The growth rate of two transplantable murine tumors, 3LL lung carcinoma and B16F10 melanoma, is influenced by Hyal-1, a locus determining hyaluronidase levels and polymorphism.

The effect of 2 different levels of serum hyaluronidase on tumor development was studied by comparing the development of 2 transplantable tumors, the 3LL lung carcinoma and the B16F10 melanoma, in mice of the C57BL/6 and the congenic HW23 strains. The reasoning behind the study was that, in vitro, removal by hyaluronidase of the hyaluronan present in the extracellular matrix of tumor cells renders the latter more accessible to effector T cells. In the mouse, the levels and molecular forms of circulating hyaluronidase are under the influence of different alleles at the Hyal-1 locus on chromosome 9. C57BL/6 mice which have the Hyal-1b allele have only a 60,000-kDa form of hyaluronidase in the circulation, whereas the congenic HW23 strain has, on a C57BL/6 background, the BALB/c-derived Hyal-1a allele, characterized by the presence of the 60-, 120- and 140-kDa forms and of 3 times as much enzyme activity as the C57BL/6 strain. These 2 mouse strains that are genetically almost identical can therefore be used to compare the effect of different levels of circulating hyaluronidase on tumor development. Two different tumors were studied: the 3LL lung carcinoma and the B16F10 melanoma. After intrafootpad inoculation, both tumors developed more slowly in the congenic Hyal-1a HW23 strain, as measured by a slower rate of increase in local tumor size and by a prolonged survival time. These results are in favor of the hypothesis that the Hyal-1a allele, determining higher hyaluronidase levels, enhances resistance to tumor development.