Recent studies demonstrated that cancer stem cells (CSCs) have higher tumorigenesis properties than those of differentiated cancer cells and that transcriptional factor-SOX2 plays a vital role in maintaining the unique properties of CSCs; however, the function and underlying mechanism of SOX2 in carcinogenesis of lung cancer are still elusive. This study applied immunohistochemistry to analyze the expression of SOX2 in human lung tissues of normal individuals as well as patients with adenocarcinoma, squamous cell carcinoma, and large cell and small cell carcinoma and demonstrated specific overexpression of SOX2 in all types of lung cancer tissues. This finding supports the notion that SOX2 contributes to the tumorigenesis of lung cancer cells and can be used as a diagnostic probe. In addition, obviously higher expression of oncogenes c-MYC, WNT1, WNT2, and NOTCH1 was detected in side population (SP) cells than in non-side population (NSP) cells of human lung adenocarcinoma cell line-A549, revealing a possible mechanism for the tenacious tumorigenic potential of CSCs. To further elucidate the function of SOX2 in tumorigenesis of cancer cells, A549 cells were established with expression of luciferase and doxycycline-inducible shRNA targeting SOX2. We found silencing of SOX2 gene reduces the tumorigenic property of A549 cells with attenuated expression of c-MYC, WNT1, WNT2, and NOTCH1 in xenografted NOD/SCID mice. By using the RNA-Seq method, an additional 246 target cancer genes of SOX2 were revealed. These results present evidence that SOX2 may regulate the expression of oncogenes in CSCs to promote the development of human lung cancer.
References
[1]
Garcia-Barrado MJ, Sancho C, Iglesias-Osma MC, Moratinos J (2001) Effects of verapamil and elgodipine on isoprenaline-induced metabolic responses in rabbits. Eur J Pharmacol 415: 105–115.
[2]
Kruger JA, Kaplan CD, Luo Y, Zhou H, Markowitz D, et al. (2006) Characterization of stem cell-like cancer cells in immune-competent mice. Blood 108: 3906–3912.
[3]
Hope KJ, Jin L, Dick JE (2004) Acute myeloid leukemia originates from a hierarchy of leukemic stem cell classes that differ in self-renewal capacity. Nat Immunol 5: 738–743.
[4]
You L, He B, Xu Z, Uematsu K, Mazieres J, et al. (2004) Inhibition of Wnt-2-mediated signaling induces programmed cell death in non-small-cell lung cancer cells. Oncogene 23: 6170–6174.
[5]
Du L, Wang H, He L, Zhang J, Ni B, et al. (2008) CD44 is of functional importance for colorectal cancer stem cells. Clin Cancer Res 14: 6751–6760.
[6]
Kato H, Ichinose Y, Ohta M, Hata E, Tsubota N, et al. (2004) A randomized trial of adjuvant chemotherapy with uracil-tegafur for adenocarcinoma of the lung. N Engl J Med 350: 1713–1721.
[7]
Winton T, Livingston R, Johnson D, Rigas J, Johnston M, et al. (2005) Vinorelbine plus cisplatin vs. observation in resected non-small-cell lung cancer. N Engl J Med 352: 2589–2597.
[8]
Pine SR, Marshall B, Varticovski L (2008) Lung cancer stem cells. Dis Markers 24: 257–266.
[9]
Jemal A, Siegel R, Ward E, Murray T, Xu J, et al. (2007) Cancer statistics, 2007. CA Cancer J Clin 57: 43–66.
[10]
Le QT, Chen E, Salim A, Cao H, Kong CS, et al. (2006) An evaluation of tumor oxygenation and gene expression in patients with early stage non-small cell lung cancers. Clin Cancer Res 12: 1507–1514.
[11]
Gutova M, Najbauer J, Gevorgyan A, Metz MZ, Weng Y, et al. (2007) Identification of uPAR-positive chemoresistant cells in small cell lung cancer. PLoS One 2: e243.
[12]
Leung EL, Fiscus RR, Tung JW, Tin VP, Cheng LC, et al. (2010) Non-small cell lung cancer cells expressing CD44 are enriched for stem cell-like properties. PLoS One 5: e14062.
