CD44 is a glycoprotein expressed in leucocytes and a marker of leukemia-initiating cells, being shown to be important in the pathogenesis of T cell acute lymphoblastic leukemia (T-ALL).
In addition, quantitative real-time polymerase chain reaction was used to study changes in the expression of tumor suppressor proteins 53 and 21 ( P53 and P21), cluster of differentiation 44 ( CD44), and B cell-specific Moloney murine leukemia virus integration site 1 ( BMI-1) upon treatments.
On the basis of our prior work highlighting CD44 as a marker of leukemia-initiating cells in animal models and because cancer stem cells are postulated to possess intrinsic resistance to conventional chemotherapy, we examined whether CD44 itself might play a role in mediating chemoresistance.
Our results suggest that polymeric nanoparticle-mediated silencing of CD44 might be a useful technique for inhibiting LSPC interactions with their microenvironment, thereby prohibiting leukemia progression or sensitizing LSPC to chemotherapy.
CD44 is involved in development and progress of hematological neoplasias by enhancement of apoptotic resistance, invasiveness, as well as regulation of bone marrow homing, and mobilization of leukemia-initiating cells into the peripheral blood.
While in normal individuals all these molecules are broadly expressed on leukocytes, in patients with leukemias the following deviations were observed: (a) at least one of the examined molecules was missing in 64/68 cases (94%); in 12/68 cases (18%) both molecules LFA-1 and ICAM-1 were missing, in 37/68 (54%) either LFA-1 or ICAM-1, and in 15/68 cases (22%) adhesion molecules other than LFA-1 or ICAM-1 were missing; (b) the expression of CD11a/CE18, CD58, CD59 on leukemic cells was heterogeneous, without any clear correlation to the subclass of leukemia; (c) in the majority of cases, CD54 (45/68; 66%) and CD44 (36/68; 53%) were missing, however showing a tendency of expression on leukemic cells with more mature immunophenotype.
In the current study, the temporal pattern of infiltration of a CD10- pre-B leukemia line (G2) in various murine tissues and the progression of the disease in the whole animal were monitored by quantifying human CD44 mRNA expression by the polymerase chain reaction (PCR).