Epithelial ovarian cancer: focus on targeted therapy

Synergistic antitumor effect of liposomal-based formulations of olaparib and topotecan in primary epithelial ovarian cancer cells

BACKGROUND

Olaparib is a PARP inhibitor inducing synthetic lethality in tumors with deficient homologous recombination (HRD) caused by BRCA1/2 mutations. The FDA has approved monotherapy for first-line platinum-sensitive, recurrent high-grade epithelial ovarian cancer. Combination therapy alongside DNA-damaging therapeutics is a promising solution to overcome the limited efficacy in patients with HRD. The present study was designed to develop topotecan- and olaparib-loaded liposomes (TLL and OLL) and assess the effectiveness of their combination in patient-derived ovarian cancer samples.

METHODS

We used HEOC, four clear-cell tumors (EOC 1-4), malignant ascites, and an OCI-E1p endometrioid primary ovarian cancer cell line and performed NGS analysis of BRCA1/2 mutation status. Antiproliferative activity was determined with the MTT assay. The Chou-Talalay algorithm was used to investigate the in vitro pharmacodynamic interactions of TLLs and OLLs.

RESULTS

The OLL showed significantly higher efficacy in all ovarian cancer types with wild-type BRCA1/2 than a conventional formulation, suggesting potential for increased in vivo efficacy. The TLL revealed substantially higher toxicity to EOC 1, EOC 3, ascites and lower toxicity to HEOC than the standard formulation, suggesting better therapeutic efficacy and safety profile. The combination of studied compounds showed a higher reduction in cell viability than drugs used individually, demonstrating a synergistic antitumor effect at most of the selected concentrations.

CONCLUSIONS

The concentration-dependent response of different ovarian cancer cell types to combination therapy confirms the need for in vitro optimization to maximize drug cytotoxicity. The OLL and TLL combination is a promising formulation for further animal studies, especially for eliminating epithelial ovarian cancer with wild-type BRCA1/2.

An in-Depth Analysis of Ovarian Cancer: Pathogenesis and Clinical Manifestation

Ovarian cancer is characterized by the establishment of tolerance, the recurrence of disease, as well as a poor prognosis. Gene signatures in ovarian cancer cells enable cancer medicine research, therapy, prevention, & management problematic. Notwithstanding advances in tumor puncture surgery, novel combinations regimens, and abdominal radiation, which can provide outstanding reaction times, the bulk of gynecological tumor patients suffer from side effects & relapse. As a consequence, more therapy alternatives for individuals with ovarian cancer must always be studied to minimize side effects and improve progression-free and total response rates. The development of cancer medications is presently undergoing a renaissance in the quest for descriptive and prognostic ovarian cancer biomarkers. Nevertheless, abnormalities in the BRCA2 or BRCA1 genes, a variety of hereditary predispositions, unexplained onset and progression, molecular tumor diversity, and illness staging can all compromise the responsiveness and accuracy of such indicators. As a result, current ovarian cancer treatments must be supplemented with broad-spectrum & customized targeted therapeutic approaches. The objective of this review is to highlight recent contributions to the knowledge of the interrelations between selected ovarian tumor markers, various perception signs, and biochemical and molecular signaling processes, as well as one's interpretation of much more targeted and effective treatment interventions.

Meta-analysis based gene expression profiling reveals functional genes in ovarian cancer

Background: Ovarian cancer causes high mortality rate worldwide, and despite numerous attempts, the outcome for patients with ovarian cancer are still not well improved. Microarray-based gene expressional analysis provides with valuable information for discriminating functional genes in ovarian cancer development and progression. However, due to the differences in experimental design, the results varied significantly across individual datasets.

Methods: In the present study, the data of gene expression in ovarian cancer were downloaded from Gene Expression Omnibus (GEO) and 16 studies were included. A meta-analysis based gene expression analysis was performed to identify differentially expressed genes (DEGs). The most differentially expressed genes in our meta-analysis were selected for gene expression and gene function validation.

Results: A total of 972 DEGs with P-value < 0.001 were identified in ovarian cancer, including 541 up-regulated genes and 431 down-regulated genes, among which 92 additional DEGs were found as gained DEGs. Top five up- and down-regulated genes were selected for the validation of gene expression profiling. Among these genes, up-regulated CD24 molecule (CD24), SRY (sex determining region Y)-box transcription factor 17 (SOX17), WFDC2, epithelial cell adhesion molecule (EPCAM), innate immunity activator (INAVA), and down-regulated aldehyde oxidase 1 (AOX1) were revealed to be with consistent expressional patterns in clinical patient samples of ovarian cancer. Gene functional analysis demonstrated that up-regulated WFDC2 and INAVA promoted ovarian cancer cell migration, WFDC2 enhanced cell proliferation, while down-regulated AOX1 was functional in inducing cell apoptosis of ovarian cancer.

