Pathophysiology of Gastric MALT Lymphoma

Park, Gyeongsin; Kang, Chang Suk

Abstract

Early gastric mucosa-associated lymphoid tissue (MALT) lymphoma is considered as an antigen-dependent disease associated with long standing antigenic stimulation by Helicobacter pylori (H. pylori) which induces chronic immune response and lymphoid tissue development at the gastric mucosa normally devoid of lymphoid tissue. With disease progression, antigen-independent clones occur via genetic alterations inducing aberrant activation of nuclear factor kappaB (NF-kappaB) pathway which is essential for regulation of normal lymphocyte development and activation. Four major translocations, including t (11;18)/API2-MALT1, t (1;14)/BCL10-IGH, t (14;18)/(IGH-MALT1 and t (3;14)/FOXP1-IGH, occur mutually exclusively and lead to generation of cIAP2-MALT1 fusion protein or overexpression of BCL10, MALT1 and Foxp1. Translocation t (3;14)(q27;q32)/BCL6-IGH and t (1;2)(p22;p12)/BCL10-IGkappaL also occur in some MALT lymphomas. Mutational inactivation of A20, global NF-kappaB inhibitor, involve the development of especially translocation-negative MALT lymphoma. Downstream effects of most genetic alteration converge on the same NF-kappaB mediated oncogenic pathway. This review discusses the current advances in the pathophysiology underlying the development of gastric MALT lymphoma and its progression.