PLK1 inhibition exhibits strong anti-tumoral activity in CCND1-driven breast cancer metastases with acquired palbociclib resistance

Palbociclib-based high-throughput combination drug screening identifies synergistic therapeutic options in HPV-negative head and neck squamous cell carcinoma

BACKGROUND

Deregulation of cell-cycle pathway is ubiquitously observed in human papillomavirus negative (HPV^neg) head and neck squamous cell carcinoma (HNSCC). Despite being an attractive target, CDK4/6 inhibition using palbociclib showed modest or conflicting results as monotherapy or in combination with platinum-based chemotherapy or cetuximab in HPV^neg HNSCC. Thus, innovative agents to augment the efficacy of palbociclib in HPV^neg HNSCC would be welcomed.

METHODS

A collection of 162 FDA-approved and investigational agents was screened in combinatorial matrix format, and top combinations were validated in a broader panel of HPV^neg HNSCC cell lines. Transcriptional profiling was conducted to explore the molecular mechanisms of drug synergy. Finally, the most potent palbociclib-based drug combination was evaluated and compared with palbociclib plus cetuximab or cisplatin in a panel of genetically diverse HPV^neg HNSCC cell lines and patient-derived xenograft models.

RESULTS

Palbociclib displayed limited efficacy in HPV^neg HNSCC as monotherapy. The high-throughput combination drug screening provided a comprehensive palbociclib-based drug-drug interaction dataset, whereas significant synergistic effects were observed when palbociclib was combined with multiple agents, including inhibitors of the PI3K, EGFR, and MEK pathways. PI3K pathway inhibitors significantly reduced cell proliferation and induced cell-cycle arrest in HPV^neg HNSCC cell lines when combined with palbociclib, and alpelisib (a PI3Kα inhibitor) was demonstrated to show the most potent synergy with particularly higher efficacy in HNSCCs bearing PIK3CA alterations. Notably, when compared with cisplatin and cetuximab, alpelisib exerted stronger synergism in a broader panel of cell lines. Mechanistically, RRM2-dependent epithelial mesenchymal transition (EMT) induced by palbociclib, was attenuated by alpelisib and cetuximab rather than cisplatin. Subsequently, PDX models with distinct genetic background further validated that palbociclib plus alpelisib had significant synergistic effects in models harboring PIK3CA amplification.

CONCLUSIONS

This study provides insights into the systematic combinatory effect associated with CDK4/6 inhibition and supports further initiation of clinical trials using the palbociclib plus alpelisib combination in HPV^neg HNSCC with PIK3CA alterations.

The Role of RNA-Binding Protein HuR in Lung Cancer by RNA Sequencing Analysis

Background: The overexpression of human antigen R (HuR) has been proven in various types of cancer and is associated with the poor survival lung cancer patients. HuR overexpression stabilizes the mRNA of tumor-promoting genes by binding with 3′-UTR AU-rich elements. However, the role of HuR in the proliferation of lung cancer is unclear.

Methods: HuR expression was assessed using immunohistochemistry of tumor tissue samples from ten patients with lung cancer and ten patients with benign lung disease. Gene, protein, mRNA, and lncRNA changes in A549 HuR knockdown (KD) cells were assessed by single-cell RNA sequencing analysis. Furthermore, cell proliferation, migration, and invasion were determined by Cell Counting Kit-8 (CCK-8) assays and Transwell assays with or without Matrigel. The cell cycle was assessed by propidium iodide staining. The protein level, mRNA level and half-life of PLK1 were detected by western blotting and RT-qPCR.

Results: In clinical patients, the expression of HuR was significantly higher in lung cancer patients than in patients with benign lung disease. RNA sequencing analysis of A549 HuR knockdown cells revealed that the main function of HuR was related to ribonucleoprotein complex biogenesis. HuR was found to regulate signaling pathways mainly related to the spliceosome, RNA transport and the cell cycle. HuR KD suppressed the proliferation, migration and invasion of A549 cells, indicating its promotive role in these processes.

Conclusion: These results demonstrate that HuR plays an important role in the progression of lung cancer.

GATA3 and MDM2 are synthetic lethal in estrogen receptor-positive breast cancers

Synthetic lethal interactions, where the simultaneous but not individual inactivation of two genes is lethal to the cell, have been successfully exploited to treat cancer. GATA3 is frequently mutated in estrogen receptor (ER)-positive breast cancers and its deficiency defines a subset of patients with poor response to hormonal therapy and poor prognosis. However, GATA3 is not yet targetable. Here we show that GATA3 and MDM2 are synthetically lethal in ER-positive breast cancer. Depletion and pharmacological inhibition of MDM2 significantly impaired tumor growth in GATA3-deficient models in vitro, in vivo and in patient-derived organoids/xenograft (PDOs/PDX) harboring GATA3 somatic mutations. The synthetic lethality requires p53 and acts via the PI3K/Akt/mTOR pathway. Our results present MDM2 as a therapeutic target in the substantial cohort of ER-positive, GATA3-mutant breast cancer patients. With MDM2 inhibitors widely available, our findings can be rapidly translated into clinical trials to evaluate in-patient efficacy.

