In this study, a comprehensive analysis was conducted to understand the molecular mechanisms underlying prostate cancer by examining differential gene expression between tumor and non-tumor samples. Using a volcano plot derived from limma-voom, a total of 45,828 differentially expressed genes (DEGs) were identified, with a stringent threshold of a log fold change (FC) greater than or equal to 2.5 and a p-value less than 0.05 (Ritchie et al. 2015). Among these, 18,998 genes were upregulated, while 26,830 were downregulated.
Gene Ontology (GO) and KEGG pathway analyses revealed that these DEGs are involved in critical pathways related to cancer, such as the Ras signaling pathway and lipid metabolism (Ashburner et al. 2000; Kanehisa et al. 2021). The Ras signaling pathway, in particular, is known to be pivotal in cancer development and progression, making it a significant focus in cancer research. Additionally, the involvement of lipid metabolism pathways suggests potential alterations in metabolic processes associated with cancer.
To further elucidate the interactions among DEGs, we utilized the STRING database to construct protein-protein interaction (PPI) networks. The PPI network for upregulated genes comprised 57 nodes and 143 edges, while the network for downregulated genes included a smaller number of nodes and edges with distinct connectivity patterns. The clustering coefficients for upregulated and downregulated networks were 0.242 and 0.404, respectively, indicating a higher degree of clustering among downregulated genes.
The MCODE plugin in Cytoscape identified several key clusters within these networks. Cluster 1, with a high MCODE score of 9.750, consisted of 38 nodes and 308 edges, suggesting a densely interconnected network. Clusters 2 and 3, though smaller, also showed significant interaction patterns, particularly around FTO and PNLIP in Cluster 2 and 3. Through cluster analysis 10 hub node genes were identified the hub genes were PLA2G2F, PLA2G2D, PLA2G1B, PLA2G10, PLA2G5, PLA2G3, LPCAT4, PLB1, PLA2G12A, PLA2G2E. This dense clustering underscores the complex and highly interconnected nature of the molecular changes associated with prostate cancer.
Molecular docking studies using PyRx software aimed to evaluate the interaction of nine phytochemicals with prostate cancer target proteins. They are 1BBC (PLA2G12A), 1KQU (PLA2G1B), 1KVO (LPCAT4), 1POD (PLA2G3), 1TRN (PLB1), 3U8H (PLA2G5), 5WZM (PLA2G2E), 5WZO (PLA2G2F), 5WZT(PLA2G2F), 8ERC (PLA2G10). The results demonstrated varied binding affinities across different target proteins. Curcumin exhibited the strongest binding affinity towards proteins 1KQU and 5WZO, with docking scores of -7.7 kcal/mol. Resveratrol, quercetin, and epigallocatechin gallate showed better binding to protein 5WZM with docking scores ranging from − 8 to -9 kcal/mol.
The binding affinities of sulforaphane and lycopene were moderate, with scores of -4.0 and − 7.1 kcal/mol, respectively. Notably, anthocyanins, capsaicin, and gingerol displayed considerable binding affinity with protein 8ERC, with scores of -8.6, -7.6, and − 6.9 kcal/mol, respectively. These findings suggest that these phytochemicals could have potential therapeutic effects in prostate cancer by interacting effectively with specific target proteins.
Toxicity prediction using ProTox-II indicated that lycopene is a lead compound due to its low toxicological profile coupled with excellent docking results and binding affinity. This highlights its potential as a safer therapeutic option with promising efficacy.
The integration of gene expression analysis, PPI network construction, and molecular docking provides a multifaceted understanding of the molecular mechanisms driving prostate cancer. The identification of key pathways and interactions, along with the promising results from phytochemical docking studies, suggests that targeted therapeutic approaches involving these compounds could be beneficial for drug design for prostate cancer.
Additionally, further exploration of the specific roles of the hub genes and their interactions within the identified clusters could provide deeper insights into the molecular underpinnings of prostate cancer and guide the development of novel therapeutic strategies. Our study highlights the importance of a multi-approach strategy in understanding prostate cancer mechanisms and emphasizes the potential of natural compounds in cancer therapy.