High LIN28A and PLK4 co‑expression is associated with poor prognosis in epithelial ovarian cancer

The microRNA Let-7 and its exosomal form: Epigenetic regulators of gynecological cancers

Many types of gynecological cancer (GC) are often silent until they reach an advanced stage, and are therefore often diagnosed too late for effective treatment. Hence, there is a real need for more efficient diagnosis and treatment for patients with GC. During recent years, researchers have increasingly studied the impact of microRNAs cancer development, leading to a number of applications in detection and treatment. MicroRNAs are a particular group of tiny RNA molecules that regulate regular gene expression by affecting the translation process. The downregulation of numerous miRNAs has been observed in human malignancies. Let-7 is an example of a miRNA that controls cellular processes as well as signaling cascades to affect post-transcriptional gene expression. Recent research supports the hypothesis that enhancing let-7 expression in those cancers where it is downregulated may be a potential treatment option. Exosomes are tiny vesicles that move through body fluids and can include components like miRNAs (including let-7) that are important for communication between cells. Studies proved that exosomes are able to enhance tumor growth, angiogenesis, chemoresistance, metastasis, and immune evasion, thus suggesting their importance in GC management.

Preclinical characterization and clinical trial of CFI-400945, a polo-like kinase 4 inhibitor, in patients with relapsed/refractory acute myeloid leukemia and higher-risk myelodysplastic neoplasms

CFI-400945 is a selective oral polo-like kinase 4 (PLK4) inhibitor that regulates centriole duplication. PLK4 is aberrantly expressed in patients with acute myeloid leukemia (AML). Preclinical studies indicate that CFI-400945 has potent in vivo efficacy in hematological malignancies and xenograft models, with activity in cells harboring TP53 mutations. In this phase 1 study in very high-risk patients with relapsed/refractory AML and myelodysplastic syndrome (MDS) (NCT03187288), 13 patients were treated with CFI-400945 continuously in dose escalation from 64 mg/day to 128 mg/day. Three of the 9 efficacy evaluable AML patients achieved complete remission (CR). Two of 4 AML patients (50%) with TP53 mutations and complex monosomal karyotype achieved a CR with 1 patient proceeding to allogenic stem cell transplant. A third patient with TP53 mutated AML had a significant reduction in marrow blasts by > 50% with an improvement in neutrophil and platelet counts. Responses were observed after 1 cycle of therapy. Dose-limiting toxicity was enteritis/colitis. A monotherapy and combination therapy study with a newer crystal form of CFI-400945 in patients with AML, MDS and chronic myelomonocytic leukemia (CMML) is ongoing (NCT04730258).

Prolonged overexpression of PLK4 leads to formation of centriole rosette clusters that are connected via canonical centrosome linker proteins

Centrosome amplification is a hallmark of cancer and PLK4 is one of the responsible factors for cancer associated centrosome amplification. Increased PLK4 levels was also shown to contribute to generation of cells with centriole amplification in mammalian tissues as olfactory neuron progenitor cells. PLK4 overexpression generates centriole rosette (CR) structures which harbor more than two centrioles each. Long term PLK4 overexpression results with centrosome amplification, but the maturation of amplified centrioles in CRs and linking of PLK4 induced amplified centrosomes has not yet been investigated in detail. Here, we show evidence for generation of large clustered centrosomes which have more than 2 centriole rosettes and define these structures as centriole rosette clusters (CRCs) in cells that have high PLK4 levels for 2 consecutive cell cycles. In addition, we show that PLK4 induced CRs follow normal centrosomal maturation processes and generate CRC structures that are inter-connected with canonical centrosomal linker proteins as C-Nap1, Rootletin and Cep68 in the second cell cycle after PLK4 induction. Increased PLK4 levels in cells with C-Nap1 and Rootletin knock-out resulted with distanced CRs and CRCs in interphase, while Nek2 knock-out inhibited separation of CRCs in prometaphase, providing functional evidence for the binding of CRC structures with centrosomal linker proteins. Taken together, these results suggest a cell cycle dependent model for PLK4 induced centrosome amplification which occurs in 2 consecutive cell cycles: (i) CR state in the first cell cycle, and (ii) CRC state in the second cell cycle.

