Targeting PIM Kinases Affects Maintenance of CD133 Tumor Cell Population in Hepatoblastoma

Inhibition of PIM Kinases Promotes Neuroblastoma Cell Differentiation to a Neuronal Phenotype

BACKGROUND

Neuroblastoma arises from aberrancies in neural stem cell differentiation. PIM kinases contribute to cancer formation, but their precise role in neuroblastoma tumorigenesis is poorly understood. In the current study, we evaluated the effects of PIM kinase inhibition on neuroblastoma differentiation.

METHODS

Versteeg database query assessed the correlation between PIM gene expression and the expression of neuronal stemness markers and relapse free survival. PIM kinases were inhibited with AZD1208. Viability, proliferation, motility were measured in established neuroblastoma cells lines and high-risk neuroblastoma patient-derived xenografts (PDXs). qPCR and flow cytometry detected changes in neuronal stemness marker expression after AZD1208 treatment.

RESULTS

Database query showed increased levels of PIM1, PIM2, or PIM3 gene expression were associated with higher risk of recurrent or progressive neuroblastoma. Increased levels of PIM1 were associated with lower relapse free survival rates. Higher levels of PIM1 correlated with lower levels of neuronal stemness markers OCT4, NANOG, and SOX2. Treatment with AZD1208 resulted in increased expression of neuronal stemness markers.

CONCLUSIONS

Inhibition of PIM kinases differentiated neuroblastoma cancer cells toward a neuronal phenotype. Differentiation is a key component of preventing neuroblastoma relapse or recurrence and PIM kinase inhibition provides a potential new therapeutic strategy for this disease.

The Role of PIM Kinases in Pediatric Solid Tumors

PIM kinases have been identified as potential therapeutic targets in several malignancies. Here, we provide an in-depth review of PIM kinases, including their structure, expression, activity, regulation, and role in pediatric carcinogenesis. Also included is a brief summary of the currently available pharmaceutical agents targeting PIM kinases and existing clinical trials.

Metastatic human hepatoblastoma cells exhibit enhanced tumorigenicity, invasiveness and a stem cell-like phenotype

BACKGROUND/PURPOSE

Metastatic hepatoblastoma continues to pose a significant treatment challenge, primarily because the precise mechanisms involved in metastasis are not fully understood, making cell lines and preclinical models that depict the progression of disease and metastasis-related biology paramount. We aimed to generate and characterize a metastatic hepatoblastoma cell line to create a model for investigation of the molecular mechanisms associated with metastasis.

MATERIALS/METHODS

Using a murine model of serial tail vein injections of the human hepatoblastoma HuH6 cell line, non-invasive bioluminescence imaging, and dissociation of metastatic pulmonary lesions, we successfully established and characterized the metastatic human hepatoblastoma cell line, HLM_3.

RESULTS

The HLM_3 cells exhibited enhanced tumorigenicity and invasiveness, both in vitro and in vivo compared to the parent HuH6 cell line. Moreover, HLM_3 metastatic hepatoblastoma cells exhibited a stem cell-like phenotype and were more resistant to the standard chemotherapeutic cisplatin.

CONCLUSION

This newly described metastatic hepatoblastoma cell line offers a novel tool to study mechanisms of tumor metastasis and evaluate new therapeutic strategies for metastatic hepatoblastoma.

CRISPR/Cas9-mediated knockout of PIM3 suppresses tumorigenesis and cancer cell stemness in human hepatoblastoma cells

Hepatoblastoma remains one of the most difficult childhood tumors to treat and is alarmingly understudied. We previously demonstrated that Proviral Insertion site in Maloney murine leukemia virus (PIM) kinases, specifically PIM3, are overexpressed in human hepatoblastoma cells and function to promote tumorigenesis. We aimed to use CRISPR/Cas9 gene editing with dual gRNAs to introduce large inactivating deletions in the PIM3 gene and achieve stable PIM3 knockout in the human hepatoblastoma cell line, HuH6. PIM3 knockout of hepatoblastoma cells led to significantly decreased proliferation, viability, and motility, inhibited cell-cycle progression, decreased tumor growth in a xenograft murine model, and increased animal survival. Analysis of RNA sequencing data revealed that PIM3 knockout downregulated expression of pro-migratory and pro-invasive genes and upregulated expression of genes involved in apoptosis and differentiation. Furthermore, PIM3 knockout decreased hepatoblastoma cancer cell stemness as evidenced by decreased tumorsphere formation, decreased mRNA abundance of stemness markers, and decreased cell surface expression of CD133, a marker of hepatoblastoma stem cell-like cancer cells. Reintroduction of PIM3 into PIM3 knockout cells rescued the malignant phenotype. Successful CRISPR/Cas9 knockout of PIM3 kinase in human hepatoblastoma cells confirmed the role of PIM3 in promoting hepatoblastoma tumorigenesis and cancer cell stemness.

