Cytokinetic effects of Wee1 disruption in pancreatic cancer

Advanced Design, Synthesis, and Evaluation of Highly Selective Wee1 Inhibitors: Enhancing Pharmacokinetics and Antitumor Efficacy

Wee1 is a kinase that regulates cell cycle arrest in response to DNA damage. Wee1 inhibition is a potential strategy to suppress the growth of tumors with defective p53 or DNA repair pathways. However, the development of Wee1 inhibitors faces some challenges. AZD1775, the first-in-class Wee1 inhibitor, has poor kinase selectivity and dose-limiting toxicity. Here, we report the discovery of 12h, a highly selective and potent Wee1 inhibitor with a favorable pharmacokinetic profile. 12h showed strong antiproliferative effects against Lovo cells, a colorectal cancer cell line, both in vitro and in vivo. Moreover, 12h showed a clean kinase profile and effectively induced cell apoptosis. Our results suggest that 12h is a promising drug candidate for further development as a novel anticancer agent.

Construction and Validation of a Newly Prognostic Signature for CRISPR-Cas9-Based Cancer Dependency Map Genes in Breast Cancer

Cancer Dependency Map (CDM) genes comprise an extensive series of genome-scale RNAi-based loss-of-function tests; hence, it served as a method based on the CRISPR-Cas9 technique that could assist scientists in investigating potential gene functions. These CDM genes have a role in tumor cell survival and proliferation, suggesting that they may be used as new therapeutic targets for some malignant tumors. So far, there have been less research on the involvement of CDM genes in breast cancer, and only a tiny percentage of CDM genes have been studied. In this study, information of patients with breast cancer was extracted from The Cancer Genome Atlas (TCGA), from which differentially expressed CDM genes in breast cancer were determined. A variety of bioinformatics techniques were used to assess the functions and prognostic relevance of these confirmed CDM genes. In all, 290 CDM genes were found differentially expressed. Six CDM genes (SRF, RAD51, PMF1, EXOSC3, EXOC1, and TSEN54) were found to be associated with the prognosis of breast cancer samples. Based on the expression of the identified CDM genes and their coefficients, a prognosis model was constructed for prediction, according to which patients with breast cancer were separated into two risk groups. Those with high risk had substantially poorer overall survival (OS) than patients in the other risk group in the TCGA training set, TCGA testing set, and an external cohort from Gene Expression Omnibus (GEO) database. The area under the receiver operating characteristic (ROC) curve for this prognostic signature was, respectively, 0.717 and 0.635 for TCGA training and testing sets, demonstrating its reliability in predicting the prognosis of patients with breast cancer. We next created a nomogram using the six CDM genes discovered to create a therapeutically useful model. The Human Protein Atlas database was used to acquire all immunohistochemistry staining images of the discovered CDM genes. The proportions of tumor-infiltrating immune cells, as well as the expression levels of checkpoint genes, varied substantially between the two risk groups, according to the analyses of immune response. In conclusion, the findings of this research may aid in the understanding of the prognostic value and biological roles of CDM genes in breast cancer.

The KRAS-regulated kinome identifies WEE1 and ERK coinhibition as a potential therapeutic strategy in KRAS-mutant pancreatic cancer

Oncogenic KRAS drives cancer growth by activating diverse signaling networks, not all of which have been fully delineated. We set out to establish a system-wide profile of the KRAS-regulated kinase signaling network (kinome) in KRAS-mutant pancreatic ductal adenocarcinoma (PDAC). We knocked down KRAS expression in a panel of six cell lines and then applied multiplexed inhibitor bead/MS to monitor changes in kinase activity and/or expression. We hypothesized that depletion of KRAS would result in downregulation of kinases required for KRAS-mediated transformation and in upregulation of other kinases that could potentially compensate for the deleterious consequences of the loss of KRAS. We identified 15 upregulated and 13 downregulated kinases in common across the panel of cell lines. In agreement with our hypothesis, all 15 of the upregulated kinases have established roles as cancer drivers (e.g., SRC, TGF-β1, ILK), and pharmacological inhibition of one of these upregulated kinases, DDR1, suppressed PDAC growth. Interestingly, 11 of the 13 downregulated kinases have established driver roles in cell cycle progression, particularly in mitosis (e.g., WEE1, Aurora A, PLK1). Consistent with a crucial role for the downregulated kinases in promoting KRAS-driven proliferation, we found that pharmacological inhibition of WEE1 also suppressed PDAC growth. The unexpected paradoxical activation of ERK upon WEE1 inhibition led us to inhibit both WEE1 and ERK concurrently, which caused further potent growth suppression and enhanced apoptotic death compared with WEE1 inhibition alone. We conclude that system-wide delineation of the KRAS-regulated kinome can identify potential therapeutic targets for KRAS-mutant pancreatic cancer.

