GARCIA Mariana Gabriela
congresos y reuniones científicas
Increased hyaluronan (HA) levels are associated with tumor invasion in murine lymphoma cell lines.
Washington, DC, USA
Congreso; 101º Reunión Anual de la AACR; 2010
HA is a glycosaminoglycan component of the mammalian extracellular matrix (ECM) where it has a structural function influencing hydration. HA biosynthesis is carried out by HA synthases (Has) existing three isoforms: Has-1,-2 and -3. The control for HA deposition occurs at catabolism mainly by the action of hyaluronidases (Hyal), being Hyal-1, -2 and -3 the most important ones. Increased levels of HA as well as differential expression of Has/Hyals have been found in the ECM within tumors and have been related with tumor invasion and metastasis.The aim of this work was to analyze the ability of lymphoma cells to produce HA and to evaluate HA levels within the tumors induced by these cells. For this purpose, we used murine lymphoma cells resistant to doxorubicin (LBR-D160), vincristine (LBR-V160), and a sensitive line (LBR-) with dissimilar invasive behaviour in vivo, being LBR-V160 the less aggressive one. First we evaluated endogenous HA surface expression by flow cytometry finding that LBR- presented higher HA expression than LBR-D160 and LBR-V160 (p<0.01 respectively). Secondly, we studied mRNA expression for Has-1, Has-2, Has-3 and Hyal-1, Hyal-2 and Hyal-3 by RT-PCR. We observed that none of the cell lines presented Has-1 and Has-2, but all of them expressed similar levels of Has-3 mRNA. Although we were unable to detect Hyal-1, Hyal-2 was found significantly decreased in LBR- compared with LBR-D160 and LBR-V160 (p<0.05 repectively). Besides, Hyal-3 was similarly expressed in the 3 cell lines. Finally BALB/c mice were injected with tumor cells or vehicle, sacrificed and infiltrated lung, lymph nodes, spleen and liver as well as blood were taken for ELISA measurement of HA. Serum HA levels were increased in LBR- and LBR-D160 injected mice compared with control mice (4.1±1.2 and 3.9±0.8 µg/ml vs. 1.9±0.4 µg/ml; P<0.05), finding no differences in LBR-V160 injected mice (2.5±1.1 µg/ml). In lungs from LBR-D160 injected mice, HA concentration was increased compared with control (0.4±0.1 vs. 0.2±0.1 µg/mg tissue wet weight; P<0.05), while no changes were observed in LBR- or LBR-V160 injected mice. Besides, a slight increase in HA levels was observed in lymph nodes from LBR- and LBR-D160 injected mice compared with control mice (3.1±3.0 and 2.7±2.2 µg/mg tissue vs. 1.0±0.8 µg/mg tissue), while no changes were observed in spleen and liver.Our results showed an association between tumor progression and HA levels in this lymphoma model since mice injected with the cell lines with major invasive capacity (LBR- and LBR-D160) presented increased serum HA levels as well as increased deposition of HA in infiltrated lungs and lymph nodes. In LBR- this may be explained by the ability of this cell line to express more HA than the other ones which could be related with decreased Hyal-2 expression. Further analysis of Has/Hyal balance in the infiltrated organs will contribute to understanding the causes of HA increase in LBR-D160 injected mice.