Conclusion: Our study shed light on the molecular mechanisms underlying the development of ovarian cancer, and facilitated the understanding of novel diagnostic and therapeutic targets in ovarian cancer.

Exosomes secreted by chemoresistant ovarian cancer cells promote angiogenesis

Background

Ovarian cancer (OC) has the highest mortality rate in gynecologic tumors. Despite decades of continuous efforts, the survival rate of patients has not improved significantly, mostly due to drug resistance. Exosomes are hot topics in recent years. Cells can affect the biological behaviors of other cells by transferring exosomes. So far, numerous researchers have found that tumor cells can secrete exosomes which play a important role in the development of tumors. Solid tumors can promote angiogenesis. When drug resistance occurs, it seems that more blood vessels form. We suppose that exosomes derived from chemoresistant OC cells can also promote angiogenesis.

Results

We investigate whether exosomes secreted by chemoresistant SKOV3-DDP cells (SKOV3-DDP-exo) and sensitive SKOV3 cells (SKOV3-exo) influence angiogenesis. After exosomes were extracted, exosomes were co-cultured with HUVECs. We found that SKOV3-DDP-exo and SKOV3-exo are absorbed by endothelial cells and promote the proliferation, migration, invasion and tube formation of endothelial cells. Moreover, SKOV3-DDP-exo is more powerful in angiogenesis, suggesting that parts of the components of SKOV3-DDP-exo are significantly radical. We also found that miR-130a was highly expressed in drug-resistant OC cells. Also, we found that miR-130a in SKOV3-DDP-exo is higher than SKOV3-exo. Therefore, we suggest that miR-130a in exosomes is the main cause of chemoresistant OC cells promoting angiogenesis.

An omentum-inspired 3D PEG hydrogel for identifying ECM-drivers of drug resistant ovarian cancer

Ovarian cancer (OvCa) is a challenging disease to treat due to poor screening techniques and late diagnosis. There is an urgent need for additional therapy options, as patients recur in 70% of cases. The limited availability of clinical treatment options could be a result of poor predictions in early stage drug screens on standard tissue culture polystyrene (TCPS). TCPS does not capture the mechanical and biochemical cues that cells experience in vivo, which can impact how cells will respond to a drug. Therefore, an in vitro model that captures some of the microenvironment features that the cells experience in vivo could provide better insights into drug responses. In this study, we formed 3D multicellular tumor spheroids (MCTS) in microwells and encapsulated them in 3D omentum-inspired hydrogels. SKOV-3 MCTS were resistant to Paclitaxel in our 3D hydrogels compared to a monolayer on TCPS. Toward clinical application, we tested cells from patients [ovarian carcinoma ascites spheroids (OCAS)] who had been treated with Paclitaxel, and drug responses predicted by using the 3D omentum-inspired hydrogels demonstrated the lack of the Paclitaxel response of these samples. Additionally, we observed the presence of collagen production around the encapsulated SKOV-3 MCTS, but not significantly on TCPS. Our results demonstrated that our 3D omentum-inspired hydrogel is an improved in vitro drug testing platform to study the OvCa drug response for patient-derived cells and helped us identify collagen 3 as a potential driver of Paclitaxel resistance in 3D.

Efficacy and safety of olaparib maintenance therapy in platinum-sensitive ovarian cancer patients with BRCA mutations: a meta-analysis on randomized controlled trials

Background: Olaparib, a potent oral poly (ADP-ribose) polymerase inhibitor, exhibits antitumor activity and prevents the recurrence in advanced ovarian cancer. In this article, we assessed the efficacy and safety of olaparib maintenance therapy on platinum-sensitive ovarian cancer patients with BRCA mutations through a meta-analysis of available randomized controlled trials (RCTs) to provide more evidence for its clinical applications.

Methods: We searched PubMed, Embase, Wanfang, CNKI, Web of Science, Cochrane Library, and VIP databases from 1 August 2018 to identify RCTs and finally included four RCTs (seven articles) with 567 eligible participants beyond the participants, interventions, comparisons, outcomes, and study design regulation. The outcomes of olaparib efficacy including progression-free survival (PFS) and overall survival (OS) were measured by HR and 95% CI, while the quality of life was evaluated by calculating the combination of P-value. Seven common adverse events were tested by risk ratio and 95% CI as the outcomes of olaparib safety. These data were analyzed, and the forest figures were produced using Review Manager 5.3.

