Efficient induction of apoptosis by wee1 kinase inhibition in hepatocellular carcinoma cells

The Traces of Dysregulated lncRNAs-Associated ceRNA Axes in Retinoblastoma: A Systematic Scope Review

PURPOSE

Long non-coding RNAs are an essential component of competing endogenous RNA regulatory axes and play their role by sponging microRNAs and interfering with the regulation of gene expression. Because of the broadness of competing endogenous RNA interaction networks, they may help investigate treatment targets in complicated disorders.

METHODS

This study performed a systematic scoping review to assess verified loops of competing endogenous RNAs in retinoblastoma, emphasizing the competing endogenous RNAs axis related to long non-coding RNAs. We used a six-stage approach framework and the PRISMA guidelines. A systematic search of seven databases was done to locate suitable papers published before February 2022. Two reviewers worked independently to screen articles and collect data.

RESULTS

Out of 363 records, fifty-one articles met the inclusion criteria, and sixty-three axes were identified in desired articles. The majority of the research reported several long non-coding RNAs that were experimentally verified to act as competing endogenous RNAs in retinoblastoma: XIST/NEAT1/MALAT1/SNHG16/KCNQ1OT1, respectively. At the same time, around half of the studies investigated unique long non-coding RNAs.

CONCLUSIONS

Understanding the many features of this regulatory system may aid in elucidating the unknown etiology of Retinoblastoma and providing novel molecular targets for therapeutic and clinical applications.

AZD1775 and anti-PD-1 antibody synergistically sensitize hepatoma to radiotherapy

BACKGROUND

Radiation (IR)-induced DNA damage triggers cell cycle arrest and has a suppressive effect on the tumor microenvironment (TME). Wee1, a cell cycle regulator, can eliminate G2/M arrest by phosphorylating cyclin-dependent kinase 1 (CDK1). Meanwhile, programed death-1/programed death ligand-1 (PD-1/PDL-1) blockade is closely related to TME. This study aims to investigate the effects and mechanisms of Wee1 inhibitor AZD1775 and anti-PD-1 antibody (anti-PD-1 Ab) on radiosensitization of hepatoma.

METHODS

The anti-tumor activity of AZD1775 and IR was determined by 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide (MTT) assay on human and mouse hepatoma cells HepG2, Hepa1-6, and H22. The anti-hepatoma mechanism of AZD1775 and IR revealed by flow cytometry and Western blot in vitro . A hepatoma subcutaneous xenograft mice model was constructed on Balb/c mice, which were divided into control group, IR group, AZD1775 group, IR + AZD1775 group, IR + anti-PD-1 Ab group, and the IR + AZD1775 + anti-PD-1 Ab group. Cytotoxic CD8 + T cells in TME were analyzed by flow cytometry.

RESULTS

Combining IR with AZD1775 synergistically reduced the viability of hepatoma cells in vitro . AZD1775 exhibited antitumor effects by decreasing CDK1 phosphorylation to reverse the IR-induced G2/M arrest and increasing IR-induced DNA damage. AZD1775 treatment also reduced the proportion of PD-1 + /CD8 + T cells in the spleen of hepatoma subcutaneous xenograft mice. Further studies revealed that AZD1775 and anti-PD-1 Ab could enhance the radiosensitivity of hepatoma by enhancing the levels of interferon γ (IFNγ) + or Ki67 + CD8 T cells and decreasing the levels of CD8 + Tregs cells in the tumor and spleen of the hepatoma mice model, indicating that the improvement of TME was manifested by increasing the cytotoxic factor IFNγ expression, enhancing CD8 + T cells proliferation, and weakening CD8 + T cells depletion.

CONCLUSIONS

This work suggests that AZD1775 and anti-PD-1 Ab synergistically sensitize hepatoma to radiotherapy by enhancing IR-induced DNA damage and improving cytotoxic CD8 + T cells in TME.

Mutational Landscape and Precision Medicine in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fourth most common malignancy worldwide and exhibits a universal burden as the incidence of the disease continues to rise. In addition to curative-intent therapies such as liver resection and transplantation, locoregional and systemic therapy options also exist. However, existing treatments carry a dismal prognosis, often plagued with high recurrence and mortality. For this reason, understanding the tumor microenvironment and mutational pathophysiology has become the center of investigation for disease control. The use of precision medicine and genetic analysis can supplement current treatment modalities to promote individualized management of HCC. In the search for personalized medicine, tools such as next-generation sequencing have been used to identify unique tumor mutations and improve targeted therapies. Furthermore, investigations are underway for specific HCC biomarkers to augment the diagnosis of malignancy, the prediction of whether the tumor environment is amenable to available therapies, the surveillance of treatment response, the monitoring for disease recurrence, and even the identification of novel therapeutic opportunities. Understanding the mutational landscape and biomarkers of the disease is imperative for tailored management of the malignancy. In this review, we summarize the molecular targets of HCC and discuss the current role of precision medicine in the treatment of HCC.

