Acetylcholinesterase blockade does not account for the adverse cardiovascular effects of the antitumor drug irinotecan: a preclinical study

Irinotecan‐induced severe hypotension in a patient with lung cancer

Most hypotension during chemotherapy is caused by an allergic mechanism. Conversely, non‐allergic hypotension due to chemotherapy is rare. In this case report, we present a patient who suffered severe hypotension followed by the administration of irinotecan‐based chemotherapy and some supportive care such as steroids for preventing emesis. A 71‐year‐old man with hypertension was diagnosed with stage IV small cell lung cancer (sT1cN3M0). Severe hypotension occurred in the patient after every administration of chemotherapy. Finally, he was able to receive all four courses of chemotherapy as planned along with the medical staff’s support care. This case provides that a regimen that contained irinotecan and steroid could cause hypotension and the mechanism is partially explained by inhibiting choline esterase and adrenal insufficiency. We should be careful about non‐allergic hypotension when we administer irinotecan‐based chemotherapy.

AKR1C3 and Its Transcription Factor HOXB4 Are Promising Diagnostic Biomarkers for Acute Myocardial Infarction

Background: A recent study disclosed that ferroptosis was an important myocyte death style in myocardial infarction (MI). However, the diagnostic value of ferroptosis regulators and correlated underlying mechanisms in acute myocardial infarction (AMI) remain unknown.

Methods: Bioinformatical analyses were conducted to identify the candidate biomarkers for AMI, and the collected local samples were used to validate the findings via real-time quantitative PCR. Bioinformatical analysis and luciferase reporter assay were implemented to identify the transcriptional factor. Transient transfection and ferroptosis characteristic measurement, including glutathione peroxidase 4, malondialdehyde, iron, and glutathione, was performed to verify the ability of the candidate gene to regulate the ferroptosis of cardiomyocytes. A meta-analysis was conducted in multiple independent cohorts to clarify the diagnostic value.

Results: A total of 121 ferroptosis regulators were extracted from previous studies, and aldo-keto reductase family 1 member C3 (AKR1C3) was significantly downregulated in the peripheral blood samples of AMI cases from the analysis of GSE48060 and GSE97320. HOXB4 served as a transcriptional activator for AKR1C3 and could suppress the ferroptosis of the H9C2 cells treated with erastin. Besides this, peripheral blood samples from 16 AMI patients and 16 patients without coronary atherosclerotic disease were collected, where AKR1C3 and HOXB4 both showed a high diagnostic ability. Furthermore, a nomogram including HOXB4 and AKR1C3 was established and successfully validated in six independent datasets. A clinical correlation analysis displayed that AKR1C3 and HOXB4 were correlated with smoking, CK, CK-MB, and N-terminal-pro-B-type natriuretic peptide.

Conclusion: Taken together, this study demonstrates that AKR1C3 and HOXB4 are promising diagnostic biomarkers, providing novel insights into the ferroptosis mechanisms of AMI.

Perspectives on biologically active camptothecin derivatives

Camptothecins (CPTs) are cytotoxic natural alkaloids that specifically target DNA topoisomerase I. Research on CPTs has undergone a significant evolution from the initial discovery of CPT in the late 1960s through the study of synthetic small-molecule derivatives to investigation of macromolecular constructs and formulations. Over the past years, intensive medicinal chemistry efforts have generated numerous CPT derivatives. Three derivatives, topotecan, irinotecan, and belotecan, are currently prescribed as anticancer drugs, and several related compounds are now in clinical trials. Interest in other biological effects, besides anticancer activity, of CPTs is also growing exponentially, as indicated by the large number of publications on the subject during the last decades. Therefore, the main focus of the present review is to provide an ample but condensed overview on various biological activities of CPT derivatives, in addition to continued up-to-date coverage of anticancer effects.

