Impact of the putative cancer stem cell markers and growth factor receptor expression on the sensitivity of ovarian cancer cells to treatment with various forms of small molecule tyrosine kinase inhibitors and cytotoxic drugs

Synergistic Effects of Neratinib in Combination With Palbociclib or Miransertib in Brain Cancer Cells

Background

Aberrant expression and activation of epidermal growth factor receptor (EGFR) resulted in approval of several forms of EGFR inhibitors in the treatment of patients with a wide range of epithelial cancers. However, no EGFR inhibitor has yet been approved for the treatment of patients with brain cancer, indicating that targeting EGFR alone may not be sufficient in some patients.

Methods

In this study, we investigated the role of all members of the EGFR family, other growth factor receptors, cell-cycle proteins, and downstream cell signaling pathways (e.g., mitogen-activated protein kinase (MAPK), serine/threonine protein kinase (AKT), signal transducer and activator of transcription (STAT3), Src, Abelson murine leukemia viral oncogene homolog (Abl)) on the growth of a panel of human brain cancer cell lines (HBCCLs). We examined the growth response of HBCCLs to treatment with 17 targeted agents compared to two cytotoxic drugs.

Results

Of the targeted agents, the irreversible pan-human epidermal growth factor receptor (HER) inhibitors neratinib and afatinib were more effective than erlotinib and lapatinib at inhibiting the growth of all HBCCLs, and the cyclin-dependent kinase (CDK)1/2/5/9 inhibitor dinaciclib was the most potent targeted agent. We found that treatment with Src/Abl/c-kit inhibitor dasatinib, signal transducer and activator of transcription (STAT3) inhibitor stattic, Abl/platelet-derived growth factor receptor (PDGFR)α/vascular endothelial growth factor (VEGFR)2/fibroblast growth factor receptor (FGFR)1 inhibitor ponatinib, and the tropomyosin receptor kinase (TRK)/ROS proto-oncogene 1 receptor tyrosine kinase (ROS)/anaplastic lymphoma kinase (ALK) inhibitor entrectinib, also inhibited the growth of all HBCCLs. Interestingly, these agents were more effective in inhibiting growth of HBCCLs when proliferating at a slower rate. In addition to inhibiting the proliferation of HBCCLs, treatment with neratinib, dinaciclib, dasatinib, stattic and trametinib inhibited the migration of brain tumor cell line A172.

Conclusions

Notably, we found that treatment with neratinib in combination with palbociclib (CDK4/6 inhibitor), or miransertib (AKT1/2/3 inhibitor) resulted in synergistic growth inhibition of all HBCCLs. Our results support that repurposing drugs like neratinib in combination with the palbociclib or miransertib may be of therapeutic potential in brain cancer and warrants further investigations.

Paradigm Shift: A Comprehensive Review of Ovarian Cancer Management in an Era of Advancements

Ovarian cancer (OC) is the female genital malignancy with the highest lethality. Patients present a poor prognosis mainly due to the late clinical presentation allied with the common acquisition of chemoresistance and a high rate of tumour recurrence. Effective screening, accurate diagnosis, and personalised multidisciplinary treatments are crucial for improving patients' survival and quality of life. This comprehensive narrative review aims to describe the current knowledge on the aetiology, prevention, diagnosis, and treatment of OC, highlighting the latest significant advancements and future directions. Traditionally, OC treatment involves the combination of cytoreductive surgery and platinum-based chemotherapy. Although more therapeutical approaches have been developed, the lack of established predictive biomarkers to guide disease management has led to only marginal improvements in progression-free survival (PFS) while patients face an increasing level of toxicity. Fortunately, because of a better overall understanding of ovarian tumourigenesis and advancements in the disease's (epi)genetic and molecular profiling, a paradigm shift has emerged with the identification of new disease biomarkers and the proposal of targeted therapeutic approaches to postpone disease recurrence and decrease side effects, while increasing patients' survival. Despite this progress, several challenges in disease management, including disease heterogeneity and drug resistance, still need to be overcome.

Anticancer and Biological Effects of Some Natural Compounds and Theoretical Investigation of them Against RdRP of SARS-COV-2: In Silico and In Vitro Studies

In this study, Skullcapflavone I and Skullcapflavone II molecules showed good inhibitory activities against α-glucosidase and sorbitol dehydrogenase enzymes with IC50 values of 102.66 ± 8.43 and 95.04 ± 11.52 nM for α-glucosidase and 38.42 ± 3.82 and 28.81 ± 3.26 µM for sorbitol dehydrogenase. The chemical activities of Skullcapflavone I and Skullcapflavone II against α-glucosidase and sorbitol dehydrogenase were assessed by conducting the molecular docking study. The anticancer activities of the compounds were examined against SW-626, SK-OV-3, OVCAR3, and Caov-3 cell lines. The chemical activities of Skullcapflavone I and Skullcapflavone II against some of the expressed surface receptor proteins (estrogen receptor, EGFR, androgen receptor, and GnRH receptor) in the mentioned cell lines were investigated using in silico calculations. Moreover, the activity of the compounds against RNA polymerase of SARS-COVE-2 was also assessed using the molecular modeling study. These compounds created strong contacts with the enzymes and receptors. The considerable binding affinity of the compounds to the enzymes and proteins showed their ability as inhibitors. Furthermore, even at modest dosages, these substances markedly reduced the viability of ovarian cancer cells. Additionally, the viability of ovarian cancer cells was significantly decreased by a 300 μM dosage of all compounds. Antiovarian cancer results of Skullcapflavone I on SK-OV-3, SW-626, OVCAR3, and Caov-3 were 63.14, 1.55, 19.42, and 52.04 µM, respectively. Also, cytotoxicity results of Skullcapflavone II on SK-OV-3, SW-626, OVCAR3, and Caov-3 were 5.18, 21.44, 33.87, and 72.66 µM, respectively.

