Cutting Edge Molecular Therapy for Acute Myeloid Leukemia

Progress and challenges of multidrug resistance proteins in diseases

Chemotherapy remains the first choice for patients with advanced cancers when other treatments are ineffective. Multidrug resistance (MDR) is an unavoidable factor that negatively affects the effectiveness of cancer chemotherapy drugs. Researchers are trying to reduce MDR, improve the effectiveness of chemotherapeutic drugs, and alleviate patient suffering to positively contribute to disease treatment. MDR also occurs in inflammation and genetic disorders, which increases the difficulty of clinically beneficial treatments. The ATP-binding cassette (ABC) is an active transporter that plays an important role in the barrier and secretory functions of many normal cells. As the C subfamily in the ABC family, multidrug resistance proteins (MRPs/ABCCs) export a variety of antitumour drugs and are expressed in a variety of cancers. The present review summarises the role of MRPs in cancer and other diseases and recent research progress of MRP inhibitors to better examine the mechanism and function of MRPs, and establish a good relationship with clinical treatment.

The beginning of a new therapeutic era in acute myeloid leukemia

In the field of AML, the early 2000s were shaped by the advent of novel molecular biology technologies including high-throughput sequencing that improved prognostic classification, response evaluation through the quantification of minimal residual disease, and the launch of research on targeted therapies. Our knowledge of leukemogenesis, AML genetic diversity, gene-gene interactions, clonal evolution, and treatment response assessment has also greatly improved. New classifications based on chromosomal abnormalities and gene mutations are now integrated on a routine basis. These considerable efforts contributed to the discovery and development of promising drugs which specifically target gene mutations, apoptotic pathways and cell surface antigens as well as reformulate classical cytotoxic agents. In less than 2 years, nine novels drugs have been approved for the treatment of AML patients, and many others are being intensively investigated, in particular immune therapies. There are now numerous clinical research opportunities offered to clinicians, thanks to these new treatment options. We are only at the start of a new era which should see major disruptions in the way we understand, treat, and monitor patients with AML.

Histone methyltransferase EZH2 epigenetically affects CCNA1 expression in acute myeloid leukemia

Cyclin A1 (CCNA1) is an alternative A-type cyclin that is expressed in acute myeloid leukemia (AML). However, its functions in AML cell chemoresistance, an important cause for mortality, are incompletely understood. The purpose of this study was to expound the role and potential mechanism of CCNA1 in AML cell chemoresistance. Upregulation of CCNA1 promoted resistance of AML cells to PKC412, AC220, and AraC. Mechanistically, it was confirmed that CCNA1 transcription was negatively regulated by forkhead box A2 (FOXA2), and the downregulation of FOXA2 promoted chemoresistance in AML cells. Moreover, the promoter sequence of CCNA1 has a significant H3K27me3 modification. Enhancer of zeste homolog 2 (EZH2) enhanced H3K27me3 modification of CCNA1 promoter to inhibit CCNA1 expression, thus promoting sensitivity of AML cells to drugs. Taken together, these findings lead to deeper insights into the mechanism of AML cell chemo-sensitivity by inhibiting CCNA1 at the transcriptional level.

Targeting of Protein Kinase CK2 in Acute Myeloid Leukemia Cells Using the Clinical-Grade Synthetic-Peptide CIGB-300

Protein kinase CK2 has emerged as an attractive therapeutic target in acute myeloid leukemia (AML), an advent that becomes particularly relevant since the treatment of this hematological neoplasia remains challenging. Here we explored for the first time the effect of the clinical-grade peptide-based CK2 inhibitor CIGB-300 on AML cells proliferation and viability. CIGB-300 internalization and subcellular distribution were also studied, and the role of B23/nucleophosmin 1 (NPM1), a major target for the peptide in solid tumors, was addressed by knock-down in model cell lines. Finally, pull-down experiments and phosphoproteomic analysis were performed to study CIGB-interacting proteins and identify the array of CK2 substrates differentially modulated after treatment with the peptide. Importantly, CIGB-300 elicited a potent anti-proliferative and proapoptotic effect in AML cells, with more than 80% of peptide transduced cells within three minutes. Unlike solid tumor cells, NPM1 did not appear to be a major target for CIGB-300 in AML cells. However, in vivo pull-down experiments and phosphoproteomic analysis evidenced that CIGB-300 targeted the CK2α catalytic subunit, different ribosomal proteins, and inhibited the phosphorylation of a common CK2 substrates array among both AML backgrounds. Remarkably, our results not only provide cellular and molecular insights unveiling the complexity of the CIGB-300 anti-leukemic effect in AML cells but also reinforce the rationale behind the pharmacologic blockade of protein kinase CK2 for AML-targeted therapy.

Clinical Implications of Inflammation in Acute Myeloid Leukemia

Recent advances in the description of the tumor microenvironment of acute myeloid leukemia, including the comprehensive analysis of the leukemic stem cell niche and clonal evolution, indicate that inflammation may play a major role in many aspects of acute myeloid leukemia (AML) such as disease progression, chemoresistance, and myelosuppression. Studies on the mechanisms of resistance to chemotherapy or tyrosine kinase inhibitors along with high-throughput drug screening have underpinned the potential role of glucocorticoids in this disease classically described as steroid-resistant in contrast to acute lymphoblastic leukemia. Moreover, some mutated oncogenes such as RUNX1, NPM1, or SRSF2 transcriptionally modulate cell state in a manner that primes leukemic cells for glucocorticoid sensitivity. In clinical practice, inflammatory markers such as serum ferritin or IL-6 have a strong prognostic impact and may directly affect disease progression, whereas interesting preliminary data suggested that dexamethasone may improve the outcome for AML patients with a high white blood cell count, which paves the way to develop prospective clinical trials that evaluate the role of glucocorticoids in AML.