Elsevier

Oral Oncology

Volume 45, Issue 10, October 2009, Pages e150-e154
Oral Oncology

PTEN/AKT pathway involved in histone deacetylases inhibitor induced cell growth inhibition and apoptosis of oral squamous cell carcinoma cells

https://doi.org/10.1016/j.oraloncology.2009.05.563Get rights and content

Summary

Histone deacetylases (HDACs) inhibitors induce cell growth arrest and apoptosis in a wide variety of tumor cells. The purpose of this study was to evaluate the effects of trichostatin A (TSA), one of the HDACs inhibitors, on proliferation and apoptosis of oral squamous cell carcinoma cells. Exposure of Tca83 cells (established from human tongue squamous cell carcinoma) to TSA resulted in cell growth inhibition and apoptosis in a dose-dependent manner as measured with MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay and DAPI (4′6′diamidino-2-phenylindole dihydrochloride) staining. Western blot showed that both total PTEN and membrane-bound PTEN were induced by TSA treatment, whereas phosphorylation level (Ser 473) of AKT was correspondingly down-regulated by TSA treatment. Knock-down of PTEN expression with PTEN siRNA could sufficiently block 0.25 μg/ml TSA induced inhibition of cell growth, but failed to block 0.5 μg/ml TSA induced inhibition of cell growth and apoptosis. Moreover, induction of apoptosis by TSA treatment was also demonstrated by cytochrome C releasing and induction of caspase-3. Conclusively, the results suggested that PTEN/AKT pathway was involved in TSA induced cell growth inhibition and apoptosis of oral squamous cell carcinoma cells. HDACs inhibitors could be potential anticancer drugs for chemotherapy of oral squamous cell carcinoma.

Introduction

Histone deacetylases (HDACs) are enzymes that regulate chromatin structure and function by catalyzing the hydrolysis of the acetyl group from the N-terminal lysine residues of the nucleosomal core histones.1 In active chromatin, the core histones are highly hyperacetylated, whereas in inactive chromatin, the core histones are deacetylated and often cytosine methylated.1 Transcriptional activators usually bind and recruit histone acetyl transferases (HATs) to activate genes expression. In contrast, transcriptional repressors and co-repressors can interact with HDACs to inactivate genes expression.1

Inhibition of HDACs can induce silenced genes re-expression and induce cell growth arrest and apoptosis in a wide variety of tumor cells, including breast cancer cells, prostate cancer cells, hepatoma cells, pancreatic adenocarcinoma cells, lymphoma cells, lung cancer cells, and leukemic cells.2, 3, 4, 5, 6, 7, 8 Therefore, HDACs inhibitors are recognized as potential anticancer agents. One of the HDACs inhibitors, suberoylanilide hydroxamic acid (SAHA), has been in clinical trials for patients with both hematologic and solid tumors.9, 10 Moreover, SAHA has also been the first FDA-approved HDACs inhibitor for treatment of cutaneous T-cell lymphoma.11 The proapoptotic effects of HDACs inhibitors have been mainly correlated with the accumulation of acetylated histones and consequent changes in tumor suppressor genes expression.1 However, alteration of the functions of non-histone substrates also plays important roles in HDACs inhibitors induced cell growth arrest and apoptosis.12 Although several different signal pathways are demonstrated to be involved in the proapoptotic effects of HDACs inhibitors,4, 5, 6, 7, 8 the underlying molecular mechanisms are still not fully elucidated.

The PTEN (Phosphatase and tensin homolog deleted on chromosome 10) gene is a tumor suppressor that reverses the action of phosphoinositide 3-kinase (PI3K) by catalyzing the removal of the 3′ phosphate of phosphatidylinositol 3,4,5-trisphosphate (PIP3), which is necessary for AKT activation.13, 14, 15 PTEN has a single catalytic domain possessing both lipid phospho-inositol and protein phosphatase activities. The lipid phospho-inositol phosphatase activity is essential for PTEN to antagonizes the activity of growth factor-stimulated PI3K/AKT signaling pathway that activates many downstream cellular processes, including cell growth, apoptosis, and cell motility.13, 14, 15, 16 Activation of PTEN blocks cell cycle in the G1 phase and thereby to suppress tumor formation and progression.17 Besides p53 and Erg-1,18, 19 few other agents are known to activate PTEN so far. Considering AKT is involved in proapoptotic effects of HDACs inhibitors,12 it was theoretically and practically important to examine whether or not PTEN was activated by HDACs inhibitors.

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer and does not respond well to chemotherapy along. However, chemotherapy still plays important roles in the treatment of OSCC. It is usually used in combination with surgery or radiation therapy, or to treat advanced unresectable OSCC in the palliative setting.20 Although the combinational approaches are effective for OSCC, the currently used agents still have some serious side effects. Therefore, it is still clinically needed to develop novel anticancer agents to fight oral cancer. Although HDACs inhibitors are potential anticancer drugs, the effects of HDACs inhibitors on OSCC cells remain unknown.

The purpose of the present study was to evaluate the effects of trichostatin A (TSA), one of the HDACs inhibitors, on cell proliferation and apoptosis of OSCC cells, and to examine whether or not PTEN/AKT pathway was involved in TSA induced cell growth inhibition and apoptosis of the cells.

