Retinoic Acid Receptor-β Gene Reexpression and Biological Activity in SHI-1 Cells after Combined Treatment with 5-Aza-2′-Deoxycytidine and All-<b><i>Trans</i></b> Retinoic Acid

Abstract

Background: This study was conducted to determine the antineoplastic activities of 5-aza-2′-deoxycytidine (decitabine; DAC) and all-trans retinoic acid (ATRA), administered either alone or in combination, on in vitro cultured SHI-1 cells as well as their effects on the expression of the tumor suppressor gene p16^INK4a (p16) and the retinoic acid receptor (RAR)-β. Methods: Cellgrowth inhibition, differentiation and apoptosis were determined in SHI-1 cells treated with DAC and/or ATRA, and the combination index of the two compounds was calculated. Methylation of the p16 and RAR-β genes in SHI-1 cells was detected by methylation-specific polymerase chain reaction (PCR). Real-time quantitative reverse transcriptase PCR was used to detect mRNA expression of the p16 and RAR-β genes, and Western blot analysis was performed for protein expression. Results: The drug combination had a synergistic effect on growth inhibition, differentiation and apoptosis of SHI-1 cells, and the effects of DAC and ATRA weredependent on time. DAC, either alone or in combination with ATRA, induced demethylation of the genes p16 and RAR-β, whereas ATRA alone had no effect on methylation. The RAR-β gene was reexpressed following DAC-ATRA combination treatment, and both agents had no effect on p16 expression. Conclusion: The results revealed that DAC used in combination with ATRA has significant clinical potential in the treatment of acute monocytic leukemia. © 2014 S. Karger AG, Basel

Decitabine combined with all-trans retinoic acid as treatment in a case of primary myelofibrosis transforming into acute myeloid leukaemia

“…Previously, the present authors administered 15 mg/m 2 /day decitabine (days 1–5) combined with 20 mg/m 2 /day all-trans RA (days 1–28) to successfully treat 31 cases of myeloid neoplasms not suitable for intensive chemotherapy, with an ORR of 58.1% and a 2-year survival rate of 26.6%. 15 The side effects were mainly tolerable haematologic toxicities. In the present case, the same regimen was used to treat a patient diagnosed with PMF–tAML.…”

“…[15][16][17][18] Previous studies found that all-trans RA plus decitabine could induce the apoptosis and differentiation of leukemia cell lines K562, SHI-1 and U937 via upregulation of RARb gene expression. 15,17,18 In clinical practice, the ORR to treatment with alltrans RA plus decitabine in patients with myeloid leukaemia who cannot tolerate strong chemotherapy is 58.1%, with a median overall survival of 11 months. 19 In the present case, the diagnosis of PMF transforming into AML in addition to complex karyotypes, predicted a poor prognosis.…”

“…14 Numerous researchers have highlighted the synergistic effect of promoting tumour cell apoptosis and differentiation by combination therapy using all-trans RA and decitabine. 15–18 Previous studies found that all-trans RA plus decitabine could induce the apoptosis and differentiation of leukemia cell lines K562, SHI-1 and U937 via upregulation of RARβ gene expression. 15,17,18 In clinical practice, the ORR to treatment with all-trans RA plus decitabine in patients with myeloid leukaemia who cannot tolerate strong chemotherapy is 58.1%, with a median overall survival of 11 months.…”

RARβ Expression in Keratinocytes from Potentially Malignant Oral Lesions: The Functional Consequences of Re-Expression by De-Methylating Agents

“…The potential of the combination of effects of a methylating agent, such as 5-AZA-CdR with retinoids, has been explored in a number of different malignant and pre-neoplastic conditions [23][24][25]. The observation of loss of expression of some retinoid receptors by promoter methylation, associated with loss of retinoid sensitivity and thus retinoid-related modulation of differentiation and cell cycle arrest, indicates that this is potentially a useful concept for chemoprevention.…”

“…These agents, including 5-aza-2 -deoxycytidine (5-AZA-CdR), have been used clinically in the treatment of myelodysplastic syndromes and AML, where retinoid therapy is also employed. The effects of such combinations have been reported in vitro and in vivo clinical studies, with promising effects [23,24]. The approach has also been assessed in solid tumours, such as breast carcinoma and neuroblastoma [25,26].…”