Differential expression of SALL4 in CTCs derived from hydatidiform moles and gestational trophoblastic neoplasms

Problem To investigate EMT phenotype and SALL4 expression of circulating tumour cells (CTCs) in patients with gestational trophoblastic neoplasm (GTN). Method of study CanPatrol CTC detection system in combination with SALL4 RNA in situ hybridization was used to investigate the profile of CTCs in different types of gestational trophoblastic disease (GTD). Circulating CTCs were phenotyped and annotated with SALL4 expression in 41 GTD patients, including 12 HM and 29 GTN, as well as 22 pregnant volunteers. Results A positive correlation between the number of CTC and serum β-hCG concentration was found among the GTN patients. The number of E/M-CTC was positively correlated with serum β-hCG, while M-CTC was positively correlated with prognostic score. Comparison among malignant GTD, benign GTD and healthy pregnant women revealed a significant difference in the number of total CTC, E/M-CTC, and M-CTC but not in E-CTC. ROC analysis was conducted to evaluate the performance of CTC phenotypes in distinguishing GTD patients from healthy pregnant women yielding an AUC as 0.826. Youden's index was maximal at the cutoff value of 8.5/4 mL with sensitivity and specificity at 53.66% and 100%, respectively. SALL4 expression was evaluated in GTD patients with CTC count greater than cutoff value. SALL4 high expressing CTCs (>2 signal dots) were detected in 66.67% (10/15) of malignant GTD patients but not in benign patients (0/5). Conclusion Differential expression of SALL4 was seen in CTCs derived from hydatidiform moles and GTN. CTC profiling may be developed as an adjunct marker to diagnose GTN.