Multistage pH-responsive codelivery liposomal platform for synergistic cancer therapy

Background

Small interfering RNA (siRNA) is utilized as a potent agent for cancer therapy through regulating the expression of genes associated with tumors. While the widely application of siRNAs in cancer treatment is severely limited by their insufficient biological stability and its poor ability to penetrate cell membranes. Targeted delivery systems hold great promise to selectively deliver loaded drug to tumor site and reduce toxic side effect. However, the elevated tumor interstitial fluid pressure and efficient cytoplasmic release are still two significant obstacles to siRNA delivery. Co-delivery of chemotherapeutic drugs and siRNA represents a potential strategy which may achieve synergistic anticancer effect. Herein, we designed and synthesized a dual pH-responsive peptide (DPRP), which includes three units, a cell-penetrating domain (polyarginine), a polyanionic shielding domain (ehG)n, and an imine linkage between them. Based on the DPRP surface modification, we developed a pH-responsive liposomal system for co-delivering polo-like kinase-1 (PLK-1) specific siRNA and anticancer agent docetaxel (DTX), D-Lsi/DTX, to synergistically exhibit anti-tumor effect.

Results

In contrast to the results at the physiological pH (7.4), D-Lsi/DTX lead to the enhanced penetration into tumor spheroid, the facilitated cellular uptake, the promoted escape from endosomes/lysosomes, the improved distribution into cytoplasm, and the increased cellular apoptosis under mildly acidic condition (pH 6.5). Moreover, both in vitro and in vivo study indicated that D-Lsi/DTX had a therapeutic advantage over other control liposomes. We provided clear evidence that liposomal system co-delivering siPLK-1 and DTX could significantly downregulate expression of PLK-1 and inhibit tumor growth without detectable toxic side effect, compared with siPLK-1-loaded liposomes, DTX-loaded liposomes, and the combinatorial administration.

Conclusion

These results demonstrate great potential of the combined chemo/gene therapy based on the multistage pH-responsive codelivery liposomal platform for synergistic tumor treatment.

Graphical Abstract

Spine‑specific downregulation of LAPTM5 expression promotes the progression and spinal metastasis of estrogen receptor‑positive breast cancer by activating glutamine‑dependent mTOR signaling

Estrogen receptor-positive (ER⁺) breast cancer (BC) is a malignancy that is prone to metastasis to the spine, which is difficult to treat and often results in poor prognosis. However, the mechanism underlying the tumorigenesis and spinal metastasis of ER⁺ BC remains unclear. Lysosomal protein transmembrane 5 (LAPTM5) has been reported as a tumor suppressor in several types of cancer, but its role in ER⁺ BC has not been described. Here, by analyzing a gene sequencing dataset and ER⁺ BC tissues, tumor-adjacent normal tissues and spinal metastatic tissues from patients and mouse models, we found that LAPTM5 expression is negatively related to the progression and spinal metastasis of ER⁺ BC. Subsequently, in vitro experiments demonstrated that downregulation of LAPTM5 expression promoted the proliferation, migration, and chemoresistance of ER⁺ BC cells by activating glutamine-dependent mTOR signaling. A high level of CX3CL1 could inhibit LAPTM5 expression, explaining how ER⁺ BC metastasized to the spine. Thus, we found that LAPTM5 functions as a tumor suppressor in ER⁺ BC and that the CX3CL/CX3CR1/LAPTM5/glutamine axis mediates the spinal metastasis of ER⁺ BC. This axis may be a promising therapeutic target for ER⁺ BC.

A human breast cancer-derived xenograft and organoid platform for drug discovery and precision oncology

Models that recapitulate the complexity of human tumors are urgently needed to develop more effective cancer therapies. We report a bank of human patient-derived xenografts (PDXs) and matched organoid cultures from tumors that represent the greatest unmet need: endocrine-resistant, treatment-refractory and metastatic breast cancers. We leverage matched PDXs and PDX-derived organoids (PDxO) for drug screening that is feasible and cost-effective with in vivo validation. Moreover, we demonstrate the feasibility of using these models for precision oncology in real time with clinical care in a case of triple-negative breast cancer (TNBC) with early metastatic recurrence. Our results uncovered a Food and Drug Administration (FDA)-approved drug with high efficacy against the models. Treatment with this therapy resulted in a complete response for the individual and a progression-free survival (PFS) period more than three times longer than their previous therapies. This work provides valuable methods and resources for functional precision medicine and drug development for human breast cancer.

Welm and colleagues present a biobank of human-derived xenografts and organoids and demonstrate its value for high-throughput drug screening and applied precision medicine.

