Liyi Zhang

Department of Thoracic Surgery, Peking UniversityCancer Hospital, Beijing

Objective: Wepreviously found that TRA16, testicular orphan nuclear receptor-4(TR4)-associated protein, suppressed the TR4-mediated ERβ activity in non-smallcell lung cancer cells (NSCLC) cells, suggesting that TRA16 plays a role inNSCLC development. The hypothesis of cancer stem cells has been proposed toexplainthe chemotherapeutic failure in a variety of cancers including NSCLC.This study was designed to investigated the role of TRA16 in chemo-resistant inNSCLC cells. Method: Immunohistochemistryof TRA16 was conducted in 435 patients who underwent surgical resection.Lentivirus-mediated stable knock-down was performed to suppress the TRA16expression level in A549 and H1299 cells. Chemotherapeutic drug streatment and assessmentof treatment responses were evaluated by CCK8 assays in these cells. Expressionof stemcell–related markers were measured using quantitative reversetranscription PCR and western blotting. Serum-free sphere forming assay wascarried out to test self-renewal and tumorigenic potential of sh-TRA16 cells invitro and in vivo. Result: Immunohistochemicalevaluation of clinical samples disclosed expression of TRA16 was elevated intumor specimens compared with their counterpart normal lungtissue. ElevatedTRA16 expression was associated with worse prognosis inoverall survival (OS) (P=0.019).Further study of 89 patients who received neoadjuvant chemotherapy indicatedthat positive TRA16 was correlated with worse objectiveremission rate (ORR) ofchemotherapy drugs. Knockdown of TRA16 levels in A549 and H1299 cells led toincreased drug sensitivity to the chemotherapeutic drugs-induced cytotoxicitycompared with those control cells. Moreover, aberrant TRA16 expression couldmodulate the expression levels of several stemcell–related genes like CD133 andABCG2. Knock-down of TRA16 also suppressed sphere-forming activity in vitro andtumorigenicity in vivo. Conclusion: Collectively，ourresults show TRA16 is a potential biomarker for poor prognosis in NSCLC and mayplay a role in the development of chemoresistance in NSCLC cells.

KeyWords：TRA16  NSCLC chemoresistance