Exploring the phytochemical composition and the anticancer potential of Haliclona fascigera and Stylissa carteri Red Sea sponges in colon cancer treatment: A promising approach

• Haliclona fascigera (HFE) and Stylissa carteri (SCE) showed significant cytotoxic activity against HCT116 and HT-29 colorectal cancer cell lines. • 59 previously unreported metabolites, predominantly nitrogenous compounds, were identified in HFE and SCE. • SCE induced significant S-phase apoptosis, while HFE caused G2-phase arrest and led to higher rates of late apoptosis in both cancer cell lines. • Both extracts downregulated the anti-apoptotic gene Bcl-Xl and upregulated p53 expression, with HFE exhibiting a stronger regulatory effect. • Eicosanamide, hyptolide, and palmitic acid showed promise as anticancer drugs targeting KRAS p.G12C and Bcl-2 by molecular docking. This study investigates the phytochemical composition and anticancer properties of extracts from the marine sponges Haliclona fascigera (HFE) and Stylissa carteri ( SCE) , collected from the Red Sea coast of Jeddah, Saudi Arabia, against human colorectal cancer cell lines HCT116 and HT-29 employing SRB assay at varying concentrations (ranging from 0.01 to 1000 µg/mL), compared to the positive control doxorubicin (DOX). The RP-HPLC-QTOF-MS and tandem MS/MS revealed the presence of 59 metabolites belonging to several classes that were described for the first time in HFE and SCE with a predominance of nitrogenous compounds. SCE exhibited a markedly more pronounced cytotoxic effect, with IC 50 of 1.9 ± 0.04 µg/mL for the HCT-116 cell line and 7.8 ± 0.6 µg/mL for the HT-29 cell line. In contrast, HFE demonstrated higher IC 50 values of 46.5 ± 1.3 µg/mL for HCT-116 and 61.9 ± 2.2 µg/mL for HT-29, indicating that SCE is significantly more potent than HFE , particularly in the HCT-116 cell line. Cell cycle analysis indicated that SCE predominantly induces apoptosis in the S-phase, while HFE significantly affects the G2-phase. Flow cytometric analysis demonstrated late apoptosis in both cell lines, with HFE inducing late apoptosis in 88.72 % of HCT-116 cells and 90.50 % of HT-29 cells, while SCE induced late apoptosis in 58.36 % of HCT-116 cells and 72.22 % of HT-29 cells. Treatment with HFE and SCE led to significant downregulation of the anti-apoptotic gene Bcl-Xl in both HCT116 and HT-29 cells, with HFE showing the strongest effect, especially in HT-29 cells (0.10-fold change). For the pro-apoptotic p53 gene, both extracts increased expression levels, with HFE yielding the highest upregulation in HCT116 cells (1.51-fold change). This suggests that these sponge extracts promote apoptosis by decreasing anti-apoptotic signalling while enhancing pro-apoptotic pathways, potentially aiding in cancer cell viability reduction.The study evaluates the binding affinities of various compounds against Bcl-2, Human Survivin, and KRAS p.G12C, which are key targets in colorectal cancer. Eicosanamide exhibited the highest binding affinities, outperforming both the co-crystallized ligands and Doxorubicin in several cases, making it a promising candidate for further investigation. Hyptolide and Palmitic Acid also showed significant potential, especially against KRAS p.G12C and Bcl-2, indicating their potential as multi-target inhibitors in colorectal cancer therapy. These findings indicate that both sponge extracts possess promising anticancer properties, with SCE being a particularly potent candidate for further investigation and potential therapeutic applications.