Folate-mediated targeted PLK1 inhibition therapy for ovarian cancer: A comparative study of molecular inhibitors and siRNA therapeutics

PLK1 is a promising target for clinical treatment of diverse malignancies including ovarian cancer (OC), in which PLK1 over-expression is often correlated with poor prognosis and short survival. PLK1 can be blocked with small molecular inhibitors like volasertib (Vol) or silenced with PLK1-specific siRNA (siPLK1), hence effectively suppressing tumor growth. Surprisingly, despite intensive work on molecular inhibitor and siRNA therapeutics, there is no direct comparison between them reported for targeted tumor therapy. Herein, we employing folate as a ligand and polymersomes as a nanovehicle performed a comparative study on Vol and siPLK1 in inhibiting OC in vitro and in vivo. Folate-targeted polymersomal Vol and siPLK1 (termed as FA-Ps-Vol and FA-Ps-siPLK1, respectively) were both nano-sized and stable, and displayed an optimal FA density of 20% for SKOV-3 cells. Notably, FA-Ps-Vol and FA-Ps-siPLK1 exhibited an IC₅₀ of 193 and 770 nM, respectively, to SKOV-3 cells, indicating a greater potency of Vol than siPLK1. The markedly increased uptake for FA-Ps-Vol and FA-Ps-siPLK1 compared with respective non-targeted controls by SKOV-3 tumor xenografts in mice confirmed that FA mediates strong OC-targeting in vivo. Intriguingly, FA-Ps-Vol while greatly lessening toxic effects of Vol potently repressed tumor growth with a remarkable tumor inhibition rate (TIR) of 97% at 20 mg (i.e. 32.4 µmol) Vol equiv./kg. FA-Ps-siPLK1 achieved effective tumor inhibition (TIR = ca. 87% or 90%) at 2 or 4 mg (i.e. 0.15 or 0.3 µmol) siPLK1 equiv./kg without causing adverse effects. This comparative study highlights that molecular inhibitor has the advantage of easy dose escalation and potent protein inhibition at the expense of certain adverse effects while siRNA therapeutics has low toxicity with moderate protein inhibition in vivo. STATEMENT OF SIGNIFICANCE: PLK1 is a promising target for the development of innovative and specific treatments against diverse malignancies. Interestingly, despite intensive work on molecular inhibitors and siRNA against PLK1, little work has been directed to compare their efficacy in targeted tumor therapy. Here, we employed folate as a ligand and polymersomes as a nanovehicle and have performed a comparative study on volasertib and siPLK1 in inhibiting ovarian cancer in vitro and in vivo. Our data show that the dose of volasertib can be easily escalated to induce prominent antitumor efficacy at the expense of certain adverse effects, while siPLK1 brings about moderate protein inhibition and antitumor therapy without causing toxicity at two-orders-of-magnitude lower dose.

Identification of hub genes for early detection of bone metastasis in breast cancer

BACKGROUND

Globally, among all women, the most frequently detected and diagnosed and the most lethal type of cancer is breast cancer (BC). In particular, bone is one of the most frequent distant metastases 24in breast cancer patients and bone metastasis arises in approximately 80% of advanced patients. Thus, we need to identify and validate early detection markers that can differentiate metastasis from non-metastasis breast cancers.

METHODS

GSE55715, GSE103357, and GSE146661 gene expression profiling data were downloaded from the GEO database. There was 14 breast cancer with bone metastasis samples and 8 breast cancer tissue samples. GEO2R was used to screen for differentially expressed genes (DEGs). The volcano plots, Venn diagrams, and annular heatmap were generated by using the ggplot2 package. By using the cluster Profiler R package, KEGG and GO enrichment analyses of DEGs were conducted. Through PPI network construction using the STRING database, key hub genes were identified by cytoHubba. Finally, K-M survival and ROC curves were generated to validate hub gene expression.

RESULTS

By GO enrichment analysis, 143 DEGs were enriched in the following GO terms: extracellular structure organization, extracellular matrix organization, leukocyte migration class II protein complex, collagen tridermic protein complex, extracellular matrix structural constituent, growth factor binding, and platelet-derived growth factor binding. In the KEGG pathway enrichment analysis, DEGs were enriched in Staphylococcus aureus infection, Complement and coagulation cascades, and Asthma. By PPI network analysis, we selected the top 10 genes, including SLCO2B1, STAB1, SERPING1, HLA-DOA, AIF1, GIMAP4, C1orf162, HLA-DMB, ADAP2, and HAVCR2. By using TCGA and THPA databases, we validated 2 genes, SERPING1 and GIMAP4, that were related to the early detection of bone metastasis in BC.

CONCLUSIONS

2 abnormally expressed hub genes could play a pivotal role in the breast cancer with bone metastasis by affecting bone homeostasis imbalance in the bone microenvironment.

Combination of Abemaciclib following Eribulin Overcomes Palbociclib-Resistant Breast Cancer by Inhibiting the G2/M Cell Cycle Phase

Breast cancer remains a leading cancer burden among women worldwide. Acquired resistance of cyclin-dependent kinase (CDK) 4/6 inhibitors occurs in almost all hormone receptor (HR)-positive subtype cases, comprising 70% of breast cancers, although CDK4/6 inhibitors combined with endocrine therapy are highly effective. CDK4/6 inhibitors are not expected to cooperate with cytotoxic chemotherapy based on the basic cytotoxic chemotherapy mode of action that inhibits rapidly proliferating cells. The palbociclib-resistant preclinical model developed in the current study investigated whether the combination of abemaciclib, CDK4/6 inhibitor with eribulin, an antimitotic chemotherapy could be a strategy to overcome palbociclib-resistant HR-positive breast cancer. The current study demonstrated that sequential abemaciclib treatment following eribulin synergistically suppressed CDK4/6 inhibitor-resistant cells by inhibiting the G2/M cell cycle phase more effectively. The current study showed the significant association of the pole-like kinase 1 (PLK1) level and palbociclib resistance. Moreover, the cumulative PLK1 inhibition in the G2/M phase by each eribulin or abemaciclib proved to be a mechanism of the synergistic effect. The synergistic antitumor effect was also supported by in vivo study. The sequential combination of abemaciclib following eribulin merits further clinical trials to overcome resistance to CDK4/6 inhibitors in HR-positive breast cancer.