Results: Compared with other interventions (ie, placebo or chemotherapy drugs), olaparib significantly prolonged PFS (HR=0.31, 95% CI=0.15–0.62) and slightly improved OS (HR=0.75, 95% CI=0.56–0.99), but did not influence the quality of life (P=0.058) in the patients with platinum-sensitive BRCA-mutated ovarian cancer. Additionally, the toxicity profile of olaparib involved anemia, fatigue, vomiting, diarrhea, and nausea with grade 1–2.

Conclusion: This meta-analysis suggests that olaparib maintenance therapy is effective and well-tolerated for the patients with platinum-sensitive BRCA-mutated ovarian cancer. More updated RCTs and long-term follow-up should be conducted to compare and analyze the efficacy and toxicity of olaparib at different doses in ovarian cancer patients.

Lewis(y) antigen-mediated positive feedback loop induces and promotes chemotherapeutic resistance in ovarian cancer

The present study aimed to investigate the association between Lewis(y) antigen and chemoresistance in ovarian cancer and to elucidate the underlying molecular mechanisms. Lewis(y) expression in chemoresistant ovarian cancer tissues and cells was detected by immunohistochemistry. α1,2‑fucosyltransferase (FUT1) expression in different ovarian cancer chemotherapy-resistant cells was analyzed by reverse transcription-quantitative PCR (RT-qPCR). Genes differentially expressed in the chemoresistant and sensitive groups were screened using a gene chip followed by validation using RT-qPCR and western blot analysis. We found that Lewis(y) and FUT1 expression in ovarian cancer cells was significantly increased following the induction of drug resistance. The positive expression rate and intensity of Lewis(y) in ovarian cancer chemoresistant tissues were also significantly higher than those in the sensitive group. Compared with the non-resistant cell lines, the differentially expressed genes were mainly enriched in the terms related to the transmembrane receptor protein tyrosine kinase signaling pathway and positive regulation of cell proliferation. Interaction network analysis predicted genes participating in the regulation of apoptotic processes. The highly differential expression of Annexin A4 (ANXA4), BCL2 interacting killer (BIK), transmembrane 4 L six family member 4 (TM4SF4) and pleckstrin homology-like domain family A member 1 (PHLDA1) was validated using RT-qPCR in ovarian cancer cell lines. Finally, ANXA4 expression was increased at both the mRNA and protein level in the drug‑resistant cells, and in addition, ANXA4 contained a Lewis(y) structure. The expression of Bcl-2 and other anti-apoptotic proteins increased with the increase of Lewis(y) expression. After blocking Lewis(y) using an antibody, the expression of the involved signaling pathway and apoptosis-related proteins decreased significantly. These findings provide strong evidence that Lewis(y) is a component of the structure of the ANXA4 membrane protein. Its overexpression can abnormally activate signaling pathways and regulate the expression of a number of factors, forming a positive feedback loop to induce the chemoresistance of ovarian cancer cells, and ultimately promoting the progression of ovarian cancer.

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.

Dihydroartemisinin selectively inhibits PDGFRα-positive ovarian cancer growth and metastasis through inducing degradation of PDGFRα protein

To develop traditional medicines as modern pharmacotherapies, understanding their molecular mechanisms of action can be very helpful. We have recently reported that Artemisinin and its derivatives, which are clinically used anti-malarial drugs, have significant effects against ovarian cancer, but the direct molecular targets and related combination therapy have been unclear. Herein, we report that dihydroartemisinin, one of the most active derivatives of Artemisinin, directly targets platelet-derived growth factor receptor-alpha (PDGFRα) to inhibit ovarian cancer cell growth and metastasis. Dihydroartemisinin directly binds to the intercellular domain of PDGFRα, reducing its protein stability by accelerating its ubiquitin-mediated degradation, which further inactivates downstream phosphoinositide 3-Kinase and mitogen-activated protein kinase pathways and subsequently represses epithelial–mesenchymal transition, inhibiting cell growth and metastasis of PDGFRα-positive ovarian cancer in vitro and in vivo. A combinational treatment reveals that dihydroartemisinin sensitizes ovarian cancer cells to PDGFR inhibitors. Our clinical study also finds that PDGFRα is overexpressed and positively correlated with high grade and metastasis in human ovarian cancer. Considering that Artemisinin compounds are currently clinically used drugs with favorable safety profiles, the results from this study will potentiate their use in combination with clinically used PDGFRα inhibitors, leading to maximal therapeutic efficacy with minimal adverse effects in PDGFRα-positive cancer patients. These findings also shed high light on future development of novel Artemisinin-based targeted therapy.