Therapeutically viable generation of neurons with antisense oligonucleotide suppression of PTB

Methods to enhance adult neurogenesis by reprogramming glial cells into neurons enable production of new neurons in the adult nervous system. Development of therapeutically viable approaches to induce new neurons is now required to bring this concept to clinical application. Here, we successfully generate new neurons in the cortex and dentate gyrus of the aged adult mouse brain by transiently suppressing polypyrimidine tract binding protein 1 using an antisense oligonucleotide delivered by a single injection into cerebral spinal fluid. Radial glial-like cells and other GFAP-expressing cells convert into new neurons that, over a 2-month period, acquire mature neuronal character in a process mimicking normal neuronal maturation. The new neurons functionally integrate into endogenous circuits and modify mouse behavior. Thus, generation of new neurons in the dentate gyrus of the aging brain can be achieved with a therapeutically feasible approach, thereby opening prospects for production of neurons to replace those lost to neurodegenerative disease.

PIM kinases mediate resistance to cisplatin chemotherapy in hepatoblastoma

Despite increasing incidence, treatment for hepatoblastoma has not changed significantly over the past 20 years. Chemotherapeutic strategies continue to rely on cisplatin, as it remains the most active single agent against hepatoblastoma. However, chemoresistance remains a significant challenge with 54–80% of patients developing resistance to chemotherapy after 4–5 cycles of treatment. Stem cell-like cancer cells (SCLCCs) are a subset of cells thought to play a role in chemoresistance and disease recurrence. We have previously demonstrated that Proviral Integration site for Moloney murine leukemia virus (PIM) kinases, specifically PIM3, play a role in hepatoblastoma cell proliferation and tumor growth and maintain the SCLCC phenotype. Here, we describe the development of a cisplatin-resistant hepatoblastoma xenograft model of the human HuH6 cell line and a patient-derived xenograft, COA67. We provide evidence that these cisplatin-resistant cells are enriched for SCLCCs and express PIM3 at higher levels than cisplatin-naïve cells. We demonstrate that PIM inhibition with AZD1208 sensitizes cisplatin-resistant hepatoblastoma cells to cisplatin, enhances cisplatin-mediated apoptosis, and decreases the SCLCC phenotype seen with cisplatin resistance. Together, these findings indicate that PIM inhibition may be a promising adjunct in the treatment of hepatoblastoma to effectively target SCLCCs and potentially decrease chemoresistance and subsequent disease relapse.

Protein kinase PIM2: A simple PIM family kinase with complex functions in cancer metabolism and therapeutics

PIM2 (proviral integration site for Moloney murine leukemia virus 2) kinase plays an important role as an oncogene in multiple cancers, such as leukemia, liver, lung, myeloma, prostate and breast cancers. PIM2 is largely expressed in both leukemia and solid tumors, and it promotes the transcriptional activation of genes involved in cell survival, cell proliferation, and cell-cycle progression. Many tumorigenic signaling molecules have been identified as substrates for PIM2 kinase, and a variety of inhibitors have been developed for its kinase activity, including SMI-4a, SMI-16a, SGI-1776, JP11646 and DHPCC-9. Here, we summarize the signaling pathways involved in PIM2 kinase regulation and PIM2 mechanisms in various neoplastic diseases. We also discuss the current status and future perspectives for the development of PIM2 kinase inhibitors to combat human cancer, and PIM2 will become a therapeutic target in cancers in the future.

PIM447 inhibits oncogenesis and potentiates cisplatin effects in hepatoblastoma

BACKGROUND

Novel therapies are needed for patients with hepatoblastoma because of an increasing incidence of disease and poor prognosis for advanced, refractory, and recurrent disease. PIM kinases promote tumorigenesis in hepatoblastoma. A novel PIM inhibitor, PIM447, has shown promise in inhibiting oncogenesis in hematologic and lymphoid malignancies. We hypothesized that PIM inhibition with PIM447 would result in decreased tumorigenesis in hepatoblastoma.

METHODS

The effects of PIM447 on hepatoblastoma viability, proliferation, motility, apoptosis, and tumor cell stemness were assessed in HuH6, a human hepatoblastoma cell line, and COA67, a human hepatoblastoma patient-derived xenograft.

