Synthetic tambjamine analogues induce mitochondrial swelling and lysosomal dysfunction leading to autophagy blockade and necrotic cell death in lung cancer

Abstract

Current pharmacological treatments for lung cancer show very poor clinical outcomes, therefore, the development of novel anticancer agents with different mechanisms of action is urgently needed. Cancer cells have a reversed pH gradient compared to normal cells, which favors cancer progression by promoting proliferation, metabolic adaptation and evasion of apoptosis. In this regard, the use of ionophores to modulate intracellular pH appears as a promising new therapeutic strategy. Indeed, there is a growing body of evidence supporting ionophores as a novel antitumor drugs. Despite this, little is known about the implications of pH deregulation and homeostasis imbalance triggered by ionophores at the cellular level. In this work, we deeply analyze for the first time the anticancer effects of tambjamine analogues, a group of highly effective anion selective ionophores, at the cellular and molecular level. First, their effects on cell viability were determined in several lung cancer cell lines and patient-derived cancer stem cells, demonstrating their potent cytotoxic effects. Then, we have characterized the induced lysosomal deacidification, as well as, the massive cytoplasmic vacuolization observed after treatment with these compounds, which is consistent with mitochondrial swelling. Finally, the activation of several proteins involved in stress response, autophagy and apoptosis was also detected, although necrosis was the main mechanism of cell death induced.Altogether, these evidences suggest that tambjamine analogues provoke an imbalance in cellular ion homeostasis that triggers mitochondrial dysfunction and lysosomal deacidification leading to a potent cytotoxic effect through necrosis in lung cancer cell lines and cancer stem cells.

Anion transport and supramolecular medicinal chemistry

“…21 Following the study of the cytotoxicity of these compounds, a detailed study of the anti-cancer effect of tambjamine analogues 134 and 135 was carried out in several lung cancer cell lines by Pérez-Tomás and co-workers. 41 Treatment of A549 cells with these derivatives led to cytoplasmic vacuolization as a result of loss of mitochondrial potential and mitochondrial swelling. This could also trigger mitophagy (mitochondrial autophagy).…”

Indole-based perenosins as highly potent HCl transporters and potential anti-cancer agents

“…To investigate this further, Annexin-V was used as a marker with flow cytometry analysis to evaluate apoptosis in MDA-MB-231 cells after treatments with 2 (best transporter) and 6 (most potent) at their respective IC 50 values. It is known that synthetic transporters can disrupt ion homeostasis in cells and induce cell death via an apoptotic pathway 3 , 22 , 32 , 63 , 64 .…”

“…The disruption of autophagy by small molecule anion transporters results in the suppression of cell proliferation which is more pronounced in tumour cells 28 . A second family of recognised H + /Cl − cotransporters, the tambjamines 29 – 31 , have also been shown to induce lysosomal dysfunction 29 and autophagy blockage 32 as well as cancer cell death 3 .

Figure 1 Schematic of prodigiosin (left) and perenosin (right) showing the chemical structures of these H + /Cl − cotransporters as free receptors and their respective HCl complexes.

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Inhibition of Human Enhancer of Zeste Homolog 2 with Tambjamine Analogs

“…We have synthesized and studied synthetic analogs of these natural products, which proved to possess potent anticancer activity in vitro, including activity against cancer stem cells 12 . We are also studying in depth the molecular mechanisms responsible for this activity 13 . A series of these derivatives were submitted to the Target Drug Discovery Program, within the Open innovation drug discovery panel, operated by Lilly a .…”

“…Yield: 59%. 1 H NMR (300 MHz, CDCl 3 ) δ =13.56 (s, 1H),11.48 (d, J = 12.8 Hz, 1H), 10.19 (s, 1H), 5H), (m, 3H), 6.97 (t, J = 7.5 Hz, 1H), 6.92 (s, 1H), 6.03 (s, 1H), 3.75 (s, 3H, OCH 3 ), 1.29 (s, 9H…”