Citations

Abstract1q21 gain is a common cytogenetic abnormality featuring high‐risk multiple myeloma (HRMM). However, the molecular mechanism underlying the adverse prognostic effect of 1q21 gain remains largely unclear. Here, we report that ARNT/HIF‐1β, a 1q21 gene, is highly expressed in HRMM and induced by microenvironmental hypoxia, which confers drug resistance and correlates with inferior outcome. Analysis of the gene expression profile database revealed that ARNT expression was upregulated in MM and increased with disease progression or in HRMM subtypes (particularly 1q21 gain), while correlated to shorter overall survival. In a cohort of 40 MM patients, qPCR further validated that ARNT expression was higher in MM patients than normal donors. MM cells carrying 1q21 gain or acquired drug resistance displayed a robust increase in HIF‐1β protein level. Hypoxia induced HIF‐1β expression via a NF‐κB‐dependent process. Notably, HIF‐1β overexpression impaired bortezomib sensitivity, whereas shRNA knockdown of ARNT reversed hypoxia‐mediated drug resistance. Together, these findings suggest that ARNT/HIF‐1β might represent a novel biomarker for risk stratification and prognosis of HRMM patients, as well as a potential therapeutic target for overcoming 1q21 gain‐ or microenvironment‐mediated and acquired drug resistance in MM.

Abstract Purpose: ZIP4 is overexpressed in human pancreatic cancer and promotes tumor growth. However, little is known about the role of ZIP4 in advanced stages of this dismal neoplasm. Our goal is to study the underlying mechanism and define a novel signaling pathway controlled by ZIP4-modulating pancreatic tumor metastasis. Experimental Design: The expression of ZIP4, ZO-1, claudin-1, and ZEB1 in human pancreatic cancer tissues, genetically engineered mouse model, xenograft tumor model, and pancreatic cancer cell lines were examined, and the correlations between ZIP4 and those markers were also analyzed. Functional analysis of ZO-1, claudin-1, and ZEB1 was investigated in pancreatic cancer cell lines and orthotopic xenografts. Results: Genetic inactivation of ZIP4 inhibited migration and invasion in pancreatic cancer and increased the expression of ZO-1 and claudin-1. Conversely, overexpression of ZIP4 promoted migration and invasion and increased the expression of ZEB1 and downregulation of the aforementioned epithelial genes. ZIP4 downregulation of ZO-1 and claudin-1 requires the transcriptional repressor ZEB1. Further analysis demonstrated that ZIP4-mediated repression of ZO-1 and claudin-1 leads to upregulation of their targets FAK and Paxillin. Silencing of ZIP4 caused reduced phosphorylation of FAK and Paxillin, which was rescued by simultaneous blocking of ZO-1 or claudin-1. Clinically, we demonstrated that ZIP4 positively correlates with the levels of ZEB1 and inversely associates with the expression of ZO-1 and claudin-1. Conclusions: These findings suggest a novel pathway activated by ZIP4-controlling pancreatic cancer invasiveness and metastasis, which could serve as a new therapeutic target for this devastating disease. Clin Cancer Res; 24(13); 3186–96. ©2018 AACR.