Skin lesions in chronic myeloid leukemia patients during dasatinib treatment

Cellular damage photosensitized by dasatinib, radical-mediated mechanisms and photoprotection in reconstructed epidermis

Dasatinib (DAS) is an anticancer drug employed in the treatment of certain hematological malignancies. Although DAS has been mainly developed for oral administration, it has recently garnered attention for its possible topical application. The use of topical drugs can cause photosensitivity, which is not listed as an adverse reaction for DAS. Since DAS absorbs UVA, it could potentially induce photosensitivity reactions and lead to oxidative damage to cellular targets. This study aims to investigate whether DAS exhibits phototoxic reactions on primary cellular targets in both solution and artificial skin, mimicking topical drug administration. It also examines the potential generation of highly reactive intermediates like organic radicals and ROS, which could trigger photosensitivity reactions. Upon DAS irradiation in the UVA region, the first transient species detected was the diradicaloid triplet excited state (3DAS∗) with an absorption maximum of around 490 nm, which was quenched by oxygen to produce singlet oxygen. Quenching experiments with linoleic acid and 3-methylindole indicated that radical-mediated (Type I) photosensitized damage to lipids and proteins is possible. However, the lack of triplet quenching with guanosine suggests that the Type II mechanism also plays a role in the photooxidation of biomolecules. Accordingly, the neutral red uptake phototoxicity test (photoirritation factor of 5) and the comet assay, revealed that this drug is photo(geno)toxic to cells. Moreover, investigations on lipid photoperoxidation, and protein and DNA photooxidation strongly support that different cellular compartments are potential targets for DAS-induced phototoxicity. Regarding its potential application in topical dermatological formulations, an O/W emulsion of DAS was prepared and tested in reconstructed human epidermis, and a significant phototoxicity was also demonstrated. Fortunately, this undesired side effect disappeared upon formulation of DAS along with a sunscreen. Thus, for topical treatments, the photosensitivity reactions induced by DAS can be prevented by using formulations including appropriate UVA filters.

Combined dasatinib and quercetin treatment contributes to skin rejuvenation through selective elimination of senescent cells in vitro and in vivo

The skin's protective functions are compromised over time by both endogenous and exogenous aging. Senescence is well-documented in skin phenotypes, such as wrinkling and sagging, a consequence of the senescence-associated secretory phenotype (SASP) that involves the accumulation of senescent fibroblasts, chronic inflammation, and collagen remodeling. Although therapeutic approaches for eliminating senescent cells from the skin are available, their efficacy remains unclear. Accordingly, we aimed to examine the effects of dasatinib in combination with quercetin (D + Q) on senescent human skin fibroblasts and aging human skin. Senescence was induced in human dermal fibroblasts (HDFs) using approaches such as long-term passaging, ionizing radiation, and doxorubicin treatment. The generated senescent cells were treated with D + Q or vehicle. Additionally, a mouse-human chimera model was generated by subcutaneously transplanting whole-skin grafts of aged individuals onto nude mice. Mouse models were administered D + Q or vehicle by oral gavage for 30 days. Subsequently, skin samples were harvested and stained for senescence-associated beta-galactosidase. Senescence-associated markers were assessed by western blotting, reverse transcription-quantitative PCR and histological analyses. Herein, D + Q selectively eliminated senescent HDFs in all cellular models of induced senescence. Additionally, D + Q-treated aged human skin grafts exhibited increased collagen density and suppression of the SASP compared with control grafts. No adverse events were observed during the study period. Collectively, D + Q could ameliorate skin aging through selective elimination of senescent dermal fibroblasts and suppression of the SASP. Our findings suggest that D + Q could be developed as an effective therapeutic approach for combating skin aging.

Leukemia Cutis-The Current View on Pathogenesis, Diagnosis, and Treatment

Leukemia cutis (LC) is defined as the leukemic infiltration of the epidermis, the dermis, and the subcutaneous tissue. Leukemia cutis may follow or occur simultaneously with the diagnosis of systemic leukemia. However, cutaneous lesions are occasionally diagnosed as the primary manifestation of leukemia. Leukemic skin infiltrations demonstrate considerable variation regarding a number of changes, distribution, and morphology. The highest incidence of LC is observed in chronic lymphocytic leukemia, monocytic and myelomonocytic acute myeloid leukemia, and T-cell lineage leukemia. Although the pathogenic mechanism of the invasion of leukemic cells into the skin is not well understood, chemokine receptors and adhesion molecules as well as the genetic characteristics of leukemia are thought to play a role. Leukemic skin lesions may be localized or disseminated and may occur alone or in combination on any site of the skin, most frequently in the trunk and extremities. The most common clinical presentations of leukemia cutis are papules, nodules, macules, plaques, and ulcers. In most patients, the complete or partial resolution of cutaneous infiltrations occurs simultaneously with hematologic remission. However, in patients with resistant disease or recurrent skin infiltration, local radiotherapy can be used. This review presents recent data on the pathogenesis, diagnosis, and treatment of leukemic skin involvement in different types of leukemia.

