Signal transducer and activator of transcription 3 (STAT3), a member of the STAT protein family, can be phosphorylated by receptor-associated Janus kinases (JAKs) in response to stimulation by cytokines and growth factors. It forms homo- or heterodimers that can translocate to the cell nucleus where they act as transcription activators. Constitutive activation of STAT3 has been found to be associated with initiation and progression of various cancers. It can exert proliferative as well as anti-apoptotic effects. This review focuses on the role of STAT3 in pathogenesis i.e., proliferation, differentiation, migration, and apoptosis of hematological malignancies viz. leukemia, lymphoma and myeloma, and briefly highlights the potential therapeutic approaches developed against STAT3 activation pathway.

STAT3 is an oncogenic transcription factor that controls the expression of genes associated with oncogenesis and malignant progression. Persistent activation of STAT3 is observed in human malignancies, including hepatocellular carcinoma (HCC) and multiple myeloma (MM). Here, we have investigated the action of Tris(dibenzylideneacetone) dipalladium 0 (Tris DBA) on STAT3 signaling in HCC and MM cells. Tris DBA decreased cell viability, increased apoptosis, and inhibited IL-6 induced/constitutive activation of STAT3, JAK1, JAK2, and Src in HCC and MM cells. Tris DBA downmodulated the nuclear translocation of STAT3 and reduced its DNA binding ability. It upregulated the expression of SHP2 (protein and mRNA) to induce STAT3 dephosphorylation, and the inhibition of SHP2 reversed this effect. Tris DBA downregulated the expression of STAT3-driven genes, suppressed cell migration/invasion. Tris DBA significantly inhibited tumor growth in xenograft MM and orthotopic HCC preclinical mice models with a reduction in the expression of various prosurvival biomarkers in MM tumor tissues without displaying significant toxicity. Overall, Tris DBA functions as a good inhibitor of STAT3 signaling in preclinical HCC and MM models.