The transmembrane and secreted protein delta-like 1 homolog (DLK1) belongs to the EGF-like family. It is widely accepted that DLK1 plays important roles in regulating cell differentiation, such as adipogenesis and osteogenesis. Aberrant expression of DLK1 has been found in various types of human cancers, including lung cancer. A previous study in this lab has revealed that DLK1 is associated with tumor invasion, although the mechanism is still unknown. To explore the potential effects that DLK1 might have on invasion, DLK1 was overexpressed or knocked down in the human lung cancer cell lines. The protein's influences on cell invasion were subsequently evaluated. A transwell assay showed that DLK1 overexpression significantly promoted cancer cell invasion. Western blotting and gelatin zymography analysis indicated that DLK1 could affect both matrix metalloproteinase-9 (MMP9) expression and its extracellular activity. An analysis of NOTCH1 and HES1 gene expression and Notch intracellular domain (NICD) nuclear translocation during DLK1 stimulation or depletion demonstrated that DLK1 could activate Notch signaling in lung cancer cells. Additionally, the elevated expression of MMP9 induced by DLK1 stimulation could be significantly decreased by inhibiting Notch signaling using γ-secretase inhibitor (GSI). The data presented in this study suggest that DLK1 can promote the invasion of lung cancer cells by upregulating MMP9 expression, which depends on Notch signaling.
References
[1]
Jemal A, Siegel R, Ward E, Hao Y, Xu J, et al. (2008) Cancer statistics, 2008. CA Cancer J Clin 58: 71–96. doi: 10.3322/ca.2007.0010
[2]
Herbst RS, Lippman SM (2007) Molecular signatures of lung cancer—toward personalized therapy. N Engl J Med 356: 76–78. doi: 10.1056/nejme068218
[3]
Glittenberg M, Pitsouli C, Garvey C, Delidakis C, Bray S (2006) Role of conserved intracellular motifs in Serrate signalling, cis-inhibition and endocytosis. EMBO J 25: 4697–4706. doi: 10.1038/sj.emboj.7601337
[4]
Bray SJ, Takada S, Harrison E, Shen SC, Ferguson-Smith AC (2008) The atypical mammalian ligand Delta-like homologue 1 (Dlk1) can regulate Notch signalling in Drosophila. BMC Dev Biol 8: 11. doi: 10.1186/1471-213x-8-11
[5]
Nueda ML, Baladron V, Sanchez-Solana B, Ballesteros MA, Laborda J (2007) The EGF-like protein dlk1 inhibits notch signaling and potentiates adipogenesis of mesenchymal cells. J Mol Biol 367: 1281–1293. doi: 10.1016/j.jmb.2006.10.043
[6]
Nueda ML, Garcia-Ramirez JJ, Laborda J, Baladron V (2008) dlk1 specifically interacts with insulin-like growth factor binding protein 1 to modulate adipogenesis of 3T3-L1 cells. J Mol Biol 379: 428–442. doi: 10.1016/j.jmb.2008.03.070
[7]
Wang Y, Sul HS (2009) Pref-1 regulates mesenchymal cell commitment and differentiation through Sox9. Cell Metab 9: 287–302. doi: 10.1016/j.cmet.2009.01.013
[8]
Sul HS (2009) Minireview: Pref-1: role in adipogenesis and mesenchymal cell fate. Mol Endocrinol 23: 1717–1725. doi: 10.1210/me.2009-0160
[9]
Abdallah BM, Boissy P, Tan Q, Dahlgaard J, Traustadottir GA, et al. (2007) dlk1/FA1 regulates the function of human bone marrow mesenchymal stem cells by modulating gene expression of pro-inflammatory cytokines and immune response-related factors. J Biol Chem 282: 7339–7351. doi: 10.1074/jbc.m607530200
[10]
Li L, Forman SJ, Bhatia R (2005) Expression of DLK1 in hematopoietic cells results in inhibition of differentiation and proliferation. Oncogene 24: 4472–4476. doi: 10.1038/sj.onc.1208637
[11]
Begum A, Kim Y, Lin Q, Yun Z (2012) DLK1, delta-like 1 homolog (Drosophila), regulates tumor cell differentiation in vivo. Cancer Lett 318: 26–33. doi: 10.1016/j.canlet.2011.11.032
[12]
Xu X, Liu RF, Zhang X, Huang LY, Chen F, et al. (2012) DLK1 as a potential target against cancer stem/progenitor cells of hepatocellular carcinoma. Mol Cancer Ther 11: 629–638. doi: 10.1158/1535-7163.mct-11-0531
[13]
Yu F, Hao X, Zhao H, Ge C, Yao M, et al. (2010) Delta-like 1 contributes to cell growth by increasing the interferon-inducible protein 16 expression in hepatocellular carcinoma. Liver Int 30: 703–714. doi: 10.1111/j.1478-3231.2010.02214.x
[14]
Yin D, Xie D, Sakajiri S, Miller CW, Zhu H, et al. (2006) DLK1: increased expression in gliomas and associated with oncogenic activities. Oncogene 25: 1852–1861. doi: 10.1038/sj.onc.1209219
[15]
Ceder JA, Jansson L, Helczynski L, Abrahamsson PA (2008) Delta-like 1 (Dlk-1), a novel marker of prostate basal and candidate epithelial stem cells, is downregulated by notch signalling in intermediate/transit amplifying cells of the human prostate. Eur Urol 54: 1344–1353. doi: 10.1016/j.eururo.2008.03.006
[16]
Liu Y, Tan J, Li L, Li S, Zou S, et al. (2010) [Study on the molecular mechanisms of dlk1 stimulated lung cancer cell proliferation]. Zhongguo Fei Ai Za Zhi 13: 923–927.
