Bladder cancer is the ninth most diagnosed cancer worldwide, with over 6 lakh new cases and approximately 2.2 lakh deaths reported in 2022. The badder cancer affects men more frequenly than women, and is ranked as the sixth most frequent cancer and the ninth leading cause of cancer-related deaths among men (Bray et al., 2024), posing a major threat to men's health. Among the empirically recognised bladder cancer risk factors, tobacco smoking, occupational risk (aluminum and rubber production, painting, firefighting), environmental exposure (gamma radiation, heavy metals), and genetic predispositions are significant ones (Parida and Patel, 2023). Of the various regulators of cellular processes, metals occupy quite dominant position owing to their diverse roles in metabolism and cell signaling in the human body (Rodriguez et al., 2025). For instance, sodium and potassium play crucial roles in nutrient absorption, renal filtration, and action potential generation. Magnesium and calcium are vital for hard biological structure formation (teeth and bone), cell signaling, and structural stability of macromolecules (proteins and DNA). Similarly, iron, copper, and zinc form prosthetic groups required for enzymatic activity (Rodriguez et al., 2025). In contrast, heavy metals pose significant harm to the body even at low doses, and have neglible, if any, known physiological significance hitherto (Parida and Patel, 2023). Generally, heavy metal contamination arises from anthropogenic activities, subsequently polluting the soil, water, air, and food. Eventually, heavy metals enter the human body through these contaminated sources (Keshav Krishna and Rama Mohan, 2016), adversely affecting the bodily functions. Cigarette smoke—potential source of health hazard—contains approximately 400 chemical elements, including nicotine, tar, carbon monoxide, and environmental contaminants such as heavy metals (As, Cd, Cr, Ni, and Pb) (Stellman and Djordjevic, 2009), making smoking highly dangerous to health. The presence of heavy metals in tobacco—consumed in various forms—is attributed to their accumulation in tobacco crops through soil contamination (Bernhard et al., 2005). The Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC) have classified heavy metals; namely, As, Cd, Cr, Ni, and Pb, as “known” human carcinogens (Chang et al., 2016; Parida and Patel, 2023). The carcinogenic potential of these heavy metals is attributed to their ability to cause oxidative stress, autophagy, epigenetic modifications, and microRNA dysregulation, among others (Saran et al., 2021; Wang et al., 2021; Zhu and Costa, 2020). Aberrant shift in DNA methylation and histone marks are well-known epigenetic modifications capable of orchestrating tumor progression and metastasis (Davalos and Esteller, 2023). DNA methyltransferase (DNMT) family—consisting of DNMT1, DNMT3A, and DNMT3B—plays crucial role in establishing and maintaining methylation of the promoter-related CpG islands and genome-wide non-CpG regions. They can hypermethylate the tumor suppressor genes abnormally and block their activity, thereby facilitating genomic instability and carcinogenesis (Kulis and Esteller, 2010; Lyko, 2018; Wong, 2021). While DNMT3A and DNMT3B are responsible for establishing de novo DNA methylation patterns, DNMT1 acts as a maintenance enzyme, preserving DNA methylation pattern during DNA replication (Subramaniam et al., 2014). Consequently, upregulated DNMT1 is associated with various kinds of cancers, including breast, bladder, colon, kidney, pancreatic, gastric, and esophageal squamous cell carcinoma (Guo et al., 2018; Lyko, 2018; Robertson et al., 1999; Wang et al., 2018; Wong, 2021; Xie et al., 2017). Hypermethylation of tumor suppressor genes leads to dysregulation of the cell cycle and apoptosis, promoting metastatic behavior in cancer cells. Elevated expression of DNMT1 has been implicated in the silencing several tumor suppressor genes. Therefore, inhibition of DNMT1 suppresses growth, invasion, and migration in esophageal cancer (Bai et al., 2016), providing potential therapeutic target. DNMT1, independent of its catalytic function, can also modulate several cellular processes, including cell cycle, DNA damage repair, and stem cell functions (Mohan, 2022). Hypermethylation also suppresses the expression of Transmembrane Protein 130 (TMEM130)—known to be critically involved in cellular chemotaxis, adhesison, apoptosis, and autophagy—leading to the migration of triple negative breast cancer (TNBC) cell lines; namely, MDA-MB-231 and BT549 (Liu et al., 2021b), underscoring significance of genetic methylation in carcinogenesis. Therefore, application of demethylating agents and DNMT inhibitor (DNMTi) mitigates hypermethylation-induced carcinogenesis, rendering them effective for treating cancer such as multiple myeloma and acute myeloid leukemia (AML) (Issa, 2007; Janzarik, 1979; Yamada et al., 2023). For instance, decitabine (i.e., 5-aza-2′-deoxycytidine)—a DNA hypomethylating agent (HMA)—causes hypomethylation by inhibiting DNA methyltransferase 1 (DNMT1), thereby modulating expression of several genes and associated processes. In addition to the hematological malignancies, several clinical studies have examined the efficacy of decitabine in treating solid tumors both as a stand-alone treatment or in combination with chemotherapy (Nie et al., 2014). Decitabine also forms aberrant DNMT1-DNA covalent bonds, thereby causing mitotic perturbations (Yabushita et al., 2023), inhibiting cell division. Decitabine has an elevated response rate and minimal side effects in patients, suggesting its usefulness for targated cancer treatment. In this background, we assessed the effects of decitabine on heavy metal-induced proliferation, mitochondrial membrane potential, ROS generation, and migration in the T24 urinary bladder cancer cell line. Furthermore, the study also evaluated gene expression of DNMT1 and DNMT3B in the presence of individual heavy metals, decitabine alone, and heavy metal-decitabine combinations in T24 urinary bladder cancer cell line, as well as their effects on the global DNA methylation.