Targeting receptor tyrosine kinases in ovarian cancer: Genomic dysregulation, clinical evaluation of inhibitors, and potential for combinatorial therapies

Epithelial ovarian cancer (EOC) remains one of the leading causes of cancer-related deaths among women worldwide. Receptor tyrosine kinases (RTKs) have long been sought as therapeutic targets for EOC, as they are frequently hyperactivated in primary tumors and drive disease relapse, progression, and metastasis. More recently, these oncogenic drivers have been implicated in EOC response to poly(ADP-ribose) polymerase (PARP) inhibitors and epigenome-interfering agents. This evidence revives RTKs as promising targets for therapeutic intervention of EOC. This review summarizes recent studies on the role of RTKs in EOC malignancy and the use of their inhibitors for clinical treatment. Our focus is on the ERBB family, c-Met, and VEGFR, as they are linked to drug resistance and targetable using commercially available drugs. The importance of these RTKs and their inhibitors is highlighted by their impact on signal transduction and intratumoral heterogeneity in EOC and successful use as maintenance therapy in the clinic through suppression of the VEGF/VEGFR axis. Finally, the therapeutic potential of RTK inhibitors is discussed in the context of combinatorial targeting via co-inhibiting proliferative and anti-apoptotic pathways, epigenomic/transcriptional programs, and harnessing the efficacy of PARP inhibitors and programmed cell death 1/ligand 1 immune checkpoint therapies.

The adaptor protein VEPH1 interacts with the kinase domain of ERBB2 and impacts EGF signaling in ovarian cancer cells

Upregulation of ERBB2 and activating mutations in downstream KRAS/BRAF and PIK3CA are found in several ovarian cancer histotypes. ERBB2 enhances signaling by the ERBB family of EGF receptors, and contains docking positions for proteins that transduce signaling through multiple pathways. We identified the adaptor protein ventricular zone-expressed pleckstrin homology domain-containing protein 1 (VEPH1) as a potential interacting partner of ERBB2 in a screen of proteins co-immunoprecipitated with VEPH1. In this study, we confirm a VEPH1 - ERBB2 interaction by co-immunoprecipitation and biotin proximity labelling and show that VEPH1 interacts with the juxtamembrane-kinase domain of ERBB2. In SKOV3 ovarian cancer cells, which bear a PIK3CA mutation and ERBB2 overexpression, ectopic VEPH1 expression enhanced EGF activation of ERK1/2, and mTORC2 activation of AKT. In contrast, in ES2 ovarian cancer cells, which bear a BRAF^V600E mutation with VEPH1 amplification but low ERBB2 expression, loss of VEPH1 expression enabled further activation of ERK1/2 by EGF and enhanced EGF activation of AKT. VEPH1 expression in SKOV3 cells enhanced EGF-induced cell migration consistent with increased Snail2 and decreased E-cadherin levels. In comparison, loss of VEPH1 expression in ES2 cells led to decreased cell motility independent of EGF treatment despite higher levels of N-cadherin and Snail2. Importantly, we found that loss of VEPH1 expression rendered ES2 cells less sensitive to BRAF and MEK inhibition. This study extends the range of adaptor function of VEPH1 to ERBB2, and indicates VEPH1 has differential effects on EGF signaling in ovarian cancer cells that may be influenced by driver gene mutations.

Dual Knockdown of Musashi RNA-Binding Proteins MSI-1 and MSI-2 Attenuates Putative Cancer Stem Cell Characteristics and Therapy Resistance in Ovarian Cancer Cells

In ovarian cancer, therapy resistance mechanisms complicate cancer cell eradication. Targeting Musashi RNA-binding proteins (MSI) may increase therapeutic efficacy. Database analyses were performed to identify gene expression associations between MSI proteins and key therapy resistance and cancer stem cell (CSC) genes. Then, ovarian cancer cells were subjected to siRNA-based dual knockdown of MSI-1 and MSI-2. CSC and cell cycle gene expression was investigated using quantitative polymerase chain reaction (qPCR), western blots, and flow cytometry. Metabolic activity and chemoresistance were assessed by MTT assay. Clonogenic assays were used to quantify cell survival post-irradiation. Database analyses demonstrated positive associations between MSI proteins and putative CSC markers NOTCH, MYC, and ALDH4A1 and negative associations with NOTCH inhibitor NUMB. MSI-2 expression was negatively associated with the apoptosis regulator p21. MSI-1 and MSI-2 were positively correlated, informing subsequent dual knockdown experiments. After MSI silencing, CSC genes were downregulated, while cell cycle progression was reduced. Metabolic activity was decreased in some cancer cells. Both chemo- and radioresistance were reduced after dual knockdown, suggesting therapeutic potential. Dual knockdown of MSI proteins is a promising venue to impede tumor growth and sensitize ovarian cancer cells to irradiation and chemotherapy.

