Knockdown of HE4 suppresses tumor growth and invasiveness in lung adenocarcinoma through regulation of EGFR signaling

It has been shown that the high expression of human epididymis protein 4(HE4)in most lung cancers is related to the poor prognosis of patients,but the mechanism of pathological transformation of HE4 in lung cancer is still unclear.The current study is expected to clarify the function and mechanism of HE4 in the occurrence and metastasis of lung adenocarcinoma(LUAD).Immunoblotting evaluated HE4 expression in lung cancer cell lines and biopsies,and through analysis of The Cancer Genome Atlas(TCGA)dataset.Frequent HE4 overexpression was demonstrated in LUAD,but not in lung squamous cell carcinoma(LUSC),indicating that HE4 can serve as a biomarker to distinguish between LUAD and LUSC.HE4 knockdown significantly inhibited cell growth,colony formation,wound healing,and invasion,and blocked the G1-phase of the cell cycle in LUAD cell lines through inactivation of the EGFR signaling downstream including PI3K/AKT/mTOR and RAF/MAPK pathways.The first-line EGFR inhibitor gefitinib and HE4 shRNA had no synergistic inhibitory effect on the growth of lung adenocarcinoma cells,while the third-line EGFR inhibitor osimertinib showed additive anti-proliferative effects.Moreover,we provided evidence that HE4 regulated EGFR expression by transcription regulation and protein interaction in LUAD.Our findings suggest that HE4 positively modulates the EGFR signaling pathway to promote growth and invasiveness in LUAD and highlight that targeting HE4 could be a novel strategy for LUAD treatment.

Therapeutic targets in gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs) are the most common type of mesenchymal tumor of the gastrointestinal tract. The tumorigenesis of GISTs is driven by gain-of-function mutations in KIT or plateletderived growth factor receptor α(PDGFRA),resultingin constitutive activation of the tyrosine kinase and its downstream signaling pathways. Oncogenic KIT or PDGFRA mutations are compelling therapeutic targets for the treatment of GISTs,and the KIT/PDGFRA inhibitor imatinib is the standard of care for patients with metastatic GISTs. However,most GIST patients develop clinical resistance to imatinib and other tyrosine kinase inhibitors. Five mechanisms of resistance have been characterized:(1) acquisition of a secondary point mutation in KIT or PDGFRA;(2) genomic amplification of KIT;(3) activation of an alternative receptor tyrosine kinase;(4) loss of KIT oncoprotein expression; and(5) wild-type GIST. Currently,sunitinib is used as a secondline treatment for patients after imatinib failure,and regorafenib has been approved for patients whose disease is progressing on both imatinib and sunitinib. Phase Ⅱ/Ⅲ trials are currently in progress to evaluate novel inhibitors and immunotherapies targeting KIT,its downstream effectors such as phosphatidylinositol 3-kinase,protein kinase B and mammalian target of rapamycin,heat shock protein 90,and histone deacetylase inhibitor. Other candidate targets have been identified,including ETV1,AXL,insulin-like growth factor 1 receptor,KRAS,FAS receptor,protein kinase c theta,ANO1(DOG1),CDC37,and aurora kinase A. These candidates warrant clinical evaluation as novel therapeutic targets in GIST.