Abstract
Stathmin-1 is a microtubule depolymerization protein that regulates cell division, growth, migration, and invasion. Overexpression of stathmin-1 has been observed to be associated with metastasis, poor prognosis, and chemoresistance in various human cancers. Our previous studies found that serum stathmin-1 was significantly elevated in patients with esophageal squamous cell carcinoma (ESCC) by ELISAs. Here, we constructed high-affinity monoclonal antibodies and then developed a competitive AlphaLISA for rapid, accurate quantitation of stathmin-1 in serum. Compared to ELISA, our homogeneous AlphaLISA showed better sensitivity and accuracy, a lower limit of detection, and a wider linear range. The measurements of nearly 1000 clinical samples showed that serum stathmin-1 level increased dramatically in patients with squamous cell carcinoma (SCC), especially in ESCC, with a sensitivity and a specificity of 81% and 94%, respectively. Even for early stage ESCC, stathmin-1 achieved an area under the receiver operating characteristic curve (AUC) of 0.88. Meanwhile, raised concentrations of stathmin-1 were associated with lymph node metastasis and advanced cancer stage. Notably, various types of SCC showed significantly higher AUCs in serum stathmin-1 detection compared to adenocarcinoma. Furthermore, we confirmed that stathmin-1 was enriched in the oncogenic exosomes, which can explain the reason why it enters into the blood to serve as a tumor surrogate. In conclusion, this large-scale and systematic study of serum stathmin-1 measured by our newly established AlphaLISA showed that stathmin-1 is a very promising diagnostic and predictive marker for SCC in the clinic, especially for ESCC.