Abstract 5575: Identification of Novel <i>RBBP6</i> transcripts: modulation by <i>Drimia calcarata</i> plant extracts

Abstract Cancer, an assortment of maladies that are epitomized by deregulated cell proliferation, remains a thorn throughout the world. The soaring cancer cases can be attributed to deregulation of cancer-related genes and lack of effective therapeutics. Thus, this work was aimed at understanding the anticancer mechanisms associated with Drimia calcarata (D. calcarata) plant extracts, targeting cancer-related genes; particularly, Retinoblastoma binding protein 6 (RBBP6) gene. D. calcarata phytochemicals were extracted using both water and methanol, and characterized using Liquid Chromatography Mass Spectrometry (LC-MS). The resultant extracts were used to treat various lung cancer cell lines; namely, H1437, H1573 and A549 cells. The inhibitory effects and half maximal inhibitory concentration (IC50) values of D. calcarata extracts were established using the (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) and Muse® Count and Viability assays. Using the IC50 values, induction of cellular apoptosis was evaluated using both fluorescence microscopy, and the Muse® Cell Analyzer, while gene expression analysis was done using Polymerase Chain Reaction (PCR). The D. calcarata extracts, water and methanol, were found to contain a number of compounds with anticancer activities, which include Psoralene (C11H6O3), Limonin-17-beta-D-glucoside (C32H42O14), Oleuropein (C25H31O13), Isorhamnetin derivative (C16H12O7), and various uncharacterized compounds. The anticancer cancer activities were demonstrated to involve apoptosis induction, which was measured by both fluorescence microscopy and flow cytometry. Additionally, and most importantly, PCR showed that the D. calcarata extracts modulated the expression of novel RBBP6 splice variants. Intriguingly, the D. calcarata plant extracts differentially regulated the expression of novel RBBP6 transcripts in different lung cancer cells. D. calcarata extracts down-regulated RBBP6 transcripts 1 and 2; however, subjecting the A549 cells to stress, D. calcarata extracts and curcumin, resulted in the expression of a novel transcript that has not been identified previous. In H1437 and H1573 cells, this novel transcript is down-regulated by the D. calcarata plant extracts. In H1437, the RBBP6 transcripts 1 and 2 were up-regulated by the D. calcarata plant extracts. This suggests that RBBP6 gene can be targeted for development of novel biomarkers, and D. calcarata extracts should be further explored for novel therapeutic targets. Citation Format: Zukile Mbita, Kagiso Laka. Identification of Novel RBBP6 transcripts: modulation by Drimia calcarata plant extracts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5575.