Induction of Apoptosis in Cisplatin-Resistant Ovarian Cancer via Valproic Acid Deacetylation of lncRNA H19
Jonaphine Rae Mata
Introduction Ovarian cancer is the most lethal female reproductive system disease1. Although the five-year survival rate is 92% with early detection, the more common late diagnosis is an overture to malignancy, with a five-year survival rate of 17%2. In this late stage, resistance to platinum-based chemotherapy presents a major barrier to treatment. Studies have focused on genetic therapeutic targets to combat ovarian cancer’s resistance to the chemotherapeutic drug, Cisplatin3-4. Prior studies demonstrated the influential role of lncRNA H19 in the carcinogenesis of Cisplatin-resistant ovarian cancer, showing its upregulation in drug-resistant cells and elucidating its role as an inhibitor of apoptosis5-8. Recent studies demonstrated that Cisplatin+VPA treatment precludes H19’s anti-apoptotic effects in Cisplatin-resistant ovarian cancer via VPA’s modulation of H19 via deacetylation9-10. Thus, these findings propose a potential therapy to combat Cisplatin-resistant ovarian cancer. Methods. Using transcriptome sequencing, differential expression between wild-type ovarian cancer (A2780S) and Cisplatin-resistant (A2780-DR) cells was elucidated5. To determine VPA effects on H19, lung adenocarcinoma cells were treated with VPA, and results were analyzed via RT-PCR, BASP/COBRA and Western Blot9. In another study, A2780 and A2780-DR cells were treated with Cisplatin, VPA or Cisplatin+VPA for 48 hours10. Cell viability was then quantified via MTT. RT-PCR quantified the expression of H19, EZH2, p21 and PTEN, relevant proteins in H19’s anti-apoptotic downstream pathways10. To investigate if VPA effects were indeed mediated via H19 blockage, H19 knockdown (H19si) cells were transfected in A2780 cells, with the apoptotic rate determined via Annexin-V/PI10. Results. Transcriptome sequencing showed higher expression of H19 in A2780-DR cells versus A2780 cells (p=0.0036)5. RT-PCR, BASP/COBRA and Western Blot analyses demonstrated that after VPA treatment, H19 expression decreased with concomitant decrease of its HDAC expression9. MTT results showed that Cisplatin+VPA was the most lethal to both A2780 and A2780-DR cells10. RT-PCR results showed Cisplatin+VPA or VPA alone downregulated H19 and EZH2 and upregulated pro-apoptotic p21 and PTEN10. Lastly, H19si transfection studies exhibited upregulation of apoptosis by 80% in H19 knockdown cells when Cisplatin was added into the culture, compared to only 54.79% in control cells10. Conclusion. H19 is an essential target in the pharmacotherapy of Cisplatin-resistant ovarian cancer as demonstrated by its upregulation in A2780-DR cells5. Adjunct treatment of VPA with Cisplatin shows great promise in the treatment of Cisplatin-resistant ovarian cancer as studies prove VPA downregulation of H19 via histone deacetylation, and findings of significant decreased A2780-DR cell viability after Cisplatin+VPA treatment9-10.
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