Overexpression of the Receptor for Hyaluronan-Mediated Motility (RHAMM) Characterizes the Malignant Clone in Multiple Myeloma: Identification of Three Distinct RHAMM Variants

Hyaluronan network: a driving force in cancer progression

Hyaluronan is one of the most abundant macromolecules of the extracellular matrix and regulates several physiological cell and tissue properties. However, hyaluronan has been shown to accumulate together with its receptors in various cancers. In tumors, accumulation of hyaluronan system components (hyaluronan synthesizing/degrading enzymes and interacting proteins) associates with poor outcomes of the patients. In this article, we review the main roles of hyaluronan in normal physiology and cancer, and further discuss the targeting of hyaluronan system as an applicable therapeutic strategy.

RHAMM-target peptides inhibit invasion of breast cancer cells

RHAMM is hyaluronan- receptor with multiple functions in the cell, RHAMM is involved in proliferation, motility, migration, invasion, mitotic spindle formation in tumour cells. Therefore, RHAMM could be a relevant target for molecular targeted therapies against tumors.The role of RHAMM-target peptides in inhibition invasion for preventing breast cancer has not yet been investigated. Base on this, we analyzed the RHAMM-target peptides for their therapeutic activity against breast cancer cells. In the present study, we examined the effect of RHAMM-target peptides on the invasion of breast cancer cells (MDAMB- 231), using confocal microscopy. We shown that RHAMM-target peptides decreased formation of invadopodia of breast cancer cells. The treatment of breast cancer cells by RHAMM -target peptides inhibited the invasion up to 99 %. Additionally, RHAMM-target peptides induced the morphological changes of of breast cancer cells. Therefore, based on these results, we can conclude that RHAMM-target peptides may be potential anti-cancer agents.

Genetic deletion of receptor for hyaluronan-mediated motility (Rhamm) attenuates the formation of aggressive fibromatosis (desmoid tumor)

Aggressive fibromatosis (desmoid tumor) is a locally invasive soft tissue neoplasm associated with mutations resulting in beta-catenin-mediated transcriptional activation. This tumor is composed of cells with histological and molecular characteristics common to proliferating mesenchymal cells of dermal wounds. Using immunohistochemistry and RT-PCR, we show that Rhamm, a protein with an important role in wound healing and neoplastic progression, is also expressed at high levels in aggressive fibromatosis. A mouse harboring a targeted deletion in Rhamm was generated, resulting in viable Rhamm-/- animals. Rhamm-/- mice were crossed with Apc/Apc1638N mice, which harbor a targeted mutation in the Apc gene predisposing animals to gastrointestinal and aggressive fibromatosis tumors. Rhamm deficiency significantly decreased the number of aggressive fibromatosis tumors formed, but did not alter the number of gastrointestinal polyps. Cell culture studies show that Rhamm regulates cell proliferation in both fibroblasts and fibromatosis cells under conditions of low density, but not high density. These results suggest that Rhamm regulates proliferation of cells with sparse cell-cell contacts, such as occurs in aggressive fibromatosis; provides the first genetic evidence implicating Rhamm in tumor pathology; and suggest Rhamm blockade as a potential therapeutic target for this otherwise difficult-to-treat neoplasm.