Prognostic value of tumor markers and ctDNA in patients with resectable gastric cancer receiving perioperative treatment: results from the CRITICS trial

AIM

To evaluate the prognostic value of tumor markers in a European cohort of patients with resectable gastric cancer.

METHODS

We performed a post hoc analysis of the CRITICS trial, in which 788 patients received perioperative therapy. Association between survival and pretreatment CEA, CA 19-9, alkaline phosphatase, neutrophils, hemoglobin and lactate dehydrogenase were explored in uni- and multivariable Cox regression analyses. Likelihoods to receive potentially curative surgery were investigated for patients without elevated tumor markers versus one of the tumor markers elevated versus both tumor markers elevated. The association between tumor markers and the presence of circulating tumor DNA (ctDNA) was explored in 50 patients with available ctDNA data.

RESULTS

In multivariable analysis, in which we corrected for allocated treatment and other baseline characteristics, elevated pretreatment CEA (HR 1.43; 95% CI 1.11-1.85, p < 0.001) and CA 19-9 (HR 1.79; 95% CI 1.42-2.25, p < 0.001) were associated with worse OS. Likelihoods to receive potentially curative surgery were 86%, 77% and 60% for patients without elevated tumor marker versus either elevated CEA or CA 19-9 versus both elevated, respectively (p < 0.001). Although both preoperative presence of ctDNA and tumor markers were prognostic for survival, no association was found between these two parameters.

CONCLUSION

CEA and CA 19-9 were independent prognostic factors for survival in a large cohort of European patients with resectable gastric cancer. No relationship was found between tumor markers and ctDNA. These factors could potentially guide treatment choices and should be included in future trials to determine their definitive position.

TRIAL REGISTRATION

ClinicalTrial.gov identifier: NCT00407186. EudraCT number: 2006-00413032.

A Unified Transcriptional, Pharmacogenomic, and Gene Dependency Approach to Decipher the Biology, Diagnostic Markers, and Therapeutic Targets Associated with Prostate Cancer Metastasis

Simple Summary

This manuscript demonstrates how integrated bioinformatic and statistical reanalysis of publicly available genomic datasets can be utilized to identify molecular pathways and biomarkers that may be clinically relevant to metastatic prostate cancer (mPrCa) progression. The most notable observation is that the transition from primary prostate cancer to mPrCa is characterized by upregulation of processes associated with DNA replication, metastasis, and events regulated by the serine/threonine kinase PLK1. Moreover, our analysis also identified over-expressed genes that may be exploited for potential targeted therapeutics and minimally invasive diagnostics and monitoring of mPrCa. The primary data analyzed were two transcriptional datasets for tissues derived from normal prostate, primary prostate cancer, and mPrCa. Also incorporated in the analysis were the transcriptional, gene dependency, and drug response data for hundreds of cell lines, including those derived from prostate cancer tissues.

Abstract

Our understanding of metastatic prostate cancer (mPrCa) has dramatically advanced during the genomics era. Nonetheless, many aspects of the disease may still be uncovered through reanalysis of public datasets. We integrated the expression datasets for 209 PrCa tissues (metastasis, primary, normal) with expression, gene dependency (GD) (from CRISPR/cas9 screen), and drug viability data for hundreds of cancer lines (including PrCa). Comparative statistical and pathways analyses and functional annotations (available inhibitors, protein localization) revealed relevant pathways and potential (and previously reported) protein markers for minimally invasive mPrCa diagnostics. The transition from localized to mPrCa involved the upregulation of DNA replication, mitosis, and PLK1-mediated events. Genes highly upregulated in mPrCa and with very high average GD (~1) are potential therapeutic targets. We showed that fostamatinib (which can target PLK1 and other over-expressed serine/threonine kinases such as AURKA, MELK, NEK2, and TTK) is more active against cancer lines with more pronounced signatures of invasion (e.g., extracellular matrix organization/degradation). Furthermore, we identified surface-bound (e.g., ADAM15, CD276, ABCC5, CD36, NRP1, SCARB1) and likely secreted proteins (e.g., APLN, ANGPT2, CTHRC1, ADAM12) that are potential mPrCa diagnostic markers. Overall, we demonstrated that comprehensive analyses of public genomics data could reveal potentially clinically relevant information regarding mPrCa.

