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Background/aim: Chronic lymphocytic leukemia is a slowly-progressing disease in which symptoms often do not manifest until years after disease onset. In advanced stages, infection and bleeding are common. Past studies have shown that the interaction between CDK4/6 inhibitors and chemotherapy drugs can enhance the anti-tumor efficacy of drugs and limit toxicity. Therefore, in this study, the treatment effects of combining the CDK4/6 inhibitor LEE011 with chemotherapy drugs bendamustine or hydroxyurea were investigated in vitro., Materials and Methods: The mouse lymphocytic leukemia cell line L1210 was treated with LEE011 combined with hydroxyurea or bendamustine. Western blot and flow cytometry were performed to elucidate the mechanisms behind tumor suppression., Results: LEE011 combined with hydroxyurea or bendamustine significantly inhibited proliferation of L1210 cell lines in a concentration- and time-dependent manner as well as increased the arrest of cells in G 1 and S phases. The combination of LEE011 with hydroxyurea also reduced the phosphorylation of Rb while increased the expression of total Rb protein. Furthermore, reduced expression of GPX4, which is a key protein in ferroptosis, indicates that the tumor suppression effects of this drug combination could involve ferroptosis., Conclusion: CDK4/6 inhibitor LEE011 treatment alone may not be a suitable treatment option for lymphocytic leukemia; however, our findings in vitro support the combination of LEE011 with chemotherapy drugs to enhance anti-tumor activity in lymphocytic leukemia., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Dumessa Edessa,1 Mekonnen Sisay2 1Department of Pharmacy Practice, 2Department of Pharmacology and Toxicology, School of Pharmacy, College of Health and Medical Sciences, Haramaya University, Oromia, Ethiopia Abstract: In normal cell cycle progression, transition of G0/G1 phase to synthesis (S) phase for breast and other cells is regulated by association of cyclin D and cyclin-dependent kinases 4 and 6 (CDK4/6) that leads to phosphorylation of retinoblastoma (Rb) protein. Imbalance of this cyclin D-CDK4/6-inhibitors of CDK4/6-Rb phosphorylation pathway is associated with tumorigenesis of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) breast cancers. Despite effective first-line endocrine therapy, HR+/HER2− metastatic breast cancers remain still incurable. Currently, advances in understanding of cell cycle checkpoints are evolving as promising strategy to target in treatment of various types of cancers including breast cancer. Therapies that target this cell cycle machinery in HR+/HER2− breast cancers are getting approval by the US Food and Drug administration (FDA) including ribociclib (LEE011). Ribociclib got the first FDA approval in March 13, 2017, as an initial therapy for HR+/HER2− advanced or metastatic breast cancer in combination with an aromatase inhibitor. This review, therefore, addresses the role of selective CDK4/6 inhibitors in advanced or metastatic breast cancer with a specific focus on ribociclib. Some findings of clinical trials involving ribociclib found pivotal benefits of ribociclib in HR+/HER2− metastatic breast cancer in terms of prolonging progression-free survival and objective response rates. Daily dosage range of the drug for such benefits is 50–900 mg with common daily doses of 400 or 600 mg and 600 mg in early and advanced breast cancer therapies, respectively. Along with its therapeutic benefits, however, more incident but manageable dose-limiting grade 3 or 4 toxicities, primarily hematologic adverse events, are common in patients treated with ribociclib. Generally, there are several active clinical trials undergoing to investigate the clinical efficacy and toxicity profile of the drug in various cancerous conditions other than breast cancer and will likely benefit patients with other cancer types. Keywords: cell cycle, cyclin-dependent kinase 4/6, HR+/HER2−, metastatic breast cancer, CDK4/6 inhibitors, ribociclib, LEE011

