Tumor cell-surface rhamnose-binding protein (RBP)

The tumor cell-surface rhamnose-binding protein (RBP), also known as the rhamnose-recognizing receptor, is a 67 kDa endogenous lectin that is highly expressed on the surface of various malignant cells but is largely absent from normal, non-cancerous tissues. It serves as a specific receptor for rhamnose-containing molecules, such as solasodine rhamnosyl glycosides (SRGs), which include the glycoalkaloids solamargine and solasonine. Upon binding to the RBP, these compounds are internalized through receptor-mediated endocytosis and subsequently trigger apoptosis by activating caspases and disrupting mitochondrial membranes. This receptor-mediated mechanism provides a high degree of selectivity, allowing for the targeted destruction of cancer cells while sparing healthy tissue. The RBP has been the primary target for the development of topical treatments like Curaderm for non-melanoma skin cancers and has been investigated in clinical trials for systemic cancer therapy using candidates like Coramsine.

Other names

Rhamnose-recognizing receptorEndogenous endocytic lectinEELBEC receptorMutant lectin carbohydrate-binding proteinRhamnose-binding lectin receptor

Binding of rhamnose-containing ligands (such as solasodine rhamnosyl glycosides) to the RBP receptor triggers receptor-mediated endocytosis. Following internalization, the ligands are transported to lysosomes and mitochondria, where they induce apoptosis through the activation of caspases and the upregulation of death receptors (e.g., TNFR1, Fas).