Gaining attention of immunomodulatory therapies has led to the investigation of natural protein Allium sativum lectin (ASL) for anti-cancer properties. Current investigation explores the immunomodulatory mediated anticancer effect of ASL against lung cancer. The ASL accelerates immune cell proliferation; in particular elicits "M1"-macrophage polarization of THP-1 cells, by elevating expression of CD86, interleckin-12 (IL-12) and interferon-γ (IFN-γ). Conditioned medium from ASL-treated"M1"-polarized THP-1 macrophages (ASL-CM) demonstrated significant cytotoxicity against lung cancer cells. Unraveling the mechanism, revealed that IFN-γ modulates tumor microenvironment (TME) by generating reactive oxygen species (ROS), intern leading to activation of Janus activates kinase/signal transducer and activator of transcription 1 (JAK1/STAT1) as well as ataxia-telangiectasia mutated kinase/checkpoint kinase 2 (ATM/CHK2) signalling pathway. Both the pathway converges at p53/PUMA (p53 upregulated modulator of apoptosis) to activate its downstream apoptotic protein BCL-2-associated X protein/Bcl-2 antagonist/killer (BAX, BAK), cytochrome-c and caspases to induce cell death. The in-vivo experimental results with Lewis lung carcinoma (LLC) mice model, further validated ASL mediated immunomodulatory role by regressing lung tumor with enhanced survival rate. Polarization of macrophage into "M1" phenotype were much more supportive. Reduction of tumor associated macrophages (TAM) was validated with reduced secretion of IL-1β & IL-10 and enhanced secretion IFN-γ & IL-12. The ASL activated JAK1/STAT1 and ATM/CHK2/p53 pathways, converge to induce cell death signalling was also evident. Overall ASL initiates dual signalling cascades by establishing the cross-talk between two death signalling pathways through immunomodulation. The findings suggest that ASL could be translated to possible option for combinatorial cancer immunotherapy, by reprogramming immune responses.