Multicenter Phase II Trial of the WEE1 Inhibitor Adavosertib in Refractory Solid Tumors Harboring CCNE1 Amplification

PURPOSE

Preclinical cancer models harboring CCNE1 amplification were more sensitive to adavosertib treatment, a WEE1 kinase inhibitor, than models without amplification. Thus, we conducted this phase II study to assess the antitumor activity of adavosertib in patients with CCNE1-amplified, advanced refractory solid tumors.

PATIENTS AND METHODS

Patients aged ≥ 18 years with measurable disease and refractory solid tumors harboring CCNE1 amplification, an Eastern Cooperative Oncology Group performance status of 0-1, and adequate organ function were studied. Patients received 300 mg of adavosertib once daily on days 1 through 5 and 8 through 12 of a 21-day cycle. The trial followed Bayesian optimal phase II design. The primary end point was objective response rate (ORR).

RESULTS

Thirty patients were enrolled. The median follow-up duration was 9.9 months. Eight patients had partial responses (PRs), and three had stable disease (SD) ≥ 6 months, with an ORR of 27% (95% CI, 12 to 46), a SD ≥ 6 months/PR rate of 37% (95% CI, 20 to 56), a median progression-free survival duration of 4.1 months (95% CI, 1.8 to 6.4), and a median overall survival duration of 9.9 months (95% CI, 4.8 to 15). Fourteen patients with epithelial ovarian cancer showed an ORR of 36% (95% CI, 13 to 65) and SD ≥ 6 months/PR of 57% (95% CI, 29 to 82), a median progression-free survival duration of 6.3 months (95% CI, 2.4 to 10.2), and a median overall survival duration of 14.9 months (95% CI, 8.9 to 20.9). Common treatment-related toxicities were GI, hematologic toxicities, and fatigue.

CONCLUSION

Adavosertib monotherapy demonstrates a manageable toxicity profile and promising clinical activity in refractory solid tumors harboring CCNE1 amplification, especially in epithelial ovarian cancer. Further study of adavosertib, alone or in combination with other therapeutic agents, in CCNE1-amplified epithelial ovarian cancer is warranted.

Wee1 Kinase: A Potential Target to Overcome Tumor Resistance to Therapy

During the cell cycle, DNA suffers several lesions that need to be repaired prior to entry into mitosis to preserve genome integrity in daughter cells. Toward this aim, cells have developed complex enzymatic machinery, the so-called DNA damage response (DDR), which is able to repair DNA, temporarily stopping the cell cycle to provide more time to repair, or if the damage is too severe, inducing apoptosis. This DDR mechanism is considered the main source of resistance to DNA-damaging therapeutic treatments in oncology. Recently, cancer stem cells (CSCs), which are a small subset of tumor cells, were identified as tumor-initiating cells. CSCs possess self-renewal potential and persistent tumorigenic capacity, allowing for tumor re-growth and relapse. Compared with cancer cells, CSCs are more resistant to therapeutic treatments. Wee1 is the principal gatekeeper for both G2/M and S-phase checkpoints, where it plays a key role in cell cycle regulation and DNA damage repair. From this perspective, Wee1 inhibition might increase the effectiveness of DNA-damaging treatments, such as radiotherapy, forcing tumor cells and CSCs to enter into mitosis, even with damaged DNA, leading to mitotic catastrophe and subsequent cell death.

Discovery of ZN-c3, a Highly Potent and Selective Wee1 Inhibitor Undergoing Evaluation in Clinical Trials for the Treatment of Cancer

Wee1 inhibition has received great attention in the past decade as a promising therapy for cancer treatment. Therefore, a potent and selective Wee1 inhibitor is highly desirable. Our efforts to make safer and more efficacious Wee1 inhibitors led to the discovery of compound 16, a highly selective Wee1 inhibitor with balanced potency, ADME, and pharmacokinetic properties. The chiral ethyl moiety of compound 16 provided an unexpected improvement of Wee1 potency. Compound 16, known as ZN-c3, showed excellent in vivo efficacy and is currently being evaluated in phase 2 clinical trials.

