Bin1 is linked to metastatic potential and chemosensitivity in neuroblastoma.

Neuroblastoma (NB) is the most common extracranial solidtumorinchildren [1],originatingfromneuralcrestcellsandusuallymanifesting in the sympathetic nervous system, including theadrenalmedulla,sympatheticganglia,andparaganglia.NBpatientsareassignedtoalow-,intermediate-,orhigh-riskgroupbasedontheriskclassiﬁcationsystemdeﬁnedbytheChildren’sOncologyGroup(COG). This assignment considers age at diagnosis, disease stage(using the International Neuroblastoma Staging System, INSS),tumor histopathology, DNA index, and MYCN gene status [1].Survivalinhigh-riskpatients remainspoor (<40%). To improvethesurvival rate, accurate identiﬁcation of high-risk patients is ofsigniﬁcant importancesince this determines the treatment plan.TheestablishedconsensusriskclassiﬁcationsystemforNBcontainsfewspeciﬁcmolecularmarkerstoaccountforaggressivenatureandhighmetastatic potential, limiting its utility. Identiﬁcation of speciﬁcmolecular markers of these NB features is of importance not onlybecause it will help direct treatment but it could also providepotential therapeutic targets.NB is responsible for 15% of all childhood cancer deaths, whichmainly result from relentless progression of metastatic disease.Often,thediseasehasalreadyspreadthroughoutthebodyinasmanyas 7 of 10 cases by the time it is diagnosed [2,3]. Clearly, preventionand elimination of metastatic disease would substantially improvelong-term survival. However, no effective speciﬁc therapies havebeen established against metastatic disease, which is mainly due toour incomplete understanding of the molecular mechanismsresponsible for NB metastasis. There is growing evidence thatbridging integrator-1 (Bin1), a member of the BAR domain family[4–7], may be a keymodulator of metastasis in breast, prostate, andNB cancer patients, and patients with reduced expression of Bin1have poorer prognoses and higher cancer metastasis rates [8–14].DeﬁningtheroleofBin1inNBmetastasiswouldthereforebehighlyvaluable in terms of diagnosis and treatment of the disease.Based on the modern biological view of metastasis, cancercells undergo a cascade of linked sequential steps [15–18]. In themultistep metastatic process, surviving in circulation is a crucialfactor.Indeed,ithasbeenreportedthatmosttumorcells injectedintothecirculationwererapidlyeliminatedandonlyapproximately0.01–0.1% were able to generate metastatic foci in distant organs [17,19].Tumor cell death in circulation does not seem to be mediated by theimmune system, and furthermore, there is no evidence that humanimmunodeﬁciencies are associated with increased development ofmetastasis from solid tumors [17]. Therefore, other mechanism(s)may mediate the cell death in the circulation.Anoikis (from the Greek for ‘‘homelessness’’) is a specializedform of apoptosis that is initiated by detachment of cells from theextracellular matrix (ECM). Because anchorage-dependent cellsneed to attach to ECM for their growth and survival [20–22], celldeath in the circulation may result from anoikis. It has beendemonstrated that apoptosis was observed in the lungs of mice 24–48 hr after injection of ﬂuorescent-labeled cancer cell lines into thecirculation [23]. However, cancercells withmetastaticpotential mayescape from anoikis while ﬂoating in the blood stream and thereforegenerate metastasis. Since Bin1 loss correlates with metastasis incancer patients and Bin1 has a role in apoptosis [24], we hypothesizethatBin1caninhibitNBmetastasisviapromotingcancercelldeathinblood, and resistance to anoikis may be an important mechanism ofmetastasis for the tumors expressing low level of Bin1.In this study, we examined breast cancer and NB cell lines thatwere established from patients with metastatic disease for Bin1expression levels. We also created a NB cell line that stably