Chemoprevention effects of selected Malaysian herbs via polyamines pathway in cervical cancer

Abstract

Polyamine biosynthesis, which is tightly regulated in normal cells to maintain homeostasis, is frequently dysregulated in carcinoma cells, resulting in uncontrolled proliferation, evasion of apoptosis, and enhanced cancer cell survival. As part of the World Health Organization’s (WHO) initiative to eliminate cervical cancer as a public health concern by 2030, chemoprevention strategies offer a promising approach to target vulnerable populations and reduce cancer incidence. This study aims to investigate and elucidate the mechanistic and therapeutic potential of selected Malaysian herbs as chemopreventive agents targeting the polyamine pathway in human cervical cancer, SiHa cells. Aqueous extracts of 11 selected Malaysian herbs were prepared via maceration at 60 °C with a cosolvent and subsequently lyophilised at −80°C. An initial screening of the herbs –including S. aromaticum, E. scaber, H. rosa sinensis, C. caudatus, C. ternatea, C. verum, C. zedoaria, F. deltoideia, S. crispus, C. tamala, and M. fragrans –was conducted to assess cytotoxicity against SiHa cells. Phytochemical profiling was performed using Gas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography-Mass Spectrometry (LC-MS). The antiproliferative effects were evaluated using MTT and TBE assays, while protein levels were measured using Lowry’s assay. Key genes involved in polyamine metabolism—ODC, SSAT, OAZ1, and SMOX—were analysed via quantitative PCR (qPCR). Cell death mechanisms were investigated through cell cycle analysis, annexin V assay, and caspase 3, 8, and 9 activity assays. Following cytotoxicity screening, S. aromaticum and E. scaber were selected for their highest cytotoxicity, with lowest IC50 values of 177.6 and 88.8 μg/ml at 48 hours, respectively. Both extracts significantly inhibited cell growth and reduced intracellular protein content (p < 0.05). Low endogenous polyamine levels were detected in S. aromaticum (0.585 nmol/mg) and E. scaber (0.192 nmol/mg) extracts. Polyamine biosynthesis was disrupted by the downregulation of ODC (p < 0.05) and pregulation of OAZ1, SSAT, and SMOX (p <0.05), indicating a significant reduction in polyamine production in SiHa cells following treatment. Cell cycle analysis revealed G0/G1 arrest and G2/M accumulation, while annexin V assay indicated increased in late apoptotic cell populations. Caspase assays demonstrated that both extracts increased caspase 3 activity, with E. scaber predominantly activating caspase 8 and S. aromaticum significantly increasing caspase 9 activity. This study demonstrates the in vitro efficacy of S. aromaticum and E. scaber as chemopreventive agents against cervical cancer. The findings support their potential to inhibit cell proliferation, reduce polyamine content, induce apoptosis, and cause cell cycle arrest in SiHa cells, suggesting their promise as apoptosis-mediated therapeutic candidates for cervical cancer prevention and treatment.