Tumor polo-like kinase 4 protein expression reflects lymphovascular invasion, higher Federation of Gynecology and Obstetrics stage, and shortened survival in endometrial cancer patients who undergo surgical resection

BACKGROUND

Polo-like kinase 4 (PLK4) serves as a marker for tumor features and poor outcomes in cancers. This study aimed to explore the associations of tumor PLK4 protein expression with tumor characteristics and survival in endometrial cancer (EC) patients who underwent surgical resection.

METHODS

This study included 142 EC patients who underwent surgical resection. Tumor tissue samples were obtained for tumor PLK4 protein expression detection via immunohistochemistry (IHC).

RESULTS

Among EC patients, 26.1% had a PLK4 IHC score of 0, 24.6% had a score of 1-3, 27.5% had a score of 4-6, and 21.8% had a score of 7-12. Tumor PLK4 protein expression positively associated with lymphovascular invasion (P = 0.008) and Federation of Gynecology and Obstetrics (FIGO) stage (P = 0.005). Disease-free survival (DFS) was not different between patients with tumor PLK4 IHC scores > 0 and ≤ 0 (P = 0.154) but was reduced in patients with scores > 3 vs. ≤ 3 (P = 0.009) and > 6 vs. ≤ 6 (P < 0.001). Similarly, overall survival (OS) was not different between patients with scores > 0 and ≤ 0 (P = 0.322) but was shorter in patients with scores > 3 vs. ≤ 3 (P = 0.011) and > 6 vs. ≤ 6 (P = 0.006). After adjustment, a tumor PLK4 IHC score > 6 (vs. ≤ 6) (hazard ratio (HR): 3.156, P = 0.008) or > 3 (vs. ≤ 3) (HR: 3.918, P = 0.026) was independently associated with shortened DFS and OS.

CONCLUSION

A tumor PLK4 IHC score > 6 or > 3 associates with shortened DFS and OS in EC patients who undergo surgical resection.

Role of the RNA-binding protein family in gynecologic cancers

Gynecological cancers pose a threat to women's health. Although early-stage gynecological cancers show good outcomes after standardized treatment, the prognosis of patients with advanced, met-astatic, and recurrent cancers is poor. RNA-binding proteins (RBPs) are important cellular proteins that interact with RNA through RNA-binding domains and participate extensively in post-transcriptional regulatory processes, such as mRNA alternative splicing, polyadenylation, intracellular localization and stability, and translation. Abnormal RBP expression affects the normal function of oncogenes and tumor suppressor genes in many malignancies, thus leading to the occurrence or progression of cancers. Similarly, RBPs play crucial roles in gynecological carcinogenesis. We summarize the role of RBPs in gynecological malignancies and explore their potential in the diagnosis and treatment of cancers. The findings summarized in this review may provide a guide for future research on the functions of RBPs.

Lin28A/CENPE Promoting the Proliferation and Chemoresistance of Acute Myeloid Leukemia

The prognosis of chemoresistant acute myeloid leukemia (AML) is still poor, mainly owing to the sustained proliferation ability of leukemic cells, while the microtubules have a major role in sustaining the continuity of cell cycle. In the present study, we have identified CENPE, a microtubular kinesin-like motor protein that is highly expressed in the peripheral blood of patients with chemoresistant AML. In our in vitro studies, knockdown of CENPE expression resulted in the suppression of proliferation of myeloid leukemia cells and reversal of cytarabine (Ara-C) chemoresistance. Furthermore, Lin28A, one of the RNA-binding oncogene proteins that increase cell proliferation and invasion and contribute to unfavorable treatment responses in certain malignancies, was found to be remarkably correlated with CENPE expression in chemoresistance AML. Overexpression of LIN28A promoted the proliferation and Ara-C chemoresistance of leukemic cells. RIP assay, RNA pull-down, and dual luciferase reporter analyses indicated that LIN28A bound specifically to the promoter region GGAGA of CENPE. In addition, the impacts of LIN28A on cell growth, apoptosis, cell cycle progression, and Ara-C chemoresistance were reverted by the knockdown of CENPE. Hence, Lin28A/CENPE has enhanced the proliferation and chemoresistance of AML, and therefore, it could be a prospective candidate for AML treatment.

