Clinicopathological significance of hyaluronan and hyaluronidase 2 (HYAL2) in breast cancer.

Hyaluronan (HA), as a component of extracellular matrix, has pivotal roles in both physiological and pathological condition. In breast cancer, while high molecular weight HA is produced by hyaluronan synthase, it is degraded by hyaluronidases (hyaluronidase-1 (HYAL1) and hyaluronidase-2 (HYAL2)) into low molecular weight HA (LMW HA), which is considered to have pro-tumorigenic effects in human malignancies. However, HA and HYAL2, the rate-limiting enzyme of HA degradation, have not been comprehensively examined in breast cancer and clinicopathological significance of LMW HA remains to be elucidated in breast cancer. We therefore histochemically localized HA as well as HYAL2 in 116 breast cancer tissues. In addition, we examined size-dependent function of HA on breast cancer cell proliferation and migration using MCF-7 and MDA-MB-231 breast cancer cell lines. HA was localized in both the stroma and breast carcinoma cells, while HYAL2 was predominantly localized in breast carcinoma cells. HA was significantly correlated with cell proliferation and invasion ability as well as increased risk of recurrence especially in HYAL2 positive group. On the other hand, HYAL2 was correlated with breast cancer cell proliferation and increased risk of recurrence. In addition, in vitro analyses revealed that lower molecular weight HA increased sphere forming ability and migration in MCF-7 and MDA-MB-231, whereas higher molecular weight HA inhibited them. It was concluded that HA needs to be degraded by HYAL2 to exert pro-tumorigenic effects and comprehensive HA/HYAL2 status serves as a potent prognostic factor in breast cancer.

Genetic Deficiencies of Hyaluronan Degradation.

Hyaluronan (HA) is a large polysaccharide that is broadly distributed and highly abundant in the soft connective tissues and embryos of vertebrates. The constitutive turnover of HA is very high, estimated at 5 g per day in an average (70 kg) adult human, but HA turnover must also be tightly regulated in some processes. Six genes encoding homologues to bee venom hyaluronidase (HYAL1, HYAL2, HYAL3, HYAL4, HYAL6P/HYALP1, SPAM1/PH20), as well as genes encoding two unrelated G8-domain-containing proteins demonstrated to be involved in HA degradation (CEMIP/KIAA1199, CEMIP2/TMEM2), have been identified in humans. Of these, only deficiencies in HYAL1, HYAL2, HYAL3 and CEMIP have been identified as the cause or putative cause of human genetic disorders. The phenotypes of these disorders have been vital in determining the biological roles of these enzymes but there is much that is still not understood. Deficiencies in these HA-degrading proteins have been created in mice and/or other model organisms where phenotypes could be analyzed and probed to expand our understanding of HA degradation and function. This review will describe what has been found in human and animal models of hyaluronidase deficiency and discuss how this has advanced our understanding of HA's role in health and disease.

Zfra Overrides WWOX in Suppressing the Progression of Neurodegeneration.

We reported that a 31-amino-acid Zfra protein (zinc finger-like protein that regulates apoptosis) blocks neurodegeneration and cancer growth. Zfra binds WW domain-containing oxidoreductase (WWOX) to both N- and C-termini, which leads to accelerated WWOX degradation. WWOX limits the progression of neurodegeneration such as Alzheimer's disease (AD) by binding tau and tau-hyperphosphorylating enzymes. Similarly, Zfra binds many protein targets and accelerates their degradation independently of ubiquitination. Furthermore, Zfra4-10 peptide strongly prevents the progression of AD-like symptoms in triple-transgenic (3xTg) mice during aging. Zfra4-10 peptide restores memory loss in 9-month-old 3xTg mice by blocking the aggregation of a protein cascade, including TPC6AΔ, TIAF1, and SH3GLB2, by causing aggregation of tau and amyloid ß. Zfra4-10 also suppresses inflammatory NF-κB activation. Zfra-activated Hyal-2+ CD3- CD19- Z cells in the spleen, via Hyal-2/WWOX/Smad4 signaling, are potent in cancer suppression. In this perspective review, we provide mechanistic insights regarding how Zfra overrides WWOX to induce cancer suppression and retard AD progression via Z cells.