Migrating mast cells in the gallbladder epithelium of cattle and sheep. A comparative morphologic and histochemical study

The immunohistochemistry of invasive and proliferative phenotype switching in melanoma: a case report

To date there is no effective therapy for metastatic melanoma and at the molecular level the disease progression is poorly understood. A recent study by our group led to the development of a novel phenotype switching model for melanoma progression, wherein cells transition back-and-forth between states of proliferation and invasion to drive disease progression. To explore the model's clinical relevance we interrogated phenotype-specific expression patterns in human melanoma patient material. A matched primary/metastasis pair from a human melanoma patient was obtained and immunohistochemically stained for proliferative and invasive phenotype markers. These were also stained for hypoxia and blood vessel markers. Proliferative phenotype markers Melan-A and Mitf showed consistent anti-correlation with invasive phenotype marker Wnt5A and hypoxia marker Glut-1. These also correlated with observed intra-tumoural vascularization patterns. Similar pattern distributions were present in both primary and metastasis samples. Strikingly, we observed that late phase metastatic melanoma cells adopt morphologies and behaviours identical to very early phase cells. The expression patterns observed closely matched expectations derived from previous in vitro and xenografting experiments. These results highlight the likelihood that disease progression involves melanoma cells retaining the capacity to regulate the expression of metastatic potential critical factors according to changing microenvironmental conditions.

Human mast cells adhere to and migrate on epithelial and vascular basement membrane laminins LM-332 and LM-511 via alpha3beta1 integrin

Mast cells (MCs) are multifunctional effectors of the immune system that are distributed in many tissues, often in close association with the basement membrane of blood vessels, epithelium and nerves. Laminins (LMs), a family of large alphabetagamma heterotrimeric proteins, are major components of basement membrane that strongly promote cell adhesion and migration. In this study, we investigated the role of LM isoforms and their integrin receptors in human MC biology in vitro. In functional assays, alpha3-(LM-332) and alpha5-(LM-511) LMs, but not alpha1-(LM-111), alpha2-(LM-211), or alpha4-(LM-411) LMs, readily promoted adhesion and migration of cultured MCs. These activities were strongly enhanced by various stimuli. alpha3-LM was also able to costimulate IL-8 production. Among LM-binding integrins, MCs expressed alpha(3)beta(1), but not alpha(6)beta(1), alpha(7)beta(1), or alpha(6)beta(4), integrins. Blocking Abs to alpha(3)beta(1) integrin caused inhibition of both cell adhesion and migration on alpha3- and alpha5-LMs. Immunohistochemical studies on skin showed that MCs colocalized with epithelial and vascular basement membranes that expressed alpha3- and alpha5-LMs and that MCs expressed alpha(3) integrin but not alpha(6) integrin(s). These results demonstrate a role for alpha3- and alpha5-LMs and their alpha(3)beta(1) integrin receptor in MC biology. This may explain the intimate structural and functional interactions that MCs have with specific basement membranes.