Let-7i Reduces Aggressive Phenotype and Induces BRCAness in Ovarian Cancer Cells

High-grade serous carcinoma of the ovary is a deadly gynecological cancer with poor long-term survival. Dysregulation of microRNAs has been shown to contribute to the formation of cancer stem cells (CSCs), an important part of oncogenesis and tumor progression. The let-7 family of microRNAs has previously been shown to regulate stemness and has tumor suppressive actions in a variety of cancers, including ovarian. Here, we demonstrate tumor suppressor actions of let-7i: repression of cancer cell stemness, inhibition of migration and invasion, and promotion of apoptosis, features important for cancer progression, relapse, and metastasis. Let-7i over-expression results in increased sensitivity to the PARP inhibitor olaparib in samples without BRCA mutations, consistent with induction of BRCAness phenotype. We also show that let-7i inhibits the expression of several factors involved in the homologous recombination repair (HRR) pathway, providing potential mechanisms by which the BRCAness phenotype could be induced. These actions of let-7i add to the rationale for use of this miRNA as a treatment for ovarian cancer patients, including those without mutations in the HRR pathway.

Resistin Induces LIN28A-Mediated Let-7a Repression in Breast Cancer Cells Leading to IL-6 and STAT3 Upregulation

Simple Summary

Breast cancer is the second leading cause of cancer-related death in women in the United States and exhibits significant racial disparities in clinical outcomes. Earlier, we reported that the levels of resistin and IL-6 were significantly more elevated in the serum of African American women with breast cancer than in their Caucasian American counterparts. Here, we uncover its mechanistic significance by characterizing a novel resistin/LIN28A/Let-7a/IL-6/STAT3 signaling axis supporting the growth and stemness of breast cancer cells.

Abstract

Downregulation of the Let-7 family of microRNAs (miRNAs) has been reported in several cancers, including breast malignancy; however, underlying mechanisms are not completely understood. Resistin is an important component of the tumor microenvironment, having a functional impact on the tumor cell phenotypes. Here, we examined the role of resistin in the regulation of Let-7 miRNAs and studied its downstream consequences. We found that resistin treatment led to the reduced expression of Let-7 family miRNAs in breast cancer (BC) cells, with the highest downregulation reported for Let-7a. Furthermore, resistin induced the expression of LIN28A, and its silencing abrogated resistin-mediated Let-7a suppression. Let-7a restoration or LIN28A silencing abolished the resistin-induced growth, clonogenicity, and sphere-forming ability of BC cells. Restoration of Let-7a also suppressed the resistin-induced expression of genes associated with growth, survival, and stemness. Pathway analysis suggested STAT3 as a putative central node associated with Let-7a-mediated gene regulation. In silico analysis identified STAT3 and its upstream modifier, IL-6, as putative Let-7a gene targets, which were later confirmed by 3′UTR-reporter assays. Together, our findings demonstrate a novel resistin/LIN28A/Let-7a/IL-6/STAT3 signaling axis supporting the growth and stemness of BC cells.

Association Between LIN28A Gene Polymorphisms and Glioma Susceptibility in Chinese Children

Gliomas are the most prevalent brain tumors among children and adolescents. The occurrence and development of various malignant tumors is closely related with LIN28A gene, but its relationship with glioma susceptibility has not been widely discovered. In this case-control study, we conducted four single nucleotide polymorphisms (SNPs) (rs3811464 G>A, rs3811463 T>C, rs34787247 G>A, and rs11247957 G>A) of LIN28A gene to investigate whether they increase the risk of glioma. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate their relationship. There was no significant correlation between four SNPs and glioma risk in single polymorphism and conjoint analysis. However, in stratification analysis, we found that rs3811463 TC/CC may add to the risk of glioma with clinical stage III (adjusted OR = 3.16, 95% CI = 1.15-8.70, P = .026) or stage III+IV patients (adjusted OR = 2.05, 95% CI = 1.02-4.13, P = .044). Our research suggested that four SNPs of LIN28A gene have a weak relationship with the risk of glioma in Chinese children. LIN28A rs3811463 TC/CC may increase the possibility of glioma in clinical stage III or stage III+IV patients which need larger samples and further confirmation.