Dysregulation of KIF14 regulates the cell cycle and predicts poor prognosis in cervical cancer: a study based on integrated approaches

Cervical cancer (CC) is the most common malignant tumor in females. Although persistent high-risk human papillomavirus (HPV) infection is a leading factor that causes CC, few women with HPV infection develop CC. Therefore, many mechanisms remain to be explored, such as aberrant expression of oncogenes and tumor suppressor genes. To identify promising prognostic factors and interpret the relevant mechanisms of CC, the RNA sequencing profile of CC was downloaded from the Cancer Genome Atlas and the Gene Expression Omnibus databases. The GSE63514 dataset was analyzed, and differentially expressed genes (DEGs) were obtained by weighted coexpression network analysis and the edgeR package in R. Fifty-three shared genes were mainly enriched in nuclear chromosome segregation and DNA replication signaling pathways. Through a protein-protein interaction network and prognosis analysis, the kinesin family member 14 (KIF14) hub gene was extracted from the set of 53 shared genes, which was overexpressed and associated with poor overall survival (OS) and disease-free survival (DFS) of CC patients. Mechanistically, gene set enrichment analysis showed that KIF14 was mainly enriched in the glycolysis/gluconeogenesis signaling pathway and DNA replication signaling pathway, especially in the cell cycle signaling pathway. RT-PCR and the Human Protein Atlas database confirmed that these genes were significantly increased in CC samples. Therefore, our findings indicated the biological function of KIF14 in cervical cancer and provided new ideas for CC diagnosis and therapies.

TBC1D9: An Important Modulator of Tumorigenesis in Breast Cancer

Triple-negative breast cancer (TNBC) is a major concern among the different subtypes of breast cancer (BC) due to the lack of effective treatment. In a previous study by our group aimed at understanding the difference between TNBC and non-TNBC tumors, we identified the gene TBC1 domain family member 9 (TBC1D9), the expression of which was lower in TNBC as compared to non-TNBC tumors. In the present study, analysis of TBC1D9 expression in TNBC (n = 58) and non-TNBC (n = 25) patient tumor samples validated that TBC1D9 expression can differentiate TNBC (low) from non-TNBC (high) samples and that expression of TBC1D9 was inversely correlated with grade and proliferative index. Moreover, we found that downregulation of the TBC1D9 gene decreases the proliferation marginally in non-TNBC and was associated with increased migratory and tumorigenic potential in both TNBC and luminal BC cell lines. This increase was mediated by the upregulation of ARL8A, ARL8B, PLK1, HIF1α, STAT3, and SPP1 expression in TBC1D9 knockdown cells. Our results suggest that TBC1D9 expression might limit tumor aggressiveness and that it has a differential expression in TNBC vs. non-TNBC tumors.

Oncogenic FGFR Fusions Produce Centrosome and Cilia Defects by Ectopic Signaling

A single primary cilium projects from most vertebrate cells to guide cell fate decisions. A growing list of signaling molecules is found to function through cilia and control ciliogenesis, including the fibroblast growth factor receptors (FGFR). Aberrant FGFR activity produces abnormal cilia with deregulated signaling, which contributes to pathogenesis of the FGFR-mediated genetic disorders. FGFR lesions are also found in cancer, raising a possibility of cilia involvement in the neoplastic transformation and tumor progression. Here, we focus on FGFR gene fusions, and discuss the possible mechanisms by which they function as oncogenic drivers. We show that a substantial portion of the FGFR fusion partners are proteins associated with the centrosome cycle, including organization of the mitotic spindle and ciliogenesis. The functions of centrosome proteins are often lost with the gene fusion, leading to haploinsufficiency that induces cilia loss and deregulated cell division. We speculate that this complements the ectopic FGFR activity and drives the FGFR fusion cancers.

Network Pharmacological Analysis through a Bioinformatics Approach of Novel NSC765600 and NSC765691 Compounds as Potential Inhibitors of CCND1/CDK4/PLK1/CD44 in Cancer Types

Simple Summary

Around 14 million new cancer cases, rate are reported annually, with high mortality worldswide, several mechanisms are associated with complexities in cancer, which leads to resistance to current therapeutic interventions in cancer patients. The aim of this study was to identify molecular genes responsible for cancer development, progression and resistances to therapeutic intervention, and also evaluate the potency of our novel compounds NSC7565600 and NSC765691 as potential target for these oncogenes. Using bioinformatics, we successfully identified CCND1/CDK4/PLK1/CD44 as oncogenic signatures, which drives cancer progression and resistance to treatment, and as potential druggable candidates for both NSC7565600 and NSC765691 small molecules. We also showed the antiproliferative and cytotoxic effects of these compounds against a panel of NCI-60 cancer cell lines. This suggests the potential of NSC765600 and NSC765691 compounds to inhibit CCND1/CDK4/PLK1/CD44 expressions in cancer.

Abstract

Cyclin D1 (CCND1) and cyclin-dependent kinase 4 (CDK4) both play significant roles in regulating cell cycle progression, while polo-like kinase 1 (PLK1) regulates cell differentiation and tumor progression, and activates cancer stem cells (CSCs), with the cluster of differentiation 44 (CD44) surface marker mostly being expressed. These oncogenes have emerged as promoters of metastasis in a variety of cancer types. In this study, we employed comprehensive computational and bioinformatics analyses to predict drug targets of our novel small molecules, NSC765600 and NSC765691, respectively derived from diflunisal and fostamatinib. The target prediction tools identified CCND1/CDK4/PLK1/CD44 as target genes for NSC765600 and NSC765691 compounds. Additionally, the results of our in silico molecular docking analysis showed unique ligand–protein interactions with putative binding affinities of NSC765600 and NSC765691 with CCND1/CDK4/PLK1/CD44 oncogenic signaling pathways. Moreover, we used drug-likeness precepts as our guidelines for drug design and development, and found that both compounds passed the drug-likeness criteria of molecular weight, polarity, solubility, saturation, flexibility, and lipophilicity, and also exhibited acceptable pharmacokinetic properties. Furthermore, we used development therapeutics program (DTP) algorithms and identified similar fingerprints and mechanisms of NSC765600 and NSC765691 with synthetic compounds and standard anticancer agents in the NCI database. We found that NSC765600 and NSC765691 displayed antiproliferative and cytotoxic effects against a panel of NCI-60 cancer cell lines. Based on these finding, NSC765600 and NSC765691 exhibited satisfactory levels of safety with regard to toxicity, and met all of the required criteria for drug-likeness precepts. Currently, further in vitro and in vivo investigations in tumor-bearing mice are in progress to study the potential treatment efficacies of the novel NSC765600 and NSC765691 small molecules.