The Apparent Requirement for Protein Synthesis during G2 Phase Is due to Checkpoint Activation

Protein synthesis inhibitors (e.g., cycloheximide) block mitotic entry, suggesting that cell cycle progression requires protein synthesis until right before mitosis. However, cycloheximide is also known to activate p38 mitogen-activated protein kinase (MAPK), which can delay mitotic entry through a G2/M checkpoint. Here, we ask whether checkpoint activation or a requirement for protein synthesis is responsible for the cycloheximide effect. We find that p38 inhibitors prevent cycloheximide-treated cells from arresting in G2 phase and that G2 duration is normal in approximately half of these cells. The Wee1 inhibitor MK-1775 and Wee1/Myt1 inhibitor PD0166285 also prevent cycloheximide from blocking mitotic entry, raising the possibility that Wee1 and/or Myt1 mediate the cycloheximide-induced G2 arrest. Thus, protein synthesis during G2 phase is not required for mitotic entry, at least when the p38 checkpoint pathway is abrogated. However, M phase progression is delayed in cycloheximide-plus-kinase-inhibitor-treated cells, emphasizing the different requirements of protein synthesis for timely entry and completion of mitosis.

Protein synthesis inhibitors have long been known to prevent G2 phase cells from entering mitosis. Lockhead et al. demonstrate that this G2 arrest is due to the activation of p38 MAPK, not insufficient protein synthesis, arguing that protein synthesis in G2 phase is not absolutely required for mitotic entry.

Radioimmunotherapy of human pancreatic cancer xenografts in NOD-scid mice with [64Cu]Cu-NOTA-panitumumab F(ab')2 alone or combined with radiosensitizing gemcitabine and the PARP inhibitor, rucaparib

INTRODUCTION

Our objective was to determine the feasibility of extending our previously reported PET imaging study of pancreatic cancer (PnCa) with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ to radioimmunotherapy (RIT) by exploiting the β-particle and Auger electron emissions of ⁶⁴Cu (PET theranostic concept). To enhance the effectiveness of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂, we further combined RIT with radiosensitizing gemcitabine (GEM) and the poly(ADP)ribose polymerase inhibitor (PARPi), rucaparib.

METHODS

Normal tissue toxicity was assessed in non-tumor-bearing NOD-scid mice injected i.v. with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (1.85-9.25 MBq; 10 μg) or [⁶⁴Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')₂ (12.95 MBq). Body weight was monitored, and hematopoietic (CBC), liver (ALT) and kidney [creatinine (SCr)] toxicity were assessed. RIT studies were performed in NOD-scid mice with s.c. OCIP23 human PnCa patient-derived xenografts (PDX) administered [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (3.7 MBq; 10 μg), unlabeled panitumumab F(ab')₂ (10 μg) or normal saline every two weeks. Subsequent studies evaluated RIT with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.95 MBq; 10 μg) administered alone or combined with GEM and the PARPi, rucaparib administered on a 14-day treatment cycle for up to 6 cycles in NOD-scid mice with s.c. PANC-1 human PnCa xenografts. The radiation absorbed dose in PANC-1 tumors and normal organs in mice after a single i.v. injection of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.95 MBq; 10 μg) was estimated based on previously reported biodistribution studies of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂.