Targeting WEE1 Inhibits Growth of Breast Cancer Cells That Are Resistant to Endocrine Therapy and CDK4/6 Inhibitors

Despite the success of antiestrogens in extending overall survival of patients with estrogen receptor positive (ER+) breast tumors, resistance to these therapies is prevalent. ER+ tumors that progress on antiestrogens are treated with antiestrogens and CDK4/6 inhibitors. However, 20% of these tumors never respond to CDK4/6 inhibitors due to intrinsic resistance. Here, we used endocrine sensitive ER+ MCF7 and T47D breast cancer cells to generate long-term estrogen deprived (LTED) endocrine resistant cells that are intrinsically resistant to CDK4/6 inhibitors. Since treatment with antiestrogens arrests cells in the G1 phase of the cell cycle, we hypothesized that a defective G1 checkpoint allows resistant cells to escape this arrest but increases their dependency on G2 checkpoint for DNA repair and growth, and hence, targeting the G2 checkpoint will induce cell death. Indeed, inhibition of WEE1, a crucial G2 checkpoint regulator, with AZD1775 (Adavosertib), significantly decreased cell proliferation and increased G2/M arrest, apoptosis and gamma-H2AX levels (a marker for DNA double stranded breaks) in resistant cells compared with sensitive cells. Thus, targeting WEE1 is a promising anti-cancer therapeutic strategy in standard therapy resistant ER+ breast cancer.

ONC201 induces the unfolded protein response (UPR) in high- and low-grade ovarian carcinoma cell lines and leads to cell death regardless of platinum sensitivity

Objectives

Treatment of both platinum resistant high grade (HG) and low‐grade (LG) ovarian cancer (OVCA) poses significant challenges as neither respond well to conventional chemotherapy leading to morbidity and mortality. Identification of novel agents that can overcome chemoresistance is therefore critical. Previously, we have demonstrated that OVCA has basal upregulated unfolded protein response (UPR) and that targeting cellular processes leading to further and persistent upregulation of UPR leads to cell death. ONC201 is an orally bioavailable Dopamine Receptor D2 inhibitor demonstrating anticancer activity and was found to induce UPR. Given its unique properties, we hypothesized that ONC201 would overcome platinum resistance in OVCA.

Methods

Cisplatin sensitive and resistant HG OVCA and two primary LG OVCA cell lines were studied. Cell viability was determined using MTT assay. Cell migration was studied using wound healing assay. Apoptosis and mitochondrial membrane potential were investigated using flow cytometry. Analysis of pathway inhibition was performed by Western Blot. mRNA expression of UPR related genes were measured by qPCR. In vivo studies were completed utilizing axillary xenograft models. Co‐testing with conventional chemotherapy was performed to study synergy.

Results

ONC201 significantly inhibited cell viability and migration in a dose dependent manner with IC50’s from 1‐20 µM for both cisplatin sensitive and resistant HG and LG‐OVCA cell lines. ONC201 lead to upregulation of the pro‐apoptotic arm of the UPR, specifically ATF‐4/CHOP/ATF3 and increased the intrinsic apoptosispathway. The compensatory, pro‐survival PI3K/AKT/mTOR pathway was downregulated. In vivo, weekly dosing of single agent ONC201 decreased xenograft tumor size by ~50% compared to vehicle. ONC201 also demonstrated significant synergy with paclitaxel in a highly platinum resistant OVCA cell‐line (OV433).

Conclusions

Our findings demonstrate that ONC201 can effectively overcome chemoresistance in OVCA cells by blocking pro‐survival pathways and inducing the apoptotic arm of the UPR. This is a promising, orallybioavailable therapeutic agent to consider in clinical trials for patients with both HG and LG OVCA.

Current status of ctDNA in precision oncology for hepatocellular carcinoma

The conventional method used to obtain a tumor biopsy for hepatocellular carcinoma (HCC) is invasive and does not evaluate dynamic cancer progression or assess tumor heterogeneity. It is thus imperative to create a novel non-invasive diagnostic technique for improvement in cancer screening, diagnosis, treatment selection, response assessment, and predicting prognosis for HCC. Circulating tumor DNA (ctDNA) is a non-invasive liquid biopsy method that reveals cancer-specific genetic and epigenetic aberrations. Owing to the development of technology in next-generation sequencing and PCR-based assays, the detection and quantification of ctDNA have greatly improved. In this publication, we provide an overview of current technologies used to detect ctDNA, the ctDNA markers utilized, and recent advances regarding the multiple clinical applications in the field of precision medicine for HCC.

Targeting Replicative Stress and DNA Repair by Combining PARP and Wee1 Kinase Inhibitors Is Synergistic in Triple Negative Breast Cancers with Cyclin E or BRCA1 Alteration

Simple Summary

Triple-negative breast cancer (TNBC) is a subtype of invasive breast cancer with an aggressive phenotype that has decreased survival compared with other types of breast cancers, due in part to the lack of biomarker driven targeted therapies. Here, we show that breast cancer patients whose tumors show high levels of cyclin E expression have a higher prevalence of BRCA1/2 alterations and have the worst clinical outcomes. In vitro and in vivo studies revealed that combination therapies with poly (ADP-ribose) polymerase (PARP) and Wee1 kinase inhibitors in TNBC cells with either BRCA1 mutations or high levels of cyclin E results in synergistic cell death due to induction of replicative stress and downregulation of DNA repair. These studies suggest that by preselecting patients whose tumors have high cyclin E levels or harbor mutations in BRCA1, only those cases with the highest replicative stress properties will be subjected to combination treatment and likely result in synergistic activity of the two agents.