Modelling the Functions of Polo-Like Kinases in Mice and Their Applications as Cancer Targets with a Special Focus on Ovarian Cancer

Polo-like kinases (PLKs) belong to a five-membered family of highly conserved serine/threonine kinases (PLK1-5) that play differentiated and essential roles as key mitotic kinases and cell cycle regulators and with this in proliferation and cellular growth. Besides, evidence is accumulating for complex and vital non-mitotic functions of PLKs. Dysregulation of PLKs is widely associated with tumorigenesis and by this, PLKs have gained increasing significance as attractive targets in cancer with diagnostic, prognostic and therapeutic potential. PLK1 has proved to have strong clinical relevance as it was found to be over-expressed in different cancer types and linked to poor patient prognosis. Targeting the diverse functions of PLKs (tumor suppressor, oncogenic) are currently at the center of numerous investigations in particular with the inhibition of PLK1 and PLK4, respectively in multiple cancer trials. Functions of PLKs and the effects of their inhibition have been extensively studied in cancer cell culture models but information is rare on how these drugs affect benign tissues and organs. As a step further towards clinical application as cancer targets, mouse models therefore play a central role. Modelling PLK function in animal models, e.g., by gene disruption or by treatment with small molecule PLK inhibitors offers promising possibilities to unveil the biological significance of PLKs in cancer maintenance and progression and give important information on PLKs' applicability as cancer targets. In this review we aim at summarizing the approaches of modelling PLK function in mice so far with a special glimpse on the significance of PLKs in ovarian cancer and of orthotopic cancer models used in this fatal malignancy.

Impact of Lin28 on lymph node metastasis in papillary thyroid carcinoma

Lin28 is involved in the progression of several types of tumors. Data collected from clinical trials have suggested that Lin28 expression is correlated with poor prognosis in thyroid carcinoma. The present study was conducted to investigate the association between Lin28 expression and the clinicopathological parameters of papillary thyroid carcinoma (PTC). Accordingly, the clinical data and diagnostic results from 237 patients with PTC were collected. Immunohistochemical staining was performed to evaluate the Lin28 expression levels in thyroid tissue samples. Associations between the expression levels and clinicopathological parameters were evaluated. Lin28 was expressed in 96/237 (40.5%) of PTC specimens. Compared with patients with no Lin28 expression, patients with expression had higher rates of lymph node metastasis (P<0.001) and larger tumors (P=0.011). Multivariate analysis revealed that Lin28 was associated with lymph node metastasis. Next, bioinformatics analysis was performed based using the Gene Expression Omnibus database and The Cancer Genome Atlas database. Lin28 expression was associated with aggressive tumor characteristics, such as lymph node metastasis and larger tumors. In conclusion, the present study revealed that Lin28 expression served as a risk factor for lymph node metastasis. Accordingly, Lin28 expression may be used as a prognostic marker to predict lymph node metastasis in patients with PTC. In addition, Lin28 may serve as a therapeutic target in the management of this tumor type, which may help improve patient outcomes.

Detection and analysis of multiple biomarkers in ovarian cancer: clinical significance in diagnosis, treatment, and prognosis evaluation

BACKGROUND

The purpose of this study was to explore the clinical significance of CA125, CK7, CK20, ER, PR, C-erbb2, and P-gp in ovarian cancer.

METHODS

Ovarian cancer patients were recruited from Nantong Cancer Hospital between March 2006 and July 2011. The expressions of CA125, CK7, CK20, ER, PR, C-erbb2, and P-gp were determined by immunohistochemistry (IHC).The chi-square test (χ2) was used to analyze the correlation between each index and the clinical characteristics of the patients. The patients were followed up to record the cancer recurrence time. The Kaplan-Meier method was used to map the cumulative recurrence-free survival (RFS) rate, and COX regression analysis was established for multivariate analysis.

RESULTS

The results of IHC showed that the positive expression rates of CA125, CK7, ER, C-erbb2, and P-gp in malignant ovarian cancer tissues were significantly higher than those in benign ovarian cancer tissues. CA125 expression in malignant ovarian cancer was significantly correlated with the age of patients and the Federation of International Gynecology and Obstetrics (FIGO) stage. CK7 expression in malignant ovarian cancer was significantly correlated with the age, tissue differentiation, and number of residual lesions. CK20 expression in malignant ovarian cancer was significantly correlated with the age and tissue differentiation of the patients. ER expression in malignant ovarian cancer was significantly correlated with the age of patients and FIGO stage. PR expression in malignant ovarian cancer was significantly correlated with the age of the patients. C-erbb2 expression in malignant ovarian cancer was significantly correlated with the age of the patients. P-gp expression in malignant ovarian cancer was significantly correlated with the patient age, pathological type, and tissue differentiation. The expression of CA125, CK7, CK20, C-erbb2, and P-gp had significant effects on the prognosis of patients with ovarian cancer. The COX regression analysis showed that P-gp was an independent risk factor for ovarian cancer.

