Small Proline Rich Protein 1A promotes lung adenocarcinoma progression and indicates unfavorable clinical outcomes.

Small Proline Rich Protein 1A (SPRR1A) plays a critical role in regulating squamous cell differentiation. It has been reported that SPRR1A overexpression was closely related to the progression of some tumors such as gastric cancer and colon cancer. However, the function of SPRR1A in lung adenocarcinoma (LUAD) has not been elucidated. Here we firstly examined the expression pattern of SPRR1A in LUAD tissues, which indicated that SPRR1A expression level was significantly elevated in LUAD tissues compared to normal lung tissues. High expression of SPRR1A was closely related to the larger tumor size. LUAD patients with higher SPRR1A expression had poorer overall survival and SPRR1A was identified as an independent unfavorable prognosis factor. In addition, the effects of SPRR1A on lung cancer cells were tested through cellular experiments and the result demonstrated that knockdown of SPRR1A can suppress proliferation and invasion capacities of tumor cells, while overexpressing SPRR1A exerted opposite effects. Finally, our findings were substantiated by the data obtained from in vivo xenografts using mice model. In conclusion, LUAD patients with higher SPRR1A expression were more predisposed to poorer clinical outcomes and unfavorable prognosis, indicating the potential role of SPRR1A as a novel clinical biomarker and therapeutic target.