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

A comprehensive overview of ovarian cancer stem cells: correlation with high recurrence rate, underlying mechanisms, and therapeutic opportunities

Ovarian cancer is one of the most lethal gynecological malignancies, with a recurrence rate of 70-80%, particularly in patients diagnosed at advanced stages (stage III or IV), where the five-year survival rate falls below 30%. A key driver of this recurrence is the presence of cancer stem cells (CSCs), which exhibit resistance to chemotherapy and possess the capacity for self-renewal, plasticity, and tumor regeneration. The tumor microenvironment (TME) plays a crucial role in maintaining ovarian cancer stem cells (OCSCs) by providing nutrient and oxygen gradients, extracellular matrix (ECM) interactions, immune cell modulation, and support from cancer-associated fibroblasts (CAFs). CAFs secrete growth factors, cytokines, and ECM components that create a pro-tumorigenic niche, promoting CSC maintenance, invasion, and chemoresistance. Additionally, dysregulation of critical signaling pathways, including WNT, NOTCH, PI3K/AKT/mTOR, TGF-β, JAK/STAT, Hedgehog, NF-κB, and Hippo, supports CSC stemness, plasticity, maintenance, and adaptability, thereby increasing their survival and progression. Numerous inhibitors targeting these pathways have shown promise in preclinical studies. This review discusses the molecular mechanisms underlying CSC-mediated recurrence in ovarian cancer and highlights emerging therapeutic strategies. Particular emphasis is placed on the potential of combination therapies involving routine platinum or taxane based regimens with OCSC inhibitors to overcome chemoresistance, reduce recurrence rates, and improve survival outcomes for patients with advanced-stage ovarian cancer.

The antibody-drug conjugate targeting ROR1, NBE-002, is active in high-grade serous ovarian cancer preclinical models

Background

Novel therapeutics are urgently needed for high-grade serous ovarian cancer (HGSOC). We identified the receptor tyrosine kinase-like orphan receptor 1 (ROR1) as a therapeutic target. NBE-002, an antibody-drug conjugate (ADC) consisting of a humanised anti-ROR1 antibody, huXBR1-402, linked to a highly potent anthracycline-derivative (PNU), has activity in ROR1-positive haematologic malignancies.

Objectives

This study explored the anti-cancer effects of NBE-002 alone and in combination with standard HGSOC therapies, carboplatin, paclitaxel and olaparib.

Design

A ROR1-ADC was tested in cell lines and in vivo models of HGSOC.

Methods

Different ROR1-targeting antibodies and payload compositions were constructed and tested in vitro. The dose effect of NBE-002 alone and in combination with carboplatin, paclitaxel or olaparib was analysed in ROR1+ HGSOC cell lines. Growth inhibition and apoptosis were monitored by live cell imaging and combination effects determined. Ten HGSOC PDX models were treated with NBE-002 alone, or in combination with carboplatin or olaparib, over 4 weeks and tumour volume and overall survival evaluated.

Results

Synergistic interaction was observed in two out of five HGSOC cell lines treated with NBE-002 and carboplatin (PEO4 and OC023, chemo-resistant), in one out of five treated with NBE-002 and olaparib (PEO1, BRCA2 mutated, HR deficient) and none of five treated with NBE-002 and paclitaxel. In vivo, NBE-002 exhibited activity in PA-1 xenografts and three HGSOC PDX models with high ROR1 expression, platinum sensitivity and homologous recombination DNA repair deficient (HRD). When NBE-002 was combined with carboplatin, activity was observed in 7 of 10 ROR1-expressing PDX models, regardless of platinum or HRD status. The activity was demonstrated in combination with olaparib in both PDX tested, one HRD and one HRD reverted.

Conclusion

The ROR1-targeting ADC, NBE-002, has therapeutic potential in HGSOC, with single agent activity observed both in vitro and in vivo. Broader clinical applications were evident when NBE-002 was combined with carboplatin or olaparib.

ROR1 facilitates glioblastoma growth via stabilizing GRB2 to promote c-Fos expression in glioma stem cells

BACKGROUND

Glioma stem cells (GSCs) are the root cause of tumorigenesis, recurrence, and therapeutic resistance in glioblastoma (GBM), the most prevalent and lethal type of primary adult brain malignancy. The exploitation of novel methods targeting GSCs is crucial for the treatment of GBM. In this study, we investigate the function of the novel ROR1-GRB2-c-Fos axis in GSCs maintenance and GBM progression.

METHODS

The expression characteristics of ROR1 in GBM and GSCs were assessed by bioinformatic analysis, patient specimens, and patient-derived GSCs. Lentivirus-mediated gene knockdown and overexpression were conducted to evaluate the effect of ROR1 on GSCs proliferation and self-renewal both in vitro and in vivo. The downstream signaling of ROR1 in GSCs maintenance was unbiasedly determined by RNA-seq and validated both in vitro and in vivo. Finally, rescue assays were performed to further validate the function of the ROR1-GRB2-c-Fos axis in GSCs maintenance and GBM progression.

RESULTS

ROR1 is upregulated in GBM and preferentially expressed in GSCs. Disruption of ROR1 markedly impairs GSC proliferation and self-renewal, and inhibits GBM growth in vivo. Moreover, ROR1 stabilizes GRB2 by directly binding and reducing its lysosomal degradation, and ROR1 knockdown significantly inhibits GRB2/ERK/c-Fos signaling in GSCs. Importantly, ectopic expression of c-Fos counteracts the effects caused by ROR1 silencing both in vitro and in vivo.

CONCLUSIONS

ROR1 plays essential roles in GSCs maintenance through binding to GRB2 and activation of ERK/c-Fos signaling, which highlights the therapeutic potential of targeting the ROR1-GRB2-c-Fos axis.

Cancer stem cells: Masters of all traits

Cancer is a heterogeneous disease, which contributes to its rapid progression and therapeutic failure. Besides interpatient tumor heterogeneity, tumors within a single patient can present with a heterogeneous mix of genetically and phenotypically distinct subclones. These unique subclones can significantly impact the traits of cancer. With the plasticity that intratumoral heterogeneity provides, cancers can easily adapt to changes in their microenvironment and therapeutic exposure. Indeed, tumor cells dynamically shift between a more differentiated, rapidly proliferating state with limited tumorigenic potential and a cancer stem cell (CSC)-like state that resembles undifferentiated cellular precursors and is associated with high tumorigenicity. In this context, CSCs are functionally located at the apex of the tumor hierarchy, contributing to the initiation, maintenance, and progression of tumors, as they also represent the subpopulation of tumor cells most resistant to conventional anti-cancer therapies. Although the CSC model is well established, it is constantly evolving and being reshaped by advancing knowledge on the roles of CSCs in different cancer types. Here, we review the current evidence of how CSCs play a pivotal role in providing the many traits of aggressive tumors while simultaneously evading immunosurveillance and anti-cancer therapy in several cancer types. We discuss the key traits and characteristics of CSCs to provide updated insights into CSC biology and highlight its implications for therapeutic development and improved treatment of aggressive cancers.