Section snippets

Cell culture

TCa83 cells, previously established from human tongue OSCC in Peking University School of Stomatology and already been used in many studies,21, 22 were cultured in DMEM (Gibco/Invitrogen) with 10% fetal bovine serum at 37 °C with 5% CO2 in a humidified atmosphere. For cell treatment, TSA (Sigma) dissolved in Me2SO was added in culture medium, while for corresponding controls, the same volume of solvent was added in culture medium.

MTT assay

Cell proliferation was assessed with MTT

Induction of cell growth inhibition and apoptosis of OSCC cells by TSA treatment

To examine the effects of TSA on OSCC cells, TCa83 cells were treated with TSA at concentrations of 0, 0.5, 1.0, and 2.0 μg/ml for different time periods. As shown in Fig. 1, MTT assay showed that the proliferation of TCa83 cells was inhibited by TSA in a dose-dependent manner after treatment for 24 h (Fig. 1A and B). Continued treatment with TSA for 36 h induced TCa83 cells apoptosis, also in a dose-dependent manner (Fig. 1B and C) and differentiation as indicated by neurite extension was seen (

Discussion

In the present study, we showed that PTEN/AKT signal pathway was involved in HDACs inhibitor TSA induced inhibition of cell growth and apoptosis of OSCC cells. Previous studies have demonstrated that rare cell lines are able to escape from the proapoptotic effects of HDACs inhibitors. Consistently, the present study showed that HDACs inhibitor TSA had similar proapoptotic effects on OSCC cells (Fig. 1). The results further supported that HDACs inhibitors could be a broad-spectrum anticancer

Conflict of Interest Statement

None declared.

Acknowledgements

This work was supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (No. 2006-331).

References (26)

  • M. Donadelli et al.

    Trichostatin A, an inhibitor of histone deacetylases, strongly suppresses growth of pancreatic adenocarcinoma cells

    Mol Carcinog

    (2003)
  • H. Duan et al.

    Histone deacetylase inhibitors down-regulate bcl-2 expression and induce apoptosis in t(14;18) lymphomas

    Mol Cell Biol

    (2005)
  • H.R. Kim et al.

    Trichostatin A induces apoptosis in lung cancer cells via simultaneous activation of the death receptor-mediated and mitochondrial pathway?

    Exp Mol Med

    (2006)
  • Cited by (37)

    • Glucose signaling in the brain and periphery to memory

      2020, Neuroscience and Biobehavioral Reviews
      Citation Excerpt :

      CREB recruitment is usually coupled with a recruitment of histone acetyl transferase (HAT) protein, namely, p300 which can remove HDAC2 to induce the acetylation of surrounding chromatin proteins leading to transcriptional activation (Cho and Cavalli, 2014; Peixoto and Abel, 2013). It has been known that Akt can enhance histone acetylation directly or indirectly in cell lines and also in tissues (Chen and Li, 2011; Gan and Zhang, 2009; Huang and Chen, 2005; Liu et al., 2013). It is therefore possible that glucose might enhance histone acetylation by enhancing phosphorylation of Akt.

    • BMI1 and PTEN are key determinants of breast cancer therapy: A plausible therapeutic target in breast cancer

      2018, Gene
      Citation Excerpt :

      This PTEN activation leads to inhibition of tumor growth (Meng et al., 2016). This study is supported by the previous studies of Gan and Zhang, 2009 where TSA not only induces PTEN expression but also PTEN membrane translocation (activation). The over expression of wild-type PTEN, but not K163-mutated PTEN, facilitates the inhibition of cell proliferation, migration and invasion.

    • Resveratrol regulates PTEN/Akt pathway through inhibition of MTA1/HDAC unit of the NuRD complex in prostate cancer

      2015, Biochimica et Biophysica Acta - Molecular Cell Research
      Citation Excerpt :

      In this study we have presented evidence that not only up-regulation but activation of PTEN occurs, at least in part, through resveratrol inhibition of components of NuRD deacetylation complex. It has already been reported that TSA promotes PTEN transcriptional activation by increasing acetylation of histones at the PTEN promoter [26] and TSA treatment induced PTEN-mediated apoptosis in oral squamous cell carcinoma [50]. In our experiments, resveratrol increased acetylation of PTEN in MTA1 knockdown cells similar to the effects of HDAC inhibitors, SAHA and TSA, indicating the involvement of MTA1/HDAC complex in PTEN deacetylation.

    • HDAC inhibitor DWP0016 suppresses miR-22 to induce growth inhibition and apoptosis via p53-independent PTEN activation in neuroblastoma SH-SY5Y cells

      2013, Process Biochemistry
      Citation Excerpt :

      As activation of PTEN inhibited PI3K/Akt pathway, we found DWP0016 significantly down regulated the protein expression of p-PI3K and p-Akt. These results were consistent to studies with certain HDAC inhibitors about the regulations on PTEN and PI3K/Akt pathway in other carcinoma cells [50–52]. Previous reports showed promotion of PTEN-p53 physical association and the recruitment of the PTEN-p53 complex to the p53 binding sites in the PTEN promoter, leading to PTEN transcriptional activation [53,54].

    View all citing articles on Scopus
    View full text