In vitro modelling of the physiological and diseased female reproductive system

The maladies affecting the female reproductive tract (FRT) range from infections to endometriosis to carcinomas. In vitro models of the FRT play an increasingly important role in both basic and translational research, since the anatomy and physiology of the FRT of humans and other primates differ significantly from most of the commonly used animal models, including rodents. Using organoid culture to study the FRT has overcome the longstanding hurdle of maintaining epithelial phenotype in culture.  Both ECM-derived and engineered materials have proved critical for maintaining a physiological phenotype of FRT cells in vitro by providing the requisite 3D environment, ligands, and architecture. Advanced materials have also enabled the systematic study of factors contributing to the invasive metastatic processes. Meanwhile, microphysiological devices make it possible to incorporate physical signals such as flow and cyclic exposure to hormones. Going forward, advanced materials compatible with hormones and optimised to support FRT-derived cells' long-term growth, will play a key role in addressing the diverse array of FRT pathologies and lead to impactful new treatments that support the improvement of women's health. STATEMENT OF SIGNIFICANCE: The female reproductive system is a crucial component of the female anatomy. In addition to enabling reproduction, it has wide ranging influence on tissues throughout the body via endocrine signalling. This intrinsic role in regulating normal female biology makes it susceptible to a variety of female-specific diseases. However, the complexity and human-specific features of the reproductive system make it challenging to study. This has spurred the development of human-relevant in vitro models for helping to decipher the complex issues that can affect the reproductive system, including endometriosis, infection, and cancer. In this Review, we cover the current state of in vitro models for studying the female reproductive system, and the key role biomaterials play in enabling their development.

LncRNA SDHAP1 confers paclitaxel resistance of ovarian cancer by regulating EIF4G2 expression via miR-4465

Ovarian cancer has ranked as one of the leading causes of female morbidity and mortality around the world, which affects ∼239,000 patients and causes 152,000 deaths every year. Chemotherapeutic resistance of ovarian cancer remains a devastating actuality in clinic. The aberrant upregulation of long non-coding RNA succinate dehydrogenase complex flavoprotein subunit A pseudogene 1 (lncRNA SDHAP1) in the Paclitaxel (PTX)-resistant ovarian cancer cell lines has been reported. However, studies focussed on SDHAP1 in its regulatory function of chemotherapeutic resistance in ovarian cancer are limited, and the detailed mechanisms remain unclear. In this study, we demonstrated that SDHAP1 was upregulated in PTX-resistant SKOV3 and Hey-8 ovarian cancer cell lines while the level of miR-4465 was downregulated. Knocking-down SDHAP1 induced re-acquirement of chemo-sensitivity to PTX in ovarian cancer cells in vitro. Mechanically, SDHAP1 upregulated the expression of EIF4G2 by sponging miR-4465 and thus facilitated the PTX-induced apoptosis in ovarian cancer cells. The regulation network involving SDHAP1, miR-4465 and EIF4G2 could be a potential therapy target for the PTX-resistant ovarian cancer.

Determining the effects of trastuzumab, cetuximab and afatinib by phosphoprotein, gene expression and phenotypic analysis in gastric cancer cell lines

BACKGROUND

Gastric cancer is the fifth most frequently diagnosed cancer and the third leading cause of cancer death worldwide. The molecular mechanisms of action for anti-HER-family drugs in gastric cancer cells are incompletely understood. We compared the molecular effects of trastuzumab and the other HER-family targeting drugs cetuximab and afatinib on phosphoprotein and gene expression level to gain insights into the regulated pathways. Moreover, we intended to identify genes involved in phenotypic effects of anti-HER therapies.

METHODS

A time-resolved analysis of downstream intracellular kinases following EGF, cetuximab, trastuzumab and afatinib treatment was performed by Luminex analysis in the gastric cancer cell lines Hs746T, MKN1, MKN7 and NCI-N87. The changes in gene expression after treatment of the gastric cancer cell lines with EGF, cetuximab, trastuzumab or afatinib for 4 or 24 h were analyzed by RNA sequencing. Significantly enriched pathways and gene ontology terms were identified by functional enrichment analysis. Furthermore, effects of trastuzumab and afatinib on cell motility and apoptosis were analyzed by time-lapse microscopy and western blot for cleaved caspase 3.