The RB-E2F1 pathway is an important mechanism of cell-cycle control, and deregulation of this pathway is one of the key factors contributing to tumorigenesis. Cyclin-dependent kinases (CDKs) and Cyclin D have been known to increase in aggressive thyroid cancer. However, there has been no study to investigate effects of a selective CDK 4/6 inhibitor, Ribociclib (LEE011), in thyroid cancer. Performing Western blotting, we found that RB phosphorylation and the expression of Cyclin D are significantly higher in papillary thyroid cancer (PTC) cell lines as well as anaplastic thyroid cancer (ATC) cell lines, compared with normal thyroid cell line and follicular thyroid cancer cell line. LEE011 dose-dependently inhibited RB phosphorylation and also decreased the expressions of its target genes such as FOXM1, Cyclin A1, and Myc in ATC. Furthermore, LEE011 induced cell cycle arrest in G0-G1 phase and cell apoptosis, and inhibited cell proliferation in ATC. Consistently, oral administration of LEE011 to ATC xenograft models strongly inhibited tumor growth with decreased expressions of pRB, pAKT and Ki-67, and also significantly increased tumor cell apoptosis. Taken together, our data support the rationale for clinical development of the CDK4/6 inhibitor as a therapy for patients with aggressive thyroid cancer. [ABSTRACT FROM AUTHOR]

Introduction: The emergence of cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors marked a significant advancement in the treatment of advanced breast cancer. Ribociclib is an orally bioavailable, highly selective inhibitor of CDK4/6. In combination with various endocrine therapies, ribociclib has demonstrated clinical activity as a first-line therapy for patients with HR+, HER2− advanced breast cancer, without compromising the favorable toxicity profile associated with endocrine therapy. Thus, ribociclib is now considered a new standard of care for HR+, HER2− advanced breast cancer. Areas covered: This review provides a concise overview of the preclinical and clinical development of ribociclib, including evidence of its clinical activity and safety profile when combined with endocrine therapy in HR+, HER2− advanced breast cancer. Expert commentary: CDK4/6 inhibition represents a promising treatment option for patients with HR+ metastatic breast cancer. Ribociclib significantly improved progression-free survival in patients receiving first-line endocrine therapy for HR+, HER2− advanced breast cancer. Planned and ongoing trials investigating ribociclib in combination with other endocrine therapies and in various clinical settings will help to determine the optimal treatment sequence for different patient populations. [ABSTRACT FROM PUBLISHER]

Background/Aim: Cyclin-dependent kinases (CDKs) are crucial for cell cycle regulation, and alterations in the cell cycle are often observed in human cancer. CDK4/6 in particular orchestrates G1 phase progression and the G1/S transition. Here, we investigated the in vitro effects of the CDK4/6 inhibitor LEE011 in human neuroendocrine tumor cells. Methods: The human neuroendocrine tumor cell lines BON1, QGP1, NCI-H727 and GOT1 were treated with different concentrations of LEE011 alone and in combination with 5-fluor ouracil and everolimus. Results: Cell viability decreased in a time- and dose-dependent manner in BON1, QGP1, and NCIH727 cells upon LEE011 treatment, whereas GOT1 cells were treatment resistant. Treatment sensitivity towards LEE011 was associated with the high expression of cyclin D1 and Rb. LEE011 caused the dephosphorylation of Rb and a subsequent G1 phase cell cycle arrest. Combined treatment with LEE011 and 5-fluorouracil or everolimus showed a significant enhancement in the inhibition of cell viability when compared to single-substance treatments due to PI3K-AktmTOR and Ras-Raf-MEK-ERK pathway downregulation and cooperative downregulation of cell cycle components. However, LEE011 also exhibited antagonizing effects with 5-fluorouracil, protecting NET cells from DNA-damaging chemotherapy by blocking PARP cleavage and caspase-3/7 activity. Conclusions: Our data demonstrate that the CDK 4/6 inhibitor LEE011 exhibits promising anti-tumoral properties alone and in combination treatment approaches with 5-fluorouracil or everolimus in human neuroendocrine tumor cell lines. [ABSTRACT FROM AUTHOR]

Introduction: The introduction of CDK4/6 inhibitors, such as ribociclib, has changed the treatment landscape for post-menopausal women with HR+/HER2- advanced or metastatic breast cancer. As first-line treatment of HR+/HER2- MBC, the addition of a CDK4/6 inhibitor to an aromatase inhibitor improves progression-free survival compared to an aromatase inhibitor alone. Areas covered: In this drug profile, we review the current market for HR+/HER2- MBC, as well as the characteristics, mechanism, pharmacology, pharmacodynamics, pharmacokinetics, metabolism, clinical efficacy, toxicities, monitoring, and dosing modification of the CDK4/6 inhibitor ribociclib. Expert commentary: CDK4/6 inhibitors, such as ribociclib, improve outcomes in post-menopausal women with HR+/HER2- MBC. The most common toxicity of ribociclib is neutropenia, which is generally not complicated and can be managed with dose modification and/or supportive care measures. Additional research will help better define the optimal clinical use of ribociclib. [ABSTRACT FROM AUTHOR]