Dasatinib causes keratinocyte apoptosis via inhibiting high mobility group Box 1-mediated mitophagy

Dasatinib, a second-generation BCR-ABL inhibitor, is currently used as first-line treatment for patients with chronic myeloid leukemia. However, dasatinib treatment increases the risk of severe cutaneous toxicity, which limits its long-term safe use in clinic. The underlying mechanism for dasatinib-induced cutaneous toxicity has not been clarified. In this study, we tested the toxicity of dasatinib on human immortal keratinocyte line (HaCaT) and normal human epidermal keratinocytes (NHEK). We found that dasatinib directly caused cytotoxicity on keratinocytes, which could be the explanation of the clinical characteristic of pathology. Mechanistically, dasatinib impaired mitophagy by downregulating HMGB1 protein level in keratinocytes, which led to the accumulation of dysfunctional mitochondria. Mitochondria-derived ROS caused DNA damage and cell apoptosis. More importantly, we confirmed that overexpression of HMGB1 could reverse dasatinib-induced keratinocyte apoptosis, and preliminarily explored the intervention effect of saikosaponin A, which could increase HMGB1 expression, on cutaneous toxicity caused by dasatinib. Collectively, our study revealed that dasatinib induced keratinocyte apoptosis via inhibiting HMGB1-mediated mitophagy and saikosaponin A could be a viable strategy for prevention of dasatinib-induced cutaneous toxicity.

Ferrochelatase: Mapping the Intersection of Iron and Porphyrin Metabolism in the Mitochondria

Porphyrin and iron are ubiquitous and essential for sustaining life in virtually all living organisms. Unlike iron, which exists in many forms, porphyrin macrocycles are mostly functional as metal complexes. The iron-containing porphyrin, heme, serves as a prosthetic group in a wide array of metabolic pathways; including respiratory cytochromes, hemoglobin, cytochrome P450s, catalases, and other hemoproteins. Despite playing crucial roles in many biological processes, heme, iron, and porphyrin intermediates are potentially cytotoxic. Thus, the intersection of porphyrin and iron metabolism at heme synthesis, and intracellular trafficking of heme and its porphyrin precursors are tightly regulated processes. In this review, we discuss recent advances in understanding the physiological dynamics of eukaryotic ferrochelatase, a mitochondrially localized metalloenzyme. Ferrochelatase catalyzes the terminal step of heme biosynthesis, the insertion of ferrous iron into protoporphyrin IX to produce heme. In most eukaryotes, except plants, ferrochelatase is localized to the mitochondrial matrix, where substrates are delivered and heme is synthesized for trafficking to multiple cellular locales. Herein, we delve into the structural and functional features of ferrochelatase, as well as its metabolic regulation in the mitochondria. We discuss the regulation of ferrochelatase via post-translational modifications, transportation of substrates and product across the mitochondrial membrane, protein-protein interactions, inhibition by small-molecule inhibitors, and ferrochelatase in protozoal parasites. Overall, this review presents insight on mitochondrial heme homeostasis from the perspective of ferrochelatase.

Chronic myeloid leukemia-leukemia cutis mimicking a neutrophilic panniculitis-like leukemia cutis: Report of a rare case

While drug-induced panniculitis is not uncommon in chronic myeloid leukemia (CML) patients on tyrosine kinase inhibitor therapy, it is rare for CML to initially present as a leukemic panniculitis. We present the case of a 45-year-old male with no relevant prior medical history presenting with 6 months of migratory nodules, 2 months of drenching night sweats, and a 20 pound weight loss. Physical examination showed firm subcutaneous nodules with overlying ecchymoses present on the right lateral thigh and left lower back. Biopsy of a nodule from the right thigh showed a subcutaneous lobular panniculitis involved by a dense infiltrate of neutrophils and granulocyte precursors. Fluorescent in-situ hybridization (FISH) was positive for t(9;22)(q34;q11.2)BCR-ABL1 fusion. A concurrent hemogram revealed a white blood cell count elevation of 600,000 K/μL. Bone marrow biopsy examination showed marked myeloid expansion with an increase in granulocyte precursors and Philadelphia chromosome positivity by FISH, consistent with bone marrow involvement by CML. Herein, we describe this unusual and rare case of CML initially presenting as a neutrophilic panniculitis-like leukemia cutis. Arriving at this challenging diagnosis may be easily missed without clinical and laboratory correlation, which would certainly lead to the patient's not receiving life-saving treatment.

Targeting kinases with thymoquinone: a molecular approach to cancer therapeutics

Kinases are enzymes that are important for cellular functions, but their overexpression has strong connections with carcinogenesis, rendering them important targets for anticancer drugs. Thymoquinone (TQ) is a natural compound with proven anticancer activities, at least in preclinical studies. TQ can target several kinases, including phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinase (MAPK), Janus kinase/signal transducers and activators of transcription (JAK/STAT), polo-like kinase 1 (PLK1), and tyrosine kinase in different cancer cells and animal models. Inhibiting the activity of kinases or suppressing their expression might be among the mechanisms of TQ anticancer activity. In this review, we discuss the role of TQ in kinase regulation in different cancer models.