Unlocking the potential: advancements and future horizons in ROR1-targeted cancer therapies

While receptor tyrosine kinase-like orphan receptor 1 (ROR1) is typically expressed at low levels or absent in normal tissues, its expression is notably elevated in various malignant tumors and conditions, including chronic lymphocytic leukemia (CLL), breast cancer, ovarian cancer, melanoma, and lung adenocarcinoma. This distinctive feature positions ROR1 as an attractive target for tumor-specific treatments. Currently, several targeted drugs directed at ROR1 are undergoing clinical development, including monoclonal antibodies, antibody-drug conjugates (ADCs), and chimeric antigen receptor T-cell therapy (CAR-T). Additionally, there are four small molecule inhibitors designed to bind to ROR1, presenting promising avenues for the development of PROTAC degraders targeting ROR1. This review offers updated insights into ROR1's structural and functional characteristics, embryonic development implications, cell survival signaling pathways, and evolutionary targeting strategies, all of which have the potential to advance the treatment of malignant tumors.

Therapeutic advances in the targeting of ROR1 in hematological cancers

Receptor tyrosine kinases (RTKs) are key cell surface receptors involved in cell communication and signal transduction, with great importance in cell growth, differentiation, survival, and metabolism. Dysregulation of RTKs, such as EGFR, VEGFR, HER2 or ROR, could lead to various diseases, particularly cancers. ROR1 has emerged as a promising target in hematological malignancies. The development of ROR1 targeted therapies is continuously growing leading to remarkable novel therapeutical approaches using mAbs, antibody-drug conjugates, several small molecules or CAR T cells which have shown encouraging preclinical results. In the hematological field, mAbs, small molecules, BiTEs or CAR T cell therapies displayed promising outcomes with the clinical trials data encouraging the use of anti-ROR1 therapies. This paper aims to offer a comprehensive analysis of the current landscape of ROR1-targeted therapies in hematological malignancies marking the innovative approaches with promising preclinical and clinical. Offering a better understanding of structural and functional aspects of ROR1 could lead to new perspectives in targeting a wide spectrum of malignancies.

Roles of miRNAs in regulating ovarian cancer stemness

Ovarian cancer is one of the gynaecology malignancies with the highest mortality rate. Ovarian cancer stem cell (CSC) is a subpopulation of ovarian cancer cells with increased self-renewability, aggression, metastatic potentials, and resistance to conventional anti-cancer therapy. The emergence of ovarian CSC is a critical factor that promotes treatment resistance and frequent relapse among ovarian cancer patients, leading to poor clinical outcomes. MicroRNA (miRNA) is a short, non-protein-coding RNA that regulates ovarian CSC development. Although multiple original research articles have discussed the CSC-regulatory roles of different miRNAs in ovarian cancer, there is a deficiency of a review article that can summarize the findings from different research papers. To narrow the gap in the literature, this review aimed to provide an up-to-date summary of the CSC-regulatory roles of various miRNAs in modulating ovarian cancer cell stemness. This review will begin by giving an overview of ovarian CSC and the pathways responsible for driving its appearance. Next, the CSC-regulatory roles of miRNAs in controlling ovarian CSC development will be discussed. Overall, more than 60 miRNAs have been reported to play CSC-regulatory roles in the development and progression of ovarian cancer. By targeting various downstream targets, these miRNAs can control the signaling activities of PI3K/AKT, EGFR/ERK, WNT/ß-catenin, NF-kß, Notch, Hippo/YAP, EMT, and DNA repair pathways. Hence, these CSC-modulatory miRNAs have the potential to be used as prognostic biomarkers in predicting the clinical outcomes of ovarian cancer patients. Targeting CSC-promoting miRNAs or increasing the expressions of CSC-repressing miRNAs can help slow ovarian cancer progression. However, more in-depth functional and clinical trials must be carried out to evaluate the suitability, safety, sensitivity, and specificity of these CSC-regulating miRNAs as prognostic biomarkers or therapeutic targets.

Novel humanized monoclonal antibodies against ROR1 for cancer therapy

BACKGROUND

Overexpression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) contributes to cancer cell proliferation, survival and migration, playing crucial roles in tumor development. ROR1 has been proposed as a potential therapeutic target for cancer treatment. This study aimed to develop novel humanized ROR1 monoclonal antibodies and investigate their anti-tumor effects.

METHODS

ROR1 expression in tumor tissues and cell lines was analyzed by immunohistochemistry and flow cytometry. Antibodies from mouse hybridomas were humanized by the complementarity-determining region (CDR) grafting technique. Surface plasmon resonance spectroscopy, ELISA assay and flow cytometry were employed to characterize humanized antibodies. In vitro cellular assay and in vivo mouse experiment were conducted to comprehensively evaluate anti-tumor activity of these antibodies.

RESULTS

ROR1 exhibited dramatically higher expression in lung adenocarcinoma, liver cancer and breast cancer, and targeting ROR1 by short-hairpin RNAs significantly inhibited proliferation and migration of cancer cells. Two humanized ROR1 monoclonal antibodies were successfully developed, named h1B8 and h6D4, with high specificity and affinity to ROR1 protein. Moreover, these two antibodies effectively suppressed tumor growth in the lung cancer xenograft mouse model, c-Myc/Alb-cre liver cancer transgenic mouse model and MMTV-PyMT breast cancer mouse model.

CONCLUSIONS

Two humanized monoclonal antibodies targeting ROR1, h1B8 and h6D4, were successfully developed and exhibited remarkable anti-tumor activity in vivo.

Extracellular vesicles and cancer stem cells: a deadly duo in tumor progression

The global incidence of cancer is increasing, with estimates suggesting that there will be 26 million new cases and 17 million deaths per year by 2030. Cancer stem cells (CSCs) and extracellular vesicles (EVs) are key to the resistance and advancement of cancer. They play a crucial role in tumor dynamics and resistance to therapy. CSCs, initially discovered in acute myeloid leukemia, are well-known for their involvement in tumor initiation, progression, and relapse, mostly because of their distinct characteristics, such as resistance to drugs and the ability to self-renew. EVs, which include exosomes, microvesicles, and apoptotic bodies, play a vital role in facilitating communication between cells within the tumor microenvironment (TME). They have a significant impact on cellular behaviors and contribute to genetic and epigenetic changes. This paper analyzes the mutually beneficial association between CSCs and EVs, emphasizing their role in promoting tumor spread and developing resistance mechanisms. This review aims to investigate the interaction between these entities in order to discover new approaches for attacking the complex machinery of cancer cells. It highlights the significance of CSCs and EVs as crucial targets in the advancement of novel cancer treatments, which helps stimulate additional research, promote progress in ideas for cancer treatment, and provide renewed optimism in the effort to reduce the burden of cancer.

