineage, which was caused by limited autophagy activation in an Wnt/mTOR-dependent manner. RNA sequencing and microRNA microarray assays revealed that miR-155-induced C/EBPß downregulation activated the Wnt/mTOR pathway and promoted autophagy repression and differentiation arrest in early-stage myeloid-derived suppressor cells. Furthermore, inhibition of Wnt/mTOR signaling suppressed both tumor growth and the immunosuppressive functions of early-stage myeloid-derived suppressor cells. Thus, SOCS3 deficiency-dependent autophagy repression and their regulatory mechanisms could contribute to the immunosuppressive tumor microenvironment. Our study proposes a novel mechanism for promoting early-stage myeloid-derived suppressor cell survival, which might shed new light on a potential target of oncologic therapy.

Early myeloid-derived suppressor cells accelerate epithelial-mesenchymal transition by downregulating ARID1A in luminal A breast cancer.

Early myeloid-derived suppressor cells (eMDSCs) are a newly characterized subclass of MDSCs, which exhibit more potent immunosuppressive capacity than classical MDSCs. Previously, we found high eMDSCs infiltration was correlated with poor prognosis of breast cancer, though the regulatory mechanisms have not been fully understood. Here, we constructed a 21-gene signature to evaluate the status of eMDSCs infiltration within breast cancer tissues and found that highly infiltrated eMDSCs affected the prognosis of breast cancer patients, especially in luminal A subtype. We also found that eMDSCs promoted epithelial-mesenchymal transition (EMT) and accelerated cell migration and invasion in vitro. Meanwhile, eMDSCs significantly downregulated ARID1A expression in luminal A breast cancer, which was closely associated with EMT and was an important prognostic factor in breast cancer patients. Moreover, significant changes of EMT-related genes were detected in luminal A breast cancer cells after co-cultured with eMDSCs or ARID1A knock-down and overexpression of ARID1A significantly reversed this procedure. These results implied that eMDSCs might suppress the ARID1A expression to promote EMT in luminal A breast cancer cells, which might provide a new light on developing novel treatment regimens for relapsed luminal A breast cancer after conventional therapies.

Diagnostic Model Incorporating Clinicopathological Characteristics of Delphian Lymph Node Metastasis Risk Profiles in Papillary Thyroid Cancer.

The Delphian lymph node (DLN), also known as the prelaryngeal node, is one component of the central lymph node. The DLN has been well studied in laryngeal cancer, although its significance in papillary thyroid cancer (PTC) remains unclear. We retrospectively analyzed 936 patients with PTC who underwent thyroidectomy by a single surgeon in Tianjin Cancer Hospital from 2017 to 2019. Moreover, 250 PTC patients who underwent thyroidectomy by another surgeon in Tianjin Cancer Hospital from January 2019 to April 2019 were used as a validation cohort. Among the 936 patients with PTC, 581 patients (62.1%) had DLNs, of which 177 samples with metastasis (177/581, 30.5%) were verified. DLN metastasis was significantly correlated with sex, age, tumor size, bilateral cancer, multifocality, extrathyroidal extension, lymphovascular invasion and central and lateral neck lymph node metastasis. Multivariate analysis revealed that independent risk factors for DLN metastasis included age, gender, tumor size, extrathyroid extension, lymphovascular invasion and central lymph node metastasis, which determined the nomogram. In particular, tumor size was proven to be one of the most predominant single predictors. The diagnostic model had an area under the curve (AUC) of 0.829 (95% confidence interval, 0.804-0.854). The internal and external validations of the nomogram were 0.819 and 0.745, respectively. Our results demonstrate that DLN metastasis appears to be a critical parameter for predicting metastatic disease of the central compartments. Furthermore, this study provides a precise criterion for assessing DLN metastasis and has great clinical significance for treating PTC.