Abstract

The identification of biomarker-driven targeted therapies for patients with triple negative breast cancer (TNBC) remains a major clinical challenge, due to a lack of specific targets. Here, we show that cyclin E, a major regulator of G1 to S transition, is deregulated in TNBC and is associated with mutations in DNA repair genes (e.g., BRCA1/2). Breast cancers with high levels of cyclin E not only have a higher prevalence of BRCA1/2 mutations, but also are associated with the worst outcomes. Using several in vitro and in vivo model systems, we show that TNBCs that harbor either mutations in BRCA1/2 or overexpression of cyclin E are very sensitive to the growth inhibitory effects of AZD-1775 (Wee 1 kinase inhibitor) when used in combination with MK-4837 (PARP inhibitor). Combination treatment of TNBC cell lines with these two agents results in synergistic cell killing due to induction of replicative stress, downregulation of DNA repair and cytokinesis failure that results in increased apoptosis. These findings highlight the potential clinical application of using cyclin E and BRCA mutations as biomarkers to select only those patients with the highest replicative stress properties that may benefit from combination treatment with Wee 1 kinase and PARP inhibitors.

The lncRNA XIST/miR-125b-2-3p axis modulates cell proliferation and chemotherapeutic sensitivity via targeting Wee1 in colorectal cancer

Background

Numerous reports on microRNAs have illustrated their role in tumor growth and metastasis. Recently, a new prognostic factor, miR‐125b‐2‐3p, has been identified for predicting chemotherapeutic sensitivity in advanced colorectal cancer (CRC). However, the specific mechanisms and biological functions of miR‐125b‐2‐3p in advanced CRC under chemotherapy have yet to be elucidated.

Methods

MiR‐125b‐2‐3p expression was detected by real‐time PCR (RT‐PCR) in CRC tissues. The effects of miR‐125b‐2‐3p on the growth, metastasis, and drug sensitivity of CRC cells were tested in vitro and in vivo. Based on multiple databases, the upstream competitive endogenous RNAs (ceRNAs) and the downstream genes for miR‐125b‐2‐3p were predicted by bioinformatic analysis, followed by the experiments including luciferase reporter assays, western blot assays, and so on.

Results

MiR‐125b‐2‐3p was significantly lowly expressed in the tissues and cell lines of CRC. Higher expression of miR‐125b‐2‐3p was associated with relatively lower proliferation rates and fewer metastases. Moreover, overexpressed miR‐125b‐2‐3p remarkably improved chemotherapeutic sensitivity of CRC in vivo and in vitro. Mechanistically, miR‐125b‐2‐3p was absorbed by long noncoding RNA (lncRNA) XIST regulating WEE1 G2 checkpoint kinase (WEE1) expression. The upregulation of miR‐125b‐2‐3p inhibited the proliferation and epithelial‐mesenchymal transition (EMT) of CRC induced by lncRNA XIST.

Conclusions

Lower miR‐125b‐2‐3p expression resulted in lower sensitivity of CRC to chemotherapy and was correlated with poorer survival of CRC patients. LncRNA XIST promoted CRC metastasis acting as a ceRNA for miR‐125b‐2‐3p to mediate WEE1 expression. LncRNA XIST‐miR‐125b‐2‐3p‐WEE1 axis not only regulated CRC growth and metastasis but also contributed to chemotherapeutic resistance to CRC.

Wee1 kinase inhibitor AZD1775 potentiates CD8+ T cell-dependent antitumour activity via dendritic cell activation following a single high dose of irradiation

As standard treatments for cancer, DNA-damaging chemotherapeutic agents and irradiation therapy improve survival in patients with various cancers. Wee1, a kinase associated with the cell cycle, causes G2/M cell cycle arrest to allow repair of injured DNA in cancer cells, and a Wee1 inhibitor has been confirmed to lead to apoptosis in cancer cells. Recently, there has been renewed interest in exploring the immune environment which plays a significant role in tumour suppression. A Wee1 inhibitor combined with radiotherapy has been tested in lung, pancreatic, and prostate cancer and melanoma in vivo or in vitro. There is still no research evaluating the immunoregulatory effects of AZD1775 plus high-dose irradiation (IR) in vivo. T cell killing and CD8+ T cell depletion assays demonstrated that the combination of AZD1775 and IR delayed tumour growth in breast cancer mouse models. Additionally, combination treatment also suppressed the expression of PD-L1, a co-inhibitor, through the STAT3-IRF1 axis. The importance and originality of this study are that it explores the internal and external mechanisms of AZD1775 combined with a single high dose of IR and provides a rationale for applying the combination therapy described above in a clinical trial.