RESULTS

PIM447 significantly decreased the viability, proliferation, and motility of HuH6 and COA67 cells. Apoptosis significantly increased following PIM447 treatment. PIM447 had a significant impact on tumor cell stemness as evidenced by decreased expression of CD133 and reduced ability of HuH6 and COA67 cells to form tumorspheres. Furthermore, combining PIM447 with cisplatin resulted in a significant decrease in cell viability compared to either treatment alone.

CONCLUSION

We showed that PIM447 inhibits oncogenesis and potentiates the effects of cisplatin in hepatoblastoma and, therefore, warrants further investigation as a potential therapeutic agent for hepatoblastoma.

CircRNA CDR1as promotes hepatoblastoma proliferation and stemness by acting as a miR-7-5p sponge to upregulate KLF4 expression

Hepatoblastoma (HB) is a malignant embryonal tumor of the liver that consists of heterogenous populations of stem/progenitor cells. Although circular RNAs (circRNAs) play an essential role in tumor development, the effects of circRNA on the proliferation of HB cells, especially cancer stem cells (CSCs), remain unclear. We found that the circRNA, CDR1as, was highly expressed in CSC-enriched populations of HB cell lines. Results from flow cytometric and sphere-forming assays revealed that CDR1as knockdown in HB cell lines decreased the proportion of stem cells. The Cell Counting Kit-8 (CCK-8) assay, colony formation experiments, and EdU assay revealed that CDR1as knockdown in HB cell lines decreased cell growth and the colony-forming abilities. Biotin-coupled probe pull-down assays and biotin-coupled microRNA capture were conducted to evaluate the interaction between CDR1as and miR-7-5p. Dual-luciferase reporter assays demonstrated that Kruppel-like factor 4 (KLF4), expression of which is highly correlated with cancer stemness, was a target of miR-7-5p. Overall, the knockdown of CDR1as significantly inhibited the proliferation and stemness of HB cells by reducing the sponge activity on miR-7-5p and subsequently suppressing the interaction between miR-7-5p and KLF4. Results from this study suggest that CDR1as is an oncogene that effects the proliferation and stemness of HBs.

Targeting protein palmitoylation decreases palmitate‑induced sphere formation of human liver cancer cells

Although non-alcoholic fatty liver disease (NAFLD) is considered a benign disorder, hepatic steatosis has been proposed to be involved in the tumorigenesis of liver cancer. However, the underlying mechanism for carcinogenesis in fatty liver diseases remains unclear. Cancer stem cells (CSCs) have been hypothesized to serve a key role in tumorigenesis. Tumor formation begins with a subset of heterogeneous cells that share properties with stem cells, such as self-renewal and undifferentiated properties. Our previous study reported that the saturated fatty acid palmitate (PA) significantly enhanced the CSC properties of the HepG2 human liver cancer cell line; however, its underlying mechanisms are unknown. In the present study, a proteomic approach was used to investigate the palmitoylation of proteins in HepG2 CSCs. CSC behavior was induced in HepG2 cells via 200 µM PA. Proteomic analysis was performed to identify post-transcriptional modifications of proteins in HepG2 CSCs in response to PA treatment. The present study identified proteins modified by palmitoylation in HepG2 CSC spheres formed following PA treatment. It was therefore hypothesized that palmitoylation may be crucial for CSC sphere formation. Furthermore, the present study demonstrated that two palmitoylation inhibitors, tunicamycin (5, 10 and 25 µg/ml) and 2-bromohexadecanoic acid (25, 50 and 150 µM), significantly decreased CSC sphere formation without affecting cell viability. An association was identified between sphere formation capacity and tumor-initiating capacity of CSCs. The results of the present study demonstrated that protein palmitoylation may influence the PA-induced CSC tumor-initiating capacity, and that the inhibition of palmitoylation may be a suitable chemopreventive strategy for treating patients with NAFLD.

Association of CMYC polymorphisms with hepatoblastoma risk

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in genes may affect gene expression and contribute to cancer susceptibility. This study aimed to explore the association between CMYC gene polymorphisms and hepatoblastoma risk.

METHODS

Hepatoblastoma patients and cancer-free controls were recruited and matched by age and sex. Genotypes were determined by TaqMan, and the strength of the association of interest was determined by calculating odds ratios (ORs) and 95% confidence intervals (CIs). The distributions of various CMYC genotypes among subjects were recorded, followed by analyses of associations between CMYC polymorphisms and hepatoblastoma risk.

RESULTS

A total of 213 hepatoblastoma patients and 958 cancer-free controls were enrolled. No significant associations between the CMYC rs4645943 and rs2070583 polymorphisms and hepatoblastoma risk were found (all P>0.05). In stratification analysis based on age, sex, and clinical stage, the CMYC rs4645943 and rs2070583 polymorphisms were not associated with hepatoblastoma susceptibility (all P>0.05).

