MCL1

Overview

MCL1 encodes Mcl-1 (myeloid cell leukemia 1), a member of the BCL-2 family of apoptosis regulators. It is best known as an anti-apoptotic protein that helps cells survive by restraining the intrinsic mitochondrial cell-death pathway. In cancer biology, MCL1 is frequently studied because many tumor cells rely on Mcl-1 to evade apoptosis, maintain survival under stress, and resist therapy. As a result, MCL1 has become an important target in drug discovery, especially in malignancies where resistance to other BCL-2 family inhibitors is a concern.

Biologically, Mcl-1 functions within a network that includes BCL-2, BCL-xL, and BH3-only proteins such as NOXA. Its expression is often tightly regulated and can change rapidly in response to signaling pathways that control transcription, translation, and protein stability. Because of this short-lived nature, Mcl-1 is a frequent point of convergence for therapies that suppress survival signaling, including CDK9/CDK12/13 inhibition, and for combination strategies involving venetoclax, BCL-XL inhibitors, PI3K pathway inhibition, or immunotherapy approaches such as CAR-T cells and NK cells.

Focus of Latest Publications

Recent publications have continued to position MCL1 as a central anti-apoptotic target in cancer and immune-cell biology. Several studies focused on the development of direct Mcl-1 inhibitors. One report described novel sophocarpine derivatives as potential dual Bcl-2 and Mcl-1 inhibitors for hepatocellular carcinoma, referencing the selective Mcl-1 inhibitor AZD5991 as a comparator in the broader therapeutic context. Another study reported a novel tetrahydro-β-carboline Mcl-1 inhibitor with antitumor activity and the ability to overcome cisplatin resistance, reinforcing the idea that Mcl-1 blockade may help address drug resistance rather than simply improve potency.

MCL1 was also examined as part of combination and pathway-based apoptosis strategies. In acute myeloid leukemia research, inhibition of BCL-2 and PI3K signaling enhanced the cytotoxicity of gemtuzumab ozogamicin, with cell-line-dependent changes in apoptotic regulators including MCL-1 and p53. In T-ALL, investigators evaluated sensitivity to venetoclax (BCL-2), A1331852 (BCL-XL), AZD5991 (MCL-1), and dual BCL-2/BCL-XL inhibition, including combinations with natural killer (NK) cells, highlighting MCL1 as one arm of a broader BH3-mimetic strategy.

A separate mechanistic study showed that inhibition of CDK9 or CDK12/13 rapidly downregulated the short-lived anti-apoptotic proteins Mcl1 and Bfl1/A1 in Jurkat leukemia cells and SUDHL1 lymphoma cells, while BCL-2 and BCL-xL were not affected. This supports a transcriptional dependency of MCL1 expression and explains why CDK-Targeted therapies such as atuveciclib, AZD4573, THZ531, and SR4835 are often discussed in relation to apoptosis induction. In another study, Aurora kinase A overexpression promoted T-lymphocyte apoptosis through the NOXA/MCL-1 pathway, linking MCL1 to immune-cell survival as well as cancer cell biology.

MCL1 also appeared in studies of tumour-immune crosstalk and the tumour microenvironment. Single-cell transcriptomic analysis of single-day nonactivated IL-18-armed CAR T cells showed upregulation of MCL1 alongside IL7R and KLF2, with suppression of inhibitory checkpoint genes such as PDCD1, TOX, and HAVCR2. This suggests that MCL1 may contribute to persistence or survival programs in engineered T cells. In another immunology-focused context, MCL1 was discussed in relation to T-lymphocytes, tumor infiltrating lymphocytes, and immune-based therapeutic strategies, including anti-CD28 stimulation and broader cancer immunotherapy settings.

Additional studies used computational and cell-based approaches to explore MCL1-associated anticancer activity. berberine chloride was reported to have favorable docking interactions with multiple cancer-related targets, including MCL1 complexes, in breast cancer models such as MDA-MB-231 and 4T1 cells. Nobiletin was shown to induce apoptosis in A549 cells by mimicking BH3-only proteins and downregulating anti-apoptotic proteins including BCL-2 and MCL-1. Across these studies, MCL1 consistently emerged as a survival factor whose inhibition or downregulation can sensitize cancer cells to apoptosis and improve responses to other therapies.