Antitumor activity of a newly developed monoclonal antibody against ROR1 in ovarian cancer cells

Receptor-tyrosine-kinase-like Orphan Receptor 1 (ROR1) is a tyrosine-protein kinase transmembrane receptor and ROR1 overexpression is associated with a poor prognosis in various cancers, including ovarian cancer. Targeting of ROR1 has been evaluated as a novel cancer therapy strategy. This study developed a novel chimeric anti-ROR1 Fab antibody (named ROR1-cFab) and then assessed the antitumor activity of this antibody in ovarian cancer cells, an in vitro model of preclinical cancer therapy. A ROR1-cFab prokaryotic expression vector was constructed from positive fusion cells (splenocytes from mice with high ROR1 immune titers were fused with myeloma cells) after three rounds of sub-clone affinity screening. Then, a variety of assays were employed to assess the binding selectivity and specificity of ROR1-cFab to ROR1 protein. Furthermore, CCK8, flow cytometric apoptosis, wound healing, and Transwell migration assays were used to assess antitumor activity of this newly developed anti-ROR1 antibody in ovarian cancer cells. We demonstrated that ROR1-cFab could specifically bind to ROR1 protein and ROR1-positive ovarian cancer A2780 cells. Functional assays revealed that ROR1-cFab inhibited tumor cell proliferation and migration, as well as inducing apoptosis of ROR1-positive A2780 cells in a dose dependent manner. These effects were not observed in ROR1-negative lose386 cells. In conclusion, ROR1-cFab is a novel anti-ROR1 antibody with a high affinity to ROR1 protein and inhibitory effects on ROR1-positive cells. Future studies will determine whether the ROR1-cFab might be a promising candidate for treatment of ROR1-positive ovarian cancer.

Genomic markers of ovarian adenocarcinoma and its relevancy to the effectiveness of chemotherapy

Ovarian cancer is the eighth most common cancer and the seventh highest cause of cancer-associated mortality in women worldwide. It is the second highest cause of mortality among female reproductive malignancies. The current standard first-line treatment for advanced ovarian cancer includes a combination of surgical debulking and standard systemic platinum-based chemotherapy with carboplatin and paclitaxel. Although a deeper understanding of this disease has been attained, relapse occurs in 70% of patients 18 months subsequent to the first-line treatment. Therefore, it is crucial to develop a novel drug that effectively affects ovarian cancer, particularly tumors that are resistant to current chemotherapy. The aim of the present study was to identify genes whose expression may be used to predict survival time or prognosis in ovarian cancer patients treated with chemotherapy. Gene or protein expression is an important issue in chemoresistance and survival prediction in ovarian cancer. In the present study, the research group consisted of patients treated at the Surgical Clinic of the Gynecology and Obstetrics Gynecological Clinical Hospital, Poznan University of Medical Sciences (Poznan, Poland) between May 2006 and November 2014. Additional eligibility criteria were a similar severity (International Federation of Gynecolgy and Obstetrics stage III) at the time of diagnosis, treatment undertaken in accordance with the same schedule, and an extremely good response to treatment or a lack of response to treatment. The performance of the OncoScan^® assay was evaluated by running the assay on samples obtained from the four patients and by following the recommended protocol outlined in the OncoScan assay manual. The genomic screening using Affymetrix OncoScan Arrays resulted in the identification of large genomic rearrangements across all cancer tissues. In general, chromosome number changes were detected in all examined tissues. The OncoScan arrays enabled the identification of ~100 common somatic mutations. Chemotherapy response in ovarian cancer is extremely complex and challenging to study. The present study identified specific genetic alterations associated with ovarian cancer, but not with response for treatment.

High expressions of BCL6 and Lewis y antigen are correlated with high tumor burden and poor prognosis in epithelial ovarian cancer

Aberrant regulation of BCL6 plays crucial oncogenic roles in various malignant tumors; howbeit, the function of BCL6 in tumorigenesis of ovarian cancer remains unclear. The aim of this study is to investigate the role of BCL6 in ovarian cancer. The methods of immunohistochemical staining, quantitative real-time polymerase chain reaction, immunocytochemical staining, and gene expression profile enrichment analysis were performed to identify the possible role of BCL6 in ovarian cancer. We observed that the expression of BCL6 was significantly higher in ovarian cancer tissues and correlated with higher tumor burden including advanced International Federation of Gynecology and Obstetrics stages, poor differentiation, Type II ovarian cancer, the presence of >1 cm residual tumor size, and appearance of recurrence or death (all p < 0.05). The expression patterns of Lewis y were similar to these of BCL6. Multivariate Cox analysis demonstrated that advanced International Federation of Gynecology and Obstetrics stage, lymph node metastasis, residual tumor size >1 cm, as well as high expressions of BCL6 and Lewis y antigen were independent factors of worse progression-free survival and overall survival (all p < 0.05). There was a positive correlation of the expressions of BCL6 and Lewis y antigen. The associated genes with BCL6 in response to Lewis y antigen were identified, including four upregulated genes ( SOCS3, STAT1, PPARG, and GADD45A) and three downregulated genes ( ACAN, E2F3, and ZBTB7B). In conclusion, the high expressions of BCL6 and Lewis y antigen are associated with development, high tumor burden, and worse prognosis of ovarian cancer and targeting BCL6 could be a novel therapeutic strategy for ovarian cancer treatment.