RESULTS

The Luminex analysis of kinase activity revealed no effects of trastuzumab, while alterations of AKT1, MAPK3, MEK1 and p70S6K1 activations were observed under cetuximab and afatinib treatment. On gene expression level, cetuximab mainly affected the signaling pathways, whereas afatinib had an effect on both signaling and cell cycle pathways. In contrast, trastuzumab had little effects on gene expression. Afatinib reduced average speed in MKN1 and MKN7 cells and induced apoptosis in NCI-N87 cells. Following treatment with afatinib, a list of 14 genes that might be involved in the decrease of cell motility and a list of 44 genes that might have a potential role in induction of apoptosis was suggested. The importance of one of these genes (HBEGF) as regulator of motility was confirmed by knockdown experiments.

CONCLUSIONS

Taken together, we described the different molecular effects of trastuzumab, cetuximab and afatinib on kinase activity and gene expression. The phenotypic changes following afatinib treatment were reflected by altered biological functions indicated by overrepresentation of gene ontology terms. The importance of identified genes for cell motility was validated in case of HBEGF.

Pyrrole derivatives as potential anti-cancer therapeutics: synthesis, mechanisms of action, safety

Pyrrole derivatives (PDs) chloro-1-(4-chlorobenzyl)-4-((3-(trifluoromethyl)phenyl)amino)-1H-pyrrole-2,5-dione (MI-1) and 5-amino-4-(1,3-benzothyazol-2-yn)-1-(3-methoxyphenyl)-1,2-dihydro-3H-pyrrole-3-one (D1) were synthesised as inhibitors of several protein kinases including EGFR and VEGFR. The aim of the study was to reveal the exact mechanisms of PDs' action EGFR and VEGFR are involved in. We observed, that both PDs could bind with EGFR and VEGFR and form stable complexes. PDs entered into electrostatic interactions with polar groups of phospholipid heads in cell membrane, and the power of interaction depended on the nature of PD radical substituents (greater for MI-1 and smaller for D1). Partial intercalation of MI-1 into the membrane hydrophobic zone also occurred. PDs concentrations induced apoptosis in malignant cells but normal ones had different sensitivity to those. MI-1 and D1 acted like antioxidants in inflamed colonic tissue, as evidenced by reduce of lipid and protein peroxidation products (by 43-67%) and increase of superoxide dismutase activity (by 40 and 58%) with restoring these values to control ones. MI-1 restored reduced haemoglobin and normalised elevated platelets and monocytes in settings of colorectal cancer, whereas D1 normalised only platelets. Thus, MI-1 and D1 could be used as competitive inhibitors of EGFR and VEGFR and antioxidants, which might contribute to realisation of their anti-inflammatory, proapoptotic and antitumor activity.

Endocytic degradation of ErbB2 mediates the effectiveness of neratinib in the suppression of ErbB2-positive ovarian cancer

The tyrosine kinase receptor ErbB2 is frequently found to be overexpressed in multiple cancer types. Targeted therapeutic approaches against ErbB2 have shown promising results and received FDA approvals in the treatment of breast cancer. However, this approach has not been granted in ovarian cancers till now. In order to assess the validity of ErbB2-targeted therapy in ovarian cancer, we investigated the effectiveness of two FDA-approved tyrosine kinase inhibitors of ErbB2, lapatinib and neratinib, on the growth of ovarian cancers. We observed that both lapatinib and neratinib displayed inhibitory effects towards the proliferation and migration of ErbB2-positive ovarian cancer cells in vitro, with neratinib showing stronger suppression in general. Neratinib treatment led to the reduction of ErbB2 protein levels, with concomitant attenuation of the phosphorylation of AKT, MEK, and ERK1/2. Immunofluorescence assays revealed that neratinib induced the internalization and lysosomal degradation of ErbB2, which was accompanied by its hyperubiquitylation. Lapatinib and neratinib also repressed the in vivo growth of SKOV3 cells, and neratinib downregulated ErbB2 levels in xenograft tumors to cause potent inhibition. Therefore, the ubiquitylation-mediated endocytic degradation of ErbB2 incurred by neratinib treatment conferred potent inhibition of ovarian cancer growth. Clinical investigations of neratinib in ErbB2-positive ovarian cancer are warranted.

CCL2 secreted from cancer-associated mesothelial cells promotes peritoneal metastasis of ovarian cancer cells through the P38-MAPK pathway

Epithelial ovarian cancer (EOC) is considered to secrete various factors in order to promote peritoneal dissemination through cell-to-cell interaction between cancer and mesothelial cells. We previously revealed that TGF-β secreted from EOC induces normal human peritoneal mesothelial cells (HPMCs) to differentiate into cancer-associated mesothelial cells (CAMCs). However, the relationship between tumor cells and CAMCs in EOC is still unclear. We hypothesized that CAMCs also secrete chemokines that attract cancer cells and induce peritoneal dissemination of EOC. We examined chemokines secreted from HPMCs and CAMCs by human chemokine array, and revealed that conditioned medium of CAMCs (CAMCs-CM) included many types of chemokines. The signals of CCL2 were the highest compared with other chemokines. The secretion and relative expression of CCL2 were significantly higher in CAMCs. Recombinant CCL2 promoted trans-mesothelial migration of HPMCs and the migration and invasion by EOC cells. In addition, CCL2 secreted from CAMCs promoted invasion of EOC cells. Furthermore, the neutralizing antibody of CCL2 reduced invasion by EOC. Clinical outcomes of patients whose tissue expressed higher CCR2 were significantly poorer than in patients whose tissue expression was lower. CCL2 activated the phosphorylation of p38 mitogen-activated protein kinase (MAPK). In addition, CAMCs-CM activated the p38 MAPK pathway. Phosphorylation of p38 MAPK reduced with the presence of neutralizing antibody of CCL2. In conclusion, these data indicate CCL2 in CAMCs-CM promoted the malignant potential of EOC. CCL2 plays a crucial role in the tumor microenvironment of EOC.

