MYCN and HDAC5 transcriptionally repress CD9 to trigger invasion and metastasis in neuroblastoma

Abstract

The systemic and resistant nature of metastatic neuroblastoma renders it largely incurable with current multimodal treatment. Clinical progression stems mainly from the increasing burden of metastatic colonization. Therapeutically inhibiting the migration-invasion-metastasis cascade would be of great benefit, but the mechanisms driving this cycle are as yet poorly understood. In-depth transcriptome analyses and ChIP-qPCR identified the cell surface glycoprotein, CD9, as a major downstream player and direct target of the recently described GRHL1 tumor suppressor. CD9 is known to block or facilitate cancer cell motility and metastasis dependent upon entity. High-level CD9 expression in primary neuroblastomas correlated with patient survival and established markers for favorable disease. Low-level CD9 expression was an independent risk factor for adverse outcome. MYCN and HDAC5 colocalized to the CD9 promoter and repressed transcription. CD9 expression diminished with progressive tumor development in the TH-MYCN transgenic mouse model for neuroblastoma, and CD9 expression in neuroblastic tumors was far below that in ganglia from wildtype mice. Primary neuroblastomas lacking MYCN amplifications displayed differential CD9 promoter methylation in methyl-CpG-binding domain sequencing analyses, and high-level methylation was associated with advanced stage disease, supporting epigenetic regulation. Inducing CD9 expression in a SH-EP cell model inhibited migration and invasion in Boyden chamber assays. Enforced CD9 expression in neuroblastoma cells transplanted onto chicken chorioallantoic membranes strongly reduced metastasis to embryonic bone marrow. Combined treatment of neuroblastoma cells with HDAC/DNA methyltransferase inhibitors synergistically induced CD9 expression despite hypoxic, metabolic or cytotoxic stress. Our results show CD9 is a critical and indirectly druggable suppressor of the invasion-metastasis cycle in neuroblastoma.

Histone deacetylase�5 promotes the proliferation and invasion of lung cancer cells

“…HDAC5 was extensively expressed in many human cancers. HDAC5, overexpressed in neuroblastoma, was found to trigger neuroblastoma cell invasion and metastasis (25), and knockdown of HDAC5 restrained breast cancer cell proliferation, invasion and metastasis (15). Furthermore, the effect of HDAC5 on A549 cell invasion was evaluated by Transwell invasion assay.…”

Unscheduled HDAC4 repressive activity in human fibroblasts triggers TP53‐dependent senescence and favors cell transformation

“…The ability of HDAC4‐TM to regulate genes involved in adhesion and motility was confirmed in the morphological analysis of soft agar foci as well as in the results obtained with Matrigel invasion and evasion assays. These results indicate that HDAC4‐expressing cells exhibit a strong invasive phenotype, further supported by previous studies on the invasive, migrating and metastatic activities of class IIa HDACs (Cao et al ., ; Cernotta et al ., ; Di Giorgio et al ., ; Fabian et al ., ; Mottet et al ., ).…”

Inhibition of CD9 expression reduces the metastatic capacity of human hepatocellular carcinoma cell line MHCC97-H

“…Functional studies have demonstrated that CD9 serves a role in tumor cell motility and adhesion, and may have an effect on metastasis (41)(42)(43). Previous studies reported that overexpression of CD9 in breast, prostate, colon, lung, neuroblastoma and ovarian carcinoma cells appeared to suppress the motility and metastatic potential of cells (44)(45)(46)(47)(48)(49). However, CD9 expression varies greatly among different organ tumors, and may either promote or inhibit metastasis (36).…”