Wee1 Inhibition Enhances the Anti-Tumor Effects of Capecitabine in Preclinical Models of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype defined by lack of hormone receptor expression and non-amplified HER2. Adavosertib (AZD1775) is a potent, small-molecule, ATP-competitive inhibitor of the Wee1 kinase that potentiates the activity of many DNA-damaging chemotherapeutics and is currently in clinical development for multiple indications. The purpose of this study was to investigate the combination of AZD1775 and capecitabine/5FU in preclinical TNBC models. TNBC cell lines were treated with AZD1775 and 5FU and cellular proliferation was assessed in real-time using IncuCyte^® Live Cell Analysis. Apoptosis was assessed via the Caspase-Glo 3/7 assay system. Western blotting was used to assess changes in expression of downstream effectors. TNBC patient-derived xenograft (PDX) models were treated with AZD1775, capecitabine, or the combination and assessed for tumor growth inhibition. From the initial PDX screen, two of the four TNBC PDX models demonstrated a better response in the combination treatment than either of the single agents. As confirmation, two PDX models were expanded for statistical comparison. Both PDX models demonstrated a significant growth inhibition in the combination versus either of the single agents. (TNBC012, p < 0.05 combo vs. adavosertib or capecitabine, TNBC013, p < 0.01 combo vs. adavosertib or capecitabine.) An enhanced anti-proliferative effect was observed in the adavosertib/5FU combination treatment as measured by live cell analysis. An increase in apoptosis was observed in two of the four cell lines in the combination when compared to single-agent treatment. Treatment with adavosertib as a single agent resulted in a decrease in p-CDC2 in a dose-dependent manner that was also observed in the combination treatment. An increase in γH2AX in two of the four cell lines tested was also observed. No significant changes were observed in Bcl-xL following treatment in any of the cell lines. The combination of adavosertib and capecitabine/5FU demonstrated enhanced combination effects both in vitro and in vivo in preclinical models of TNBC. These results support the clinical investigation of this combination in patients with TNBC, including those with brain metastasis given the CNS penetration of both agents.

Targeting replication stress response using polypurine reverse hoogsteen hairpins directed against WEE1 and CHK1 genes in human cancer cells

In response to DNA damage, cell cycle checkpoints produce cell cycle arrest to repair and maintain genomic integrity. Due to the high rates of replication and genetic abnormalities, cancer cells are dependent on replication stress response (RSR) and inhibitors of this pathway are being studied as an anticancer approach. In this direction, we investigated the inhibition of CHK1 and WEE1, key components of RSR, using Polypurine Reverse Hoogsteen hairpins (PPRHs) as gene silencing tool. PPRHs designed against WEE1 or CHK1 reduced the viability of different cancer cell lines and showed an increase of apoptosis in HeLa cells. The effect of the PPRHs on cell viability were dose- and time-dependent in HeLa cells. Both the levels of mRNA and protein for each gene were decreased after treatment with the PPRHs. When analyzing the levels of the two CHK1 mRNA splicing variants, CHK1 and CHK1-S, there was a proportional decrease of the two forms, thus maintaining the same expression ratio. PPRHs targeting WEE1 and CHK1 also proved to disrupt cell cycle after 15 h of treatment. Moreover, PPRHs showed a synergy effect when combined with DNA damaging agents, such as methotrexate or 5-Fluorouracil, widely used in clinical practice. This work validates in vitro the usage of PPRHs as a silencing tool against the RSR genes WEE1 and CHK1 and corroborates the potential of inhibiting these targets as a single agent therapy or in combination with other chemotherapy agents in cancer research.

Upregulated microRNAs in membranous glomerulonephropathy are associated with significant downregulation of IL6 and MYC mRNAs