WNT5B drives osteosarcoma stemness, chemoresistance and metastasis

BACKGROUND

Treatment for osteosarcoma, a paediatric bone cancer with no therapeutic advances in over three decades, is limited by a lack of targeted therapies. Osteosarcoma frequently metastasises to the lungs, and only 20% of patients survive 5 years after the diagnosis of metastatic disease. We found that WNT5B is the most abundant WNT expressed in osteosarcoma tumours and its expression correlates with metastasis, histologic subtype and reduced survival.

METHODS

Using tumor-spheroids to model cancer stem-like cells, we performed qPCR, immunoblotting, and immunofluorescence to monitor changes in gene and protein expression. Additionally, we measured sphere size, migration and forming efficiency to monitor phenotypic changes. Therefore, we characterised WNT5B's relevance to cancer stem-like cells, metastasis, and chemoresistance and evaluated its potential as a therapeutic target.

RESULTS

In osteosarcoma cell lines and patient-derived spheres, WNT5B is enriched in stem cells and induces the expression of the stemness gene SOX2. WNT5B promotes sphere size, sphere-forming efficiency, and cell proliferation, migration, and chemoresistance to methotrexate (but not cisplatin or doxorubicin) in spheres formed from conventional cell lines and patient-derived xenografts. In vivo, WNT5B increased osteosarcoma lung and liver metastasis and inhibited the glycosaminoglycan hyaluronic acid via upregulation of hyaluronidase 1 (HYAL1), leading to changes in the tumour microenvironment. Further, we identified that WNT5B mRNA and protein correlate with the receptor ROR1 in primary tumours. Targeting WNT5B through inhibition of WNT/ROR1 signalling with an antibody to ROR1 reduced stemness properties, including chemoresistance, sphere size and SOX2 expression.

CONCLUSIONS

Together, these data define WNT5B's role in driving osteosarcoma cancer stem cell expansion and methotrexate resistance and provide evidence that the WNT5B pathway is a promising candidate for treating osteosarcoma patients.

KEY POINTS

WNT5B expression is high in osteosarcoma stem cells leading to increased stem cell proliferation and migration through SOX2. WNT5B expression in stem cells increases rates of osteosarcoma metastasis to the lungs and liver in vivo. The hyaluronic acid degradation enzyme HYAL1 is regulated by WNT5B in osteosarcoma contributing to metastasis. Inhibition of WNT5B with a ROR1 antibody decreases osteosarcoma stemness.

Overall review of curative impact and barriers of CAR-T cells in osteosarcoma

Osteosarcoma (OS) is a rare form of cancer and primary bone malignancy in children and adolescents. Current therapies include surgery, chemotherapy, and amputation. Therefore, a new therapeutic strategy is needed to dramatically change cancer treatment. Recently, chimeric antigen receptor T cells (CAR-T cells) have been of considerable interest as it has provided auspicious results and patients suffering from low side effects after injection that resolve with current therapy. However, there are reports that cytokine release storm (CRS) can be observed in some patients. In addition, as researchers have faced problems that limit and suppress T cells, further studies are required to resolve these problems. In addition, to maximize the therapeutic benefit of CAR-T cell therapy, researchers have suggested that combination therapy could be better used to treat cancer by overcoming any problems and reducing side effects as much as possible. This review summarizes these problems, barriers, and the results of some studies on the evaluation of CAR-T cells in patients with osteosarcoma.

Exploration of macrocyclic peptide binders to the extracellular CRD domain of human receptor tyrosine kinase-like orphan receptor 1 (ROR1)

Elevated levels of receptor tyrosine kinase-like orphan receptor 1 (RORl) expression are observed in multiple hematological and solid tumors, but not in most of the healthy adult tissues, identifying ROR1 as an attractive target for tumor-specific therapy. Herein we will describe the discovery of macrocyclic peptides as binders of the extracellular Cysteine-Rich Domain (CRD) of human ROR1 via mRNA in vitro selection technology using the PDPS platform, followed by exploration of sidechain SAR of parent macrocycle peptides, fluorescently labeled analogs, and a Peptide Drug Conjugate (PDC). The parent macrocyclic peptides represented by Compound 1 and Compound 14 displayed nanomolar cell-based binding to ROR1 and relatively good internalization in 786-O and MDA-MB-231 tumor cell lines. However, these peptides were not observed to induce apoptosis in Mia PaCa-2 cells, a model pancreatic tumor cell line with a relatively low level of cell surface expression of ROR1.

Defining the Role of Metastasis-Initiating Cells in Promoting Carcinogenesis in Ovarian Cancer

Ovarian cancer is the deadliest gynecological malignancy with a high prevalence of transcoelomic metastasis. Metastasis is a multi-step process and only a small percentage of cancer cells, metastasis-initiating cells (MICs), have the capacity to finally establish metastatic lesions. These MICs maintain a certain level of stemness that allows them to differentiate into other cell types with distinct transcriptomic profiles and swiftly adapt to external stresses. Furthermore, they can coordinate with the microenvironment, through reciprocal interactions, to invade and establish metastases. Therefore, identifying, characterizing, and targeting MICs is a promising strategy to counter the spread of ovarian cancer. In this review, we provided an overview of OC MICs in the context of characterization, identification through cell surface markers, and their interactions with the metastatic niche to promote metastatic colonization.

ROR1-STAT3 signaling contributes to ovarian cancer intra-tumor heterogeneity

Wnt pathway dysregulation through genetic and non-genetic alterations occurs in multiple cancers, including ovarian cancer (OC). The aberrant expression of the non-canonical Wnt signaling receptor ROR1 is thought to contribute to OC progression and drug resistance. However, the key molecular events mediated by ROR1 that are involved in OC tumorigenesis are not fully understood. Here, we show that ROR1 expression is enhanced by neoadjuvant chemotherapy, and Wnt5a binding to ROR1 can induce oncogenic signaling via AKT/ERK/STAT3 activation in OC cells. Proteomics analysis of isogenic ROR1-knockdown OC cells identified STAT3 as a downstream effector of ROR1 signaling. Transcriptomics analysis of clinical samples (n = 125) revealed that ROR1 and STAT3 are expressed at higher levels in stromal cells than in epithelial cancer cells of OC tumors, and these findings were corroborated by multiplex immunohistochemistry (mIHC) analysis of an independent OC cohort (n = 11). Our results show that ROR1 and its downstream STAT3 are co-expressed in epithelial as well as stromal cells of OC tumors, including cancer-associated fibroblasts or CAFs. Our data provides the framework to expand the clinical utility of ROR1 as a therapeutic target to overcome OC progression.

