Drago-Ferrante Rosa, Pentimalli Francesca, Carlisi Daniela, De Blasio Anna, Saliba Christian, Baldacchino Shawn, Degaetano James, Debono Joseph, Caruana-Dingli Gordon, Grech Godfrey, Scerri Christian, Tesoriere Giovanni, Giordano Antonio, Vento Renza, Di Fiore Riccardo
Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Polyclinic, Palermo, Italy.
Oncology Research Center of Mercogliano (CROM), Istituto Nazionale per lo Studio e la Cura dei Tumori "Fondazione Giovanni Pascale", IRCCS, Naples, Italy.
Oncotarget. 2017 Apr 25;8(17):28939-28958. doi: 10.18632/oncotarget.15960.
MiR-29 family dysregulation occurs in various cancers including breast cancers. We investigated miR-29b-1 functional role in human triple negative breast cancer (TNBC) the most aggressive breast cancer subtype. We found that miR-29b-1-5p was downregulated in human TNBC tissues and cell lines. To assess whether miR-29b-1-5p correlated with TNBC regenerative potential, we evaluated cancer stem cell enrichment in our TNBC cell lines, and found that only MDA-MB-231 and BT-20 produced primary, secondary and tertiary mammospheres, which were progressively enriched in OCT4, NANOG and SOX2 stemness genes. MiR-29b-1-5p expression inversely correlated with mammosphere stemness potential, and miR-29b-1 ectopic overexpression decreased TNBC cell growth, self-renewal, migration, invasiveness and paclitaxel resistance repressing WNT/βcatenin and AKT signaling pathways and stemness regulators. We identified SPINDLIN1 (SPIN1) among predicted miR-29b-1-5p targets. Consistently, SPIN1 was overexpressed in most TNBC tissues and cell lines and negatively correlated with miR-29b-1-5p. Target site inhibition showed that SPIN1 seems to be directly controlled by miR-29b-1-5p. Silencing SPIN1 mirrored the effects triggered by miR-29b-1 overexpression, whereas SPIN1 rescue by SPIN1miScript protector, determined the reversal of the molecular effects produced by the mimic-miR-29b-1-5p. Overall, we show that miR-29b-1 deregulation impacts on multiple oncogenic features of TNBC cells and their renewal potential, acting, at least partly, through SPIN1, and suggest that both these factors should be evaluated as new possible therapeutic targets against TNBC.
MiR-29家族失调发生在包括乳腺癌在内的多种癌症中。我们研究了miR-29b-1在人类三阴性乳腺癌（TNBC）（最具侵袭性的乳腺癌亚型）中的功能作用。我们发现miR-29b-1-5p在人类TNBC组织和细胞系中表达下调。为了评估miR-29b-1-5p是否与TNBC的再生潜能相关，我们在TNBC细胞系中评估了癌症干细胞富集情况，发现只有MDA-MB-231和BT-20能产生原代、二代和三代乳腺球，这些乳腺球中OCT4、NANOG和SOX2干性基因逐渐富集。MiR-29b-1-5p的表达与乳腺球干性潜能呈负相关，miR-29b-1异位过表达可降低TNBC细胞的生长、自我更新、迁移、侵袭能力及对紫杉醇的耐药性，同时抑制WNT/β连环蛋白和AKT信号通路以及干性调节因子。我们在预测的miR-29b-1-5p靶标中鉴定出SPINDLIN1（SPIN1）。一致的是，SPIN1在大多数TNBC组织和细胞系中过表达，且与miR-29b-1-5p呈负相关。靶位点抑制表明SPIN1似乎直接受miR-29b-1-5p调控。沉默SPIN1可模拟miR-29b-1过表达引发的效应，而通过SPIN1 miScript保护剂拯救SPIN1，则可逆转模拟miR-29b-1-5p产生的分子效应。总体而言，我们表明miR-29b-1失调会影响TNBC细胞的多种致癌特征及其更新潜能，至少部分是通过SPIN1起作用，并建议应将这两个因素评估为针对TNBC的新的潜在治疗靶点。
