GRP75-upregulated HMGA1 Expression Promotes Stage I Lung Adenocarcinoma Progression by Activating the JNK/c-JUN Signaling Pathway

Background: Recurrence is a major challenge in early-stage lung adenocarcinoma (LUAD) treatment. However, the recurrence mechanism is still unclear, and no biomarkers can predict recurrence in early-stage LUAD. Here, we investigated the role and mechanism of high-mobility group AT-hook 1 (HMGA1) and glucose-regulated protein 75-kDa (GRP75) in stage I LUAD and evaluated their potential as biomarkers for predicting the recurrence and prognosis of stage I LUAD. Methods: : A TCGA dataset was used to investigate the clinical significance of HMGA1 and GRP75 in early-stage LUAD. Western blotting and immunohistochemistry were used to measure protein expression levels. The biological functions of HMGA1 and GRP75 in LUAD were investigated both in vitro and in vivo through overexpression and knockdown experiments. The interaction and regulation between HMGA1 and GRP75 were evaluated with coimmunoprecipitation and ubiquitination assays. The downstream signaling pathway of the GRP75/HMGA1 axis was investigated by mRNA-sequencing analysis. Results: : High expression of HMGA1 and GRP75 was associated with recurrence and a poor prognosis in stage I LUAD patients. In particular, HMGA1 had potential as an independent prognostic factor. Overexpression of GRP75 or HMGA1 promoted LUAD cell growth and metastasis, while silencing GRP75 or HMGA1 inhibited LUAD cell growth and metastasis. In vitro and clinical data showed that the expression level of GRP75 positively regulated HMGA1 in LUAD and that GRP75 played an HMGA1-dependent role. In addition, GRP75 prolonged the half-life of HMGA1 by inhibiting HMGA1 ubiquitination via direct binding to HMGA1. Finally, we demonstrated that the GRP75/HMGA1 axis played a role by activating JNK/c-JUN signaling in LUAD. Conclusions: : The activation of GRP75/HMGA1/JNK/c-JUN signaling is an important mechanism that promotes the progression of stage I LUAD, and a high level of HMGA1 is a novel biomarker for predicting recurrence and prognosis in patients with stage I LUAD.