A series of novel hybrid structure derivatives, containing both LEE011 and Cabozantinib pharmacophore, were designed, synthesized and evaluated. Surprisingly, a compound 4d was discovered that highly exhibited effective and selective activity of CDK9 inhibition with IC 50 = 12 nM. It effectively induced apoptosis in breast and lung cancer cell lines at nanomolar level. Molecular docking of 4d to ATP binding site of CDK9 kinase demonstrated a new hydrogen bonding between F atom of 4-(3-fluorobenzyloxy) group and ASN116 residue, compared with the positive control, LEE011. The compound 4d could block the cell cycle both in G0/G1 and G2/M phase to prevent the proliferation and differentiation of cancer cells. Mice bared-breast cancer treated with compound 4d showed significant suppression of cancer with low toxicity. Taken together, this novel compound 4d could be a promising drug candidate for clinical application. [ABSTRACT FROM AUTHOR]

Background: Overexpression of cyclin D1 dependent kinases 4 and 6 (CDK4/6) is a common feature of many human cancers including leukemia. LEE011 is a novel inhibitor of both CDK4 and 6. To date, the molecular function of LEE011 in leukemia remains unclear. Methods: Leukemia cell growth and apoptosis following LEE011 treatment was assessed through CCK-8 and annexin V/propidium iodide staining assays. Cell senescence was assessed by β-galactosidase staining and p16INK4a expression analysis. Gene expression profiles of LEE011 treated HL-60 cells were investigated using an Arraystar Human LncRNA array. Gene ontology and KEGG pathway analysis were then used to analyze the differentially expressed genes from the cluster analysis. Results: Our studies demonstrated that LEE011 inhibited proliferation of leukemia cells and could induce apoptosis. Hoechst 33,342 staining analysis showed DNA fragmentation and distortion of nuclear structures following LEE011 treatment. Cell cycle analysis showed LEE011 significantly induced cell cycle G1 arrest in seven of eight acute leukemia cells lines, the exception being THP-1 cells. β-Galactosidase staining analysis and p16INK4a expression analysis showed that LEE011 treatment can induce cell senescence of leukemia cells. LncRNA microarray analysis showed 2083 differentially expressed mRNAs and 3224 differentially expressed lncRNAs in LEE011-treated HL-60 cells compared with controls. Molecular function analysis showed that LEE011 induced senescence in leukemia cells partially through downregulation of the transcriptional expression of MYBL2. Conclusions: We demonstrate for the first time that LEE011 treatment results in inhibition of cell proliferation and induction of G1 arrest and cellular senescence in leukemia cells. LncRNA microarray analysis showed differentially expressed mRNAs and lncRNAs in LEE011-treated HL-60 cells and we demonstrated that LEE011 induces cellular senescence partially through downregulation of the expression of MYBL2. These results may open new lines of investigation regarding the molecular mechanism of LEE011 induced cellular senescence. [ABSTRACT FROM AUTHOR]

Background/aim: Colorectal cancer (CRC) is one of the most common malignancies and cause of cancer-related deaths worldwide. The combination of chemotherapeutics working with different mechanisms enhances the therapeutic effects and delays the development of resistance. This study investigated the anticancer effect of the combination of ribociclib (LEE011) and irinotecan (SN38) on CRC cells., Materials and Methods: HT-29 and SW480 cells were treated with LEE011, SN38, or the combination of LEE011 and SN38. Cell viability and cell cycle distribution were analyzed. The expression of cell cycle- and apoptosis-related proteins was determined using western blot., Results: The combination of LEE011 and SN38 elicited a synergistic antiproliferative effect on HT-29 (PIK3CA P449T mutation) cells, and an antagonistic antiproliferative effect on SW480 (KRAS G12V mutation) cells. LEE011 inhibited retinoblastoma protein (Rb) phosphorylation and led to G 1 arrest in HT-29 and SW480 cells. SN38 treatment caused a significant increase in the phosphorylation levels of Rb, cyclin B1, and CDC2 in SW480 cells and induced S phase arrest. Furthermore, SN38 treatment increased the phosphorylation levels of p53 and activated caspase-3 and caspase-8 in HT-29 and SW480 cells. LEE011-induced G 1 arrest contributed to its synergistic antiproliferative effect with SN38 in HT-29 cells through the down-regulation of the phosphorylation of Rb. In addition, it elicited an antagonistic effect with SN38 in SW480 cells by changing the phosphorylation levels of Rb and activating caspase-8., Conclusion: The effects of the combination of LEE011 and conventional chemotherapy drugs on CRC depend on the chemotherapy drug and the specific gene mutation harbored by tumor cells., (Copyright © 2023 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The cell cycle has been an enticing target for treatment of breast cancer for decades. Until recently, however, no cell cycle inhibitors have proven clinically successful. Recently, three novel oral inhibitors of CDK4/6 have been developed. These agents have varying efficacy and overlapping toxicities. All are being evaluated not only in clinical trials as single agents but also in combination with endocrine therapies, chemotherapies, and other targeted therapies specifically in the treatment of breast cancer. One has been recently FDA approved. Here, we will describe the preclinical and early clinical trials supporting the development of these drugs and discuss their future role in the clinic. [ABSTRACT FROM AUTHOR]

