Cytochrome P450 4B1 (CYP4B1) plays crucial roles in biotransforming of xenobiotics. Its predominant extrahepatic expression has been associated with certain tissue-specific toxicities. However, the expressions of CYP4B1 in various cancers and hence their potential roles in cancer development were inclusive. In this work, existing knowledge on expression and regulation of CYP4B1 gene and protein, catalysis of CYP4B1, association of CYP4B1 with cancers, contradicting findings about human CYP4B1 activities as well as the employing CYP4B1 in suicide gene approach for cancer treatment were reviewed. To date, it appears that there is a wide spectrum of tissue distribution of CYP4B1 with lungs as the predominant sites. Several nuclear receptors are possibly responsible for regulating its gene expression. The involvement of CYP4B1 in cancer was considered via activation of procarcinogens and neovascularization. However, human CYP4B1 was found to be inactive due to a substitution of proline with serine at position 427. Suicide gene approach combining reengineered CYP4B1 and prodrug 4-ipomeanol (4-IPO) has shown a promising potential for targeted cancer therapy. Further studies should focus on the verification of human CYP4B1 catalytic activities. More compounds with similar structure as 4-IPO should be tested to identify more alternative agents for the suicide gene approach in cancer treatment.
This study aimed to explore factors associated, specifically belief factors, with self-reported tobacco smoking status. A sample of 300 students was recruited from a private university in Malaysia. Data was collected using a pre-tested self-administrated questionnaire that investigated various factors including socio-demographics, socio-economic status, smoking behavior and beliefs on tobacco smoking. The main tobacco use in this study sample was cigarettes and the estimated prevalence of self-reported cigarette smoking was 10.3%. In bivariate analysis, self-reported cigarette smoking was significantly associated with socio-demographic, behavioral factors and faculty of study (P<0.05). In multivariate modeling, being male and a non-medical student, did not exercise, having a smoker father and brother or sister, suffering from financial difficulties and having the belief that smokers had more friends, all had statistically significant associations (P<0.05) with self-reported cigarette smoking. Social and interpersonal factors were associated with self-reported cigarette smoking status. A comprehensive health model focusing on changing the social norms of parent and sibling tobacco smoking and students' beliefs, alongside nurturing skills of dealing with stressful situations, warrant implementation.
With more than 80 cytochrome P450 (CYP) encoding genes found in the nematode Caenorhabditis elegans (C. elegans), the cyp35 genes are one of the important genes involved in many biological processes such as fatty acid synthesis and storage, xenobiotic stress response, dauer and eggshell formation, and xenobiotic metabolism. The C. elegans CYP35 subfamily consisted of A, B, C, and D, which have the closest homolog to human CYP2 family. C. elegans homologs could answer part of the hunt for human disease genes. This review aims to provide an overview of CYP35 in C. elegans and their human homologs, to explore the roles of CYP35 in various C. elegans biological processes, and how the genes of cyp35 upregulation or downregulation are influenced by biological processes, upon exposure to xenobiotics or changes in diet and environment. The C. elegans CYP35 gene expression could be upregulated by heavy metals, pesticides, anti-parasitic and anti-chemotherapeutic agents, polycyclic aromatic hydrocarbons (PAHs), nanoparticles, drugs, and organic chemical compounds. Among the cyp35 genes, cyp-35A2 is involved in most of the C. elegans biological processes regulation. Further venture of cyp35 genes, the closest homolog of CYP2 which is the largest family of human CYPs, may have the power to locate cyps gene targets, discovery of novel therapeutic strategies, and possibly a successful medical regime to combat obesity, cancers, and cyps gene-related diseases.
Cathinone is the psychostimulatory major active ingredient of khat (Catha edulis Forsk) and are often co-abused with alcohols and polydrugs. With the increased consumption of khat and cathinones on a global scale, efforts should be channelled into understanding and minimising the excruciating effects of possible khat-drug interactions. This study aimed to determine the in vitro inhibitory effects of cathinone on CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 and the in silico identification of their type of interactions and residues involved. The activities of CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 were examined by fluorescence based assays using recombinant cDNA-expressed human CYPs in Vivid® P450 screening kits. Cathinone reversibly inhibited CYP1A2, CYP2A6 and CYP3A5 via competitive, uncompetitive and noncompetitive modes with inhibition constant (Ki) values of 57.12, 13.75 and 23.57 µM respectively. Cathinone showed negligible inhibitory effects on CYP2B6, CYP2C8, CYP2C19, CYP2E1 and CYP2J2. Cathinone showed negligible time dependent inhibition on all 8 CYPs. Docking studies was performed on cathinone with CYP1A2, CYP2A6 and CYP3A5 following their inhibition in vitro. Cathinone is bound to a few key amino acid residues in the active sites while π-π interactions are formed in aromatic clusters of CYP1A2 and CYP3A5. These findings offer valuable reference for the use of cathinones and khat when combined with therapeutic drugs that are metabolised by CYP enzymes especially patients on medications metabolised by CYP1A2, CYP2A6 and CYP3A5.
Cathine is the stable form of cathinone, the major active compound found in khat (Catha edulis Forsk) plant. Khat was found to inhibit major phase I drug metabolizing cytochrome P450 (CYP) enzyme activities in vitro and in vivo. With the upsurge of khat consumption and the potential use of cathine to combat obesity, efforts should be channelled into understanding potential cathine-drug interactions, which have been rather limited. The present study aimed to assess CYPs activity and inhibition by cathine in a high-throughput in vitro fluorescence-based enzyme assay and molecular docking analysis to identify how cathine interacts within various CYPs' active sites. The half maximal inhibitory concentration (IC50) values of cathine determined for CYP2A6 and CYP3A4 were 80 and 90 μM, while CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP2J2 and CYP3A5 showed no significant inhibition. Furthermore, in Ki analysis, the Lineweaver-Burk plots depicted non-competitive mixed inhibition of cathine on both CYP2A6 and CYP3A4 with Ki value of 63 and 100 μM, respectively. Cathine showed negligible time-dependent inhibition on CYPs. Further, molecular docking studies showed that cathine was bound to CYP2A6 via hydrophobic, hydrogen and π-stacking interactions and formed hydrophobic and hydrogen bonds with active site residues in CYP3A4. Both molecular docking prediction and in vitro outcome are in agreement, granting more detailed insights for predicting CYPs metabolism besides the possible cathine-drug interactions. Cathine-drug interactions may occur with concomitant consumption of khat or cathine-containing products with medications metabolized by CYP2A6 and CYP3A4.