1- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran; Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran , mohsentatar@ymail.com
2- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
3- Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
2- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
3- Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Abstract: (54 Views)
Background: Colorectal cancer (CRC) is a leading cause of cancer-related mortality, underscoring the need for novel therapies targeting key drivers of tumor progression. Telomerase, which is reactivated in 85 - 90% of CRCs, confers unlimited replicative potential and represents a promising therapeutic target. Valproic acid (VPA), a histone deacetylase inhibitor with documented anticancer properties, has unclear effects on telomerase activity and human telomerase reverse transcriptase (hTERT) expression in CRC.
Methods: Six human CRC cell lines (HCT116, HT-29/219, LS180, SW1116, SW480, and SW742) were treated with 1.5 mM VPA for 72 hours. Telomerase activity was evaluated using a non-isotopic TRAP assay in both intact cells and cell-free systems. hTERT mRNA expression was quantified by real-time RT-PCR and normalized to GAPDH using the 2-ΔΔCt method. Statistical significance was assessed using the t-test or ANOVA, with P < 0.05 considered statistically significant.
Results: VPA significantly reduced telomerase activity in SW480 (27.7 ± 6.24%), SW742 (33.2 ± 12.34%), HT-29/219 (18.6 ± 4.6%), and LS180 (21.8 ± 5.32%) cells (P < 0.05), but not in HCT116 or SW1116 cells. No inhibition was observed in cell-free systems treated with 1.5 - 5 mM VPA, indicating an indirect mechanism of action. hTERT mRNA expression was significantly downregulated in HCT116 (38.0 ± 8%), LS180 (49.3 ± 10.18%), and HT-29/219 (34.8 ± 14.2%) cells (P < 0.05), while changes in the remaining cell lines were not statistically significant.
Conclusion: VPA indirectly inhibits telomerase activity in a subset of CRC cell lines, primarily through transcriptional repression of hTERT. These findings suggest that transcriptional regulation is a key underlying mechanism, although post-transcriptional or post-translational processes may also contribute in a cell line-specific manner. Overall, the results highlight the therapeutic potential of VPA for targeting telomerase in CRC, particularly as part of combination strategies with telomere-shortening agents.
Methods: Six human CRC cell lines (HCT116, HT-29/219, LS180, SW1116, SW480, and SW742) were treated with 1.5 mM VPA for 72 hours. Telomerase activity was evaluated using a non-isotopic TRAP assay in both intact cells and cell-free systems. hTERT mRNA expression was quantified by real-time RT-PCR and normalized to GAPDH using the 2-ΔΔCt method. Statistical significance was assessed using the t-test or ANOVA, with P < 0.05 considered statistically significant.
Results: VPA significantly reduced telomerase activity in SW480 (27.7 ± 6.24%), SW742 (33.2 ± 12.34%), HT-29/219 (18.6 ± 4.6%), and LS180 (21.8 ± 5.32%) cells (P < 0.05), but not in HCT116 or SW1116 cells. No inhibition was observed in cell-free systems treated with 1.5 - 5 mM VPA, indicating an indirect mechanism of action. hTERT mRNA expression was significantly downregulated in HCT116 (38.0 ± 8%), LS180 (49.3 ± 10.18%), and HT-29/219 (34.8 ± 14.2%) cells (P < 0.05), while changes in the remaining cell lines were not statistically significant.
Conclusion: VPA indirectly inhibits telomerase activity in a subset of CRC cell lines, primarily through transcriptional repression of hTERT. These findings suggest that transcriptional regulation is a key underlying mechanism, although post-transcriptional or post-translational processes may also contribute in a cell line-specific manner. Overall, the results highlight the therapeutic potential of VPA for targeting telomerase in CRC, particularly as part of combination strategies with telomere-shortening agents.
Keywords: Colorectal Cancer (Colorectal Neoplasms), Valproic Acid, hTERT Expression, Elomerase Activity
Article Type: Research |
Subject:
Cellular and Molecular Biology
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