Modified natriuretic peptides and their potential roles in cancer treatment

Figures

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  Fig. 1. Schematic structures of the NPs. Amino acid sequences of αANP, BNP, CNP, DNP, UNP and ventricular natriuretic peptides (VNP) with biological activity in vertebrates, the amino acid in urodilatin are identical to the four C-terminal a.a. of kaliuretic peptide and identical (Yellow mark). ANP, BNP, CNP, DNP and UNP have been identified in mammals, while VNP has been identified in tetrapods and teleostean fish.

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  Fig. 2. Human ANP(A), BNP(B), CNP(C), and DNP(D)gene structure, biosynthetic pathway, source and primary function. (A) ANP is originally synthesized as a 151-amino acid precursor, which is further synthesized as a 126-amino acid pro ANP (γ-ANP) in the atrial myocytes of the heart, along with a 25-amino acid signal peptide. After removal of signal peptide by signal peptidase in the endoplasmic reticulum, pro ANP is store in atrial cardiomyocyte granules. In the heart, then pro ANP is proteolyzed into an active αANP (28-amino acid) and an inactive NT-proANP by the convertase Corin. The NT-proANP contains other three natriuretic peptides, the long-acting natriuretic peptide (LANP), the vessel dilator (VSDL), and the kaliuretic peptide (KP); In the kidney, the ANP prohormone is cleaved between amino acid (a.a.) 94 and 95; (B) Ventricular myocytes produce a precursor of 134 amino acid (pre-pro BNP), which is further cleaved to obtain a signal peptide and pro-BNP (108-amino acid). During the secretion process, pro-BNP is cleaved by enzyme Furin into a biologically active BNP (32-amino acid), and another fragment of biologically inactive NT-proBNP (76-amino acid) which comprises an N-terminal…

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  Fig. 3. Natriuretic peptides and their receptor binding and themolecular signaling pathways. When the receptor binds to the ligand, it triggers the production of catalytic guanylate cyclase (cGMP), increases the level of cGMP in the cell, activates downstream signaling pathways, and causes physiological effects. (A) ANP and BNP have high specificity and affinity for binding to NPR-A (Binding association with NPR-A: ANP > BNP > CNP > DNP; (B) CNP without C-terminal has high activity for binding to NPR-B(Binding relationship with NPR-B: CNP > ANP > BNP > DNP); (C) ANP/BNP/CNP/DNP all play their biological roles by mediating the intracellular cGMP level; (D) NPR-C is a scavenging receptor that can scavenge NPs and reduce their concentration, which is comparable to the affinity of the three NPs. (Binding relationship with NPR-C: ANP ≥ CNP ≥ BNP ≥ DNP).

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  Fig. 4. Preparation of ANP by expressing multiple copies of genes in tandem. Three ANP genes were connected in tandem, and the fusion protein His6-K-ANP-K-ANP-K-ANP (His6-ANP3) was recombinantly expressed in E. coli The linker (lysine) was inserted between ANP and the fusion tag and ANP.(Lys: lysine).

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  Fig. 5. The fusion of BNP and human serum albumin reduces proteolysis through three clearance pathways. ① The Large steric hindrance of BNP, so the elimination half-life of AlbuBNP in mice is 19 h, which is a dramatic increase from 3 min for BNP; ②Mediated with NPR-C receptor; ③Glomerular filtration BNP.

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  Fig. 6. CNP and sildenafil synergistically inhibit the growth of RD-GC-B xenograft tumors. Sildenafil as a selective PDE5 inhibitor, is added to inhibit its degradation in vitro. The combination of CNP and sildenafil can inhibit theinhibit the Raf/MEK/ERK pathway and exert an anti-proliferative effect on RMS cells.