High Expression of SPRR1B Indicates Unfavorable Clinical Outcomes in Lung Adenocarcinoma

Abstract Backgrounds: Small proline-rich protein 1B (SPRR1B) was initially identified as an envelope protein of keratinocytes, which plays essential roles in squamous cell differentiation. Recently its involvement in malignancies was also explored in head and neck squamous cell carcinoma. However, whether SPRR1B participates in adenocarcinoma progression remains unknown. Here we aimed to investigate the expression and function of SPRR1B in lung adenocarcinoma (LAC).Methods: SPRR1B expression level was examined in LAC samples and adjacent nontumorous samples through quantitative RT-PCR assay and immunohistochemistry staining. Univariate and multivariate analyses were performed to estimate the prognostic role of SPRR1B. Cellular experiments were performed to reveal the function of SPRR1B in LAC cells. Results: The SPRR1B level in LAC samples was significantly higher compared with adjacent samples. Moreover, higher SPRR1B level was correlated with poor tumor differentiation and advanced tumor stage. LAC patients with higher SPRR1B level had worse overall survival. Moreover, SPRR1B was confirmed as an independent unfavorable prognosis factor. Cellular data indicated that knockdown of SPRR1B could attenuate the proliferation capacity of LAC cells. Conclusions: Our results demonstrated that high SPRR1B level was significantly correlated with unfavorable clinical features and poor prognosis of LAC patients. SPRR1B might serve as a novel prognostic indicator and potential drug target for LAC treatment.