Hypoxia induction of SH2D3A triggers malignant progression of lung cancer

Lung cancer is the most prevalent and aggressive cancer and is one of the leading causes of cancer-related death worldwide. Hypoxia in the tumor microenvironment is associated with poor patient survival and is a crucial characteristic of solid tumors. A subset of tumor cells, termed cancer stem cells (CSCs), with self-renewal and differentiation capabilities simultaneously, are regarded as responsible for cancer tumorigenesis, resistance to therapeutics, and cancer relapse. Recent advances have revealed that hypoxia plays an essential role in CSCs self-replication maintenance. Yet, the underlying mechanisms of hypoxia that trigger the stemness maintenance of CSCs are still poorly understood. Here, we provide evidence showing that SH2D3A expression level was increased in lung cancer and lung CSCs, and high expression of SH2D3A was associated with the overall survival of patients with lung cancer. Mechanistically, HIF-2α, which is a key transcription factor in response to hypoxia directly binds to the SH2D3A promoter and facilitates SH2D3A expression at the transcription level. SH2D3A was found to be functionally important for lung CSC malignant behaviors such as uncontrolled self-replication and proliferation. We demonstrated that pharmacological downregulation of SH2D3A expression by AM966, a small molecule compound, efficiently induces tumor regression in vitro and in vivo. Thus, this study highlights the biological implications of SH2D3A as a novel prognostic marker and therapeutic target in lung cancer in the future.