The natural terthiophene α-terthienylmethanol induces S phase cell cycle arrest of human ovarian cancer cells via the generation of ROS stress

Ovarian cancer is the most lethal gynecological malignancy worldwide. Thiophenes such as terthiophene have been shown to have anti-tumor effects on several cancer cell lines, including ovarian cancer cells. However, the underlying mechanisms behind the anti-proliferative effect of thiophenes are poorly understood. In this study, we investigated the molecular mechanisms underlying the anti-proliferative effect of α-terthienylmethanol, a terthiophene isolated from Eclipta prostrata (False Daisy), on human ovarian cancer cells. We found that α-terthienylmethanol is a more potent inhibitor of cell growth than is cisplatin in human ovarian cancer cells. α-Terthienylmethanol induces cell cycle arrest in ovarian cancer cells, as shown by the accumulation of cells in S phase. In addition, α-terthienylmethanol induced a change in S phase-related proteins cyclin A, cyclin-dependent kinase 2, and cyclin D2. Knockdown of cyclin A using specific siRNAs significantly compromised α-terthienylmethanol-induced S phase arrest. We further demonstrated that α-terthienylmethanol induced an increase in intracellular ROS, and the antioxidant N-acetyl-l-cysteine significantly reversed the S phase arrest induced by α-terthienylmethanol. Moreover, α-terthienylmethanol significantly increased the levels of p-H2AX, a DNA damage marker. These results suggest that α-terthienylmethanol inhibits the growth of human ovarian cancer cells by S phase cell cycle arrest via induction of ROS stress and DNA damage.

Gene expression profile analysis in response to α1,2-fucosyl transferase (FUT1) gene transfection in epithelial ovarian carcinoma cells

The aim of this study was to identify differentially expressed genes (DEGs) in response to α1,2-fucosyl transferase (FUT1) gene transfection in epithelial ovarian cancer cells. Human whole-genome oligonucleotide microarrays were used to determine whether gene expression profile may differentiate the epithelial ovarian cell line Caov-3 transfected with FUT1 from the empty plasmid-transfected cells. Quantitative real-time PCR and immunohistochemical staining validated the microarray results. Gene expression profile identified 215 DEGs according to the selection criteria, in which 122 genes were upregulated and 93 genes were downregulated. Gene Ontology (GO) and canonical pathway enrichment analysis were applied, and we found that these DEGs are involved in BioCarta mammalian target of rapamycin (mTOR) pathway, BioCarta eukaryotic translation initiation factor 4 (EIF4) pathway, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in cancer. Interaction network analysis predicted genes participating in the regulatory connection. Highly differential expression of TRIM46, PCF11, BCL6, PTEN, and FUT1 genes was validated by quantitative real-time PCR in two cell line samples. Finally, BCL6 and Lewis Y antigen were validated at the protein level by immunohistochemistry in 103 paraffin-embedded ovarian cancer tissues. The identification of genes in response to FUT1 may provide a theoretical basis for the investigations of the molecular mechanism of ovarian cancer.

Analysis of the gene expression profile in response to human epididymis protein 4 in epithelial ovarian cancer cells

