Differences of molecular expression mechanisms among neural cell adhesion molecule 1, synaptophysin, and chromogranin A in lung cancer cells

Abstract

Neural cell adhesion molecule 1 (NCAM1), synaptophysin (SYPT), and chromogranin A (CGA) are immunohistochemical markers for diagnosing lung neuroendocrine tumors (LNETs). However, the precise expression mechanisms have not been studied in enough detail. The purpose of the present study is to define the molecular mechanisms of NCAM1, SYPT, and CGA gene expressions, using cultivated lung cancer cells and focusing upon NeuroD1 (ND1), achaete-scute homolog-like 1 (ASCL1), and known transcription factors, repressor element 1 (RE1)-silencing transcription factor (REST) and c-AMP responsive element-binding protein (CREB). Promoter assays, chromatin immunoprecipitation, and transfection experiments revealed that ND1 activated NCAM1, that ASCL1 weakly upregulated SYPT expression, and that CGA expression was not regulated by ND1 or ASCL1. REST expression was restricted in non-small cell lung cancer (NSCLC) cells, and knockdown of REST could cause as much SYPT expression as in SCLC cells and weak CGA expression in NSCLC cells. However, CGA gene upregulation via CREB activation was not found in REST-lacking NSCLC cells, indicating the requirement of some additional mechanism for sufficient expression. These results suggest that NCAM1, SYPT and CGA expressions are differently regulated by neuroendocrine phenotype-specific transcription factors and provide a reason why NCAM1 and SYPT are frequently expressed in LNETs, irrespective of malignancy grade.

Loss of the Keratin Cytoskeleton Is Not Sufficient to Induce Epithelial Mesenchymal Transition in a Novel KRAS Driven Sporadic Lung Cancer Mouse Model

“…5 ). Furthermore, chromogranin A, CD56, and synaptophysin, are immunohistochemical markers typically expressed in small cell neuroendocrine carcinomas of the lung [23], [24]. However, both keratin-positive and -negative tumors in the KRAS×KIIf/− mice did not express any of these markers ( Fig.…”

NeuroD1 regulates survival and migration of neuroendocrine lung carcinomas via signaling molecules TrkB and NCAM

“…3C). Because the correlation between NCAM and NeuroD1 expression has been made via overexpression data and promoter binding predicted in silico, we investigated whether endogenous NeuroD1 directly bound NCAM promoter elements (24,(32)(33)(34). We found 10 consensus E-box CANNTG binding sites upstream of the transcriptional start site in the NCAM promoter.…”

Recent advances in histogenesis research of lung neuroendocrine cancers: Evidence obtained from functional analyses of primitive neural/neuroendocrine cell‐specific transcription factors

“…demonstrated that ASCL1 directly activates miR‐375 , which functions as a sufficient inducer of neuroendocrine differentiation . ASCL1 was also reported to upregulate synaptophysin and increase tumor‐initiating capacity via upregulation of the candidate stem cell markers CD133 and aldehyde dehydrogenase 1A1 (ALDH1A1) …”

“…NeuroD1 expressed in a mouse embryonic carcinoma cell line weakly upregulated primitive neuronal/neuroendocrine cell‐specific transcription factors such as POU3F1, POU3F2, ASCL1, hairy and enhancer of split 5 (HES5), and delta‐like 1 (Dll1) as direct transcriptional targets . SmCCs and LCNECs specifically express NeuroD1; in turn, NeuroD1 directly upregulates neural cell adhesion molecule 1 (NCAM1, also known as CD56) and growth modulating molecule insulin‐like growth factor binding protein 2 (IGFBP2) …”