The Neurotensin Receptor-1 Pathway Contributes to Human Ductal Breast Cancer Progression

BACKGROUND: The neurotensin (NTS) and its specific high affinity G protein coupled receptor, the NT1 receptor (NTSR1), are considered to be a good candidate for one of the factors implicated in neoplastic progression. In breast cancer cells, functionally expressed NT1 receptor coordinates a series of transforming functions including cellular migration and invasion. METHODS AND RESULTS: we investigated the expression of NTS and NTSR1 in normal human breast tissue and in invasive ductal breast carcinomas (IDCs) by immunohistochemistry and RT-PCR. NTS is expressed and up-regulated by estrogen in normal epithelial breast cells. NTS is also found expressed in the ductal and invasive components of IDCs. The high expression of NTSR1 is associated with the SBR grade, the size of the tumor, and the number of metastatic lymph nodes. Furthermore, the NTSR1 high expression is an independent factor of prognosis associated with the death of patients. CONCLUSION: these data support the activation of neurotensinergic deleterious pathways in breast cancer progression

Expression of Neurotensin and NT1 Receptor in Human Breast Cancer: A Potential Role in Tumor Progression

International audienceEmerging evidence supports neurotensin as a trophic and antiapoptotic factor, mediating its control via the high-affinity neurotensin receptor (NT1 receptor) in several human solid tumors. In a series of 51 patients with invasive ductal breast cancers, 34% of all tumors were positive for neurotensin and 91% positive for NT1 receptor. We found a coexpression of neurotensin and NT1 receptor in a large proportion (30%) of ductal breast tumors, suggesting a contribution of the neurotensinergic signaling cascade within breast cancer progression. Functionally expressed NT1 receptor, in the highly malignant MDA-MB-231 human breast cancer cell line, coordinated a series of transforming functions, including cellular migration, invasion, induction of the matrix metalloproteinase (MMP)-9 transcripts, and MMP-9 gelatinase activity. Disruption of NT1 receptor signaling by silencing RNA or use of a specific NT1 receptor antagonist, SR48692, caused the reversion of these transforming functions and tumor growth of MDA-MB-231 cells xenografted in nude mice. Our findings support the contribution of neurotensin in human breast cancer progression and point out the utility to develop therapeutic molecules targeting neurotensin or NT1 receptor signaling cascade. These strategies would increase the range of therapeutic approaches and be beneficial for specific patients

Neurotensin receptor 1 gene activation by the Tcf/b-catenin pathway is an early event in human colonic adenomas

International audienceAlterations in the Wnt/APC (adenomatous polyposis coli) signalling pathway, resulting in b-catenin/T cell factor (Tcf)-dependent transcriptional gene activation, are frequently detected in familial and sporadic colon cancers. The neuropeptide neurotensin (NT) is widely distributed in the gastrointestinal tract. Its proliferative and survival effects are mediated by a G-protein coupled receptor, the NT1 receptor. NT1 receptor is not expressed in normal colon epithelial cells, but is over expressed in a number of cancer cells and tissues suggesting a link to the outgrowth of human colon cancer. Our results demonstrate that the upregulation of NT1 receptor occurring in colon cancer is the result of Wnt/APC signalling pathway activation. We first established the functionality of the Tcf response element within the NT1 receptor promoter. Consequently, we observed the activation of NT1 receptor gene by agents causing b-catenin cytosolic accumulation, as well as a strong decline of endogenous receptor when wt-APC was restored. At the cellular level, the re-establishment of wt-APC phenotype resulted in the impaired functionality of NT1 receptor, like the breakdown in NT-induced intracel-lular calcium mobilization and the loss of NT pro-invasive effect. We corroborated the Wnt/APC signalling pathway on the NT1 receptor promoter activation with human colon carcinogenesis, and showed that NT1 receptor gene activation was perfectly correlated with nuclear or cytoplasmic b-catenin localization while NT1 receptor was absent when b-catenin was localized at the cell-cell junction in early adenomas of patients with familial adenomatous polyposis, hereditary non-polyposis colorectal cancer and loss of het-erozygosity tumours. In this report we establish a novel link in vitro between the Tcf/b-catenin pathway and NT1 receptor promoter activation

NTSR1 expression in IDCs and global survival duration.

<p>Kaplan-Maier analysis for global survival duration in both groups with low (<80%) and high (≥80%) NTSR1 expression. Probability of overall death for patients with high NTSR1 expression (n = 38) versus patients with low NTSR1 expression (n = 68).</p

Correlation of the subpopulation co-expressing NT and NT1 receptor with the major prognosis factors.

<p>Correlation of the subpopulation co-expressing NT and NT1 receptor with the major prognosis factors.</p

Neurotensin expression in IDCs.

<p>a) NTS immunohistochemistry was performed on IDCs, ductal (1) and invasive (2) components, magnification 200× for (1) and 400× for (2). b) NTS and NTSR1 transcripts in IDCs. One µg of total RNA from 11 patients with IDCs were reverse-transcribed, and specific PCR was performed for NTS, NT-1 receptor, or GAPDH (control). The SBR grade is indicated below each line. c) Example of NTS and NTSR1 regional co-localization by immunohistochemistry for NTS (right) and NTSR1 (left) at the original magnification 400×.</p

Neurotensin expression in normal breast tissue.

<p>a) <i>Left</i>, one µg of total RNA from HBEC or whole gland were reverse-transcribed and a PCR experiment specific for NTS was performed. <i>Right</i>, <i>o</i>ne µg of total RNA from HBEC cells (control, treated with 10 nM estradiol (E2) with or without 1 µM ICI 182780) was reverse-transcribed. A PCR experiment was performed using specific primers for NTS and GAPDH. b) Normal duct exposed to NTS antibody at 1/500 dilution (1), after pre-incubation with the antigen peptide for 2 h at 10 nM (2), or without primary antibody (3), and lobule exposed to NTS antibody (4). Normal tissue exposed to NTS antibody at 1/500 dilution adjacent to tumor duct (5), lobule (6). The original magnification was 200×.</p

Patients clinical characteristics.

<p>SBR; Scarff Bloom and Richardson, n = number of patients, SD = standard deviation.</p