Compartmentalized accumulation of cAMP near complexes of multidrug resistance protein 4 (MRP4) and cystic fibrosis transmembrane conductance regulator (CFTR) contributes to drug-induced diarrhea

Diarrhea is one of the most common adverse side effects observed in ∼7% of individuals consuming Food and Drug Administration (FDA)-approved drugs. The mechanism of how these drugs alter fluid secretion in the gut and induce diarrhea is not clearly understood. Several drugs are either substrates or inhibitors of multidrug resistance protein 4 (MRP4), such as the anti-colon cancer drug irinotecan and an anti-retroviral used to treat HIV infection, 3'-azido-3'-deoxythymidine (AZT). These drugs activate cystic fibrosis transmembrane conductance regulator (CFTR)-mediated fluid secretion by inhibiting MRP4-mediated cAMP efflux. Binding of drugs to MRP4 augments the formation of MRP4-CFTR-containing macromolecular complexes that is mediated via scaffolding protein PDZK1. Importantly, HIV patients on AZT treatment demonstrate augmented MRP4-CFTR complex formation in the colon, which defines a novel paradigm of drug-induced diarrhea.

High-density real-time PCR-based in vivo toxicogenomic screen to predict organ-specific toxicity

Toxicogenomics, based on the temporal effects of drugs on gene expression, is able to predict toxic effects earlier than traditional technologies by analyzing changes in genomic biomarkers that could precede subsequent protein translation and initiation of histological organ damage. In the present study our objective was to extend in vivo toxicogenomic screening from analyzing one or a few tissues to multiple organs, including heart, kidney, brain, liver and spleen. Nanocapillary quantitative real-time PCR (QRT-PCR) was used in the study, due to its higher throughput, sensitivity and reproducibility, and larger dynamic range compared to DNA microarray technologies. Based on previous data, 56 gene markers were selected coding for proteins with different functions, such as proteins for acute phase response, inflammation, oxidative stress, metabolic processes, heat-shock response, cell cycle/apoptosis regulation and enzymes which are involved in detoxification. Some of the marker genes are specific to certain organs, and some of them are general indicators of toxicity in multiple organs. Utility of the nanocapillary QRT-PCR platform was demonstrated by screening different references, as well as discovery of drug-like compounds for their gene expression profiles in different organs of treated mice in an acute experiment. For each compound, 896 QRT-PCR were done: four organs were used from each of the treated four animals to monitor the relative expression of 56 genes. Based on expression data of the discovery gene set of toxicology biomarkers the cardio- and nephrotoxicity of doxorubicin and sulfasalazin, the hepato- and nephrotoxicity of rotenone, dihydrocoumarin and aniline, and the liver toxicity of 2,4-diaminotoluene could be confirmed. The acute heart and kidney toxicity of the active metabolite SN-38 from its less toxic prodrug, irinotecan could be differentiated, and two novel gene markers for hormone replacement therapy were identified, namely fabp4 and pparg, which were down-regulated by estradiol treatment.

Topoisomerase I interactive agents

Increased insight into the mechanism of interaction of topoisomerase I interactive agents will maximize the therapeutic index and enhance the development of additional agents. Preclinical studies designed to elucidate mechanisms by which the topoisomerase I interactive agents induce cell death will be essential. The role of ABC transporters in resistance to topoisomerase I interactive agents has been recently appreciated and future studies should be directed at circumventing this resistance. The results of preclinical studies must be translated into the design of clinical trials so that these agents can be used rationally. In this regard results of preclinical studies have clearly pointed to the enhanced antitumor activity from protracted dosing of topoisomerase I interactive agents and results of clinical trials are now supporting these preclinical findings. Finally, investigators are trying to understand better the mechanism(s) of the dose-limiting toxicities observed with the currently available topoisomerase I interactive agents in an effort to enable the optimal dosing of these agents. Even though the first priority must be to determine the therapeutic potential of the currently available agents, it is reassuring to know that other topoisomerase I interactive agents are currently under development.