[13]
Yanagi S, Kishimoto H, Kawahara K, Sasaki T, Sasaki M, et al. (2007) Pten controls lung morphogenesis, bronchioalveolar stem cells, and onset of lung adenocarcinomas in mice. J Clin Invest 117: 2929–2940.
[14]
Ho MM, Ng AV, Lam S, Hung JY (2007) Side population in human lung cancer cell lines and tumors is enriched with stem-like cancer cells. Cancer Res 67: 4827–4833.
[15]
Xiang R, Liao D, Cheng T, Zhou H, Shi Q, et al. (2011) Downregulation of transcription factor SOX2 in cancer stem cells suppresses growth and metastasis of lung cancer. Br J Cancer 104: 1931.
[16]
Nakatsugawa M, Takahashi A, Hirohashi Y, Torigoe T, Inoda S, et al. (2011) SOX2 is overexpressed in stem-like cells of human lung adenocarcinoma and augments the tumorigenicity. Lab Invest 91: 1796–1804.
[17]
Takahashi K, Yamanaka S (2006) Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell 126: 663–676.
[18]
Wernig M, Meissner A, Foreman R, Brambrink T, Ku M, et al. (2007) In vitro reprogramming of fibroblasts into a pluripotent ES-cell-like state. Nature 448: 318–324.
[19]
Park IH, Zhao R, West JA, Yabuuchi A, Huo H, et al. (2008) Reprogramming of human somatic cells to pluripotency with defined factors. Nature 451: 141–146.
[20]
Miyoshi N, Ishii H, Nagai K, Hoshino H, Mimori K, et al. (2010) Defined factors induce reprogramming of gastrointestinal cancer cells. Proc Natl Acad Sci U S A 107: 40–45.
[21]
Masui S, Nakatake Y, Toyooka Y, Shimosato D, Yagi R, et al. (2007) Pluripotency governed by Sox2 via regulation of Oct3/4 expression in mouse embryonic stem cells. Nat Cell Biol 9: 625–635.
[22]
Jia X, Li X, Xu Y, Zhang S, Mou W, et al. (2011) SOX2 promotes tumorigenesis and increases the anti-apoptotic property of human prostate cancer cell. J Mol Cell Biol 3: 230–238.
[23]
Chen Y, Shi L, Zhang L, Li R, Liang J, et al. (2008) The molecular mechanism governing the oncogenic potential of SOX2 in breast cancer. J Biol Chem 283: 17969–17978.
[24]
Chen H, Thiagalingam A, Chopra H, Borges MW, Feder JN, et al. (1997) Conservation of the Drosophila lateral inhibition pathway in human lung cancer: a hairy-related protein (HES-1) directly represses achaete-scute homolog-1 expression. Proc Natl Acad Sci U S A 94: 5355–5360.
[25]
Collins BJ, Kleeberger W, Ball DW (2004) Notch in lung development and lung cancer. Semin Cancer Biol 14: 357–364.
[26]
Dang TP, Gazdar AF, Virmani AK, Sepetavec T, Hande KR, et al. (2000) Chromosome 19 translocation, overexpression of Notch3, and human lung cancer. J Natl Cancer Inst 92: 1355–1357.
[27]
Westhoff B, Colaluca IN, D’Ario G, Donzelli M, Tosoni D, et al. (2009) Alterations of the Notch pathway in lung cancer. Proc Natl Acad Sci U S A 106: 22293–22298.
[28]
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.
[29]
Xu X, Sun PL, Li JZ, Jheon S, Lee CT, et al. (2011) Aberrant Wnt1/beta-Catenin Expression is an Independent Poor Prognostic Marker of Non-small Cell Lung Cancer After Surgery. J Thorac Oncol 6: 716–724.
[30]
Iwakawa R, Kohno T, Kato M, Shiraishi K, Tsuta K, et al. (2011) MYC amplification as a prognostic marker of early-stage lung adenocarcinoma identified by whole genome copy number analysis. Clin Cancer Res 17: 1481–1489.
[31]
Allen TD, Zhu CQ, Jones KD, Yanagawa N, Tsao MS, et al. (2011) Interaction between MYC and MCL1 in the genesis and outcome of non-small-cell lung cancer. Cancer Res 71: 2212–2221.