Gentisyl Alcohol Inhibits Proliferation and Induces Apoptosis via Mitochondrial Dysfunction and Regulation of MAPK and PI3K/AKT Pathways in Epithelial Ovarian Cancer Cells

Ovarian cancer is one of the prevalent gynecological cancers occurring in women. In particular, the efficiency of standard therapeutic methods decreases when recurrence and chemoresistance ensue. To assist standard anti-cancer agents in the cure of ovarian cancer, development and application of new compounds such as small molecules or natural products are required. Gentisyl alcohol is one of the secondary metabolites that can be obtained by purification from bacteria or fungi and is known to have antibacterial, antifungal, antiviral, and anti-cancer effects. In the present study, we verified the effect of gentisyl alcohol derived from marine Arthrinium sp. on suppressing proliferation and inducing apoptosis via DNA fragmentation in human ovarian cancers cells (ES2 and OV90 cells). We also confirmed that there was an accumulation of sub-G1 cells and a loss of mitochondrial membrane potential with calcium dysregulation in gentisyl alcohol-treated ovarian cancer cells. Moreover, gentisyl alcohol up-regulated signal transduction of MAPK and PI3K/AKT pathways. Collectively, our results demonstrated the possibility of gentisyl alcohol as a novel therapeutic agent for human ovarian cancer.

Proof-of-concept validation of the mechanism of action of Src tyrosine kinase inhibitors in dystrophic mdx mouse muscle: in vivo and in vitro studies

Src tyrosine kinase (TK), a redox-sensitive protein overexpressed in dystrophin-deficient muscles, can contribute to damaging signaling by phosphorylation and degradation of β-dystroglycan (β-DG). We performed a proof-of-concept preclinical study to validate this hypothesis and the benefit-safety ratio of a pharmacological inhibition of Src-TK in Duchenne muscular dystrophy (DMD). Src-TK inhibitors PP2 and dasatinib were administered for 5 weeks to treadmill-exercised mdx mice. The outcome was evaluated in vivo and ex vivo on functional, histological and biochemical disease-related parameters. Considering the importance to maintain a proper myogenic program, the potential cytotoxic effects of both compounds, as well as their cytoprotection against oxidative stress-induced damage, was also assessed in C2C12 cells. In line with the hypothesis, both compounds restored the level of β-DG and reduced its phosphorylated form without changing basal expression of genes of interest, corroborating a mechanism at post-translational level. The histological profile of gastrocnemius muscle was slightly improved as well as the level of plasma biomarkers. However, amelioration of in vivo and ex vivo functional parameters was modest, with PP2 being more effective than dasatinib. Both compounds reached appreciable levels in skeletal muscle and liver, supporting proper animal exposure. Dasatinib exerted a greater concentration-dependent cytotoxic effect on C2C12 cells than the more selective PP2, while being less protective against H₂O₂ cytotoxicity, even though at concentrations higher than those experienced during in vivo treatments. Our results support the interest of Src-TK as drug target in dystrophinopathies, although further studies are necessary to assess the therapeutic potential of inhibitors in DMD.

Overexpression of SMARCA2 or CAMK2D is associated with cisplatin resistance in human epithelial ovarian cancer

Ovarian cancer is one of the most lethal types of gynecological cancer. Drug resistance is a major underlying cause of treatment failure, which has lead to continued poor mortality and morbidity rates in patients. In the present study, highly sensitive transcriptome sequencing was performed to systematically identify differentially expressed mRNAs in cisplatin-sensitive (A2780) and -resistant (A2780-DR) cells. Calcium/calmodulin dependent protein kinase IIδ (CAMK2D) and SWI/SNF related matrix associated actin dependent regulator of chromatin subfamily A member 2 (SMARCA2) were identified as exhibiting increased expression in cisplatin-resistant cells. Overexpression of either SMARCA2 or CAMK2D led to a significant increase in the survival rates of A2780 and SKVO3 cells following cisplatin treatment. To further verify the contribution of these two genes in the development of drug resistance, the RNA levels in tissues with different recurrence-free survival (RFS) rates were compared. An increased mRNA level of CAMK2D was detected in samples with shorter RFS rates. An apoptosis assay revealed that overexpression of SMARCA2 or CAMK2D increased the resistance of ovarian cancer cells to cisplatin, as indicated by the decreased apoptotic cell populations. The levels of these two genes also affected the cell cycle and apoptosis-associated protein expression. Quantitative proteomic analyses revealed that overexpression of SMARCA2 or CAMK2D influences multiple metabolism and cancer-associated signaling pathways, which are critical for responses to cisplatin treatment and drug resistance development.