CONCLUSIONS

Thus, the CMYC rs4645943 and rs2070583 polymorphisms were not associated with hepatoblastoma risk in the study cohort.

Wnt/β-catenin signaling as a useful therapeutic target in hepatoblastoma

Hepatoblastoma is a malignant tumor in the liver of children that generally occurs at the age of 2–3 years. There have been ample evidence from the preclinical as well as clinical studies suggesting the activation of Wnt/β-catenin signaling in hepatoblastoma, which is mainly attributed to the somatic mutations in the exon 3 of β-catenin gene. There is increased translocation of β-catenin protein from the cell surface to cytoplasm and nucleus and intracellular accumulation is directly linked to the severity of the cancer. Accordingly, the alterations in β-catenin and its target genes may be used as markers in the diagnosis and prognosis of pediatric live tumors. Furthermore, scientists have reported the therapeutic usefulness of inhibition of Wnt/β-catenin signaling in hepatoblastoma and this inhibition of signaling has been done using different methods including short interfering RNA (siRNA), miRNA and pharmacological agents. Wnt/β-catenin works in association with other signaling pathways to induce the development of hepatoblastoma including Yes-associated protein (YAP)1 (YAP-1), mammalian target of rapamycin (mTOR) 1 (mTOR-1), SLC38A1, glypican 3 (GPC3), nuclear factor κ-light-chain-enhancer of activated B cells (NF-kB), epidermal growth factor receptor, ERK1/2, tumor necrosis factor-α (TNF-α), regenerating islet-derived 1 and 3 α (REG1A and 3A), substance P (SP)/neurokinin-1 receptor and PARP-1. The present review describes the key role of Wnt/β-catenin signaling in the development of hepatoblastoma. Moreover, the role of other signaling pathways in hepatoblastoma in association with Wnt/β-catenin has also been described.

The Emerging Roles of Cancer Stem Cells and Wnt/Beta-Catenin Signaling in Hepatoblastoma

Hepatoblastoma (HB) is the most common form of primary liver malignancy found in pediatric populations. HB is considered to be clonal and arises from hepatoblasts, or embryonic liver progenitor cells. These less differentiated tumor-initiating progenitor cells, or cancer stem cells (CSCs), may contribute to tumor recurrence and resistance to therapies, and have high metastatic abilities. Phenotypic heterogeneity, undesired genetic and epigenetic alterations, and dysregulated signaling pathways provide CSCs with a survival advantage over current therapies. The molecular and cellular basis of HB and the mechanism of CSC induction are not fully understood. The Wnt/beta-catenin pathway is one of the major developmental pathways and is believed to play an important role in the pathogenesis of HB and CSC formation. This review summarizes the cellular and molecular characteristics of HB with a specific emphasis on CSCs and Wnt/beta-catenin signaling.

A Synopsis of Pediatric Patients With Hepatoblastoma and Wilms Tumor: NSQIP-P 2012-2016

BACKGROUND

Hepatoblastoma and Wilms tumor are the most common primary liver and kidney tumor in children, respectively, and little is documented about patient outcomes in the immediate perioperative period. The aim of this study was to analyze the short-term outcomes of pediatric patients after surgical resection for hepatoblastoma and Wilms tumor.

METHODS

We queried the 2012-2016 ACS National Surgical Quality Improvement Program-Pediatric (NSQIP-P) database for patients with hepatoblastoma who underwent liver resection and patients with Wilms tumor who underwent a partial or total nephrectomy. Patient demographics, preoperative, intraoperative, and postoperative characteristics were analyzed. Multivariate logistic regression was used to determine independent risk factors for unplanned reoperations.

RESULTS

There were a total of 189 patients with hepatoblastoma and 586 patients with Wilms in National Surgical Quality Improvement Program-Pediatric. The mean age of patients with hepatoblastoma was 3.1 y and 4.2 y in the Wilms group. Nine percent (n = 17) of patients underwent an unplanned reoperation after hepatectomy, and 4.1% (n = 24) of patients with Wilms experienced an unplanned reoperation. Over half of patients with hepatoblastoma (59.8%, n = 113) and 29.7% (n = 174) patients with Wilms tumor received a blood transfusion in the perioperative period. Patients in both groups demonstrated low rates of surgical site infections, but 6.3% (n = 12) of hepatoblastoma patients showed evidence of sepsis.

CONCLUSIONS

This study will allow providers to more effectively counsel families of the common morbidities in the associated perioperative period following surgical resection of either solid tumor type including the substantial risk of blood transfusion.