[32]
Pacheco-Pinedo EC, Durham AC, Stewart KM, Goss AM, Lu MM, et al. (2011) Wnt/beta-catenin signaling accelerates mouse lung tumorigenesis by imposing an embryonic distal progenitor phenotype on lung epithelium. J Clin Invest 121: 1935–1945.
[33]
Sasai K, Sukezane T, Yanagita E, Nakagawa H, Hotta A, et al. (2011) Oncogene-mediated human lung epithelial cell transformation produces adenocarcinoma phenotypes in vivo. Cancer Res 71: 2541–2549.
[34]
Lin L, Mernaugh R, Yi F, Blum D, Carbone DP, et al. (2010) Targeting specific regions of the Notch3 ligand-binding domain induces apoptosis and inhibits tumor growth in lung cancer. Cancer Res 70: 632–638.
[35]
Liu D, Kadota K, Ueno M, Nakashima N, Yokomise H, et al. (2011) Adenoviral vector expressing short hairpin RNA targeting Wnt2B has an effective antitumour activity against Wnt2B2-overexpressing tumours. Eur J Cancer. doi:10.1016/j.ejca.2011.05.003.
[36]
Sato N, Yamabuki T, Takano A, Koinuma J, Aragaki M, et al. (2010) Wnt inhibitor Dickkopf-1 as a target for passive cancer immunotherapy. Cancer Res 70: 5326–5336.
[37]
Palomero T, Lim WK, Odom DT, Sulis ML, Real PJ, et al. (2006) NOTCH1 directly regulates c-MYC and activates a feed-forward-loop transcriptional network promoting leukemic cell growth. Proc Natl Acad Sci U S A 103: 18261–18266.
[38]
Yochum GS (2011) Multiple Wnt/ss-catenin responsive enhancers align with the MYC promoter through long-range chromatin loops. PLoS One 6: e18966.
[39]
Moserle L, Ghisi M, Amadori A, Indraccolo S (2010) Side population and cancer stem cells: therapeutic implications. Cancer Lett 288: 1–9.
[40]
Wang J, Guo LP, Chen LZ, Zeng YX, Lu SH (2007) Identification of cancer stem cell-like side population cells in human nasopharyngeal carcinoma cell line. Cancer Res 67: 3716–3724.
[41]
Minn AJ, Gupta GP, Siegel PM, Bos PD, Shu W, et al. (2005) Genes that mediate breast cancer metastasis to lung. Nature 436: 518–524.
[42]
Park SB, Seo KW, So AY, Seo MS, Yu KR, et al. (2012) SOX2 has a crucial role in the lineage determination and proliferation of mesenchymal stem cells through Dickkopf-1 and c-MYC. Cell Death Differ 19: 534–545.
[43]
Seo E, Basu-Roy U, Zavadil J, Basilico C, Mansukhani A (2011) Distinct functions of Sox2 control self-renewal and differentiation in the osteoblast lineage. Mol Cell Biol 31: 4593–4608.
[44]
Basu-Roy U, Seo E, Ramanathapuram L, Rapp TB, Perry JA, et al. (2011) Sox2 maintains self renewal of tumor-initiating cells in osteosarcomas. Oncogene. doi:10.1038/onc.2011.405.
[45]
Bass AJ, Watanabe H, Mermel CH, Yu S, Perner S, et al. (2009) SOX2 is an amplified lineage-survival oncogene in lung and esophageal squamous cell carcinomas. Nat Genet 41: 1238–1242.
[46]
Hussenet T, Dali S, Exinger J, Monga B, Jost B, et al. (2010) SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas. PLoS One 5: e8960.
[47]
Matsumoto S, Tanaka F, Sato K, Kimura S, Maekawa T, et al. (2009) Monitoring with a non-invasive bioluminescent in vivo imaging system of pleural metastasis of lung carcinoma. Lung Cancer 66: 75–79.
[48]
Jenkins DE, Oei Y, Hornig YS, Yu SF, Dusich J, et al. (2003) Bioluminescent imaging (BLI) to improve and refine traditional murine models of tumor growth and metastasis. Clin Exp Metastasis 20: 733–744.
