Suberoylanilide hydroxamic acid (SAHA) inhibits EGF-induced cell transformation via reduction of cyclin D1 mRNA stability

Abstract

Suberoylanilide hydroxamic acid (SAHA) inhibiting cancer cell growth has been associated with its down-regulation of cyclin D1 protein expression at transcription level or translation level. Here, we have demonstrated that SAHA inhibited EGF-induced Cl41 cell transformation via the decrease of cyclin D1 mRNA stability and induction of G0/G1 growth arrest. We found that SAHA treatment resulted in the dramatic inhibition of EGF-induced cell transformation, cyclin D1 protein expression and induction of G0/G1 growth arrest. Further studies showed that SAHA downregulation of cyclin D1 was only observed with endogenous cyclin D1, but not with reconstitutionally expressed cyclin D1 in the same cells, excluding the possibility of SAHA regulating cyclin D1 at level of protein degradation. Moreover, SAHA inhibited EGF-induced cyclin d1 mRNA level, whereas it did not show any inhibitory effect on cyclin D1 promoter-driven luciferase reporter activity under the same experimental conditions, suggesting that SAHA may decrease cyclin D1 mRNA stability. This notion was supported by the results that treatment of cells with SAHA decreased the half-life of cyclin D1 mRNA from 6.95 h to 2.57 h. Consistent with downregulation of cyclin D1 mRNA stability, SAHA treatment also attenuated HuR expression, which has been well-characterized as a positive regulator of cyclin D1 mRNA stability. Thus, our study identifies a novel mechanism responsible for SAHA inhibiting cell transformation via decreasing cyclin D1 mRNA stability and induction of G0/G1 growth arrest in Cl41 cells.

Effects of HuR downregulation on anaplastic thyroid cancer cells

“…In particular, SAHA, a HDAC inhibitor already FDA-approved for the treatment of several neoplastic diseases (21), proved to induce HuR downregulation in mouse epidermal JB6 Cl41 cells (15). Moreover, in a previous study, we demonstrated SAHA effects on SW1736 cell viability (14), and in this study, these data have been confirmed also in 8505C cells.…”

“…In a previously study, we have demonstrated how SAHA 3 µM treatment lead to decrement of cell viability in the SW1736 cell line (14). Besides, Zhang et al have demonstrated that the treatment with SAHA induces a reduction of HuR protein expression in mouse epidermal JB6 Cl41 cells (15).…”

X-linked Inhibitor of Apoptosis Protein (XIAP) Regulation of Cyclin D1 Protein Expression and Cancer Cell Anchorage-independent Growth via Its E3 Ligase-mediated Protein Phosphatase 2A/c-Jun Axis

“…D, the indicated cells were cultured in 2% FBS for 24 h synchronization. The cells were then used to determine mRNA expression by RT-PCR as described in our previous studies (55)…”

Isorhapontigenin (ISO) inhibited cell transformation by inducing G0/G1 phase arrest via increasing MKP-1 mRNA stability

“…Hence, cyclin D1 has been regarded as an important player in cancer development as well as a target for cancer prevention and therapy [36]. Our previous study, for example, has reported that suberoylanilide hydroxamic acid (SAHA) is able to inhibit EGF-induced cell transformation through reduction of cyclin d1 mRNA stability [37]. In the present study, we found that ISO inhibition of cell transformation and cell cycle progression in Cl41 cells was mediated through downregulation of cyclin D1 protein expression.…”

“…The viability of the cells was determined using CellTiter-Glo® Luminescent Cell Viability Assay kit (Promega, Madison, WI) with a luminometer (Wallac 1420 Victor 2 multipliable counter system). The results were presented as proliferation index (relative luminescence signal to medium control)[56-57]. …”