Deciphering Common Traits of Breast and Ovarian Cancer Stem Cells and Possible Therapeutic Approaches

Breast cancer (BC) and ovarian cancer (OC) are among the most common and deadly cancers affecting women worldwide. Both are complex diseases with marked heterogeneity. Despite the induction of screening programs that increase the frequency of earlier diagnosis of BC, at a stage when the cancer is more likely to respond to therapy, which does not exist for OC, more than 50% of both cancers are diagnosed at an advanced stage. Initial therapy can put the cancer into remission. However, recurrences occur frequently in both BC and OC, which are highly cancer-subtype dependent. Therapy resistance is mainly attributed to a rare subpopulation of cells, named cancer stem cells (CSC) or tumor-initiating cells, as they are capable of self-renewal, tumor initiation, and regrowth of tumor bulk. In this review, we will discuss the distinctive markers and signaling pathways that characterize CSC, their interactions with the tumor microenvironment, and the strategies they employ to evade immune surveillance. Our focus will be on identifying the common features of breast cancer stem cells (BCSC) and ovarian cancer stem cells (OCSC) and suggesting potential therapeutic approaches.

Advances in chimeric antigen receptor T cells therapy in the treatment of breast cancer

Breast cancer (BC) is the most frequently occurring cancer type seriously threatening the lives of women worldwide. Clinically, the high frequency of diverse resistance to current therapeutic strategies advocates a demand to develop novel and effective approaches for the efficient treatment of BC. The chimeric antigen receptor T (CAR-T) cells therapy, one of the immunotherapies, has displayed powerful capacity to specifically kill and eliminate tumors. Due to the success of CAR-T therapy achieved in treating hematological malignancy, the effect of CAR-T cells therapy has been tested in various human diseases including breast cancer. This review summarized and discussed the landscape of the CAR-T therapy for breast cancer, including the advances, challenge and countermeasure of CAR-T therapy in research and clinical application. The roles of potential antigen targets, tumor microenvironment, immune escape in regulating CAR-T therapy, the combination of CAR-T therapy with other therapeutic strategies to further enhance therapeutic efficacy of CAR-T treatment were also highlighted. Therefore, our review provided a comprehensive understanding of CAR-T cell therapy in breast cancer which will awake huge interests for future in-depth investigation of CAR-T based therapy in cancer treatment.

The Role of ROR1 in Chemoresistance and EMT in Endometrial Cancer Cells

Background and Objectives: Receptor tyrosine kinase-like orphan receptor type 1 (ROR1) plays a critical role in embryogenesis and is overexpressed in many malignant cells. These characteristics allow ROR1 to be a potential new target for cancer treatment. The aim of this study was to investigate the role of ROR1 through in vitro experiments in endometrial cancer cell lines. Materials and Methods: ROR1 expression was identified in endometrial cancer cell lines using Western blot and RT-qPCR. The effects of ROR1 on cell proliferation, invasion, migration, and epithelial-mesenchymal transition (EMT) markers were analyzed in two endometrial cancer cell lines (HEC-1 and SNU-539) using either ROR1 silencing or overexpression. Additionally, chemoresistance was examined by identifying MDR1 expression and IC50 level of paclitaxel. Results: The ROR1 protein and mRNA were highly expressed in SNU-539 and HEC-1 cells. High ROR1 expression resulted in a significant increase in cell proliferation, migration, and invasion. It also resulted in a change of EMT markers expression, a decrease in E-cadherin expression, and an increase in Snail expression. Moreover, cells with ROR1 overexpression had a higher IC50 of paclitaxel and significantly increased MDR1 expression. Conclusions: These in vitro experiments showed that ROR1 is responsible for EMT and chemoresistance in endometrial cancer cell lines. Targeting ROR1 can inhibit cancer metastasis and may be a potential treatment method for patients with endometrial cancer who exhibit chemoresistance.

YAP/BRD4-controlled ROR1 promotes tumor-initiating cells and hyperproliferation in pancreatic cancer

Tumor-initiating cells are major drivers of chemoresistance and attractive targets for cancer therapy, however, their identity in human pancreatic ductal adenocarcinoma (PDAC) and the key molecules underlying their traits remain poorly understood. Here, we show that a cellular subpopulation with partial epithelial-mesenchymal transition (EMT)-like signature marked by high expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) is the origin of heterogeneous tumor cells in PDAC. We demonstrate that ROR1 depletion suppresses tumor growth, recurrence after chemotherapy, and metastasis. Mechanistically, ROR1 induces the expression of Aurora kinase B (AURKB) by activating E2F through c-Myc to enhance PDAC proliferation. Furthermore, epigenomic analyses reveal that ROR1 is transcriptionally dependent on YAP/BRD4 binding at the enhancer region, and targeting this pathway reduces ROR1 expression and prevents PDAC growth. Collectively, our findings reveal a critical role for ROR1high cells as tumor-initiating cells and the functional importance of ROR1 in PDAC progression, thereby highlighting its therapeutic targetability.

A Small Molecule Targeting the Intracellular Tyrosine Kinase Domain of ROR1 (KAN0441571C) Induced Significant Apoptosis of Non-Small Cell Lung Cancer (NSCLC) Cells

The ROR1 receptor tyrosine kinase is expressed in embryonic tissues but is absent in normal adult tissues. ROR1 is of importance in oncogenesis and is overexpressed in several cancers, such as NSCLC. In this study, we evaluated ROR1 expression in NSCLC patients (N = 287) and the cytotoxic effects of a small molecule ROR1 inhibitor (KAN0441571C) in NSCLC cell lines. ROR1 expression in tumor cells was more frequent in non-squamous (87%) than in squamous (57%) carcinomas patients, while 21% of neuroendocrine tumors expressed ROR1 (p = 0.0001). A significantly higher proportion of p53 negative patients in the ROR1+ group than in the p53 positive non-squamous NSCLC patients (p = 0.03) was noted. KAN0441571C dephosphorylated ROR1 and induced apoptosis (Annexin V/PI) in a time- and dose-dependent manner in five ROR1+ NSCLC cell lines and was superior compared to erlotinib (EGFR inhibitor). Apoptosis was confirmed by the downregulation of MCL-1 and BCL-2, as well as PARP and caspase 3 cleavage. The non-canonical Wnt pathway was involved. The combination of KAN0441571C and erlotinib showed a synergistic apoptotic effect. KAN0441571C also inhibited proliferative (cell cycle analyses, colony formation assay) and migratory (scratch wound healing assay) functions. Targeting NSCLC cells by a combination of ROR1 and EGFR inhibitors may represent a novel promising approach for the treatment of NSCLC patients.

