INSERM U908 Growth Factor Signaling in Breast Cancer, University of Lille,Villeneuve d’Ascq 59655, France.
J Biol Chem. 2012 Jan 13;287(3):1923-31. doi: 10.1074/jbc.M110.211714. Epub 2011 Nov 29.
The precursor of nerve growth factor (proNGF) has been described as a biologically active polypeptide able to induce apoptosis in neuronal cells, via the neurotrophin receptor p75(NTR) and the sortilin receptor. Herein, it is shown that proNGF is produced and secreted by breast cancer cells, stimulating their invasion. Using Western blotting and mass spectrometry, proNGF was detected in a panel of breast cancer cells as well as in their conditioned media. Immunohistochemical analysis indicated an overproduction of proNGF in breast tumors, when compared with benign and normal breast biopsies, and a relationship to lymph node invasion in ductal carcinomas. Interestingly, siRNA against proNGF induced a decrease of breast cancer cell invasion that was restored by the addition of non-cleavable proNGF. The activation of TrkA, Akt, and Src, but not the MAP kinases, was observed. In addition, the proNGF invasive effect was inhibited by the Trk pharmacological inhibitor K252a, a kinase-dead TrkA, and siRNA against TrkA sortilin, neurotensin, whereas siRNA against p75(NTR) and the MAP kinase inhibitor PD98059 had no impact. These data reveal the existence of an autocrine loop stimulated by proNGF and mediated by TrkA and sortilin, with the activation of Akt and Src, for the stimulation of breast cancer cell invasion.
神经生长因子前体（proNGF）已被描述为一种具有生物活性的多肽，能够通过神经营养因子受体 p75（NTR）和分选酶受体诱导神经元细胞凋亡。本文表明，proNGF 由乳腺癌细胞产生和分泌，刺激其侵袭。通过 Western blot 和质谱分析，在一系列乳腺癌细胞及其条件培养基中检测到 proNGF。免疫组织化学分析表明，与良性和正常乳腺活检相比，乳腺肿瘤中 proNGF 的过度产生，并与导管癌中的淋巴结浸润有关。有趣的是，针对 proNGF 的 siRNA 诱导乳腺癌细胞侵袭减少，而非可切割的 proNGF 的添加可恢复侵袭。观察到 TrkA、Akt 和 Src 的激活，但 MAP 激酶没有被激活。此外，proNGF 的侵袭作用被 Trk 药理学抑制剂 K252a、激酶失活的 TrkA 和针对 TrkA 分选酶、神经降压素的 siRNA 抑制，而针对 p75（NTR）和 MAP 激酶抑制剂 PD98059 的 siRNA 没有影响。这些数据揭示了存在由 proNGF 刺激的自分泌环，由 TrkA 和分选酶介导，通过 Akt 和 Src 的激活，刺激乳腺癌细胞侵袭。