Dysregulation of the cell cycle is a classic hallmark of cancer growth and metastatic potential. Re-establishing cell cycle control through CDK inhibition has emerged as an attractive option in the development of targeted cancer therapy. Three oral agents selectively targeting CDK4/6 have been developed: palbociclib, abemaciclib, and LEE011. Preclinical models show optimal activity in hormone receptor positive breast cancer, which may display biologic features suggesting particular dependence on the CDK4/cyclin D1/ Rb interaction. Palbociclib has been studied in a randomized phase 2 clinical trial in metastatic hormone receptor positive breast cancer in which the combination of palbociclib and endocrine therapy significantly prolonged progression-free survival over endocrine therapy alone. The toxicity profile of palbociclib and the other CDK 4/6 inhibitors in early phase I and II trials has been predominantly hematologic, characterized by limited neutropenia, as well as variable gastrointestinal toxicity. Multiple phase II and III studies are ongoing with all three agents, and are designed to explore the role of CDK 4/6 inhibition in metastatic hormone receptor positive breast cancer. The next wave of studies will examine further clinical and scientific topics, including the role of CDK 4/6 inhibition in the neo/adjuvant setting, the combination of CDK 4/6 inhibitors with other targeted therapies, and the activity of CDK 4/6 inhibitors in the HER2 positive subset of breast cancer, as well as in other cancer subtypes. Should ongoing study confirm benefits and tolerability of CDK 4/6 inhibition, combination therapy with endocrine agents may become a new standard of care for hormone receptor positive breast cancer. [ABSTRACT FROM AUTHOR]

Imbalance of the cyclin D and cyclin-dependent kinase (CDK) pathway in cancer cells may result in diversion away from a pathway to senescence and toward a more proliferative phenotype. Cancer cells may increase cyclin D-dependent activity through a variety of mechanisms. Therapeutic inhibition of CDKs in tumors to negate their evasion of growth suppressors has been identified as a key anticancer strategy. In this review, we outline the development of CDK inhibitory therapy in breast cancer, including the initial experience with the pan-CDK inhibitor flavopiridol and the next generation of oral highly selective CDK4 and CDK6 inhibitors PD0332991 (palbociclib), LEE011 (ribociclib), and LY2835219 (abemaciclib). Data from phase I and II studies in estrogen receptorpositive (ER1) breast cancer demonstrate promising efficacy with manageable toxic effects, chiefly neutropenia. We discuss these studies and the phase III studies that are accruing or nearing completion. We describe the application of such therapy to other breast cancer settings, including HER2-positive breast cancer and the adjuvant treatment of early breast cancer. We also discuss potential concerns surrounding the combination of CDK inhibitors with chemotherapy and their effects on repair of double-strand DNA breaks in cancer cells. Oral highly selective CDK inhibitors show great promise in improving the outcomes of patients with ER1 breast cancer, although caution must apply to their combination with other agents and in the early breast cancer setting. [ABSTRACT FROM AUTHOR]