The signaling pathways activated by ROR1 in cancer

The receptor tyrosine kinase orphan receptor 1 (ROR1) is a receptor for WNT5A and related Wnt proteins, that play an important role during embryonic development by regulating cell migration, cell polarity, neural patterning, and organogenesis. ROR1 exerts these functions by transducing signals from the Wnt secreted glycoproteins to the intracellular Wnt/PCP and Wnt/Ca⁺⁺ pathways. Investigations in adult human cells, particularly cancer cells, have demonstrated that besides these two pathways, the WNT5A/ROR1 axis can activate a number of signaling pathways, including the PI3K/AKT, MAPK, NF-κB, STAT3, and Hippo pathways. Moreover, ROR1 is aberrantly expressed in cancer and was associated with tumor progression and poor survival by promoting cell proliferation, survival, invasion, epithelial to mesenchymal transition, and metastasis. Consequently, numerous therapeutic tools to target ROR1 are currently being evaluated in cancer patients. In this review, we will provide a detailed description of the signaling pathways regulated by ROR1 in cancer and their impact in tumor progression.

An Overview of Ovarian Cancer: The Role of Cancer Stem Cells in Chemoresistance and a Precision Medicine Approach Targeting the Wnt Pathway with the Antagonist sFRP4

Ovarian cancer is one of the most prevalent gynecological cancers, having a relatively high fatality rate with a low five-year chance of survival when detected in late stages. The early detection, treatment and prevention of metastasis is pertinent and a pressing research priority as many patients are diagnosed only in stage three of ovarian cancer. Despite surgical interventions, targeted immunotherapy and adjuvant chemotherapy, relapses are significantly higher than other cancers, suggesting the dire need to identify the root cause of metastasis and relapse and present more precise therapeutic options. In this review, we first describe types of ovarian cancers, the existing markers and treatment modalities. As ovarian cancer is driven and sustained by an elusive and highly chemoresistant population of cancer stem cells (CSCs), their role and the associated signature markers are exhaustively discussed. Non-invasive diagnostic markers, which can be identified early in the disease using circulating tumor cells (CTCs), are also described. The mechanism of the self-renewal, chemoresistance and metastasis of ovarian CSCs is regulated by the Wnt signaling pathway. Thus, its role in ovarian cancer in promoting stemness and metastasis is delineated. Based on our findings, we propose a novel strategy of Wnt inhibition using a well-known Wnt antagonist, secreted frizzled related protein 4 (sFRP4), wherein short micropeptides derived from the whole protein can be used as powerful inhibitors. The latest approaches to early diagnosis and novel treatment strategies emphasized in this review will help design precision medicine approaches for an effective capture and destruction of highly aggressive ovarian cancer.

Anti-ROR1 CAR-T cells: Architecture and performance

The receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a membrane receptor that plays a key role in development. It is highly expressed during the embryonic stage and relatively low in some normal adult tissues. Malignancies such as leukemia, lymphoma, and some solid tumors overexpress ROR1, making it a promising target for cancer treatment. Moreover, immunotherapy with autologous T-cells engineered to express a ROR1-specific chimeric antigen receptor (ROR1 CAR-T cells) has emerged as a personalized therapeutic option for patients with tumor recurrence after conventional treatments. However, tumor cell heterogeneity and tumor microenvironment (TME) hinder successful clinical outcomes. This review briefly describes the biological functions of ROR1 and its relevance as a tumor therapeutic target, as well as the architecture, activity, evaluation, and safety of some ROR1 CAR-T cells used in basic research and clinical trials. Finally, the feasibility of applying the ROR1 CAR-T cell strategy in combination with therapies targeting other tumor antigens or with inhibitors that prevent tumor antigenic escape is also discussed.

Clinical trial registration

https://clinicaltrials.gov/, identifier NCT02706392.

Meta-Analysis of Survival Effects of Receptor Tyrosine Kinase-like Orphan Receptor 1 (ROR1)

Background and Objectives: Identification and targeting of membrane proteins in tumor cells is one of the key steps in the development of cancer drugs. The receptor tyrosine kinase-like orphan receptor (ROR) type 1 is a type-I transmembrane protein expressed in various cancer tissues, which is in contrast to its limited expression in normal tissues. These characteristics make ROR1 a candidate target for cancer treatment. This study aimed to identify the prognostic value of ROR1 expression in cancers. Materials and Methods: We conducted a comprehensive systematic search of electronic databases (PubMed) from their inception to September 2021. The included studies assessed the effect of ROR1 on overall survival (OS) and progression-free survival (PFS). Hazard ratios (HR) from collected data were pooled in a meta-analysis using Revman version 5.4 with generic inverse-variance and random effects modeling. Results: A total of fourteen studies were included in the final analysis. ROR1 was associated with worse OS (HR 1.95, 95% confidence interval (CI) 1.50−2.54; p < 0.001) with heterogeneity. The association between poor OS and ROR1 expression was high in endometrial cancer, followed by ovarian cancer, and diffuse large B cell lymphoma. In addition, ROR1 was associated with poor PFS (HR 1.84, 95% CI 1.60−2.10; p < 0.001), but heterogeneity was not statistically significant. In subgroup analysis, high ROR1 expression showed a significantly higher rate of advanced stage or lymph node metastasis. Conclusions: This meta-analysis provides evidence that ROR1 expression is associated with adverse outcome in cancer survival. This result highlights ROR1 as a target for developmental therapeutics in cancers.

Preclinical Assessment of Immunogenicity and Protectivity of Novel ROR1 Fusion Proteins in a Mouse Tumor Model

The receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a new tumor associated antigen (TAA) which is overexpressed in several hematopoietic and solid malignancies. The present study aimed to produce and evaluate different fusion proteins of mouse ROR1 (mROR1) to enhance immunogenicity and protective efficacy of ROR1. Four ROR1 fusion proteins composed of extracellular region of mROR1, immunogenic fragments of TT as well as Fc region of mouse IgG2a were produced and employed to immunize Balb/C mice. Humoral and cellular immune responses and anti-tumor effects of these fusion proteins were evaluated using two different syngeneic murine ROR1+ tumor models. ROR1-specific antibodies were induced in all groups of mice. The levels of IFN-γ, IL-17 and IL-22 cytokines in culture supernatants of stimulated splenocytes were increased in all groups of immunized mice, particularly mice immunized with TT-mROR1-Fc fusion proteins. The frequency of ROR1-specific CTLs was higher in mice immunized with TT-mROR1-Fc fusion proteins. Finally, results of tumor challenge in immunized mice showed that immunization with TT-mROR1-Fc fusion proteins completely inhibited ROR1+ tumor cells growth in two different syngeneic tumor models until day 120 post tumor challenge. Our preclinical findings, for the first time, showed that our fusion proteins could be considered as a potential candidate vaccine for active immunotherapy of ROR1-expressing malignancies.