Small Molecules Identified from a Quantitative Drug Combinational Screen Resensitize Cisplatin's Response in Drug-Resistant Ovarian Cancer Cells

Drug resistance to chemotherapy occurs in many ovarian cancer patients resulting in failure of treatment. Exploration of drug resistance mechanisms and identification of new therapeutics that overcome the drug resistance can improve patient prognosis. Following a quantitative combination screen of 6060 approved drugs and bioactive compounds in a cisplatin-resistant A2780-cis ovarian cancer cell line, 38 active compounds with IC₅₀s under 1 μM suppressed the growth of cisplatin-resistant ovarian cancer cells. Among these confirmed compounds, CUDC-101, OSU-03012, oligomycin A, VE-821, or Torin2 in a combination with cisplatin restored cisplatin's apoptotic response in the A2780-cis cells, while SR-3306, GSK-923295, SNX-5422, AT-13387, and PF-05212384 directly suppressed the growth of A2780-cis cells. One of the mechanisms for overcoming cisplatin resistance in these cells is mediated by the inhibition of epidermal growth factor receptor (EGFR), though not all the EGFR inhibitors are equally active. The increased levels of total EGFR and phosphorylated-EGFR (p-EGFR) in the A2780-cis cells were reduced after the combined treatment of cisplatin with EGFR inhibitors. In addition, a knockdown of EGFR mRNA reduced cisplatin resistance in the A2780-cis cells. Therefore, the top active compounds identified in this work can be studied further as potential treatments for cisplatin-resistant ovarian cancer. The quantitative combinational screening approach is a useful method for identifying effective compounds and drug combinations against drug-resistant cancer cells.

Mcl-1 targeting could be an intriguing perspective to cure cancer

The Bcl-2 family, which plays important roles in controlling cancer development, is divided into antiapoptotic and proapoptotic members. The change in the balance between these members governs the life and death of the cells. Mcl-1 is an antiapoptotic member of this family and its distribution in normal and cancerous tissues strongly differs from that of Bcl-2. In human cancers, where upregulation of antiapoptotic proteins is common, Mcl-1 expression is regulated independent of Bcl-2 and its inhibition promotes senescence, a major barrier to tumorigenesis. Cancer chemotherapy determines various kinds of responses, such as senescence and autophagy; however, the ideal response to chemotherapy is apoptosis. Mcl-1 is a potent oncogene that is regulated at the transcriptional, posttranscriptional, and posttranslational levels. Mcl-1 is a short-lived protein that, in the NH2 terminal region, contains sites for posttranslational regulation that can lead to proteasomal degradation. The USP9X Mcl-1 deubiquitinase regulates Mcl-1 and the levels of these two proteins are strongly correlated. Mcl-1 has three splicing variants (the antiapoptotic protein Mcl-1L and the proapoptotic proteins Mcl-1S and Mcl-1ES), each contributing toward apoptosis regulation. In cancers responsible for the most deaths in the world, the presence of Mcl-1 is associated with malignant cell growth and evasion of apoptosis. Mcl-1 is also one of the key regulators of cancer stem cells' self-renewal that contributes to tumor survival. A great number of indirect and selective Mcl-1 inhibitors have been produced and some of these have shown efficacy in several clinical trials. Thus, therapeutic manipulation of Mcl-1 can be a useful strategy to combat cancer.

LncRNA TP73‑AS1 predicts poor prognosis and promotes cell proliferation in ovarian cancer via cell cycle and apoptosis regulation

TP73‑AS1, a critical cancer‑associated long noncoding RNA (lncRNA), has been identified in esophageal cancer and glioma. However, its biological role in ovarian cancer (OC) remains to be investigated. The aim of the present study was to investigate the role of TP73‑AS1 in human OC cell lines and clinical tumor samples to determine the function of this molecule. Reverse transcription‑quantitative polymerase chain reaction analysis was carried out to detect that TP73‑AS1 was upregulated in OC tissues and cell lines. Kaplan Meier Method was applied to study the association between overall survival of patients with OC and TP73‑AS1 expression. The results suggested that patients with high expression levels of TP73‑AS1 had lower survival compared with patients with low expression level of TP73‑AS1. MTT and colony formation assays were conducted to investigate the effects of TP73‑AS1 expression on OC cell proliferation. Flow cytometry analysis was used to analyze the effects of TP73‑AS1 expression on cell cycle progression and apoptosis. Loss‑of‑function experiments revealed that TP73‑AS1 silencing was able to suppress the growth of OC cells via modulating the cell cycle and apoptosis. The results of the present study suggest that TP73‑AS1 may be an oncogenic lncRNA that promotes the proliferation of OC cells and may therefore be an effective therapeutic target in patients with OC.