Membranous glomerulonephropathy (MGN) is a glomerulopathy characterized by subepithelial deposits of immune complexes on the extracapillary side of the glomerular basement membrane. Insertion of C5b-9 (complement membrane-attack complex) into the membrane leads to functional impairment of the glomerular capillary wall. Knowledge of the molecular pathogenesis of MGN is actually scanty. MicroRNA (miRNA) profiling in MGN and unaffected tissues was performed by TaqMan Low-Density Arrays. Expression of miRNAs and miRNA targets was evaluated in Real-Time polymerase chain reaction (PCR). In vitro transient silencing of miRNAs was achieved through transfection with miRNA inhibitors. Ten miRNAs (let-7a-5p, let-7b-5p, let-7c-5p, let-7d-5p, miR-107, miR-129-3p, miR-423-5p, miR-516-3p, miR-532-3p, and miR-1275) were differentially expressed (DE) in MGN biopsies compared to unaffected controls. Interleukin 6 (IL6) and MYC messenger RNAs (mRNAs; targets of DE miRNAs) were significantly downregulated in biopsies from MGN patients, and upregulated in A498 cells following let-7a-5p or let-7c-5p transient silencing. Gene ontology analysis showed that DE miRNAs regulate pathways associated with MGN pathogenesis, including cell cycle, proliferation, and apoptosis. A significant correlation between DE miRNAs and mRNAs and clinical parameters (i.e., antiphospholipid antibodies, serum creatinine, estimated glomerular filtration, proteinuria, and serum cholesterol) has been detected. Based on our data, we propose that DE miRNAs and their downstream network may be involved in MGN pathogenesis and could be considered as potential diagnostic biomarkers of MGN.

Wee1 kinase inhibitor MK-1775 induces apoptosis of acute lymphoblastic leukemia cells and enhances the efficacy of doxorubicin involving downregulation of Notch pathway

Acute lymphoblastic leukemia (ALL) is an aggressive hematologic malignancy affecting pediatric and adult populations. Although the outcomes of ALL in children have improved markedly in previous years, limited treatment strategies are available at present for adult patients with ALL. Wee1 is a crucial cell cycle checkpoint kinase of G2/M that regulates cell cycle progression and maintains chromatin integrity. MK-1775, a selective inhibitor of Wee1 has recently been identified to be able to induce apoptosis of tumor cells by abrogating G2/M checkpoint. The present study investigated the anti-leukemic activity of MK-1775 alone and in combination with doxorubicin (Adriamycin^®; ADM) in various human ALL cell lines. MK-1775 treatment induced apoptosis of ALL cells, accompanied by unscheduled mitotic entry and downregulation of Notch pathway. The anti-leukemic activity of MK-1775 was in a concentration- and time-dependent manner. The data also indicated that it decreased the half-maximal inhibitory concentration (IC₅₀) of ADM compared with the control group. The combination of MK-1775 and ADM induced an increased apoptotic rate compared with each agent alone. In addition, the human bone marrow stromal cell HS-5 cell line was detected to exhibit an increased IC₅₀ value of MK-1775 treatment in contrast to ALL cell lines. It indicates that the hematopoietic supportive capability may remain intact during the treatment of MK-1775. Taken together, the Wee1 inhibitor MK-1775 may be an attractive agent in the treatment of patients with ALL.

Ponatinib Shows Potent Antitumor Activity in Small Cell Carcinoma of the Ovary Hypercalcemic Type (SCCOHT) through Multikinase Inhibition

Purpose: Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare, aggressive ovarian cancer in young women that is universally driven by loss of the SWI/SNF ATPase subunits SMARCA4 and SMARCA2. A great need exists for effective targeted therapies for SCCOHT.Experimental Design: To identify underlying therapeutic vulnerabilities in SCCOHT, we conducted high-throughput siRNA and drug screens. Complementary proteomics approaches profiled kinases inhibited by ponatinib. Ponatinib was tested for efficacy in two patient-derived xenograft (PDX) models and one cell-line xenograft model of SCCOHT.Results: The receptor tyrosine kinase (RTK) family was enriched in siRNA screen hits, with FGFRs and PDGFRs being overlapping hits between drug and siRNA screens. Of multiple potent drug classes in SCCOHT cell lines, RTK inhibitors were only one of two classes with selectivity in SCCOHT relative to three SWI/SNF wild-type ovarian cancer cell lines. We further identified ponatinib as the most effective clinically approved RTK inhibitor. Reexpression of SMARCA4 was shown to confer a 1.7-fold increase in resistance to ponatinib. Subsequent proteomic assessment of ponatinib target modulation in SCCOHT cell models confirmed inhibition of nine known ponatinib target kinases alongside 77 noncanonical ponatinib targets in SCCOHT. Finally, ponatinib delayed tumor doubling time 4-fold in SCCOHT-1 xenografts while reducing final tumor volumes in SCCOHT PDX models by 58.6% and 42.5%.Conclusions: Ponatinib is an effective agent for SMARCA4-mutant SCCOHT in both in vitro and in vivo preclinical models through its inhibition of multiple kinases. Clinical investigation of this FDA-approved oncology drug in SCCOHT is warranted. Clin Cancer Res; 24(8); 1932-43. ©2018 AACR.

