Early Growth Response 4 Is Involved in Cell Proliferation of Small Cell Lung Cancer through Transcriptional Activation of Its Downstream Genes

Abstract

Small cell lung cancer (SCLC) is aggressive, with rapid growth and frequent bone metastasis; however, its detailed molecular mechanism remains poorly understood. Here, we report the critical role of early growth factor 4 (EGR4), a DNA-binding, zinc-finger transcription factor, in cell proliferation of SCLC. EGR4 overexpression in HEK293T cells conferred significant upregulation of specific splice variants of the parathyroid hormone-related protein (PTHrP) gene, resulting in enhancement of the secretion of PTHrP protein, a known mediator of osteolytic bone metastasis. More importantly, depletion of EGR4 expression by siRNA significantly suppressed growth of the SCLC cell lines, SBC-5, SBC-3 and NCI-H1048. On the other hand, introduction of EGR4 into NIH3T3 cells significantly enhanced cell growth. We identified four EGR4 target genes, SAMD5, RAB15, SYNPO and DLX5, which were the most significantly downregulated genes upon depletion of EGR4 expression in all of the SCLC cells examined, and demonstrated the direct recruitment of EGR4 to their promoters by ChIP and luciferase reporter analysis. Notably, knockdown of the expression of these genes by siRNA remarkably suppressed the growth of all the SCLC cells. Taken together, our findings suggest that EGR4 likely regulates the bone metastasis and proliferation of SCLC cells via transcriptional regulation of several target genes, and may therefore be a promising target for the development of anticancer drugs for SCLC patients.

Expression and localization of sterile alpha motif domain containing 5 is associated with cell type and malignancy of biliary tree

“…On the other hand, Matsuo et al have reported that the knockdown of SAMD5 in small cell lung cancer (SCLC) cell lines by siRNA suppressed cell proliferation [42]. In contrast to the previous paper, we showed that knockdown and overexpression of SAMD5 in CC cell lines resulted in enhancement and suppression of cell growth, respectively.…”

A positive feedback loop between ZNF205‐AS1 and EGR4 promotes non‐small cell lung cancer growth

“…The cDNA oligonucleotides suppressing EGR4 expression were synthesized by GenePharma and inserted into the GenePharma SuperSilencing TM shRNA expression vector pGPH1/Hygro. The shRNAs target sites for EGR4 were 5'‐GGACCAAGAUUGAGGACUU‐3' (sh‐EGR4‐1) and 5'‐GCUACAGCGGUAGCUUCUU‐3' (sh‐EGR4‐2) …”

“…The shRNAs target sites for EGR4 were 5'-GGACCAAGAUUGAGGACUU-3' (sh-EGR4-1) and 5'-GCUACAGCGGUAGCUUCUU-3' (sh-EGR4-2). 25 The promoter region of ZNF205-AS1, from −1025 to +47 base pair (bp) upstream of the transcription start site, was PCR-amplified using the Thermo Scientific Phusion Flash High-Fidelity PCR Master Mix and the primers 5'-CTAGCTAGCGGAAAGAGGAGACGGCA-GAGCA-3' (forward) and 5'-CCCAAGCTTTGGCGGAGGTAGGA-GAGGGA-3' (reverse). The PCR products were cloned into the Nhe I and Hind III sites of pGL3-Basic Vector (Promega, Madison, WI, USA), termed as pGL3-ZNF205-AS1.…”

Peer Review #2 of "Expression and prognostic analyses of early growth response proteins (EGRs) in human breast carcinoma based on database analysis (v0.1)"

“…There are few reports on EGR4 in tumors. At present, some literature suggests that EGR4 may be an oncogene that promotes the development of NSCLC (He S et al, 2019;Matsuo T et al, 2014). However, the relationship between EGR4 and the occurrence, development, and prognosis of BC has not been reported.…”