Estetrol Combined to Progestogen for Menopause or Contraception Indication Is Neutral on Breast Cancer

Simple Summary

Hormonal treatments, especially those used to treat menopause symptoms are known to increase breast cancer risk. It is thus necessary to identify new formulations with a better benefit/risk profile. The aim of this translational study was to evaluate the breast cancer risk associated with a combination of a natural estrogen named estetrol, with progestogens such as natural progesterone and drospirenone. Since the assessment of breast cancer risk in patients during drug development is not possible given the requirement of long-term studies in large populations, this study provides new evidence that a therapeutic dose of estetrol for menopause treatment or contraception, combined with progesterone or drospirenone, may provide a better benefit/risk profile toward breast cancer risk compared to the hormonal treatments currently available for patients.

Abstract

Given the unequivocal benefits of menopause hormone therapies (MHT) and combined oral contraceptives (COC), there is a clinical need for new formulations devoid of any risk of breast cancer promotion. Accumulating data from preclinical and clinical studies support that estetrol (E4) is a promising natural estrogen for MHT and COC. Nevertheless, we report here that E4 remains active on the endometrium, even under a dose that is neutral on breast cancer growth and lung metastasis dissemination. This implies that a progestogen should be combined with E4 to protect the endometrium of non-hysterectomized women from hyperplasia and cancer. Through in vivo observations and transcriptomic analyses, our work provides evidence that combining a progestogen to E4 is neutral on breast cancer growth and dissemination, with very limited transcriptional impact. The assessment of breast cancer risk in patients during the development of new MHT or COC is not possible given the requirement of long-term studies in large populations. This translational preclinical research provides new evidence that a therapeutic dose of E4 for MHT or COC, combined with progesterone or drospirenone, may provide a better benefit/risk profile towards breast cancer risk compared to hormonal treatments currently available for patients.

Deciphering the performance of polo-like kinase 1 in triple-negative breast cancer progression according to the centromere protein U-phosphorylation pathway

In general, the lack of effective therapeutic targets has led to the poor prognosis of triple-negative breast cancer (TNBC). Polo-like kinase 1 (PLK1) has been studied extensively as an effective therapeutic objective for the progression of tumor. Although the fundamental strategy and function of PLK1 in TNBC are still unclear. Here, we demonstrated that PLK1 upregulation was significantly correlated with poor prognosis in breast cancer cases utilizing the TCGA database. Additionally, ectopic PLK1 expression promoted TNBC cell proliferation, VEGFA production, and endothelial cell tube formation, whereas PLK1 knockdown induced the opposite effects. Moreover, expression of PLK1 K82R, the kinase-dead mutant of PLK1, completely inhibited PLK1-mediated cell proliferation, VEGFA production, and tube formation. Gene Set Enrichment Analysis (GSEA) showed that PLK1 expression significantly correlated with mitosis and the VEGF signaling pathway. We further observed that PLK1 phosphorylated centromere protein U (CENPU) at residue T78, thereby regulating the signaling pathway of COX-2/HIF-1α/VEGFA and the metaphase-anaphase transition of mitosis. The mechanism underlying the activity of PLK1 was also determined using a TNBC xenograft mouse model. Moreover, a PLK1 inhibitor effectively inhibited TNBC progression. Taken together, our results revealed that PLK1 plays an important role in TNBC progression via its kinase activity and phosphorylation of CENPU. Thus, PLK1 is an effective therapeutic objective for TNBC.

The AMBRA1 E3 ligase adaptor regulates the stability of cyclin D

The initiation of cell division integrates a large number of intra- and extracellular inputs. D-type cyclins (hereafter, cyclin D) couple these inputs to the initiation of DNA replication¹. Increased levels of cyclin D promote cell division by activating cyclin-dependent kinases 4 and 6 (hereafter, CDK4/6), which in turn phosphorylate and inactivate the retinoblastoma tumour suppressor. Accordingly, increased levels and activity of cyclin D-CDK4/6 complexes are strongly linked to unchecked cell proliferation and cancer^2,3. However, the mechanisms that regulate levels of cyclin D are incompletely understood^4,5. Here we show that autophagy and beclin 1 regulator 1 (AMBRA1) is the main regulator of the degradation of cyclin D. We identified AMBRA1 in a genome-wide screen to investigate the genetic basis of  the response to CDK4/6 inhibition. Loss of AMBRA1 results in high levels of cyclin D in cells and in mice, which promotes proliferation and decreases sensitivity to CDK4/6 inhibition. Mechanistically, AMBRA1 mediates ubiquitylation and proteasomal degradation of cyclin D as a substrate receptor for the cullin 4 E3 ligase complex. Loss of AMBRA1 enhances the growth of lung adenocarcinoma in a mouse model, and low levels of AMBRA1 correlate with worse survival in patients with lung adenocarcinoma. Thus, AMBRA1 regulates cellular levels of cyclin D, and contributes to cancer development and the response of cancer cells to CDK4/6 inhibitors.

