Protein kinase C-α (PKCα) modulates cell apoptosis by stimulating nuclear translocation of NF-kappa-B p65 in urothelial cell carcinoma of the bladder
Jin Zheng, Chuize Kong, Xiaoxi Yang, Xiaolu Cui, Xuyong Lin, Zhe Zhang, Jin Zheng, Chuize Kong, Xiaoxi Yang, Xiaolu Cui, Xuyong Lin, Zhe Zhang
Abstract
Background: The protein kinase C (PKC) family comprises central regulators of multiple signal transduction processes and is involved in the progression of many cancers. Nuclear factor Kappa-B (NF-κB) is constitutively expressed in cancer tissues and stimulates the transcription of various tumor-related genes. The present study aims to investigate the clinical significance of PKCα and NF-κB p65 in bladder cancer tissues and the mechanism underlying PKCα induction of bladder cancer cell apoptotic resistance through stimulation of p65 nuclear translocation.
Methods: Expression of PKCα and NF-κB subunit p65 was detected in seven bladder cancer cell lines by western blot and in 30 bladder cancer tissue specimens by immunostaining. Immunofluorescence was performed to evaluate p65 nuclear translocation induced by Phorbol 12-myristate 13-acetate (PMA). PKCα/β selective inhibitor Gö6976, PKC pan-inhibitor sotrastaurin, and the PKC siRNA were employed to conduct PKC inhibition/knockdown in bladder cancer cells. Luciferase reporter assays were performed to measure the activity of NF-κB. Flow cytometry and TUNEL analysis were used to assess cell apoptosis.
Results: Expression of PKCα and NF-κB was found to positively correlate with tumor progression in 30 tumor tissue specimens. Furthermore, a Pearson's correlation coefficient analysis revealed a positive correlation between PKCα and NF-κB expression. Among the PKC inhibitors, the PKCα/β selective inhibitor Gö6976 yielded the most significant block of PKCα and NF-κB activation by PMA. Knockdown of NF-κB p65 remarkably induced cell apoptosis, but PMA restored p65 expression and significantly suppressed cell apoptosis that was otherwise induced by the p65 knockdown alone.
Conclusion: Our study showed that PKCα modulated cell resistance to apoptosis by stimulating NF-κB activation and thus promoted the tumorigenesis of bladder cancer.
Keywords: Apoptosis; NF-κB; PKCα; Urothelial cell cancer.
Figures
References
- Siegel RL, Miller KD, Jemal A. Cancer statistics, 2016. CA Cancer J Clin. 2016;66(1):7–30. doi: 10.3322/caac.21332.
- Pang C, Guan Y, Li H, Chen W, Zhu G. Urologic cancer in China. Jpn J Clin Oncol. 2016;46(6):497–501. doi: 10.1093/jjco/hyw034.
- Chen W, Zheng R, Baade PD, et al. Cancer statistics in China, 2015. CA Cancer J Clin. 2016;66(2):115–132. doi: 10.3322/caac.21338.
- Klotz L, Brausi MA. World urologic oncology federation bladder cancer prevention program: a global initiative. Urol Oncol. 2015;33(1):25–29. doi: 10.1016/j.urolonc.2014.07.017.
- Sylvester RJ. Natural history, recurrence, and progression in superficial bladder cancer. ScientificWorldJournal. 2006;6:2617–2625. doi: 10.1100/tsw.2006.404.
- Basu A. The potential of protein kinase C as a target for anticancer treatment. Pharmacol Ther. 1993;59(3):257–280. doi: 10.1016/0163-7258(93)90070-T.
- Nishizuka Y. The molecular heterogeneity of protein kinase C and its implications for cellular regulation. Nature. 1988;334(6184):661–665. doi: 10.1038/334661a0.
- Griner EM, Kazanietz MG. Protein kinase C and other diacylglycerol effectors in cancer. Nat Rev Cancer. 2007;7(4):281–294. doi: 10.1038/nrc2110.
- Varga A, Czifra G, Tállai B, et al. Tumor grade-dependent alterations in the protein kinase C isoform pattern in urinary bladder carcinomas. Eur Urol. 2004;46(4):462–465. doi: 10.1016/j.eururo.2004.04.014.