Green Synthesis of Platinum Nanoparticles for Biomedical Applications

The diverse biological properties of platinum nanoparticles (PtNPs) make them ideal for use in the development of new tools in therapy, diagnostics, and other biomedical purposes. "Green" PtNPs synthesis is of great interest as it is eco-friendly, less energy-consuming and minimizes the amount of toxic by-products. This review is devoted to the biosynthesis properties of platinum nanoparticles based on living organisms (bacteria, fungi, algae, and plants) use. The participation of various biological compounds in PtNPs synthesis is highlighted. The biological activities of "green" platinum nanoparticles (antimicrobial, anticancer, antioxidant, etc.), the proposed mechanisms of influence on target cells and the potential for their further biomedical application are discussed.

Role of RAS signaling in ovarian cancer

The RAS family of proteins is among the most frequently mutated genes in human malignancies. In ovarian cancer (OC), the most lethal gynecological malignancy, RAS, especially KRAS mutational status at codons 12, 13, and 61, ranges from 6-65% spanning different histo-types. Normally RAS regulates several signaling pathways involved in a myriad of cellular signaling cascades mediating numerous cellular processes like cell proliferation, differentiation, invasion, and death. Aberrant activation of RAS leads to uncontrolled induction of several downstream signaling pathways such as RAF-1/MAPK (mitogen-activated protein kinase), PI3K phosphoinositide-3 kinase (PI3K)/AKT, RalGEFs, Rac/Rho, BRAF (v-Raf murine sarcoma viral oncogene homolog B), MEK1 (mitogen-activated protein kinase kinase 1), ERK (extracellular signal-regulated kinase), PKB (protein kinase B) and PKC (protein kinase C) involved in cell proliferation as well as maintenance pathways thereby driving tumorigenesis and cancer cell propagation. KRAS mutation is also known to be a biomarker for poor outcome and chemoresistance in OC. As a malignancy with several histotypes showing varying histopathological characteristics, we focus on reviewing recent literature showcasing the involvement of oncogenic RAS in mediating carcinogenesis and chemoresistance in OC and its subtypes.

ROR1: an orphan becomes apparent

Since its initial identification in 1992 as a possible class 1 cell-surface receptor without a known parent ligand, receptor tyrosine kinase-like orphan receptor 1 (ROR1) has stimulated research, which has made apparent its significance in embryonic development and cancer. Chronic lymphocytic leukemia (CLL) was the first malignancy found to have distinctive expression of ROR1, which can help distinguish leukemia cells from most noncancer cells. Aside from its potential utility as a diagnostic marker or target for therapy, ROR1 also factors in the pathophysiology of CLL. This review is a report of the studies that have elucidated the expression, biology, and evolving strategies for targeting ROR1 that hold promise for improving the therapy of patients with CLL or other ROR1-expressing malignancies.

Developing ROR1 Targeting CAR-T Cells against Solid Tumors in Preclinical Studies

Chimeric antigen receptor (CAR)-modified T-cells (CAR-T) have demonstrated promising clinical benefits against B-cell malignancies. Yet, its application for solid tumors is still facing challenges. Unlike haematological cancers, solid tumors often lack good targets, which are ideally expressed on the tumor cells, but not by the normal healthy cells. Fortunately, receptor tyrosine kinase-like orphan receptor 1 (ROR1) is among a few good cancer targets that is aberrantly expressed on various tumors but has a low expression on normal tissue, suggesting it as a good candidate for CAR-T therapy. Here, we constructed two ROR1 CARs with the same antigen recognition domain that was derived from Zilovertamab but differing in hinge regions. Both CARs target ROR1⁺ cancer cells specifically, but CAR with a shorter IgG4 hinge exhibits a higher surface expression and better in vitro functionality. We further tested the ROR1 CAR-T in three human solid tumor xenografted mouse models. Our ROR1 CAR-T cells controlled the solid tumor growth without causing any severe toxicity. Our results demonstrated that ROR1 CAR-T derived from Zilovertamab is efficacious and safe to suppress ROR1⁺ solid tumors in vitro and in vivo, providing a promising therapeutic option for future clinical application.

Oncofetal proteins and cancer stem cells

Cancer stem cells (CSCs) are considered as a small population of cells with stem-like properties within the tumor bulk, and are largely responsible for tumor recurrence, metastasis, and therapy resistance. CSCs share critical features with embryonic stem cells (ESCs). The pluripotent transcription factors (TFs) and developmental signaling pathways of ESCs are invariably hijacked by CSCs termed ‘oncofetal drivers’ in many cancers, which are rarely detectable in adult tissues. The unique expression pattern makes oncofetal proteins ideal therapeutic targets in cancer treatment. Therefore, elucidation of oncofetal drivers in cancers is critical for the development of effective CSCs-directed therapy. In this review, we summarize the common pluripotent TFs such as OCT4, SOX2, NANOG, KLF4, MYC, SALL4, and FOXM1, as well as the development signaling including Wnt/β-catenin, Hedgehog (Hh), Hippo, Notch, and TGF-β pathways of ESCs and CSCs. We also describe the newly identified oncofetal proteins that drive the self-renewal, plasticity, and therapy-resistance of CSCs. Finally, we explore how the clinical implementation of targeting oncofetal drivers, including small-molecule inhibitors, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) can facilitate the development of CSCs-directed therapy.

EMT alterations in the solute carrier landscape uncover SLC22A10/A15 imposed vulnerabilities in pancreatic cancer

The involvement of membrane-bound solute carriers (SLCs) in neoplastic transdifferentiation processes is poorly defined. Here, we examined changes in the SLC landscape during epithelial-mesenchymal transition (EMT) of pancreatic cancer cells. We show that two SLCs from the organic anion/cation transporter family, SLC22A10 and SLC22A15, favor EMT via interferon (IFN) α and γ signaling activation of receptor tyrosine kinase-like orphan receptor 1 (ROR1) expression. In addition, SLC22A10 and SLC22A15 allow tumor cell accumulation of glutathione to support EMT via the IFNα/γ-ROR1 axis. Moreover, a pan-SLC22A inhibitor lesinurad reduces EMT-induced metastasis and gemcitabine chemoresistance to prolong survival in mouse models of pancreatic cancer, thus identifying new vulnerabilities for human PDAC.

