Hua Zhang

Tumor cell-intrinsic PD-1 in malignant ascites drives ovarian cancer progression via MAPK/ERK signaling

Programmed cell death protein 1 (PD-1), an immune checkpoint primarily expressed on T cells, plays a critical role in mediating tumor immune evasion. However, the role of PD-1 in non-immune cells remains poorly understood. Here, we report tumor cell-intrinsic PD-1 expression in malignant ascites from ovarian cancer patients. Using murine ovarian cancer models, we demonstrate that PD-1 directly promotes ovarian cancer progression. Moreover, malignant ascites markedly upregulates PD-1 expression in ID8 ovarian cancer cells, acting as a pathological amplifier that exacerbates PD-1-mediated oncogenic signaling cascades, including enhanced proliferation and metastasis both in vitro and in vivo. Mechanistically, soluble PD-L1 (sPD-L1) in ascites interacts with tumor cell-intrinsic PD-1, activating the MAPK/ERK signaling pathway through enhanced phosphorylation of ERK1/2. In contrast, PD-1 inhibition, achieved by genetic knockout or antibody blockade, reverses these tumor-promoting effects. Furthermore, pharmacological inhibition of phosphorylated ERK1/2 counteracts the tumor progression mediated by the PD-1 and prolongs survival in murine ovarian cancer models. Our study uncovers a previously unrecognized tumor-intrinsic PD-1-ERK signaling axis in ovarian cancer, that accelerates tumorigenesis and provides new insights and perspectives for PD-1/PD-L1 immune checkpoint therapy in ovarian cancer.

Lineage tracing of mutant granulosa cells reveals in vivo protective mechanisms that prevent granulosa cell tumorigenesis

AbstractOvarian granulosa cell tumors (GCTs) originate from granulosa cells (GCs) and represent the most common sex cord-stromal tumor in humans. However, the developmental regulations and molecular mechanisms underlying their etiology are largely unknown. In the current study, we combined a multi-fluorescent reporter mouse model with a conditional knockout mouse model, in which the tumor suppressor genes Pten and p27 were deleted in GCs, to perform cell lineage tracing of mutant GCs. We found that only 30% of ovaries with substantial mutant GCs developed into GCTs that derived from a single mutant GC. In-depth molecular analysis of the process of tumorigenesis demonstrated that up-regulation of immune evasion genes Cd24a and Cd47 led, in part, to the transition of mutant GCs to GCTs. Therefore, treatment with the Cd47 inhibitor RRX-001 was tested and found to efficiently suppress the growth of GCTs in vivo. Together, our study has revealed an immune evasion mechanism via CD24/CD47 upregulation to GCT formation, shedding light on the future potential clinical therapies for GCTs.