Background: Radiotherapy (RT) combined with a radiosensitizer represents an important treatment for head and neck squamous cell carcinoma (HNSCC). Only few chemotherapy agents are currently approved as radiosensitizers for targeted therapy. In this study, the potent cyclin-dependent kinase 4/6 (CDK4/6) inhibitor LEE011 was tested for potential to act as a radiosensitizer during RT., Materials and Methods: RT enhancement by LEE011 was assessed by in vitro clonogenic assay, flow cytometry, and western blot in a variety of HNSCC cell lines. The HNSCC cell line OML1 and its radiation-resistant clone OML1-R were used., Results: LEE011 induced cell-cycle arrest in SCC4/SCC25 cells during the G 1 /M phase through inhibition of retinoblastoma protein phosphorylation. LEE011 enhanced the effects of radiation in OML1 cells and overcame radiation resistance in OML1-R cells., Conclusion: LEE011 is a potential radiosensitizer that can enhance the cytotoxic effects of RT. Clinical trials including LEE011 during RT for HNSCC should be considered., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Inhibition of cyclin-dependent kinases 4 and 6 (CDK4/6) is associated with robust antitumor activity. Ribociclib (LEE011) is an orally bioavailable CDK4/6 inhibitor that is approved for the treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer, in combination with an aromatase inhibitor, and is currently being evaluated in several additional trials. Here, we report the preclinical profile of ribociclib. When tested across a large panel of kinase active site binding assays, ribociclib and palbociclib were highly selective for CDK4, while abemaciclib showed affinity to several other kinases. Both ribociclib and abemaciclib showed slightly higher potency in CDK4 -dependent cells than in CDK6 -dependent cells, while palbociclib did not show such a difference. Profiling CDK4/6 inhibitors in large-scale cancer cell line screens in vitro confirmed that RB1 loss of function is a negative predictor of sensitivity. We also found that routinely used cellular viability assays measuring adenosine triphosphate levels as a proxy for cell numbers underestimated the effects of CDK4/6 inhibition, which contrasts with assays that assess cell number more directly. Robust antitumor efficacy and combination benefit was detected when ribociclib was added to encorafenib, nazartinib, or endocrine therapies in patient-derived xenografts., Competing Interests: CONFLICTS OF INTEREST All authors are current or previous employees and stockholders of Novartis.

Natural killer/T-cell lymphoma (NKTCL) is an aggressive non-Hodgkin lymphoma that has been facing limited success with conventional treatments, urging for the discovery of alternative strategies. Recent studies including ours have revealed that EZH2 and JAK-STAT signalling pathways are key contributors to NKTCL pathogenesis. In particular, we found that EZH2 is overexpressed and directly transcriptionally activates the CCND1 gene to confer growth advantage. CCND1 codes for cyclin D1, which complexes with CDK4/6 to promote G1 to S phase transition. Therefore in this study we investigated whether inhibiting both JAK1/2 and CDK4/6, using LEE011 and ruxolitinib respectively is effective in NKTL. We first demonstrate that separate LEE011 and ruxolitinib treatment is sufficient to cause growth inhibition of NKTCL cells. More importantly, we found that there is synergistic growth inhibitory effects on NKTCL cells with combination treatment of LEE011 and ruxolitinib. The results obtained shows that the targeting of both CDK4/6 and JAK1/2 are promising to develop better treatment alternatives for NKTCL., Competing Interests: CONFLICTS OF INTEREST The authors declare no conflicts of interest.

Introduction: Breast cancer (BC) remains the most frequently diagnosed cancer and the most common cause of cancer death among women of all races worldwide. Over 80% of BC cases are hormone receptor (HR)-positive, comprised of luminal A and luminal B per molecular subtypes, imposing an urgent need to fully understand the mechanisms behind progression. Ribociclib is a selective cycline-dependent kinase 4 and 6 inhibitor. A phase 1 and a phase 3 trial have established a definitive role of ribociclib as frontline in the treatment of endocrine-sensitive advanced BC. Areas covered: Herein, the authors provide an overview of the data on ribociclib covering all aspects of the drug from its pharmacokinetics to efficacy and safety. The authors also provide their perspectives for the future. Expert opinion: Ribociclib is offering an opportunity to explore a new compound at the crossroads of different molecular activity and cell targets, which focus on endocrine-resistance reversal in multiple settings including early BC. Moreover, its activity against different subtypes of BC is being studied as is its immune-modulating effect. One cautionary note is that, in a market of concomitant similar competitors, a financial discussion will be mandatory.