Circular RNA ZNF609 promotes the malignant progression of glioma by regulating miR-1224-3p/PLK1 signaling

Objective: Previous studies have demonstrated that circular RNAs (circRNAs) play vital roles in pathological process of various diseases, including tumors. This study aimed at exploring the role and mechanism of circRNA RNA ZNF609 (circ-ZNF609) in the occurrence and development of glioma. Materials and methods: Real-time quantitative PCR (qRT-PCR) was applied to measure the expression of circ-ZNF609, miRNA-1224-3p (miR-1224-3p) and Polo-like kinase 1 (PLK1) in glioma tissues and cell lines. Furthermore, the association between circ-ZNF609 and clinical features of glioma was analyzed. CCK8 assay, EdU assay and Transwell assay were conducted to detect the effect of circ-ZNF609, miR-1224-3p and PLK1 on proliferation, migration and invasion in glioma cells. Then, we investigated the underlying mechanism of circ-ZNF609 by bioinformatics analysis, luciferase reporter assay, RNA immunoprecipitation (RIP), qRT-PCR and western blotting assay. Results: Circ-ZNF609 was confirmed prominently upregulated in glioma. Inhibition of circ-ZNF609 could obviously suppress glioma cell proliferation, migration and invasion, while overexpression of circ-ZNF609 promoted glioma growth and metastasis. In vivo, xenotransplanted tumor model also showed that overexpression of circ-ZNF609 could promote in vivo glioma growth. Mechanistically, circ-ZNF609 could promote PLK1 expression via binding to miR-1224-3p, circ-ZNF609/miR-1224-3p/PLK1 was shown responsible for circ-ZNF609 promoting glioma growth and metastasis. Conclusion: Together, our results revealed that circ-ZNF609 elevates glioma growth and metastasis via enforcing PLK1 expression by competitively binding miR-1224-3p, suggesting that circ-ZNF609 might be an underlying therapeutic target for glioma.

Treatment of Luminal Metastatic Breast Cancer beyond CDK4/6 Inhibition: Is There a Standard of Care in Clinical Practice?

BACKGROUND

CDK4/6 inhibitors have become the standard for first-line treatment of metastatic luminal breast cancer based on consistent data from several phase 3 trials demonstrating clinically meaningful improvement of progression-free as well as overall survival. In addition, they are about to become a part of adjuvant treatment for patients with high-risk luminal disease based on positive results from the first randomized phase 3 trial on abemaciclib. Nevertheless, the majority of patients with advanced or metastatic luminal breast cancer and prospectively a relevant proportion of patients treated in the adjuvant setting will eventually develop resistance to this endocrine based combination within 12-36 months, depending on the line of treatment.

CONCLUSION

Potential subsequent therapies include PI3K inhibitors, mTOR inhibitors, endocrine monotherapy, PARP inhibitors, and chemotherapy. However, these therapies have mainly been developed in the pre-CDK4/6 inhibitor era and little is known about potential cross-resistance. The concept of continuing CDK4/6 inhibition beyond progression is supported by some preclinical data, but to date there is very limited clinical evidence to support this strategy. Therefore, treatment of metastatic luminal breast cancer after progression on CDK4/6 inhibitors remains a challenge.

KEY MESSAGES

Here we review current evidence from pro- and retrospective studies and give an outlook on future developments with respect to novel therapeutic agents, including oral SERD and AKT inhibitors, which have the potential to change the therapeutic landscape in the future. Furthermore, clinical treatment algorithms and current research will also be discussed.

Expression and Gene Regulation Network of Metabolic Enzyme Phosphoglycerate Mutase Enzyme 1 in Breast Cancer Based on Data Mining

The metabolic enzyme phosphoglycerate mutase enzyme 1 (PGAM1) is a key enzyme in the glycolysis pathway, and glycolysis is closely related to cancer progression, suggesting that PGAM1 may have important functions in breast cancer. We used sequencing data from the Oncomine database and UALCAN database to analyze the expression of PGAM1 and its influence on the clinicopathological characteristics of breast cancer. LinkedOmics was used to identify genes related to PGAM1 expression, kinases, miRNAs, and transcription factors that were significantly related to PGAM1 through GSEA. cBioPortal was used to identify the alternation frequency and form of PGAM1 in breast cancer. The expression level of PGAM1 in breast cancer was significantly higher than that in normal tissues. Moreover, the expression level of PGAM1 is closely related to the molecular subtype and TP53 mutation status. The expression level of PGAM1 in HER2-positive and triple-negative tumors was significantly higher than that of luminal type. The expression level of PGAM1 in TP53-mutant tumors was higher than that in non-TP53-mutant tumors. In addition, the overall survival of patients with high PGAM1 expression was significantly worse than that of patients with low expression ( $P=0.0077$ ). Through GSEA analysis, we found multiple kinases, miRNAs, and transcription factors significantly related to PFKFB4. cBioPortal analysis showed that the mutation rate of PGAM1 in breast cancer was relatively low (4%), and the main form of mutation was high mRNA expression. This study suggests that PGAM1 is a potential diagnostic and prognostic marker in breast cancer. Through data mining, we revealed the potential regulatory network information of PGAM1, laying a foundation for further research on the role of PGAM1 in breast cancer.

