Cisplatin based therapy: the role of the mitogen activated protein kinase signaling pathway

Cisplatin is a widely used chemotherapeutic agent for treatment of various cancers. However, treatment with cisplatin is associated with drug resistance and several adverse side effects such as nephrotoxicity, reduced immunity towards infections and hearing loss. A Combination of cisplatin with other drugs is an approach to overcome drug resistance and reduce toxicity. The combination therapy also results in increased sensitivity of cisplatin towards cancer cells. The mitogen activated protein kinase (MAPK) pathway in the cell, consisting of extracellular signal regulated kinase, c-Jun N-terminal kinase, p38 kinases, and downstream mediator p90 ribosomal s6 kinase (RSK); is responsible for the regulation of various cellular events including cell survival, cell proliferation, cell cycle progression, cell migration and protein translation. This review article demonstrates the role of MAPK pathway in cisplatin based therapy, illustrates different combination therapy involving cisplatin and also shows the importance of targeting MAPK family, particularly RSK, to achieve increased anticancer effect and overcome drug resistance when combined with cisplatin.Other Information Published in: Journal of Translational Medicine License: http://creativecommons.org/licenses/by/4.0/See article on publisher's website: http://dx.doi.org/10.1186/s12967-018-1471-1</p

Downregulating OPN reduces NHE1-induced cardiomyocyte-hypertrophy and NHE1 activity.

<p>Cardiomyocytes plated on coverslips were incubated with BCECF-AM and induced with an acid load using 50 mM NH₄Cl. The rate of recovery following the acid induction was measured and used as an indicator of NHE1 activity. Upper panel, representative traces of NHE1 activity assay in H9c2 cardiomyocytes infected with GFP (control) or NHE1 in the presence and absence of siRNA OPN for 24 hours; lower panel, quantification of NHE1 activity (10–14 coverslips, from 3–4 experiments). Results are expressed as % of control (GFP) ± %SEM. <i>*p <</i> 0.05 vs. control, # vs. NHE1.</p

OPN siRNA regresses expression of the GATA-4 hypertrophic transcription factor.

<p>Upper panel, representative western blot of relative amounts of phosphorylated and total GATA4 expression in H9c2 cardiomyocytes infected with GFP (control) or active NHE1 in the presence and absence of siRNA OPN. Lower panel: quantification of experiments measuring the ratio of phosphorylated to total GATA4 protein. Results are expressed as % of control (GFP) ± %SEM (n = 4–7; representative of 3–5 experiments). <i>*p <</i> 0.05 vs. control, # vs. NHE1.</p

OPN contributes to NHE1-induced cardiomyocyte-hypertrophy.

<p>A: upper panel, representative fluorescence microscopy images of NRVMs infected with GFP (control) or active NHE1 adenovirus 24 hours post infection; lower panel, cell surface area of at least 50–70 infected NRVMs from 4–6 individual dishes were measured to represent 3–4 experiments, results expressed as % of control (GFP) ± %SEM. B: Upper panel, representative fluorescence microscopy images of H9c2 cardiomyocytes infected with adenoviruses containing GFP (control) or active NHE1 in the presence and absence of siRNA OPN for 24 hours; lower panel, cell surface area of at least 50–70 H9c2 cardiomyocytes from 4–6 individual dishes were measured to represent 3–4 experiments. C: Protein content of H9c2 cardiomyocytes expressed as μg/10 x 10⁶ cell. D: Quantification of ANP mRNA expression in H9c2 cardiomyocytes normalized to β-actin (n = 6–7; representative of 4 experiments). Results are expressed as % of control (GFP) ± %SEM. *<i>p <</i> 0.05 vs. control, <i>#</i> vs. NHE1.</p

Upregulation of NHE1 in cardiomyocytes enhances OPN expression.

<p>A: Upper panel, representative western blot of OPN protein expression in cell lysates of NRVMs infected with GFP (control) or active NHE1 adenovirus for 24 hours. Immunoblotting was against OPN (doublet at 66 kDa) and GAPDH (38 kDa). Lower level, quantification of relative levels of <i>total</i> OPN protein expression (n = 4; representative of 2–3 preparations). B: Upper panel, representative DNA gel of OPN mRNA expression in H9c2 cardiomyocytes infected with GFP (control) or active NHE1 adenovirus for 24 hours using an MOI of 20 and 30, respectively. cDNA amplification was against OPN (206 bp) and β-actin (174 bp). Lower level, quantification of OPN mRNA expression in H9c2 cardiomyocytes normalized to β-actin (n = 6–7; representative of 4 experiments). Results expressed as % of control (GFP) ± %SEM. <i>*p < 0</i>.<i>05</i> vs. control. C: Upper panel, representative western blot of OPN protein expression of H9c2 cardiomyocytes infected with NHE1 adenovirus (30 MOI) in the presence and absence of 100nM siRNA OPN for 24 hours. Immunoblotting was against OPN (doublet at 66 kDa) and α-tubulin (50 kDa); lower panel, quantification of relative levels of OPN protein expression (n = 6–9; representative of 2–3 experiments). Results are expressed as % of NHE1 ± %SEM. <i>*p < 0</i>.<i>05</i> vs. NHE1 + siRNA.</p

Empagliflozin inhibits angiotensin II-induced hypertrophy in H9c2 cardiomyoblasts through inhibition of NHE1 expression

Diabetes mellitus (DM)-induced cardiac morbidities have been the leading cause of death among diabetic patients. Recently, sodium-glucose cotransporter-2 (SGLT-2) inhibitors including empagliflozin (EMPA), which have been approved for the treatment of DM, have gained attention for their cardioprotective effect. The mechanism by which SGLT-2 inhibitors exert their cardioprotective effect remains unclear. Recent studies have suggested that EMPA exerts its cardioprotective effect by inhibiting the Na+/H+ exchanger (NHE), a group of membrane proteins that regulate intracellular pH and cell volume. Increased activity and expression of NHE isoform 1 (NHE1), the predominant isoform expressed in the heart, leads to cardiac hypertrophy. p90 ribosomal s6 kinase (p90 RSK) has been demonstrated to stimulate NHE1 activity. In our study, H9c2 cardiomyoblasts were treated with angiotensin II (ANG) to activate NHE1 and generate a hypertrophic model. We aimed to understand whether EMPA reverses the ANG-induced hypertrophic response and to elucidate the molecular pathway contributing to the cardioprotective effect of EMPA. Our study demonstrated that ANG-induced hypertrophy of H9c2 cardiomyoblasts is accompanied with increased SGLT-1 and NHE1 protein expression, an effect which is prevented in the presence of EMPA. EMPA reduces ANG-induced hypertrophy through the inhibition of SGLT-1 and NHE1 expression.Other Information Published in: Molecular and Cellular Biochemistry License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s11010-022-04411-6</p