Background/aim: Cyclin-dependent kinases (CDKs) are crucial for cell cycle regulation, and alterations in the cell cycle are often observed in human cancer. CDK4/6 in particular orchestrates G1 phase progression and the G1/S transition. Here, we investigated the in vitro effects of the CDK4/6 inhibitor LEE011 in human neuroendocrine tumor cells., Methods: The human neuroendocrine tumor cell lines BON1, QGP1, NCI-H727 and GOT1 were treated with different concentrations of LEE011 alone and in combination with 5-fluorouracil and everolimus., Results: Cell viability decreased in a time- and dose-dependent manner in BON1, QGP1, and NCI-H727 cells upon LEE011 treatment, whereas GOT1 cells were treatment resistant. Treatment sensitivity towards LEE011 was associated with the high expression of cyclin D1 and Rb. LEE011 caused the dephosphorylation of Rb and a subsequent G1 phase cell cycle arrest. Combined treatment with LEE011 and 5-fluorouracil or everolimus showed a significant enhancement in the inhibition of cell viability when compared to single-substance treatments due to PI3K-Akt-mTOR and Ras-Raf-MEK-ERK pathway downregulation and cooperative downregulation of cell cycle components. However, LEE011 also exhibited antagonizing effects with 5-fluorouracil, protecting NET cells from DNA-damaging chemotherapy by blocking PARP cleavage and caspase-3/7 activity., Conclusions: Our data demonstrate that the CDK 4/6 inhibitor LEE011 exhibits promising anti-tumoral properties alone and in combination treatment approaches with 5-fluorouracil or everolimus in human neuroendocrine tumor cell lines., (© 2017 S. Karger AG, Basel.)

CDK4/6 inhibitors are a promising new class of drugs for hormone-receptor-positive breast cancer and have been shown to overcome and delay hormone resistance in advanced breast cancer. Ribociclib, a selective oral inhibitor of CDK4/6, was approved by the US FDA for first-line treatment of hormone-receptor-positive/HER2-negative metastatic breast cancer. This review summarizes the clinical evidence available for ribociclib, from preclinical data to the pivotal studies, with a special focus on toxicity and its management. In addition, this article reviews potential new combinations under study, as well as ongoing clinical trials both in the metastatic and early setting. Finally, this review compares ribociclib activity and toxicity with those of the drugs of the same class (palbociclib and abemaciclib).

Background: Overexpression of cyclin D1 dependent kinases 4 and 6 (CDK4/6) is a common feature of many human cancers including leukemia. LEE011 is a novel inhibitor of both CDK4 and 6. To date, the molecular function of LEE011 in leukemia remains unclear., Methods: Leukemia cell growth and apoptosis following LEE011 treatment was assessed through CCK-8 and annexin V/propidium iodide staining assays. Cell senescence was assessed by β-galactosidase staining and p16 INK4a expression analysis. Gene expression profiles of LEE011 treated HL-60 cells were investigated using an Arraystar Human LncRNA array. Gene ontology and KEGG pathway analysis were then used to analyze the differentially expressed genes from the cluster analysis., Results: Our studies demonstrated that LEE011 inhibited proliferation of leukemia cells and could induce apoptosis. Hoechst 33,342 staining analysis showed DNA fragmentation and distortion of nuclear structures following LEE011 treatment. Cell cycle analysis showed LEE011 significantly induced cell cycle G 1 arrest in seven of eight acute leukemia cells lines, the exception being THP-1 cells. β-Galactosidase staining analysis and p16 INK4a expression analysis showed that LEE011 treatment can induce cell senescence of leukemia cells. LncRNA microarray analysis showed 2083 differentially expressed mRNAs and 3224 differentially expressed lncRNAs in LEE011-treated HL-60 cells compared with controls. Molecular function analysis showed that LEE011 induced senescence in leukemia cells partially through downregulation of the transcriptional expression of MYBL2., Conclusions: We demonstrate for the first time that LEE011 treatment results in inhibition of cell proliferation and induction of G 1 arrest and cellular senescence in leukemia cells. LncRNA microarray analysis showed differentially expressed mRNAs and lncRNAs in LEE011-treated HL-60 cells and we demonstrated that LEE011 induces cellular senescence partially through downregulation of the expression of MYBL2. These results may open new lines of investigation regarding the molecular mechanism of LEE011 induced cellular senescence.