Cyp4b1, a member of the mammalian cytochrome P450 monooxygenase family, can bioactivate a wide range of xenobiotics like 4-ipomeanol, leading to tissue-specific toxicities. Similar to other CYP4 family members, it can hydroxylate fatty acids and fatty alcohols. Its expression is mainly extra-hepatic, predominantly in the lung, and thus does not play a major role in hepatic P450-catalyzed phase I drug metabolism. Although human CYP4B1 has no observed catalytic activity due to a proline-to-serine substitution at position 427, its expression patterns are associated with various cancers [1,2,3].

The relationship between Cyp4b1 polymorphisms and cancer risk has been studied. In Chinese women, CYP4B1 rs2297813, rs12142787, and rs3766197 SNPs are associated with breast cancer risk, especially in certain subgroups such as those with BMI ≤ 24 kg/m2, smokers, non-drinkers, advanced-stage patients, and those who reproduced once [4]. In the Chinese Han population, missense variants in CYP4B1 (rs2297810, rs4646491, and rs2297809) are associated with an increased risk of lung cancer [5]. In human bladders, CYP4B1 was detected, and bladder-tumor patients had a significantly higher expression of CYP4B1 than non-bladder-tumor patients, suggesting it may be a risk factor for bladder cancer [6].

In conclusion, Cyp4b1 is involved in the metabolism of both xenobiotics and endogenous compounds. Despite the lack of catalytic activity in human CYP4B1, its association with various cancers, as revealed through population-based genetic studies (equivalent to in vivo studies in terms of demonstrating gene-disease relationships), indicates its potential importance in cancer development. These findings provide insights into the role of Cyp4b1 in disease and may offer new directions for cancer prevention and treatment.