ISL-1 is overexpressed in non-Hodgkin lymphoma and promotes lymphoma cell proliferation by forming a p-STAT3/p-c-Jun/ISL-1 complex

Abstract

BackgroundInsulin enhancer binding protein-1 (ISL-1), a LIM-homeodomain transcription factor, is essential for the heart, motor neuron and pancreas development. Recently, ISL-1 has been found in some types of human cancers. However, how ISL-1 exerts the role in tumor development is not clear.Methods and resultsThe expression of ISL-1 was assessed in 211 human lymphoma samples and 23 normal lymph node samples. Immunohistochemistry results demonstrated a markedly higher expression of ISL-1 in 75% of non-Hodgkin lymphoma (NHL) samples compared with that in normal lymph nodes or Hodgkin lymphoma (HL) samples. CCK-8 analysis, cell cycle assay and xenograft model were performed to characterize the association between ISL-1 expression level and biological functions in NHL. The results showed that ISL-1 overexpression obviously promoted NHL cells proliferation, changed the cell cycle distribution in vitro and significantly enhanced xenografted lymphoma development in vivo. Real-time PCR, Western blot, luciferase assay and ChIP assay were used to explore the potential regulatory targets of ISL-1 and the results demonstrated that ISL-1 activated the c-Myc expression in NHL by direct binding to a conserved binding site on the c-Myc enhancer. Further results revealed that ISL-1 could be positively regulated by the c-Jun N-terminal kinase (JNK) and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways. Both the JNK and JAK/STAT signaling inhibitors could significantly suppressed the growth of NHL cells through the down-regulation of ISL-1 as demonstrated by CCK-8 and Western blot assays. Bioinformatic analysis and luciferase assay exhibited that ISL-1 was a novel target of p-STAT3 and p-c-jun. ChIP, Co-IP and ChIP-re-IP analysis revealed that ISL-1 could participate with p-STAT3 and p-c-Jun to form a p-STAT3/p-c-Jun/ISL-1 transcriptional complex that binds directly on the ISL-1 promoter, demonstrating a positive feedback regulatory mechanism for ISL-1 expression in NHL.ConclusionsOur results provide the first evidence that ISL-1 is tightly linked to NHL proliferation and development by promoting c-Myc transcription, and its aberrant expression was regulated by p-STAT3/p-c-Jun/ISL-1 complex activation.

ISL1, a novel regulator ofCCNB1,CCNB2andc-MYCgenes, promotes gastric cancer cell proliferation and tumor growth

“…Previously, we proved that ISL1 promoted the proliferation of adult pancreatic islet cells and lymphoma cells [10, 11]. To determine the role of ISL1 in GC, we established stable ISL1-overexpressing and knockdown MKN28 and MGC803 (thereafter labeled as MGC) cell lines using pcDNA3.1-ISL1 and pLL3.7-ISL1-siRNA plasmids, respectively (Figure 2A).…”

An abnormally high expression of ISL-1 represents a potential prognostic factor in gastric cancer

“…Hansel et al [26] used global gene expression analysis and reported that ISL-1 was overexpressed in human biliary cancer. ISL-1 has also been found to participate in metastasis in pancreatic neuroendocrine neoplasms, pancreatic endocrine tumors, non-muscle-invasive bladder cancer, and non-Hodgkin lymphoma [19][20][21][22]. In addition, the level of ISL-1 protein expression is closely associated with the development of cancer, cancer cell growth, and metastasis, as well as the prognosis of patients with pancreatic endocrine tumors [21].…”

“…The plasmid pcDNA3-ISL1 and control vector pcDNA3 were separately transfected into NIH3T3 cells to establish stable ISL-1-overexpressing cells (pcDNA3-ISL-1) and control cells (pcDNA3), as previously described [22]. Five-week-old female nude mice were subcutaneously injected on the right side of the dorsum (pcDNA3-ISL-1) and left armpit (pcDNA3) with 1 × 10 7 cells suspended in 200 μL phosphate-buffered saline (PBS).…”

“…ISL-1 has previously been described to play crucial roles in development of the heart, motor neurons, and pancreas [16][17][18]. Recently, ISL-1 was implicated in the development of cancer, mainly based on the fact that expression of ISL-1 is dysregulated in a range of tumor types [19][20][21][22].…”

Highly Tumorigenic Diffuse Large B Cell Lymphoma Cells Are Produced by Coculture with Stromal Cells

“…The activation of signal transducer and activator transcription 3 (STAT3) is one of the reasons for refractory cases of DLBCL [5-7]. STAT3 signaling regulates the expression of genes that control tumor cell growth, drug resistance, and clonogenicity, and is associated with cancer stem cell characteristics [8, 9]. STAT3 is usually activated in the non-GCB group of DLBCL, while the expression of phosphorylated (p)-STAT3 goes undetected in several GCB DLBCL cell lines [10].…”