Currently, there are emerging multiple studies on human epididymis protein 4 (HE4) in ovarian cancer. HE4 possesses higher sensitivity and specificity than CA125 in the confirmative early diagnosis for ovarian cancer. Although much attention has been given to explore its clinical application, research of the basic mechanisms of HE4 in ovarian cancer are still unclear. In the present study, we provide fundamental data to identify full-scale differentially expressed genes (DEGs) in response to HE4 by use of human whole-genome microarrays in human epithelial ovarian cancer cell line ES-2 following overexpression and silencing of HE4. We found that a total of 717 genes were upregulated and 898 genes were downregulated in the HE4-overexpressing cells vs. the HE4-Mock cells, and 166 genes were upregulated and 285 were downregulated in the HE4-silenced cells vs. the HE4-Mock cells. An overlap of 16 genes consistently upregulated and 8 genes downregulated in response to HE4 were noted. These DEGs were involved in MAPK, steroid biosynthesis, cell cycle, the p53 hypoxia pathway, and focal adhesion pathways. Interaction network analysis predicted that the genes participated in the regulatory connection. Highly differential expression of the FOXA2, SERPIND1, BDKRD1 and IL1A genes was verified by quantitative real-time PCR in 4 cell line samples. Finally, SERPIND1 (HCII) was validated at the protein level by immunohistochemistry in 107 paraffin-embedded ovarian tissues. We found that SERPIND1 may act as a potential oncogene in the development of ovarian cancer. The present study displayed the most fundamental and full-scale data to show DEGs in response to HE4. These identified genes may provide a theoretical basis for investigations of the underlying molecular mechanism of HE4 in ovarian cancer.

Targeting FR-expressing cells in ovarian cancer with Fab-functionalized nanoparticles: a full study to provide the proof of principle from in vitro to in vivo

Efficient targeting in tumor therapies is still an open issue: systemic biodistribution and poor specific accumulation of drugs weaken efficacy of treatments. Engineered nanoparticles are expected to bring benefits by allowing specific delivery of drug to the tumor or acting themselves as localized therapeutic agents. In this study we have targeted epithelial ovarian cancer with inorganic nanoparticles conjugated to a human antibody fragment against the folate receptor over-expressed on cancer cells. The conjugation approach is generally applicable. Indeed several types of nanoparticles (either magnetic or fluorescent) were engineered with the fragment, and their biological activity was preserved as demonstrated by biochemical methods in vitro. In vivo studies with mice bearing orthotopic and subcutaneous tumors were performed. Elemental and histological analyses showed that the conjugated magnetic nanoparticles accumulated specifically and were retained at tumor sites longer than the non-conjugated nanoparticles.

Brown algae phlorotannins enhance the tumoricidal effect of cisplatin and ameliorate cisplatin nephrotoxicity

OBJECTIVE

The clinical application of cisplatin is limited due to its drug resistance and side effects. We investigated the effect of a phlorotannin-rich extract from the edible brown alga Ecklonia cava (PREC) and its major phlorotannin (dieckol) on cisplatin responsiveness and side effects.

METHODS

The A2780 and SKOV3 ovarian cancer cell lines and the SKOV3-bearing mouse model were used. The MTT assay was applied to assess cell viability, and the annexin V assay was employed for apoptosis analysis. Reactive oxygen species (ROS) production and protein expression were assessed by H2DCFDA staining and Western blotting, respectively.

RESULTS

We found that PREC enhanced the tumor growth-inhibitory effect of cisplatin and diminished cisplatin-induced nephrotoxicity and weight loss in SKOV3-bearing mice. PREC augmented cisplatin-induced apoptosis by activating caspases in SKOV3 and A2780 ovarian cancer cells. In addition, a combination of PREC and cisplatin-induced ovarian cancer cell apoptosis by downregulating the Akt and NFκB pathways. We further demonstrated that PREC increased intracellular ROS and that antioxidants significantly attenuated Akt-NFκB activation and apoptosis in ovarian cancer cells. In contrast, PREC inhibited cisplatin-induced ROS production and cell death in normal HEK293 kidney cells. Dieckol, a major compound in PREC, significantly enhanced the inhibition of tumor growth by cisplatin with less weight loss and kidney damage in a mouse model.

CONCLUSION

These data suggest that brown algae phlorotannins may improve the efficacy of platinum drugs for ovarian cancer by enhancing cancer cell apoptosis via the ROS/Akt/NFκB pathway and reduce nephrotoxicity by protecting against normal kidney cell damage.

Near infrared photoimmunotherapy in the treatment of disseminated peritoneal ovarian cancer

Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of intravenously injected antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein, we evaluate the efficacy of NIR-PIT in a mouse model of disseminated peritoneal ovarian cancer. In vitro and in vivo experiments were conducted with a HER2-expressing, luciferase-expressing, ovarian cancer cell line (SKOV-luc). An antibody-photosensitizer conjugate (APC) consisting of trastuzumab and a phthalocyanine dye, IRDye-700DX, was synthesized (tra-IR700) and cells or tumors were exposed to NIR light. In vitro PIT cytotoxicity was assessed with dead staining and luciferase activity in freely growing cells and in a three-dimensional (3D) spheroid model. In vivo NIR-PIT was performed in mice with tumors implanted in the peritoneum and in the flank and these were assessed by tumor volume and/or bioluminescence. In vitro NIR-PIT-induced cytotoxicity was light dose dependent. Repeated light exposures induced complete tumor cell killing in the 3D spheroid model. In vivo the antitumor effects of NIR-PIT were confirmed by significant reductions in both tumor volume and luciferase activity in the flank model (NIR-PIT vs. control in tumor volume changes at day 10, P = 0.0001; NIR-PIT vs. control in luciferase activity at day 4, P = 0.0237), and the peritoneal model (NIR-PIT vs. control in luciferase activity at day 7, P = 0.0037). NIR-PIT provided effective cell killing in this HER2-positive model of disseminated peritoneal ovarian cancer. Thus, NIR-PIT is a promising new therapy for the treatment of disseminated peritoneal tumors.

