DPP4 Inhibition, NPY_1-36, PYY_1-36, SDF-1α, and a Hypertensive Genetic Background Conspire to Augment Cell Proliferation and Collagen Production: Effects That Are Abolished by Low Concentrations of 2-Methoxyestradiol

Abstract

By reducing their metabolism, dipeptidyl peptidase 4 inhibition (DPP4I) enhances the effects of numerous peptides including neuropeptide Y 1-36 (NPY 1-36 ), peptide YY 1-36 (PYY 1-36 ), and SDF-1a. Studies show that separately NPY 1-36 , PYY 1-36 and SDF-1a stimulate proliferation of, and collagen production by, cardiac fibroblasts (CFs), preglomerular vascular smooth muscle cells (PGVSMCs), and glomerular mesangial cells (GMCs), particularly in cells isolated from genetically hypertensive rats. Whether certain combinations of these factors, in the absence or presence of DPP4I, are more profibrotic than others is unknown. Here we contrasted 24 different combinations of conditions (DPP4I, hypertensive genotype and physiologic levels [3 nM] of NPY 1-36 , PYY 1-36 , or SDF-1a) on proliferation of, and [ 3 H]-proline incorporation by, CFs, PGVSMCs, and GMCs. In all three cell types, the various treatment conditions differentially increased proliferation and [ 3 H]-proline incorporation, with a hypertensive genotype 1 DPP4I 1 NPY 1-36 1 SDF-1a being the most efficacious combination. Although the effects of this four-way combination were similar in male versus female CFs, physiologic (1 nM) concentrations of 2-methoxyestradiol (2ME; nonestrogenic metabolite of 17b-estradiol), abolished the effects of this combination in both male and female CFs. In conclusion, this study demonstrates that CFs, PGVSMCs, and GMCs are differentially activated by various combinations of NPY 1-36 , PYY 1-36 , SDF-1a, a hypertensive genetic background and DPP4I. We hypothesize that as these progrowth conditions accumulate, a tipping point would be reached that manifests in the long term as organ fibrosis and that 2ME would obviate any profibrotic effects of DPP4I, even under the most profibrotic conditions (i.e., hypertensive genotype with high NPY 1-36 1 SDF-1a levels and low 2ME levels). SIGNIFICANCE STATEMENTThis work elucidates combinations of factors that could contribute to long-term profibrotic effects of dipeptidyl peptidase 4 inhibitors and suggests a novel drug combination that could prevent any potential profibrotic effects of dipeptidyl peptidase 4 inhibitors while augmenting the protective effects of this class of antidiabetic agents.

Proline oxidase silencing inhibits p53-dependent apoptosis in MCF-7 breast cancer cells

“…In order to evaluate the role of proline in apoptosis or survival in MCF-7 iPOX and MCF-7 WT breast cancer cells, we designed several experimental conditions to increase intracellular proline level by inhibiting collagen biosynthesis (proline utilizing process). 2-Methoxyestradiol (2ME), was used as an inhibitor of collagen biosynthesis (Gelse et al 2008 ; Jackson et al 2020 ; Neamatallah et al 2019 ; Salama et al 2006 ). Both MCF-7 WT and MCF-7 iPOX cells were cultured in growth medium without glutamine.…”

“…Therefore, we used 2ME, as an inhibitor of collagen biosynthesis to increase intracellular proline level for studying the effect on POX-dependent apoptosis and autophagy (Zareba et al 2017 ). 2ME is a potent inhibitor of collagen biosynthesis (Gelse et al 2008 ; Jackson et al 2020 ; Neamatallah et al 2019 ; Salama et al 2006 ) supporting proline for POX-dependent functions (Zareba et al 2017 ). In fact, previously we found that in such conditions there was increase in the expression of autophagy markers, as Atg7 and Beclin-1 (Zareba et al 2017 ).…”

“…It has been found that proline availability for POX-dependent functions is regulated by collagen biosynthesis, the main proline utilizing process (Zareba et al 2017 ). Experimentally, 2-methoxyestradiol (2ME) was found as a potent inhibitor of collagen biosynthesis (Gelse et al 2008 ; Jackson et al 2020 ; Neamatallah et al 2019 ; Salama et al 2006 ) supporting proline for POX-dependent functions. However, the mechanism for interplay between POX and proline in regulation of apoptosis/autophagy is not well understood.…”