Chemotherapy-induced differential cell cycle arrest in B-cell lymphomas affects their sensitivity to Wee1 inhibition

Chemotherapeutic agents, e.g., cytarabine and doxorubicin, cause DNA damage. However, it remains unknown whether such agents differentially regulate cell cycle arrest in distinct types of B-cell lymphomas, and whether this phenotype can be exploited for developing new therapies. We treated various types of B cells, including primary and B lymphoma cells, with cytarabine or doxorubicin, and determined DNA damage responses, cell cycle regulation and sensitivity to a Wee1 inhibitor. We found that cyclin A2/B1 upregulation appears to be an intrinsic programmed response to DNA damage; however, different types of B cells arrest in distinct phases of the cell cycle. The Wee1 inhibitor significantly enhanced the apoptosis of G2 phase-arrested B-cell lymphomas by inducing premature entry into mitosis and mitotic catastrophe, whereas it did not affect G1/S-phase-arrested lymphomas. Cytarabine-induced G1-arrest can be converted to G2-arrest by doxorubicin treatment in certain B-cell lymphomas, which correlates with newly acquired sensitivity to the Wee1 inhibitor. Consequently, the Wee1 inhibitor together with cytarabine or doxorubicin inhibited tumor growth in vitro and in vivo more effectively, providing a potential new therapy for treating B-cell lymphomas. We propose that the differential cell cycle arrest can be exploited to enhance the chemosensitivity of B-cell lymphomas.

Targeting DNA damage in SCLC

SCLC accounts for 15% of lung cancer worldwide. Characterised by early dissemination and rapid development of chemo-resistant disease, less than 5% of patients survive 5 years. Despite 3 decades of clinical trials there has been no change to the standard platinum and etoposide regimen for first line treatment developed in the 1970's. The exceptionally high number of genomic aberrations observed in SCLC combined with the characteristic rapid cellular proliferation results in accumulation of DNA damage and genomic instability. To flourish in this precarious genomic context, SCLC cells are reliant on functional DNA damage repair pathways and cell cycle checkpoints. Current cytotoxic drugs and radiotherapy treatments for SCLC have long been known to act by induction of DNA damage and the response of cancer cells to such damage determines treatment efficacy. Recent years have witnessed improved understanding of strategies to exploit DNA damage and repair mechanisms in order to increase treatment efficacy. This review will summarise the rationale to target DNA damage response in SCLC, the progress made in evaluating novel DDR inhibitors and highlight various ongoing challenges for their clinical development in this disease.

The biology of Hepatocellular carcinoma: implications for genomic and immune therapies

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is a leading cause of cancer-related death worldwide. It is highly refractory to most systemic therapies. Recently, significant progress has been made in uncovering genomic alterations in HCC, including potentially targetable aberrations. The most common molecular anomalies in this malignancy are mutations in the TERT promoter, TP53, CTNNB1, AXIN1, ARID1A, CDKN2A and CCND1 genes. PTEN loss at the protein level is also frequent. Genomic portfolios stratify by risk factors as follows: (i) CTNNB1 with alcoholic cirrhosis; and (ii) TP53 with hepatitis B virus-induced cirrhosis. Activating mutations in CTNNB1 and inactivating mutations in AXIN1 both activate WNT signaling. Alterations in this pathway, as well as in TP53 and the cell cycle machinery, and in the PI3K/Akt/mTor axis (the latter activated in the presence of PTEN loss), as well as aberrant angiogenesis and epigenetic anomalies, appear to be major events in HCC. Many of these abnormalities may be pharmacologically tractable. Immunotherapy with checkpoint inhibitors is also emerging as an important treatment option. Indeed, 82% of patients express PD-L1 (immunohistochemistry) and response rates to anti-PD-1 treatment are about 19%, and include about 5% complete remissions as well as durable benefit in some patients. Biomarker-matched trials are still limited in this disease, and many of the genomic alterations in HCC remain challenging to target. Future studies may require combination regimens that include both immunotherapies and molecularly matched targeted treatments.

Novel pyrimidine-2,4-dione-1,2,3-triazole and furo[2,3-d]pyrimidine-2-one-1,2,3-triazole hybrids as potential anti-cancer agents: Synthesis, computational and X-ray analysis and biological evaluation

