Reprogramming of erythrocyte lifespan by NFκB‐TNFα naphthoquinone antagonist β‐lapachone is regulated by calcium overload and CK1α

Abstract

The pathophysiology of chemotherapy-associated anemia, prevalent in at least 75% of patients, remains difficult to establish. Chemotherapy-related anemia is attributed in part to eryptosis, and it is therefore of considerable interest to interrogate the toxicity of investigative anticancer compounds to red blood cells (RBCs). Beta-lapachone (LAP), an anthraquinone extracted from the bark of Lapacho tree (Tabebuia avellanedae), is effective against a myriad of cancer cells. However, the toxicity of LAP to RBCs remains unexplored. Hemoglobin leakage as a surrogate for hemolysis was photometrically measured, while flow cytometry was employed to capture phosphatidylserine (PS) exposure with Annexin-V-FITC, calcium levels with Fluo4/AM, cell size by forward scatter (FSC), and oxidative stress by H2DCFDA. Our results show that LAP, at antitumor levels (10-30 µM), induces dose-dependent hemolysis secondary to calcium influx from the extracellular space. Moreover, LAP stimulates eryptosis, as evident from PS exposure, which is associated with reduced cell volume and intracellular calcium overload. Importantly, it is also revealed that the cytotoxicity of LAP is mediated through casein kinase 1α. Altogether, this report shows, for the first time, that LAP possesses both hemolytic and eryptotic potential against RBCs that necessitates careful application in chemotherapy. Practical applicationsLapacho is a widely consumed herbal tea with origins in the Tabebuia avellanedae tree endogenous to South America. LAP is one of the active ingredients in lapacho with promising antitumor potential. We show that LAP is cytotoxic to human RBCs by virtue of eryptosis and hemolysis, and we identify associated molecular mechanisms.Given that these two manifestations are known to contribute to chemotherapyinduced anemia, our study provides invaluable insights into the suitability of LAP in cancer management and sheds some light on possible strategies to limit its undesirable side effects.

Lauric Acid, a Dietary Saturated Medium-Chain Fatty Acid, Elicits Calcium-Dependent Eryptosis

“…Our results also seem to point to a potential role for CK1α in LA-induced RBC death ( Figure 8 C), which is in congruence with the established participation of the enzyme in the toxicity of a wide array of xenobiotics as we have previously reported [ 39 , 42 , 91 , 92 ]. To the best of our knowledge, this is the first report to identify CK1α as a molecular target for LA.…”

“…Total reactive oxygen species (ROS) were labeled with 5 μM of H 2 DCFDA as previously reported [ 42 ]. Control and experimental cells were washed in PBS, suspended in Ringer buffer with 1 mM of CaCl 2 and 5 μM of H 2 DCFDA for 30 min at 37 °C away from light.…”