RESULTS

No normal tissue toxicity was observed in non-tumor-bearing NOD-scid mice administered up to 3.7 MBq (10 μg) of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ but slightly increased ALT was noted at 9.25 MBq. Administration of [⁶⁴Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')₂ (12.95 MBq; 10 μg) caused some hematopoietic toxicity but no increase in ALT or SCr or decreased body weight. A slight tumor growth delay and increased survival was noted in NOD-scid mice with s.c. OCIP23 PDX treated with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (3.7 MBq; 10 μg) or unlabeled panitumumab F(ab')₂ (10 μg) compared to normal saline treated mice. RIT with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.95 MBq; 10 μg) combined with GEM + PARPi for up to 6 cycles was most effective for the treatment of PANC-1 tumors. Tumor doubling time increased to 13.3 ± 0.9 days vs. 7.8 ± 3.7 days for RIT alone and 9.3 ± 2.2 days for normal saline treatment. Median survival was significantly longer (P < 0.05) than in mice treated with normal saline (35 days) for RIT + GEM + PARPi (71 days), GEM + PARPi (44 days) and RIT + GEM (43 days) but not for RIT alone (25 days). RIT + GEM + PARPi provided a longer median survival than RIT (P < 0.01), GEM + PARPi (P = 0.01) but not RIT + GEM (P = 0.23). Nonetheless, PANC-1 tumors grew exponentially in all treatment groups. The absorbed dose in PANC-1 tumors after a single i.v. injection of [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ (12.85 MBq; 10 μg) was 0.8 Gy, while the dose in normal organs ranged from 0.6-1.2 Gy.

CONCLUSIONS

We conclude that RIT with [⁶⁴Cu]Cu-NOTA-panitumumab F(ab')₂ did not cause significant normal tissue toxicity but was not effective when administered alone for treatment of PnCa xenografts in NOD-scid mice. Combining RIT with GEM and the PARPi, rucaparib enhanced its effectiveness but tumors continued to grow exponentially. Our results suggest that ⁶⁴Cu is not feasible for RIT of PnCa due to low tumor absorbed doses. ¹⁷⁷Lu which has a higher abundance of moderate energy β-particle emissions may be more effective than ⁶⁴Cu. The hematopoietic toxicity of [⁶⁴Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')₂ may be mediated by binding to mouse EGFR expressed on some hematopoietic stem cells.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

Direct extension of PET with ⁶⁴Cu(Cu)-NOTA-panitumumab F(ab')₂ to RIT exploiting the β-particle and Auger electron emissions of ⁶⁴Cu is not feasible. Theranostic approaches that combine PET with RIT employing ¹⁷⁷Lu may be more promising and should be explored.

Profiling of tRNA Halves and YRNA Fragments in Serum and Tissue From Oral Squamous Cell Carcinoma Patients Identify Key Role of 5' tRNA-Val-CAC-2-1 Half

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer and, as indicated by The Oral Cancer Foundation, kills at an alarming rate of roughly one person per hour. With this study, we aimed at better understanding disease mechanisms and identifying minimally invasive disease biomarkers by profiling novel small non-coding RNAs (specifically, tRNA halves and YRNA fragments) in both serum and tumor tissue from humans. Small RNA-Sequencing identified multiple 5' tRNA halves and 5' YRNA fragments that displayed significant differential expression levels in circulation and/or tumor tissue, as compared to control counterparts. In addition, by implementing a modification of weighted gene coexpression network analysis, we identified an upregulated genetic module comprised of 5' tRNA halves and miRNAs (miRNAs were described in previous study using the same samples) with significant association with the cancer trait. By consequently implementing miRNA-overtargeting network analysis, the biological function of the module (and by "guilt by association," the function of the 5' tRNA-Val-CAC-2-1 half) was found to involve the transcriptional targeting of specific genes involved in the negative regulation of the G1/S transition of the mitotic cell cycle. These findings suggest that 5' tRNA-Val-CAC-2-1 half (reduced in serum of OSCC patients and elevated in the tumor tissue) could potentially serve as an OSCC circulating biomarker and/or target for novel anticancer therapies. To our knowledge, this is the first time that the specific molecular function of a 5'-tRNA half is specifically pinpointed in OSCC.

miR-526b-3p serves as a prognostic factor and regulates the proliferation, invasion, and migration of glioma through targeting WEE1

Background: MicroRNAs play important roles in cancer progression including glioma. In this study, we aimed to explore the expression pattern, prognostic potential, and functional role of miR-526b-3p in human glioma.

Materials and methods: The expression of miR-526b-3p in glioma tissues and the adjacent non-tumor tissues was determined by quantitative RT-PCR. The chi-square test was performed to evaluate the statistical associations between miR-526b-3p level and patient characteristics. The prognostic value of miR-526b-3p was analyzed by Kaplan–Meier and Cox regression analyses. The function of miR-526b-3p was analyzed by MTT, colony formation assay, transwell assay, and flow cytometry analysis in vitro. The binding between miR-526b-3p and predicted target WEE1 was verified using dual luciferase assay and Western blot analysis.

