Repaglinide Silences the FOXO3/Lumican Axis and Represses the Associated Metastatic Potential of Neuronal Cancer Cells

Abstract

The transcription factor FOXO3 is associated with poor outcome in high-stage neuroblastoma (NB), as it facilitates chemoprotection and tumor angiogenesis. In other tumor entities, FOXO3 stimulates metastasis formation, one of the biggest challenges in the treatment of aggressive NB. However, the impact of FOXO3 on the metastatic potential of neuronal tumor cells remains largely unknown. In the present study, we uncover the small leucine-rich proteoglycan family member lumican (LUM) as a FOXO3-regulated gene that stimulates cellular migration in NB. By a drug-library screen we identified the small molecular weight compound repaglinide (RPG) as a putative FOXO3 inhibitor. Here, we verify that RPG binds to the FOXO3-DNA-binding-domain (DBD) and thereby silences the transcriptional activity of FOXO3. Consistent with the concept that the FOXO3/LUM axis enhances the migratory capacity of aggressive NB cells, we demonstrate that stable knockdown of LUM abrogates the FOXO3-mediated increase in cellular migration. Importantly, FOXO3 inhibition by RPG represses the binding of FOXO3 to the LUM promoter, inhibits FOXO3-mediated LUM RNA and protein expression, and efficiently abrogates FOXO3-triggered cellular “wound healing” as well as spheroid-based 3D-migration. Thus, silencing the FOXO3/LUM axis by the FDA-approved compound RPG represents a promising strategy for novel therapeutic interventions in NB and other FOXO3-dependent tumors.

Lumican in Carcinogenesis—Revisited

“…Other cancer cell types that have been studied regarding the lumican-dependent motility effects include lung, breast, colon, liver, bladder, and pancreatic cancer, as well as neuroblastomas [3,61,62,65,69,73,79,80,88,94,95].…”

“…Lumican pro-tumorigenic effects are also observed in gastric, bladder, colon, clear cell renal, and liver cancers [ 59 , 60 , 61 , 62 ]. A high lumican expression in gastric cancer tissues indicates a poor patient prognosis [ 48 ].…”

“…In a neuroblastoma model, lumican was a downstream mediator of FOXO3 transcription factor action and enhanced these cells’ migration. FOXO3 is correlated with a poor outcome in high-stage neuroblastoma due to its’ chemoprotective and angiogenesis-stimulating properties [ 62 ]. Notably, upon inhibiting FOXO3 by the small molecular weight compound repaglinide, the binding of FOXO3 to the LUM promoter was attenuated, abrogating the FOXO3-dependent lumican expression and decreasing neuroblastoma cell 2D- and 3D-migration [ 62 ].…”

“…FOXO3 is correlated with a poor outcome in high-stage neuroblastoma due to its’ chemoprotective and angiogenesis-stimulating properties [ 62 ]. Notably, upon inhibiting FOXO3 by the small molecular weight compound repaglinide, the binding of FOXO3 to the LUM promoter was attenuated, abrogating the FOXO3-dependent lumican expression and decreasing neuroblastoma cell 2D- and 3D-migration [ 62 ]. Regarding clear renal cell carcinoma (cRCC), the microarray analysis demonstrated a higher expression of matrix regulators lumican and CEACAM6 in metastatic tissues than patient-matched primary tissues [ 60 ].…”

Novel roles of Tsukushi in signaling pathways and multiple disease processes

“…Further research found that decorin and podocan are involved in the development of diabetic nephropathy 10,19 . In addition, some studies have found that SLRPs (decorin, biglycan, lumican, TSK, osteoadherin, osteoglycin, asporin) are shown to be involved in the pathogenesis of tumors by modulating the proliferation, apoptosis, invasion, and migration of the cancer cells 8,20–24 …”