In vitro bone metastasis dwelling in a 3D bioengineered niche

Bone is the most frequent metastasis site for breast cancer. As well as dramatically increasing disease burden, bone metastases are also an indicator of poor prognosis. One of the main challenges in investigating bone metastasis in breast cancer is engineering in vitro models that replicate the features of in vivo bone environments. Such in vitro models ideally enable the biology of the metastatic cells to mimic their in vivo behavior as closely as possible. Here, taking benefit of cutting-edge technologies both in microfabrication and cancer cell biology, we have developed an in vitro breast cancer bone-metastasis model. To do so we first 3D printed a bone scaffold that reproduces the trabecular architecture and that can be conditioned with osteoblast-like cells, a collagen matrix, and mineralized calcium. We thus demonstrated that this device offers an adequate soil to seed primary breast cancer bone metastatic cells. In particular, patient-derived xenografts being considered as a better approach than cell lines to achieve clinically relevant results, we demonstrate the ability of this biomimetic bone niche model to host patient-derived xenografted metastatic breast cancer cells. These patient-derived xenograft cells show a long-term survival in the bone model and maintain their cycling propensity, and exhibit the same modulated drug response as in vivo. This experimental system enables access to the idiosyncratic features of the bone microenvironment and cancer bone metastasis, which has implications for drug testing.

The Involvement of the hsa_circ_0088494-miR-876-3p-CTNNB1/CCND1 Axis in Carcinogenesis and Progression of Papillary Thyroid Carcinoma

Recently, growing studies have demonstrated that circular RNAs (circRNAs) function as critical players in multiple human tumors, including papillary thyroid carcinoma (PTC). However, the expression and underlying potential mechanism of circRNAs in PTC are still not fully elucidated. In this study, 14 candidate differentially expressed circRNAs (DECs) between normal thyroid tissues and benign thyroid tissues or PTC were first screened using the GSE93522 dataset by the GEO2R online tool. Then, the structural loop graphs of these 14 circRNAs were obtained through the CSCD database. After performing miRNA co-prediction by combination of CSCD and CRI databases, a potential circRNA-miRNA sub-network, consisting of 9 circRNAs and 21 miRNAs, was successfully constructed. Subsequently, the expression and prognostic values of these miRNAs were further determined by starBase, and two miRNAs, namely, miR-605-5p and miR-876-3p, were identified as key miRNAs in PTC. Then, their downstream target genes were predicted by the miRNet database. CTNNB1 and CCND1 were found to be two most potential targets of miR-876-3p by combination of multiple in silico analyses, including protein–protein interaction (PPI), hub gene screening, correlation analysis, and expression analysis. Conclusively, we established a key hsa_circ_0088494-miR-876-3p-CTNNB1/CCND1 axis linked to carcinogenesis and progression of PTC, which may provide promising therapeutic targets in treating PTC in the future.

Real life efficacy of palbociclib and endocrine therapy in HR positive, HER2 negative advanced breast cancer

BACKGROUND

Palbociclib is indicated for the treatment of hormone receptor-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC), in combination with endocrine therapy. Emerging real-life data suggest that the efficacy of a palbociclib-based therapy is highly conserved. We report the Institut Curie hospital experience.

PATIENTS AND METHODS

We retrospectively reviewed all patients with HR + HER2- ABC treated with a palbociclib-based therapy as first or second line for ABC, with an initial prescription from November 2016 to December 2018. Clinical, laboratory and imaging data were retrieved from electronic records. Data lock was December 31st, 2019. Descriptive analyses, univariate and multivariate Cox regression analyses were performed.

RESULTS

We included 310 consecutive patients. Median age was 61.8 years old. Palbociclib was prescribed in first line in 225 patients (72.6%). Before palbociclib-based therapy initiation, 122 patients (39.3%) were endocrine naive, 96 (31.0%) endocrine sensitive and 92 (29.7%) endocrine resistant. Median follow-up was 20.7 months. Median progression free survival (PFS) was 23.4 months (95%CI: 21.6-NR) in endocrine naive patients, 22.7 months (95%CI: 14.7-NR) in endocrine sensitive, and 13.4 months (95%CI: 10.7-20.8) in endocrine resistant. At 12 months from the initiation of palbociclib, 94.5% of patients were alive. By multivariate analysis, poor prognosis factors for PFS were identified in the endocrine naive/sensitive population: initial ECOG status 2, previous endocrine therapy for ABC, 3 metastatic sites or more. Toxicity profile was similar to previously published data.

CONCLUSION

In a non-selected population of patients with HR + HER2- ABC, the efficacy and safety data are strikingly similar to those previously reported.