Regioselective 1,4-disubstituted 1,2,3-triazole tethered pyrimidine-2,4-dione derivatives (5-23) were successfully prepared by the copper(I)-catalyzed click chemistry. While known palladium/copper-cocatalyzed method based on Sonogashira cross-coupling followed by the intramolecular 5-endo-dig ring closure generated novel 6-alkylfuro[2,3-d]pyrimidine-2-one-1,2,3-triazole hybrids (24b-37b), a small library of their 5-alkylethynyl analogs (24a-37a) was synthesized and described for the first time by tandem terminal alkyne dimerization and subsequent 5-endo-trig cyclization, which was additionally corroborated with computational and X-ray crystal structure analyses. The nature of substituents on alkynes and thereof homocoupled 1,3-diynes predominantly influenced the ratio of the formed products in both pathways. In vitro antiproliferative activity of prepared compounds evaluated on five human cancer cell lines revealed that N,N-1,3-bis-(1,2,3-triazole)-5-bromouracil (5-7) and 5,6-disubstituted furo[2,3-d]pyrimidine-2-one-1,2,3-triazole 34a hybrids exhibited the most pronounced cytostatic acitivities against hepatocellular carcinoma (HepG2) and cervical carcinoma (HeLa) cells with higher potencies than the reference drug 5-fluorouracil. Cytostatic effect of pyrimidine-2,4-dione-1,2,3-triazole hybrid 7 in HepG2 cells could be attributed to the Wee-1 kinase inhibition and abolishment of sphingolipid signaling mediated by acid ceramidase and sphingosine kinase 1. Importantly, this compound proved to be a non-mitochondrial toxicant, which makes it a promising candidate for further lead optimization and development of a new and more efficient agent for the treatment of hepatocellular carcinoma.

Role of TGFβ signaling pathway in biological behavior of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor with a high fatality rate and strong invasion, and surgical resection is the most effective treatment for early HCC. However, most patients have lost the chance of operation at diagnosis. Additionally, chemotherapy has a poor effect and drug toxicity. In order to improve the prognosis and treatment of HCC, elucidating the cellular and molecular mechanism of HCC and finding new treatment targets are essential. The transforming growth factor β (TGFβ) pathway is involved in hepatocellular carcinogenesis and regulates tumor cell proliferation, apoptosis, migration, invasion and differentiation. TGFβ exerts a protective effect in early HCC. With the progression of HCC, TGFβ promotes the progress of HCC. Studies suggest that Axl/14-3-3zeta signaling is central for the transforming process. Taken into consideration the crucial role of the TGFβ pathway in the development and progression of HCC, it might become an important therapeutic target for HCC in the future.

The role and mechanism of WEE1 on the cisplatin resistance reversal of the HepG2/DDP human hepatic cancer cell line

Drug resistance to cisplatin with continuous drug treatment is one of the most common causes of chemotherapy failure in hepatic carcinoma. Accumulating evidence suggests that WEE1 G2 checkpoint kinase (WEE1) is involved in cisplatin resistance, which has been demonstrated to correlate with cancer initiation and progression. However, the role and molecular mechanism of WEE1 in the drug resistance of hepatic cancer remains unclear. In the present study, using the WEE-knockdown hepatic cancer cell line HepG2/DDP, the role of WEE1 and its molecular mechanism were investigated. It was demonstrated that silencing WEE1 expression resulted in an increased cisplatin sensitivity of HepG2/DDP, in addition to an increased rate of apoptosis and intracellular concentration of rhodamine 123. The expression levels of P-gp, MDR1, MRP1, LRP, BCL-2, survivin and GST in WEE1-silenced HepG2/DDP cells were significantly reduced, and phosphorylation levels of MEK and ERK were significantly downregulated. The results demonstrated that WEE1 negatively regulated the multidrug resistance potential of human hepatic cancer cells by modulating the expression of relevant drug resistance genes and the activity of the MEK/ERK pathway. Therefore, WEE1 may be a monitoring bio-marker for drug resistance, and a therapeutic target in hepatic cancer.

Decreased miR122 in hepatocellular carcinoma leads to chemoresistance with increased arginine

Reduced expression of microRNA122 (miR122), a liver-specific microRNA, is frequent in hepatocellular carcinoma (HCC). However, its biological significances remain poorly understood. Because deregulated amino acid levels in cancers can affect their biological behavior, we determined the amino acid levels in miR122-silenced mouse liver tissues, in which intracellular arginine levels were significantly increased. The increased intracellular arginine levels were through upregulation of the solute carrier family 7 (SLC7A1), a transporter of arginine and a direct target of miR122. Arginine is the substrate for nitric oxide (NO) synthetase, and intracellular NO levels were increased in miR122-silenced HCC cells, with increased resistance to sorafenib, a multikinase inhibitor. Conversely, maintenance of the miR122-silenced HCC cells in arginine-depleted culture media, as well as overexpression of miR122 in miR122-low-expressing HCC cells, reversed these effects and rendered the cells more sensitive to sorafenib. Using a reporter knock-in construct, chemical compounds were screened, and Wee1 kinase inhibitor was identified as upregulators of miR122 transcription, which increased the sensitivity of the cells to sorafenib. These results provide an insight into sorafenib resistance in miR122-low HCC, and suggest that arginine depletion or a combination of sorafenib with the identified compound may provide promising approaches to managing this HCC subset.