The Anti-ROR1 Monoclonal Antibody Zilovertamab Inhibits the Proliferation of Ovarian and Endometrial Cancer Cells

The non-canonical Wnt signalling receptor ROR1 is aberrantly expressed in numerous cancers, including ovarian and endometrial cancer. We previously reported that silencing ROR1 could inhibit the proliferation and metastatic potential of ovarian and endometrial cancer cells in vitro. Zilovertamab is an ROR1-targeting humanised monoclonal antibody, with demonstrated safety and efficacy in clinical trials of several ROR1-related malignancies. The aim of this study was to investigate the potential of zilovertamab alone, or in combination with commonly utilised gynaecological cancer therapies (cisplatin, paclitaxel and the PARP inhibitor—Olaparib) on high-grade serous ovarian cancer (HGSOC), including models of platinum resistance and homologous recombination deficiency (CaOV3, CaOV3CisR, PEO1 and PEO4) and endometrial cancer (EC) cell lines (Ishikawa and KLE). The effect of zilovertamab (at 25 µg/mL or 50 µg/mL) +/− agents was investigated using the IncuCyte S3 Live Cell imaging system. Zilovertamab alone inhibited the proliferation of HGSOC and EC cells in vitro, including in models of platinum resistance and homologous recombination deficiency. In general, the addition of commonly used chemotherapies to a fixed dose of zilovertamab did not enhance the observed anti-proliferative activity. This study supports the potential of zilovertamab, or other ROR1-targeting therapies, for treating women with HGSOC and EC.

An organotypic model of high-grade serous ovarian cancer to test the anti-metastatic potential of ROR2 targeted Polyion complex nanoparticles

High-grade serous ovarian cancer (HGSOC) is the most lethal gynaecological malignancy. Most patients are diagnosed at late stages when the tumour has metastasised throughout the peritoneal cavity. The Wnt receptor ROR2 has been identified as a promising therapeutic target in HGSOC, with limited targeting therapeutic options currently available. Small interfering RNA (siRNA)-based therapeutics hold great potential for inhibiting the function of specific biomarkers, however major challenges remain in efficient delivery and stability. The aim of this study was to investigate the ability of nanoparticles to deliver ROR2 siRNA into HGSOC cells, including platinum resistant models, and estimate the anti-metastatic effect via a 3D organotypic model for ovarian cancer. The nanoparticles were generated by conjugating poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA) of various chain length to bovine serum albumin (BSA), followed by the condensation of ROR2 siRNA into polyplexes, also termed polyion complex (PIC) nanoparticles. The toxicity and uptake of ROR2 siRNA PIC nanoparticles in two HGSOC cell lines, CaOV3 as well as its cisplatin resistant pair (CaOV3CisR), in addition to primary cells used for the 3D organotypic model were investigated. ROR2 knockdown at both transcriptional and translational levels were evaluated via real-time PCR and western blot analysis, respectively. Following 24 h incubation with the nanoparticles, functional assays were performed including proliferation (IncuCyte S3), transwell migration and 3D co-cultured transwell invasion assays. The PICs nanoparticles exhibited negligible toxicity in the paired CaOV3 cell lines or primary cells. Treating CaOV3 and CaOV3CisR cells with ROR2 siRNA containing PICs nanoparticles significantly inhibited migration and invasion ability. The biocompatible ROR2 siRNA conjugated PICs nanoparticles provide an innovative therapeutic option. ROR2 targeting therapy shows potential in treating HGSOC including platinum resistant forms.

Stress Hormones: Emerging Targets in Gynecological Cancers

In the past decade, several discoveries have documented the existence of innervation in ovarian cancer and cervical cancer. Notably, various neurotransmitters released by the activation of the sympathetic nervous system can promote the proliferation and metastasis of tumor cells and regulate immune cells in the tumor microenvironment. Therefore, a better understanding of the mechanisms involving neurotransmitters in the occurrence and development of gynecological cancers will be beneficial for exploring the feasibility of using inexpensive β-blockers and dopamine agonists in the clinical treatment of gynecological cancers. Additionally, this article provides some new insights into targeting tumor innervation and neurotransmitters in the tumor microenvironment.

Predicting ROR1/BCL2 combination targeted therapy of small cell carcinoma of the lung

Small cell lung cancer (SCLC) remains a deadly form of cancer, with a 5-year survival rate of less than 10 percent, necessitating novel therapies. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an oncofetal protein that is emerging as a therapeutic target and is co-expressed with BCL2 in multiple tumor types due to microRNA coregulation. We hypothesize that ROR1-targeted therapy is effective in small cell lung cancer and synergizes with therapeutic BCL2 inhibition. Tissue microarrays (TMAs) and formalin-fixed paraffin-embedded (FFPE) SCLC patient samples were utilized to determine the prevalence of ROR1 and BCL2 expression in SCLC. Eight SCLC-derived cell lines were used to determine the antitumor activity of a small molecule ROR1 inhibitor (KAN0441571C) alone and in combination with the BCL2 inhibitor venetoclax. The Chou-Talalay method was utilized to determine synergy with the drug combination. ROR1 and BCL2 protein expression was identified in 93% (52/56) and 86% (48/56) of SCLC patient samples, respectively. Similarly, ROR1 and BCL2 were shown by qRT-PCR to have elevated expression in 79% (22/28) and 100% (28/28) of SCLC patient samples, respectively. KAN0441571C displayed efficacy in 8 SCLC cell lines, with an IC50 of 500 nM or less. Synergy as defined by a combination index of <1 via the Chou-Talalay method between KAN0441571C and venetoclax was demonstrated in 8 SCLC cell lines. We have shown that ROR1 inhibition is synergistic with BCL2 inhibition in SCLC models and shows promise as a novel therapeutic target in SCLC.

Tyrosine Kinase ROR1 as a Target for Anti-Cancer Therapies

Receptor tyrosine kinase ROR1 plays an essential role in embryogenesis and is overexpressed in many types of malignant tumors. Studies have demonstrated that it plays an important role in oncogenesis by activating cell survival signaling events, particularly the non-canonical WNT signaling pathway. Antibody-based immunotherapies targeting ROR1 have been developed and evaluated in preclinical and clinical studies with promising outcomes. However, small molecule inhibitors targeting ROR1 are underappreciated because of the initial characterization of ROR1 as a peusdokinase. The function of ROR1 as a tyrosine kinase remains poorly understood, although accumulating evidence have demonstrated its intrinsic tyrosine kinase activity. In this review, we analyzed the structural and functional features of ROR1 and discussed therapeutic strategies targeting this kinase.

Novel molecular regulators of breast cancer stem cell plasticity and heterogeneity

Tumors consist of heterogeneous cell populations, and tumor heterogeneity plays key roles in regulating tumorigenesis, metastasis, recurrence and resistance to anti-tumor therapies. More and more studies suggest that cancer stem cells (CSCs) promote tumorigenesis, metastasis, recurrence and drug resistance as well as are the major source for heterogeneity of cancer cells. CD24^-CD44⁺ and ALDH⁺ are the most common markers for breast cancer stem cells (BCSCs). Previous studies showed that different BCSC markers label different BCSC populations, indicating the heterogeneity of BCSCs. Therefore, defining the regulation mechanisms of heterogeneous BCSCs is essential for precisely targeting BCSCs and treating breast cancer. In this review, we summarized the novel regulators existed in BCSCs and their niches for BCSC heterogeneity which has been discovered in recent years, and discussed their regulation mechanisms and the latest corresponding cancer treatments, which will extend our understanding on BCSC heterogeneity and plasticity, and provide better prognosis prediction and more efficient novel therapeutic strategies for breast cancer.

