HIF 1 is a heterodimer consisting of a constitutively further information expressed HIF 1B subunit and a HIF 1 subunit that is regulated through O2 dependent degradation modulated by prolyl hydroxyl ation. The von Hippel Lindau tumor suppressor protein binds specifically to hydroxylated HIF 1 which is then ubiquitylated by E3 ubiquitin protein ligases and rapidly degraded Inhibitors,Modulators,Libraries by the proteasome. The dipeptide B alanyl L histidine, also known as carnosine, was described for the first time in the 19th century. Carnosine is naturally present in cardiac and skeletal muscles and the central nervous system, and is synthesized from B alanine and L histidine by carnosine synthase in muscle cells, glial cells, and oligodendrocytes. Carnosine plays a role as a physiologic pH buffering substance and antioxidant.

It induces variable effects on the cardiovascular system, including down regulation of blood pressure, Inhibitors,Modulators,Libraries inhibition of glycosylated low density lipoprotein formation, and inhibition of angio tensin converting enzyme activity. It also acts as an anti aging agent. Moreover, it inhibits proliferation of cells derived from patients with glioblastoma and the growth of tumors formed from neoplastic cell lines, such as Sarcoma 180 tumor cells, various neoplastic hu man and rodent cell lines, cells expressing the human epidermal growth factor receptor 2, and HCT116 colon cancer cells. Conversely, carnosine enhances the proliferation potential of cultured normal human fibroblasts, lengthens their lifespan, and suppresses senescence. The mechanism of its action in tumor cells remains unclear.

Proteomic studies of glioblastoma Inhibitors,Modulators,Libraries cells after treat ment with carnosine Inhibitors,Modulators,Libraries revealed significantly reduced ex pression of von Hippel Lindau binding protein 1, a protein that binds to the von Hippel Lindau pro tein and thus is linked to HIF 1 signaling. Pretreat ment with carnosine reduced the induction of HIF 1 protein in H9c2 cardiomyoblasts during hypoxia and further reduced its already low level under normoxia, the level of HIF 1 mRNA was transiently reduced after car nosine treatment, but increased after 24 h in a similar manner to controls. A similar experiment with human astrocytes showed that carnosine did not significantly alter the pattern of HIF 1 protein expression in these cells. Carbonic anhydrase IX is a membrane bound metalloenzyme that is expressed in a broad range of solid tumors.

The main function of CA IX is to maintain intracellular pH homeostasis under hypoxic conditions that are common Inhibitors,Modulators,Libraries in solid tumors although it also modulates E cadherin mediated cell adhesion via its interaction with beta catenin, which could be of poten tial significance in hypoxia induced tumor progression. CA IX contributes to ion transport and pH control Z-DEVD-FMK? by forming a bicarbonate transport metabolon with the sodium bicarbonate transporter NBCe1 and anion ex changer 2.