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The substance P (SP)/NK-1 receptor (NK1R) complex represents an intriguing anticancer target for a variety of tumors, including hepatoblastoma (HB). Therefore, NK1R antagonists, such as the clinical drug aprepitant, recently have been proposed as potent anticancer agents. However, very little is known regarding the molecular basis of NK1R inhibition in cancer. Using reverse phase protein array, Western blot, Super TOP/FOP, confocal microscopy, and sphere formation ability (SFA) assays, we identified the AKT and Wnt signaling pathways as the key targets of aprepitant in three human HB cell lines (HepT1, HepG2, and HuH6). Following NK1R blockage, we observed decreased phosphorylation of p70S6K and 4E-BP1/2 and inhibition of the canonical Wnt pathway with subsequent decrease of HB cell growth. This effect was dependent of high baseline Wnt activity either by mutational status of b-catenin or extrinsic Wnt activation. Wnt inhibition seemed to be strengthened by disruption of the FOXM1-b-catenin complex. Furthermore, treatment of HB cells with aprepitant led to reduced expression of (liver) stemness markers (AFP, CD13, SOX2, NANOG, and OCT4) and SFA when grown under cancer stem cell conditions. Taken together, we show for the first time that targeting the SP/NK1R signaling cascade inhibits canonical Wnt signaling in HB cells. These findings reveal important insight into the molecular mechanisms of the SP/NK1R complex as a critical component in a model of pediatric liver cancer and may support the development of novel therapeutic interventions for HB and other Wnt-activated cancers.

The substance P (SP)/neurokinin-1 receptor (NK1R) complex and the Wnt cascade are pivotal signaling pathways in the regulation of cell growth and hence, potent targets for future anticancer therapies. However, while the Wnt cascade has long been associated with colon cancer, little is known about the expression of the NK1R complex as a potential target in this tumor and its molecular basis in tumorigenesis in general. We treated the human colon cancer cell lines LiM6 and DLD1 with the NK1R antagonist and the clinical drug aprepitant (AP) and analyzed both growth response and downstream mechanisms using MTT-assay, reverse phase protein array (RPPA), western blot, Super TOP/FOP, confocal microscopy, and sphere formation ability (SFA) assays. Following NK1R blockage, we found significant growth inhibition of both colon cancer cell lines. When analyzing downstream mechanisms, we found a striking inhibition of the canonical Wnt pathway represented by decreased Super TOP/FOP and increased membrane stabilization of β-catenin. This effect was independent from baseline Wnt activity and mutational status of β-catenin. Further, treatment of colon cancer cells grown under cancer stem cell (CSC) conditions reduced sphere formation in both number and size after a single treatment period. We show that the NK1R can be a potent anticancer target in colon cancer and that NK1R antagonists could potentially serve as future anticancer drugs. This effect was seen not only in primary cancer cells but, for the first time, also in CSC-like cells, potentially including these cells in a therapeutic effect. Also, we describe the robust inhibition of canonical Wnt signaling through targeting the SP/NK1R signaling cascade. These findings give important insight into the molecular mechanisms of the SP/NK1R complex as a critical component in tumorigenesis and could help to identify future anticancer therapies for colon and other Wnt-activated cancers.

Secretory breast carcinoma (SBC) is a rare breast carcinoma with distinctive morphologic features and a recurrent specific chromosomal translocation t(12;15)(p13;q25), usually of low histologic grade and favorable prognosis. We describe the morphologic and genetic characteristics of 11 cases of SBC from 10 patients. Histologic and immunohistochemical analyses, fluorescence in situ hybridization using break-apart probes specific to ETV6 on 12p13, reverse transcription polymerase chain reaction with in-house probes specific to the ETV6-NTRK3 gene fusion, and DNA copy number variation by array comparative genomic hybridization analyses were performed on all cases. Seven cases were of low histologic grade, 3 were intermediate, and 1 had high-grade nuclear atypia, necrosis, and numerous mitoses. This patient had a fatal outcome. Five cases displayed low hormonal receptor expression, whereas the rest had basal-type immunoprofiles. All interpretable cases harbored an ETV6-NTRK3 gene fusion by reverse transcription polymerase chain reaction and/or an ETV6 rearrangement by fluorescence in situ hybridization, with duplication of the oncogenic derivative in 2 cases. Array comparative genomic hybridization analysis showed simplex genomic profiles. The 2 cases with ETV6-NTRK3 duplication included a gain of 12p starting from the ETV6 locus to the telomere, associated with a gain of the 15q from the centromere to NTRK3 in 1 case, and in the other a normal profile up to NTRK3 on 15q, and then a loss up to the telomere, suggesting loss of corresponding normal chromosome 15. These findings provide a novel insight into the morphologic and genetic spectrum of SBC, ranging from low-grade to high-grade histology, with occasional low hormonal receptor expression, simplex genomic profiles, and possible unfavorable course.

Abstract. The substance P (SP; also known as TAC1)/neurokinin-1 receptor (NK1R; also known as TACR1) complex is a critical part in the development of cancer. Therefore, NK1R antagonists, such as the clinical drug aprepitant, are currently under investigation as future anticancer agents. In a previous study, NK1R (TACR1) was identified as a potent anticancer target in hepatoblastoma (HB). However, little is known regarding the exact distribution of this target among HB subsets and whether it correlates with clinical features and prognosis. In the present study, mRNA was isolated from 47 children with HB, and reverse transcription-quantitative polymerase chain reaction was performed on the samples to analyze the expression of full-length-TACR1 (fl-TACR1) and truncated-TACR1 (tr-TACR1). These data were correlated with data obtained from 9 tumor-free controls, as well as with the presence of metastasis, PRETEXT, vascular invasion, histology, age of diagnosis, multifocality, CTNNB1 mutation, gender and overall survival. Additionally, the present study investigated a recently described 16-gene signature characteri zing HB known to correlate with prognosis. Compared with tumor-free liver tissue, tumorous tissue expressed TACR1 significantly higher for the truncated version (P=0.0301), and by trend also for the full-length version. Accordingly, the expression of fl-TACR1 correlated with the expression of the truncated version (P=0.0074). Furthermore, a low expression of fl-TACR1 correlated with characteristics of the 16-gene signature known to predict prognosis (P=0.0222). However, there was no correlation between tr-TACR1 and the tumor characteristics investigated, including outcome, although a clear trend was observed for some tumor characteristics. The current results reinforced the previously described findings that in HB, tr-TACR1 is overexpressed compared with tumor-free liver tissue. Furthermore, to the best of our knowledge, the present study demonstrated for the first time that tr-TACR1 is expressed ubiquitously among the different subsets of HB. Therefore, NK1R may serve as a potent anticancer target in a large variety of patients with HB, independent of tumor biology and clinical stage.

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