Ovarian cancer stem cells express ROR1, which can be targeted for anti-cancer-stem-cell therapy

Although initially responsive to chemotherapy, many patients with ovarian cancer subsequently develop relapsed and potentially fatal metastatic disease, which is thought to develop from cancer stem cells (CSCs) that are relatively resistant to conventional therapy. Here, we show that CSCs express a type I receptor tyrosine kinase-like orphan receptor (ROR1), which is expressed during embryogenesis and by many different cancers, but not normal postpartum tissues. Ovarian cancers with high levels of ROR1 had stem cell-like gene-expression signatures. Furthermore, patients with ovarian cancers with high levels of ROR1 had higher rates of relapse and a shorter median survival than patients with ovarian cancers that expressed low-to-negligible amounts of ROR1. We found that ROR1-positive (ROR1(+)) cells isolated from primary tumor-derived xenografts (PDXs) also expressed aldehyde dehydrogenase 1 (ALDH1) and had a greater capacity to form spheroids and to engraft immune-deficient mice than did ROR1-negative (ROR1(Neg)) ovarian cancer cells isolated from the same tumor population. Treatment with UC-961, an anti-ROR1 mAb, or shRNA silencing of ROR1 inhibited expression of the polycomb ring-finger oncogene, Bmi-1, and other genes associated with the epithelial-mesenchymal transition. Moreover, shRNA silencing of ROR1, depletion of ROR1(+) cells, or treatment with UC-961 impaired the capacity of ovarian cancer cells to form spheroids or tumor xenografts. More importantly, treatment with anti-ROR1 affected the capacity of the xenograft to reseed a virgin mouse, indicating that targeting ROR1 may affect CSC self-renewal. Collectively, these studies indicate that ovarian CSCs express ROR1, which contributes to their capacity to form tumors, making ROR1 a potential target for the therapy of patients with ovarian cancer.

IGF-1R inhibition potentiates cytotoxic effects of chemotherapeutic agents in early stages of chemoresistant ovarian cancer cells

The kinetics and effect of hyper activated IGF-1R signaling is not well investigated during acquirement of platinum and taxol resistance in ovarian cancer cells. Herein we reported an upregulated IGF-1R expression in early stages of cisplatin paclitaxel and cisplatin-taxol resistance. Picropodophyllin, an IGF-1R inhibitor, alone and in combination with cisplatin, paclitaxel or both at lowest possible doses could reverse the resistance at early stages. Upregulated IGF-1R was also found in primary tumors of ovarian cancer patients after three to four cycles of platinum-taxol treatment. These findings indicate that a combination of cytotoxic agents and IGF-1R inhibitor is more effective at early stages of chemoresistant ovarian cancer.

Antisense oligonucleotide suppression of human IGF-1R inhibits the growth and survival of in vitro cultured epithelial ovarian cancer cells

Background

Preclinical evaluation of the anti-neoplastic activity of antisense oligonucleotide (AS) suppression of human insulin-like growth factor I receptor (IGF-IR) in human epithelial ovarian cancer (EOC).

Methods

Ovarian cancer cells from 36 patients with EOC were investigated under serum-free tissue culture conditions. IGF-I production was evaluated by standard ELISA. IGF-IR and phosphorylated IRS-1, AKT, and MAP kinase expression and protein levels were evaluated by immunohistochemistry and Western blotting. Cancer cell growth and proliferation assays were performed in triplicates using MTT assay. Apoptosis was evaluated by TUNNEL assay.

Results

All ovarian cancer tissue samples tested produced IGF-I and expressed IGF-IR, supporting the existence of an autocrine loop. Treatment of primary ovarian cancer cell lines with an IGF-1R AS inhibited growth and proliferation and decreased clonogenicity in soft agar assay. AS treatment was demonstrated to inhibit the expression of IGF-1R and decrease the concentration of phosphorylated IRS-1, AKT, and MAP kinase signaling protein downstream of the IGF-IR. We also observed that the IGF-1R AS sensitized cancer cell lines to cisplatin in vitro through the PI3K pathway.