[17]
Falix FA, Aronson DC, Lamers WH, Gaemers IC (2012) Possible roles of DLK1 in the Notch pathway during development and disease. Biochim Biophys Acta 1822: 988–995. doi: 10.1016/j.bbadis.2012.02.003
[18]
Sanchez-Solana B, Nueda ML, Ruvira MD, Ruiz-Hidalgo MJ, Monsalve EM, et al. (2011) The EGF-like proteins DLK1 and DLK2 function as inhibitory non-canonical ligands of NOTCH1 receptor that modulate each other's activities. Biochim Biophys Acta 1813: 1153–1164. doi: 10.1016/j.bbamcr.2011.03.004
[19]
Baladron V, Ruiz-Hidalgo MJ, Nueda ML, Diaz-Guerra MJ, Garcia-Ramirez JJ, et al. (2005) dlk acts as a negative regulator of Notch1 activation through interactions with specific EGF-like repeats. Exp Cell Res 303: 343–359. doi: 10.1016/j.yexcr.2004.10.001
[20]
Bin Hafeez B, Adhami VM, Asim M, Siddiqui IA, Bhat KM, et al. (2009) Targeted knockdown of Notch1 inhibits invasion of human prostate cancer cells concomitant with inhibition of matrix metalloproteinase-9 and urokinase plasminogen activator. Clin Cancer Res 15: 452–459. doi: 10.1158/1078-0432.ccr-08-1631
[21]
Ma Y, Lin D, Sun W, Xiao T, Yuan J, et al. (2006) Expression of targeting protein for xklp2 associated with both malignant transformation of respiratory epithelium and progression of squamous cell lung cancer. Clin Cancer Res 12: 1121–1127. doi: 10.1158/1078-0432.ccr-05-1766
[22]
Huang J, Zhang X, Zhang M, Zhu JD, Zhang YL, et al. (2007) Up-regulation of DLK1 as an imprinted gene could contribute to human hepatocellular carcinoma. Carcinogenesis 28: 1094–1103. doi: 10.1093/carcin/bgl215
[23]
Kawakami T, Chano T, Minami K, Okabe H, Okada Y, et al. (2006) Imprinted DLK1 is a putative tumor suppressor gene and inactivated by epimutation at the region upstream of GTL2 in human renal cell carcinoma. Hum Mol Genet 15: 821–830. doi: 10.1093/hmg/ddl001
[24]
Stylianou S, Clarke RB, Brennan K (2006) Aberrant activation of notch signaling in human breast cancer. Cancer Res 66: 1517–1525. doi: 10.1158/0008-5472.can-05-3054
[25]
Chu D, Zhang Z, Zhou Y, Wang W, Li Y, et al.. (2011) Notch1 and Notch2 have opposite prognostic effects on patients with colorectal cancer. Ann Oncol.
[26]
Donnem T, Andersen S, Al-Shibli K, Al-Saad S, Busund LT, et al. (2010) Prognostic impact of Notch ligands and receptors in nonsmall cell lung cancer: coexpression of Notch-1 and vascular endothelial growth factor-A predicts poor survival. Cancer 116: 5676–5685. doi: 10.1002/cncr.25551
[27]
Eliasz S, Liang S, Chen Y, De Marco MA, Machek O, et al. (2010) Notch-1 stimulates survival of lung adenocarcinoma cells during hypoxia by activating the IGF-1R pathway. Oncogene 29: 2488–2498. doi: 10.1038/onc.2010.7
[28]
Kim KA, Kim JH, Wang Y, Sul HS (2007) Pref-1 (preadipocyte factor 1) activates the MEK/extracellular signal-regulated kinase pathway to inhibit adipocyte differentiation. Mol Cell Biol 27: 2294–2308. doi: 10.1128/mcb.02207-06
[29]
Wang Y, Zhao L, Smas C, Sul HS (2010) Pref-1 interacts with fibronectin to inhibit adipocyte differentiation. Mol Cell Biol 30: 3480–3492. doi: 10.1128/mcb.00057-10