CONCLUSIONS

In malignant ovarian cancer tissues, CA125, CK7, CK20, ER, PR, C-erbb2, and P-gp are over-expressed. The expression of P-gp is an independent risk factor for ovarian cancer, and it can be an important target for the treatment of malignant ovarian cancer.

YLZ-F5, a novel polo-like kinase 4 inhibitor, inhibits human ovarian cancer cell growth by inducing apoptosis and mitotic defects

PURPOSE

Polo-like kinase 4 (PLK4), a member of the polo-like kinase family, plays several important roles in mitotic regulation, including centrosome duplication, spindle formation, and cytokinesis. PLK4 overexpression is frequently detected in many human cancers, including ovarian cancer, and the inhibition of PLK4 activity results in cancer cell mitotic arrest and apoptosis. Therefore, PLK4 might be a valid therapeutic target for antitumor therapy. In the present study, we aimed to determine if YLZ-F5, a potent small-molecule inhibitor of PLK4, inhibits ovarian cancer cell growth.

METHODS AND RESULTS

MTT assay showed that YLZ-F5 inhibited ovarian cancer cell proliferation in a concentration- and time-dependent manner. The results of colony formation assays were consistent with those of the MTT assay results. In addition, YLZ-F5 induced ovarian cancer cell apoptosis that was associated with activation of caspase-3/caspase-9. Moreover, YLZ-F5 caused aberrant in centriole duplication that was associated with the inhibition of PLK4 phosphorylation. Notably, we showed that YLZ-F5 promoted the accumulation of ovarian cancer cells with mitotic defects (> 4 N DNA content) in a concentration-dependent manner. Furthermore, YLZ-F5 markedly inhibited the migration of A2780 cells.

CONCLUSION

Taken together, these findings suggest that YLZ-F5 is a potential drug candidate for human ovarian cancer.

Targeting centrosome amplification, an Achilles' heel of cancer

Due to cell-cycle dysregulation, many cancer cells contain more than the normal compliment of centrosomes, a state referred to as centrosome amplification (CA). CA can drive oncogenic phenotypes and indeed can cause cancer in flies and mammals. However, cells have to actively manage CA, often by centrosome clustering, in order to divide. Thus, CA is also an Achilles' Heel of cancer cells. In recent years, there have been many important studies identifying proteins required for the management of CA and it has been demonstrated that disruption of some of these proteins can cause cancer-specific inhibition of cell growth. For certain targets therapeutically relevant interventions are being investigated, for example, small molecule inhibitors, although none are yet in clinical trials. As the field is now poised to move towards clinically relevant interventions, it is opportune to summarise the key work in targeting CA thus far, with particular emphasis on recent developments where small molecule or other strategies have been proposed. We also highlight the relatively unexplored paradigm of reversing CA, and thus its oncogenic effects, for therapeutic gain.

Polo-like kinase 4 correlates with greater tumor size, lymph node metastasis and confers poor survival in non-small cell lung cancer

BACKGROUND

Our study aimed to investigate the association of polo-like kinase 4 (PLK4) expression with tumor features as well as survival in non-small cell lung cancer (NSCLC) patients.

METHODS

Five hundred and sixty NSCLC patients who underwent pulmonary resection were recruited, and their tumor specimens were obtained. Immunohistochemistry (IHC) staining was performed to assess PLK4 expression in tumor specimen. Follow-up documents were reviewed, and the disease-free survival (DFS) and overall survival (OS) were evaluated.

