Cytotoxic and Pro-apoptotic Effects of Curcumin and Vitamin D₃ in a Human Non-Hodgkin's Lymphoma Cell Line (Daudi):...

Non-Hodgkin's lymphoma (NHL) is a heterogeneous group of lymphoid malignancies, with B-cell lymphomas being the most common. Despite advances in conventional therapies, adverse effects and resistance remain major limitations, prompting interest in safer alternatives. Curcumin, a polyphenolic compound from Curcuma longa, and vitamin D₃ (1,25-dihydroxyvitamin D₃) are natural agents with documented anticancer and pro-apoptotic effects. However, their combined effects in B-cell NHL are underexplored.

This in vitro study evaluated the cytotoxic and pro-apoptotic effects of curcumin and vitamin D₃, individually and in combination, on Daudi cells (a human Burkitt's lymphoma cell line). Cytotoxicity was assessed by MTT assay. Apoptosis was confirmed by DAPI nuclear staining. Quantitative reverse transcription polymerase chain reaction (RT-PCR) was performed to analyse the expression of apoptosis and cell cycle regulatory genes (Bcl-2, Bak, p21, p53, caspase-3, caspase-8, caspase-9), normalised to GAPDH.

Curcumin (IC₅₀ = 1.6 µM ± 0.16) and vitamin D₃ (IC₅₀ =15 µM ± 1.12) exhibited dose-dependent cytotoxicity. Combination treatment at lower doses (curcumin 0.5 µM + vitamin D₃ 7.5 µM) produced a synergistic effect (combination index 0.81). DAPI staining confirmed apoptosis in treated cells. Gene expression analysis revealed marked downregulation of the anti-apoptotic gene Bcl-2, and significant upregulation of pro-apoptotic genes Bak, caspase-3, caspase-8, and caspase-9. Combination therapy notably enhanced Bak (6.4-fold), p53 (5.6-fold), and p21 (2.2-fold) expression compared to monotherapies, suggesting activation of both intrinsic and extrinsic apoptotic pathways.

Curcumin and vitamin D₃ demonstrated cytotoxic, pro-apoptotic effects in Daudi cells, both independently and in combination. Preclinical and clinical studies are warranted to validate these effects and establish translational applications.