- Koivunen J, Aaltonen V, Koskela S, Lehenkari P, Laato M, Peltonen J. Protein kinase C alpha/beta inhibitor Go6976 promotes formation of cell junctions and inhibits invasion of urinary bladder carcinoma cells. Cancer Res. 2004;64(16):5693–5701. doi: 10.1158/0008-5472.CAN-03-3511.
- Yokoyama Y, Ito T, Hanson V, et al. PMA-induced reduction in invasiveness is associated with hyperphosphorylation of MARCKS and talin in invasive bladder cancer cells. Int J Cancer. 1998;75(5):774–779. doi: 10.1002/(SICI)1097-0215(19980302)75:5<774::AID-IJC18>;2-6.
- Kong C, Zhu Y, Liu D, et al. Role of protein kinase C-alpha in superficial bladder carcinoma recurrence. Urology. 2005;65(6):1228–1232. doi: 10.1016/j.urology.2005.01.007.
- Naugler WE, Karin M. NF-kappaB and cancer-identifying targets and mechanisms. Curr Opin Genet Dev. 2008;18(1):19–26. doi: 10.1016/j.gde.2008.01.020.
- Bours V, Dejardin E, Goujon-Letawe F, Merville MP, Castronovo V. The NF-kappa B transcription factor and cancer: high expression of NF-kappa B- and I kappa B-related proteins in tumor cell lines. Biochem Pharmacol. 1994;47(1):145–149. doi: 10.1016/0006-2952(94)90448-0.
- Xia Y, Shen S, Verma IM. NF-κB, an active player in human cancers. Cancer Immunol Res. 2014;2(9):823–830. doi: 10.1158/2326-6066.CIR-14-0112.
- Ghosh G, Wang VY, Huang DB, Fusco A. NF-kappaB regulation: lessons from structures. Immunol Rev. 2012;246(1):36–58. doi: 10.1111/j.1600-065X.2012.01097.x.
- Whiteside ST, Israel A. I kappa B proteins: structure, function and regulation. Semin Cancer Biol. 1997;8(2):75–82. doi: 10.1006/scbi.1997.0058.
- Pahl HL. Activators and target genes of Rel/NF-kappaB transcription factors. Oncogene. 1999;18(49):6853–6866. doi: 10.1038/sj.onc.1203239.
- Blonska M, Lin X. CARMA1-mediated NF-kappaB and JNK activation in lymphocytes. Immunol Rev. 2009;228(1):199–211. doi: 10.1111/j.1600-065X.2008.00749.x.
- Sliva D, English D, Lyons D, Lloyd FP. Protein kinase C induces motility of breast cancers by upregulating secretion of urokinase-type plasminogen activator through activation of AP-1 and NF-kappaB. Biochem Biophys Res Commun. 2002;290(1):552–557. doi: 10.1006/bbrc.2001.6225.
- Shin Y, Yoon SH, Choe EY, et al. PMA-induced up-regulation of MMP-9 is regulated by a PKCalpha-NF-kappaB cascade in human lung epithelial cells. Exp Mol Med. 2007;39(1):97–105. doi: 10.1038/emm.2007.11.
- Mukherjee N, Houston TJ, Cardenas E, Ghosh R. To be an ally or an adversary in bladder cancer: the NF-κB story has not unfolded. Carcinogenesis. 2015;36(3):299–306. doi: 10.1093/carcin/bgu321.
- Du HF, Ou LP, Yang X, et al. A new PKCα/β/TBX3/E-cadherin pathway is involved in PLCε-regulated invasion and migration in human bladder cancer cells. Cell Signal. 2014;26(3):580–593. doi: 10.1016/j.cellsig.2013.11.015.
- Liu J, Kong CZ, Gong DX, Zhang Z, Zhu YY. PKC α regulates netrin-1/UNC5B-mediated survival pathway in bladder cancer. BMC Cancer. 2014;14:93. doi: 10.1186/1471-2407-14-93.
- Jiang Z, Kong C, Zhang Z, Zhu Y, Zhang Y, Chen X. Reduction of protein kinase C α (PKC-α) promote apoptosis via down-regulation of Dicer in bladder cancer. J Cell Mol Med. 2015;19(5):1085–1093. doi: 10.1111/jcmm.12503.
- Martiny-Baron G, Kazanietz MG, Mischak H, et al. Selective inhibition of protein kinase C isozymes by the indolocarbazole Gö 6976. J Biol Chem. 1993;268(13):9194–9197.
Source: PubMed