Conclusions

IGF-IR enhances the proliferation and tumorigenicity of human ovarian cancer cells and inhibition of IGF-IR by AS oligonucleotide treatment potentiates the activity of cisplatin in vitro. Therefore, IGF-1R is a potential molecular target in ovarian cancer.

Antiangiogenic agents as a maintenance strategy for advanced epithelial ovarian cancer

Bevacizumab is the first antiangiogenic agent to have demonstrated benefit as first-line and maintenance therapy in epithelial ovarian cancer (EOC), with the Gynecologic Oncology Group 218 and ICON 7 phase III trials revealing significantly prolonged progression-free survival (PFS) for carboplatin/paclitaxel plus bevacizumab followed by bevacizumab maintenance versus carboplatin/paclitaxel alone. Results are forthcoming from several phase III maintenance trials of investigational antiangiogenic agents, each evaluating PFS as the primary endpoint: AGO-OVAR12/LUME-Ovar1 (nintedanib [BIBF 1120]), AGO-OVAR16 (pazopanib), and TRINOVA-1, -2, and -3 (AMG 386). Here we review available data and ongoing clinical trials of investigational antiangiogenic agents as maintenance therapy for EOC. Current controversies, including uncertainties regarding the (1) most appropriate clinical trial endpoints, (2) optimal dosing, duration, and timing of therapy (e.g., with first-line chemotherapy and/or as maintenance monotherapy), and (3) feasibility, tolerability, and cost of adding these agents to platinum/taxane regimens are also highlighted.

Individuality in FGF1 expression significantly influences platinum resistance and progression-free survival in ovarian cancer

Background:

Ovarian cancer is frequently advanced at presentation when treatment is rarely curative. Response to first-line platinum-based chemotherapy significantly influences survival, but clinical response is unpredictable and is frequently limited by the development of drug-resistant disease.

Methods:

We used qRT–PCR analysis to assess intertumour differences in the expression of fibroblast growth factor 1 (FGF1) and additional candidate genes in human ovarian tumours (n=187), and correlated individuality in gene expression with tumour histology, chemotherapy response and survival. We used MTT assays to assess platinum chemosensitivity in drug-sensitive and drug-resistant ovarian cell lines.

Results:

Marked intertumour differences in gene expression were observed, with each tumour having a unique gene expression profile. Nine genes, including FGF1 (P=1.7 × 10⁻⁵) and FGFR2 (P=0.003), were differentially expressed in serous and nonserous tumours. MDM2 (P=0.032) and ERBB2 (P=0.064) expression was increased in platinum-sensitive patients, and FGF1 (adjusted log-rank test P=0.006), FGFR2 (P=0.04) and PDRFRB expression (P=0.037) significantly inversely influenced progression-free survival. Stable FGF1 gene knockdown in platinum-resistant A2780DPP cells re-sensitised cells to both cisplatin and carboplatin.

Conclusion:

We show for the first time that FGF1 is differentially expressed in high-grade serous ovarian tumours, and that individuality in FGF1 expression significantly influences progression-free survival and response to platinum-based chemotherapy.

Optimizing molecular-targeted therapies in ovarian cancer: the renewed surge of interest in ovarian cancer biomarkers and cell signaling pathways

The hallmarks of ovarian cancer encompass the development of resistance, disease recurrence and poor prognosis. Ovarian cancer cells express gene signatures which pose significant challenges for cancer drug development, therapeutics, prevention and management. Despite enhancements in contemporary tumor debulking surgery, tentative combination regimens and abdominal radiation which can achieve beneficial response rates, the majority of ovarian cancer patients not only experience adverse effects, but also eventually relapse. Therefore, additional therapeutic possibilities need to be explored to minimize adverse events and prolong progression-free and overall response rates in ovarian cancer patients. Currently, a revival in cancer drug discovery is devoted to identifying diagnostic and prognostic ovarian cancer biomarkers. However, the sensitivity and reliability of such biomarkers may be complicated by mutations in the BRCA1 or BRCA2 genes, diverse genetic risk factors, unidentified initiation and progression elements, molecular tumor heterogeneity and disease staging. There is thus a dire need to expand existing ovarian cancer therapies with broad-spectrum and individualized molecular targeted approaches. The aim of this review is to profile recent developments in our understanding of the interrelationships among selected ovarian tumor biomarkers, heterogeneous expression signatures and related molecular signal transduction pathways, and their translation into more efficacious targeted treatment rationales.