Repression of SHP-1 expression by p53 leads to trkA tyrosine phosphorylation and suppression of breast cancer cell proliferation

Abstract

The nerve growth factor (NGF) receptor, trkA, the tumour suppressor p53 and the phosphatase SHP-1 are critical in cell proliferation and differentiation. SHP-1 is a trkA phosphatase that dephosphorylates trkA at tyrosines (Y) 674 and 675. p53 can induce trkA activation and tyrosine phosphorylation in the absence of NGF stimulation. In breast cancer tumours trkA expression is associated with increased patient survival. TrkA protein expression is higher in breast-cancer cell lines than in normal breast epithelia. In cell lines (but not in normal breast epithelia) trkA is functional and can be NGFstimulated to promote cell proliferation. This study investigates the functional relationship between trkA, p53 and SHP-1 in breast-cancer, and reveals that in wildtype (wt) trkA expressing breast-cancer cells both endogenous wtp53, activated by therapeutic agents, and transfected wtp53 repress expression of SHP-1 through the proximal CCAAT sequence of the SHP-1-P1-promoter and the transcription factor NF-Y. In these cells trkA-Y674/Y675 phosphorylation is detected when SHP-1 protein levels decrease in a wtp53-dependent manner. Proliferation and cell-cycle assays, with cells expressing endogenous or transfected wt-trkA and a temperature-sensitive p53 grown at 32 1C (when p53 is in the wt configuration), show suppressed cell proliferation. Suppression is not detected when grown at 37 1C (when p53 is in the mutant configuration). A release from suppression is observed when these cells are transiently transfected with wt-SHP-1 and grown at 32 1C. Suppression is also detected when, as control, wt-trkA-expressing cells are transiently transfected with SHP-1-siRNA, but not when a dominant-negative (DN) mutant trkA is used to abolish wt-trkA activity. Importantly, suppression is not seen with control trkA-negative breast-cancer cells (expressing wtp53, wt-SHP-1 and undetectable trkA), transfected with Y674F/Y675F mutant-trkA. BrdUincorporation experiments reveal lack of incorporation in cells expressing wt-trkA and wtp53, or wt-trkA and SHP-1-siRNA. However, BrdU is incorporated in the presence of Y674F/Y675F mutant trkA or DN mutant trkA. These results indicate that p53 repression of SHP-1 expression leads to trkA-Y674/Y675 phosphorylation and trkA-dependent suppression of breast-cancer cell proliferation. These data provide an explanation as to why high trkA levels are associated with favourable prognosis.

TrkC signaling is activated in adenoid cystic carcinoma and requires NT-3 to stimulate invasive behavior

“…Interestingly, TrkA, which is also considered a dependence receptor with a pro-apoptotic function that is similar to TrkC when its ligand is not available, 12,53 binds p53, which mediates TrkA activities. [54][55][56][57] Tumor-suppressive TrkC activities suggest that association of TrkC overexpression with good prognosis observed in medulloblastoma 4 may be explained by lack of NT-3 stimulation. Indeed, autocrine TrkC/NT-3 loops detected recently in neuroblastomas were linked with poor prognosis.…”

Pro-nerve Growth Factor Induces Autocrine Stimulation of Breast Cancer Cell Invasion through Tropomyosin-related Kinase A (TrkA) and Sortilin Protein

“…NGF cooperates with the tyrosine kinase receptor HER2 to activate breast cancer cell growth (13), and the anti-estrogen drug tamoxifen, which is widely used in breast cancer therapy, is able to inhibit its mitogenic effect (14). In addition, repression of SHP-1 phosphatase expression by p53 leads to TrkA tyrosine phosphorylation (15). Given TrkA and p75 NTR expression in breast tumor cells (16 -18), the demonstration that NGF is overexpressed in the majority of human breast tumors and that its inhibition can result in a diminished tumor growth in preclinical models underscores the potential value of NGF as a therapeutic target (19).…”

Phosphorylation of NTRK1 at Y674/Y675 induced by TP53-dependent repression of PTPN6 expression: A potential novel prognostic marker for breast cancer

“…Moreover, overexpression of PTPN6 and TP53 was associated with poor disease-free survival. These findings strongly suggest that the presence of NTRK1-pY674/pY675, wild-type TP53, and low levels of PTPN6 expression, which are involved in suppression of breast cancer cell proliferation, 28 correlate with longer disease-free survival and a more favorable outcome in patients with breast cancer.…”

“…[47][48][49][50] Thus, in order to determine whether NTRK1-pY674/pY675 together with undetectable or low levels of PTPN6 and TP53 expression are associated with improved disease-free survival, tumors showing together this NTRK1-pY674/pY675, PTPN6, and TP53 expression pattern were analyzed as they meet the conditions described by Montano. 28 Tumors meeting these conditions were denoted as 1 and others were denoted as 0. As seen in Table 2, multivariate analysis showed this expression pattern to be an independent predictor of improved 5-, 10-, and 15-year disease-free survival by 48% (hazard ratio ¼ 0.52, P ¼ 0.021), 36% (hazard ratio ¼ 0.64, P ¼ 0.049), and 37% (hazard ratio ¼ 0.63, P ¼ 0.029) when ER, HER2, PgR, nodal status, and Ki-67 expressions were included.…”

“…Repression of PTPN6 expression induces phosphorylation of NTRK1 at Y674/Y675, leading to nerve growth factor-independent NTRK1 activation. 28 This signals to suppress breast cancer cell proliferation by promoting cell cycle arrest. 28 These findings suggest that in breast cancer, there is a functional relationship between NTRK1, PTPN6, and wild-type TP53 involved in regulating cell division.…”