Results: We found that miR-526b-3p expression was significantly downregulated in both glioma tissues and cell lines. Downregulation of miR-526b-3p was significantly associated with advanced WHO grade, lower KPS score, and inferior patient outcomes. Functional investigation indicated that overexpression of miR-526b-3p suppressed cell proliferation, migration, and invasion, and promoted apoptosis in glioma cell lines. Mechanically, WEE1 was identified as direct targets of miR-526b-3p and overexpression of WEE1 significantly suppressed the levels of WEE1. Moreover, re-introduction of WEE1 abrogates the suppression of motility and invasiveness induced by miR-526b-3p in glioma cells.

Conclusion: These findings indicate that miR-526b-3p may target WEE1 and inhibit glioma tumorigenesis and progression.

Augmented antitumor activity by olaparib plus AZD1775 in gastric cancer through disrupting DNA damage repair pathways and DNA damage checkpoint

BACKGROUND

Targeting poly ADP-ribose polymerase (PARP) has been recently identified as a promising option against gastric cancer (GC). However, PARP inhibitors alone achieve limited efficacy. Combination strategies, especially with homologous recombination (HR) impairment, are of great hope to optimize PARP inhibitor's efficacy and expand target populations but remains largely unknown. Herein, we investigated whether a WEE1/ Polo-like kinase 1 (PLK1) dual inhibitor AZD1775 reported to impair HR augmented anticancer activity of a PARP inhibitor olaparib and its underlying mechanisms.

METHODS

GC cell lines and in vivo xenografts were employed to determine antitumor activity of PARP inhibitor combined with WEE1/PLK1 dual inhibitor AZD1775. Western blot, genetic knockdown by siRNA, flow cytometry, Immunohistochemistry were performed to explore the underlying mechanisms.

RESULTS

AZD1775 dually targeting WEE1/PLK1 enhanced effects of olaparib on growth inhibition and apoptotic induction in GC cells. Mechanistic investigations elucidate that WEE1/PLK1 blockade downregulated several HR-related proteins and caused an accumulation in γH2AX. As confirmed in both GC cell lines and mice bearing GC xenografts, these effects were enhanced by AZD1775-olaparib combination compared to olaparib alone, suggesting that disrupting HR-mediated DNA damage repairs (DDR) by WEE1/PLK1 blockade might be responsible for improved GC cells' response to PARP inhibitors. Given the DNA damage checkpoint as a primary target of WEE1 inhibition, our data also demonstrate that AZD1775 abrogated olaparib-activated DNA damage checkpoint through CDC2 de-phosphorylation, followed by mitotic progression with unrepaired DNA damage (marked by increased pHH3-stained and γH2AX-stained cells, respectively).

CONCLUSIONS

PARP inhibitor olaparib combined with WEE1/PLK1 dual inhibitor AZD1775 elicited potentiated anticancer activity through disrupting DDR signaling and the DNA damage checkpoint. It sheds light on the combination strategy of WEE1/PLK1 dual inhibitors with PARP inhibitors in the treatment of GC, even in HR-proficient patients.

Wee1 Inhibitor AZD1775 Combined with Cisplatin Potentiates Anticancer Activity against Gastric Cancer by Increasing DNA Damage and Cell Apoptosis

Based on the mechanisms by which Wee1 inhibitor and cisplatin played their own role, a promising strategy of Wee1 inhibitor combined with cisplatin was proposed, which was investigated in gastric cancer (GC). Either Wee1 inhibitor AZD1775 or cisplatin alone had a certain inhibitory effect on in vitro cell proliferation; however, the inhibitory effect was more significant when AZD1775 combined with cisplatin in vitro and in vivo. The underlying mechanisms unveiled that the increased DNA damage indicated by increased γH2AX protein, as well as augmented cell apoptosis indicated by upregulated proapoptotic proteins, was responsible for the significant inhibitory effect of AZD1775 plus cisplatin. Moreover, compared to any single drug, in vitro cell migration and invasion abilities were further attenuated by AZD1775 combined with cisplatin. There were suggestive results that the potentiated cytotoxicity between AZD1775 and cisplatin deserved a deep exploration in the future.