RESULTS

According to IHC staining, there were 277 (49.5%) patients with PLK4 low expression and 283 (50.5%) patients with PLK4 high expression. PLK4 high expression was further classified into three different classes: high+, high++, high+++, and 122 (21.8%), 127 (22.7%), 34 (6.1%) patients were with PLK4 high+, high++, high+++ expression, respectively. Polo-like kinase 4 expression was correlated with larger tumor size, LYN metastasis, and higher TNM stage. As for survival, DFS and OS were lower in patients with PLK4 high expression compared with patients with PLK4 low expression. In addition, DFS and OS were the lowest in patients with PLK4 high+++ expression, followed by those with PLK4 high++ expression, PLK4 high+ expression, and then patients with PLK4 low expression. Univariate and multivariate Cox's proportional hazard regression model analyses further disclosed that PLK4 was an independent predictive factor for poor DFS and OS in NSCLC patients.

CONCLUSION

Our study preliminarily illuminates the clinical implication of PLK4 in NSCLC, while further studies are still needed to explicit the value of PLK4 in surveillance and treatment of NSCLC.

Safety and tolerability of CFI-400945, a first-in-class, selective PLK4 inhibitor in advanced solid tumours: a phase 1 dose-escalation trial

Background

CFI-400945 is a first-in-class oral inhibitor of polo-like kinase 4 (PLK4) that regulates centriole duplication. Primary objectives of this first-in-human phase 1 trial were to establish the safety and tolerability of CFI-400945 in patients with advanced solid tumours. Secondary objectives included pharmacokinetics, pharmacodynamics, efficacy, and recommended phase 2 dose (RP2D).

Methods

Continuous daily oral dosing of CFI-400945 was evaluated using a 3+3 design guided by incidence of dose-limiting toxicities (DLTs) in the first 28-day cycle. Safety was assessed by CTCAE v4.0. ORR and CBR were evaluated using RECIST v1.1.

Results

Forty-three patients were treated in dose escalation from 3 to 96 mg/day, and 9 were treated in 64 mg dose expansion. After DLT occurred at 96 and 72 mg, 64 mg was established as the RP2D. Neutropenia was a common high-grade (19%) treatment-related adverse event at ≥ 64 mg. Half-life of CFI-400945 was 9 h, with C_max achieved 2–4 h following dosing. One PR (45 cycles, ongoing) and two SD ≥ 6 months were observed (ORR = 2%; CBR = 6%).

Conclusions

CFI-400945 is well tolerated at 64 mg with dose-dependent neutropenia. Favourable pharmacokinetic profiles were achieved with daily dosing. Response rates were low without biomarker pre-selection. Disease-specific and combination studies are ongoing.

Trial Registration

Clinical Trials Registration Number – NCT01954316 (Oct 1st, 2013)

Comprehensive characterization of cancer-testis genes in testicular germ cell tumor

Cancer‐testis (CT) genes are a group of genes restrictedly expressed in testis and multiple cancers and can serve as candidate driver genes participating in the development of cancers. Our previous study identified a number of CT genes in nongerm cell tumors, but their expression pattern in testicular germ cell tumor (TGCT), a cancer type characterized by less genomic alterations, remained largely unknown. In this study, we systematically investigated the expression pattern of CT genes in TGCT samples and evaluated the transcriptome difference between TGCT and normal testis tissues, using datasets from the UCSC Xena platform, The Cancer Genome Atlas (TCGA) and the Genotype‐Tissue Expression (GTEx) project. Pathway enrichment analysis and survival analysis were conducted to evaluate the biological function and prognostic effect of expressed CT genes. We identified that 1036 testis‐specific expressed protein‐coding genes and 863 testis‐specific expressed long noncoding RNAs (lncRNAs) were expressed in TGCT samples, including 883 CT protein‐coding genes and 710 CT lncRNAs defined previously. The number of expressed CT genes was significantly higher in seminomas (P = 3.48 × 10⁻¹³) which were characterized by frequent mutations in driver genes (KIT, KRAS and NRAS). In contrast, the number of expressed CT genes showed a moderate negative correlation with the fraction of copy number altered genomes (cor = −0.28, P = 1.20 × 10⁻³). Unlike other cancers, our analysis revealed that 96.16% of the CT genes were down‐regulated in TGCT samples, while CT genes in stem cell maintenance related pathways were up‐regulated. Further survival analysis provided evidence that CT genes could also predict the prognosis of TGCT patients with both disease‐free interval and progression‐free interval as clinical endpoints. Taken together, our study provided a global view of CT genes in TGCT and provided evidence that CT genes played important roles in the progression and maintenance of TGCT.