Co-expression and prognostic significance of the HER family members, EGFRvIII, c-MET, CD44 in patients with ovarian cancer

EGFR and HER-2 are important targets but none of the monoclonal antibodies or small molecule tyrosine kinase inhibitors specific for the HER members has been approved for the treatment of patients with ovarian cancers. In some studies, co-expression of other growth factor receptors has been associated with resistance to therapy with the HER inhibitors. The aim of the present study was to determine the relative expression, cellular location, and prognostic significance of HER-family members, the EGFR mutant (EGFRvIII) c-MET, IGF-1R and the cancer stem cell biomarker CD44 in 60 patients with FIGO stage III and IV ovarian cancer. At cut off >5% of tumour cells with positive staining, 62%, 59%, 65% and 45% of the cases were EGFR, HER-2, HER-3 and HER-4 positive, and 3%, 22% and 48.3% of the cases were positive for EGFRvIII, c-MET, and CD44 respectively. Interestingly, 23% co-expressed all four members of the HER family. On univariate analysis, only EGFR staining at >50% of tumour cells (HR = 3.57, p = 0.038) and CD44 staining at 3+ intensity (HR = 7.99, p = 0.004) were associated with a poorer overall survival. EGFR expression (HR = 2.83, p = 0.019) and its co-expression with HER-2, HER-3, HER-2/HER-3, and c-MET were all associated with poorer disease-free survival. Our results suggest co-expression of the HER-family members is common in Stage III and IV ovarian cancer patients. Further studies on the prognostic significance and predictive value of all HER family member proteins for the response to treatment with various forms of the HER inhibitors are warranted.

Development of novel monoclonal antibodies against CD109 overexpressed in human pancreatic cancer

Pancreatic cancer is one of the most aggressive and lethal types of cancer, and more effective therapeutic agents are urgently needed. Overexpressed cell surface antigens are ideal targets for therapy with monoclonal antibody (mAb)-based drugs, but none have been approved for the treatment of pancreatic cancer. Here, we report development of two novel mouse mAbs, KU42.33C and KU43.13A, against the human pancreatic cancer cell line BxPC-3. Using ELISA, flow cytometry, competitive assay and immunoprecipitation followed by mass spectrometry, we discovered that these two mAbs target two distinct epitopes on the external domain of CD109 that are overexpressed by varying amounts in human pancreatic cancer cell lines. Treatment with these two naked antibodies alone did not affect tumour cell growth or migration in vitro. Of the two mAbs, only KU42.33C was useful in determining the expression of CD109 in tumour cells by Western blot and immunohistochemistry. Interestingly, immunohistochemistry of human pancreatic carcinoma tissue arrays with mAb KU42.33C showed that 94% of the 65 human pancreatic adenocarcinoma cases were CD109 positive, with no expression in normal pancreatic tissues. Our results suggest that these two novel mAbs are excellent tools for determining the expression level of CD109 in the tumour specimens and sera of patients with a wide range of cancers, in particular pancreatic cancer, and for investigating its diagnostic, prognostic and predictive value. Further research is warranted and should aim to unravel the therapeutic potential of the humanised forms or conjugated versions of such antibodies in patients whose tumours overexpress CD109 antigen.

Human epidermal growth factor receptor targeted inhibitors for the treatment of ovarian cancer

Ovarian cancer is the second most lethal gynecological cancer worldwide and while most patients respond to initial therapy, they often relapse with resistant disease. Human epidermal growth factor receptors (especially HER1/EGFR and HER2/ERBB2) are involved in disease progression; hence, strategies to inhibit their action could prove advantageous in ovarian cancer patients, especially in patients resistant to first line therapy. Monoclonal antibodies and tyrosine kinase inhibitors are two classes of drugs that act on these receptors. They have demonstrated valuable antitumor activity in multiple cancers and their possible use in ovarian cancer continues to be studied. In this review, we discuss the human epidermal growth factor receptor family; review emerging clinical studies on monoclonal antibodies and tyrosine kinase inhibitors targeting these receptors in ovarian cancer patients; and propose future research possibilities in this area.

Discovering drugs to overcome chemoresistance in ovarian cancers based on the cancer genome atlas tumor transcriptome profile

Ovarian cancer accounts for the highest mortality among gynecologic cancers, mainly due to intrinsic or acquired chemoresistance. While mechanistic-based methods have been used to identify compounds that can overcome chemoresistance, an effective comprehensive drug screening has yet to be developed. We applied a transcriptome based drug sensitivity prediction method, to the Cancer Genome Atlas (TCGA) ovarian cancer dataset to impute patient tumor response to over 100 different drugs. By stratifying patients based on their predicted response to standard of care (SOC) chemotherapy, we identified drugs that are likely more sensitive in SOC resistant ovarian tumors. Five drugs (ABT-888, BIBW2992, gefitinib, AZD6244 and lenalidomide) exhibit higher efficacy in SOC resistant ovarian tumors when multi-platform of transcriptome profiling methods were employed. Additional in vitro and clinical sample validations were carried out and verified the effectiveness of these agents. Our candidate drugs hold great potential to improve clinical outcome of chemoresistant ovarian cancer.

CXCR4 blockade with AMD3100 enhances Taxol chemotherapy to limit ovarian cancer cell growth

The standard of care for ovarian cancer includes initial treatment with chemotherapy. Despite initial efficacy, over 70% of patients develop recurrence; thus, there is a need to identify novel approaches that can improve therapeutic outcomes. We evaluated AMD3100 (Plerixafor), an FDA-approved CXCR4 inhibitor, as a potential adjunctive therapy for low-dose Taxol (Paclitaxel) by assessing the impact on in-vitro ovarian cancer cell proliferation. Proliferation was a measure for both human TOV-112D and murine ID8 ovarian cancer cells incubated with AMD3100 and Taxol, either individually or in combination. Impact of treatment was first determined for the simultaneous administration of AMD3100 and Taxol. We next assessed a sequential application of AMD3100 pretreatment, followed by AMD3100, Taxol, or a combination to test for sensitization to Taxol. In addition, we measured the impact of AMD3100 and Taxol, individually and in combination, on colony formation, an in-vitro model assay of tumor growth. Expression data, as measured by flow cytometry, show that both ID8 and TOV-112D cells are positive for CXCR4, CXCR7, and CXCL12. Combination treatment with AMD3100 (≤10 μmol/l) sensitized both ID8 and TOV-112D cells to low concentrations of Taxol (≤5 nmol/l), limiting cell proliferation and colony formation in vitro. Pretreatment with AMD3100 significantly increased the sensitivity of human ovarian cancer to low-dose Taxol or the combination of AMD3100 and Taxol, although this effect was not evident in murine cells. Importantly, for both human and murine cells, incubation with a combination of AMD3100 and Taxol had the largest impact on limiting cell proliferation. AMD3100 in combination with low-dose Taxol offers improved efficacy and the potential of reduced toxicity for the treatment of ovarian cancer.

LncRNA NEAT1 contributes to paclitaxel resistance of ovarian cancer cells by regulating ZEB1 expression via miR-194

Background

Chemoresistance is one of the major obstacles for cancer therapy in the clinic. Nuclear paraspeckle assembly transcript 1 (NEAT1) has been reported as an oncogene in most malignancies such as lung cancer, esophageal cancer, and gastric cancer. This study is designed to investigate the function of NEAT1 in paclitaxel (PTX) resistance of ovarian cancer and its potential molecular mechanism.

Patients and methods

The expressions of NEAT1 and miR-194 in ovarian cancer tissues and cells were estimated by quantitative real-time polymerase chain reaction (qRT-PCR). MTT, flow cytometry, and Western blot assays were used to assess the effect of NEAT1 on PTX resistance in PTX-resistant ovarian cancer cells. Luciferase reporter assay was applied to examine the association between NEAT1, zinc finger E-box-binding homeobox 1 (ZEB1) and miR-194. Xenograft tumor model was established to confirm the biological role of NEAT1 in PTX resistance of ovarian cancer in vivo.

Results

NEAT1 was upregulated, and miR-194 was downregulated in PTX-resistant ovarian cancer tissues and cells. Functionally, NEAT1 knockdown enhanced cell sensitivity to PTX via promoting PTX-induced apoptosis in vitro. NEAT1 was identified as a molecular sponge of miR-194 to upregulate ZEB1 expression. Mechanistically, NEAT1-knockdown-induced PTX sensitivity was mediated by miR-194/ZEB1 axis. Moreover, NEAT1 knockdown improved PTX sensitivity of ovarian cancer in vivo.

Conclusion

NEAT1 contributed to PTX resistance of ovarian cancer cells at least partly through upregulating ZEB1 expression by sponging miR-194, elucidating a novel regulatory pathway of chemoresistance in PTX-resistant ovarian cancer cells and providing a possible long noncoding RNA (lncRNA)-targeted therapy for ovarian cancer.

Synergistic effects of various Her inhibitors in combination with IGF-1R, C-MET and Src targeting agents in breast cancer cell lines

Overexpression of HER2 has been reported in around 25% of human breast cancers. Despite recent advances in HER2 targeted therapy, many patients still experience primary and secondary resistance to such treatments, the mechanisms for which are poorly understood. Here, we investigated the sensitivity of a panel of breast cancer cell lines to treatment with various types of HER-family inhibitors alone or in combination with other tyrosine kinase inhibitors or chemotherapeutic agents. We found that treatment with the second-generation irreversible HER-family inhibitors, particularly afatinib and neratinib, were more effective than treatment with the first-generation reversible inhibitors in inhibiting growth, migration and downstream cell signalling in breast cancer cells. Of the three HER2 overexpressing cell lines in this panel, SKBr3 and BT474 were highly sensitive to treatment with HER-family inhibitors, while MDA-MB-453 was comparatively resistant. Combinations of HER-family inhibitors with NVP-AEW541, dasatinib or crizotinib (inhibitors of IGF-1R, Src and c-Met/ALK, respectively) led to synergistic effects in some of the cell lines examined. In particular, treatment with a combination of Src and HER-family member inhibitors resulted in synergistic growth inhibition of MDA-MB453 cells, implicating Src as a mediator of resistance to HER2-targeting agents. Our results suggest that combining HER-family inhibitors with other TKIs such as dasatinib may have therapeutic advantages in certain breast cancer subtypes and warrants further investigation.