Conditional Ror1 knockout reveals crucial involvement in lung adenocarcinoma development and identifies novel HIF-1α regulator

We previously reported that ROR1 is a crucial downstream gene for the TTF‐1/NKX2‐1 lineage‐survival oncogene in lung adenocarcinoma, while others have found altered expression of ROR1 in multiple cancer types. Accumulated evidence therefore indicates ROR1 as an attractive molecular target, though it has yet to be determined whether targeting Ror1 can inhibit tumor development and growth in vivo. To this end, genetically engineered mice carrying homozygously floxed Ror1 alleles and an SP‐C promoter–driven human mutant EGFR transgene were generated. Ror1 ablation resulted in marked retardation of tumor development and progression in association with reduced malignant characteristics and significantly better survival. Interestingly, gene set enrichment analysis identified a hypoxia‐induced gene set (HALLMARK_HYPOXIA) as most significantly downregulated by Ror1 ablation in vivo, which led to findings showing that ROR1 knockdown diminished HIF‐1α expression under normoxia and clearly hampered HIF‐1α induction in response to hypoxia in human lung adenocarcinoma cell lines. The present results directly demonstrate the importance of Ror1 for in vivo development and progression of lung adenocarcinoma, and also identify Ror1 as a novel regulator of Hif‐1α. Thus, a future study aimed at the development of a novel therapeutic targeting ROR1 for treatment of solid tumors such as seen in lung cancer, which are frequently accompanied with a hypoxic tumor microenvironment, is warranted.

Expression of cancer stem cell markers CD24, EPHA1 and CD9 and their correlation with clinical outcome in epithelial ovarian tumours

BACKGROUND

There has been variability between laboratories in the identification of cancer stem cells (CSCs) markers for epithelial ovarian cancer (EOC). We have evaluated three new surface markers for EOC to identify CSCs precisely.

METHODS

Three new putative CSCs specific surface markers CD9, CD24 and EPHA1 identified by a bioinformatics approach were evaluated in normal ovary, fallopian tube and ovarian tumours.

RESULTS

The expression of CD9 alone was observed in normal ovarian surface epithelium and fallopian tube whereas CD24 and EPHA1 were not expressed (n= 5). CD24 was expressed in all tumours (N= 101) while CD9 and EPHA1 were expressed in 89 and 71 tumours, respectively. The statistical analysis showed significant correlation of the stage of the disease (p< 0.0001), type of surgery (p< 0.0001) and residual disease (p< 0.0001) with overall survival. Although expression of CD9, CD24 and EPHA1 was observed in the majority of tumours there was no significant correlation with outcome. In patients who underwent primary surgery, increased expression of CD24 significantly correlated with poor survival. The expression of CD24 was significantly reduced (p< 0.002) upon analysis of paired sections from patients prior to surgery and at interval debulking surgery (n= 16).

CONCLUSION

These findings suggest that overexpression of these new markers may be useful in identifying and targeting ovarian CSCs and CD24 may be a putative CSCs marker in ovarian cancer.

Caveola-forming proteins and prostate cancer

Caveolae are specialised and dynamic plasma membrane subdomains, involved in many cellular functions including endocytosis, signal transduction, mechanosensing and lipid storage, trafficking, and metabolism. Two protein families are indispensable for caveola formation and function, namely caveolins and cavins. Mutations of genes encoding these caveolar proteins cause serious pathological conditions such as cardiomyopathies, skeletal muscle diseases, and lipodystrophies. Deregulation of caveola-forming protein expression is associated with many types of cancers including prostate cancer. The distinct function of secretion of the prostatic fluid, and the unique metabolic phenotype of prostate cells relying on lipid metabolism as a main bioenergetic pathway further suggest a significant role of caveolae and caveolar proteins in prostate malignancy. Accumulating in vitro, in vivo, and clinical evidence showed the association of caveolin-1 with prostate cancer grade, stage, metastasis, and drug resistance. In contrast, cavin-1 was found to exhibit tumour suppressive roles. Studies on prostate cancer were the first to show the distinct function of the caveolar proteins depending on their localisation within the caveolar compartment or as cytoplasmic or secreted proteins. In this review, we summarise the roles of caveola-forming proteins in prostate cancer and the potential of exploiting them as therapeutic targets or biological markers.

The WNT/ROR Pathway in Cancer: From Signaling to Therapeutic Intervention

The WNT pathway is one of the major signaling cascades frequently deregulated in human cancer. While research had initially focused on signal transduction centered on β-catenin as a key effector activating a pro-tumorigenic transcriptional response, nowadays it is known that WNT ligands can also induce a multitude of β-catenin-independent cellular pathways. Traditionally, these comprise WNT/planar cell polarity (PCP) and WNT/Ca²⁺ signaling. In addition, signaling via the receptor tyrosine kinase-like orphan receptors (RORs) has gained increasing attention in cancer research due to their overexpression in a multitude of tumor entities. Active WNT/ROR signaling has been linked to processes driving tumor development and progression, such as cell proliferation, survival, invasion, or therapy resistance. In adult tissue, the RORs are largely absent, which has spiked the interest in them for targeted cancer therapy. Promising results in preclinical and initial clinical studies are beginning to unravel the great potential of such treatment approaches. In this review, we summarize seminal findings on the structure and expression of the RORs in cancer, their downstream signaling, and its output in regard to tumor cell function. Furthermore, we present the current clinical anti-ROR treatment strategies and discuss the state-of-the-art, as well as the challenges of the different approaches.

Targeting Leukemia-Initiating Cells in Acute Lymphoblastic Leukemia

The concept that different leukemias are developmentally distinct and, like in normal hematopoiesis, generated by restricted populations of cells named leukemia-initiating cells (LIC), is becoming more established. These cancer stem-like cells have been assumed to have unique properties, including the capability of self-renewing and giving rise to "differentiated" or non-LICs that make up the whole tumor. Cell populations enriched with LIC activity have been characterized in different hematopoietic malignancies, including human acute lymphoblastic leukemia (ALL). Related studies have also demonstrated that LICs are functionally distinct from bulk cells and modulated by distinct molecular signaling pathways and epigenetic mechanisms. Here we review several biological and clinical aspects related to LICs in ALL, including (i) immunophenotypic characterization of LIC-enriched subsets in human and mouse models of ALL, (ii) emerging therapeutics against regulatory signaling pathways involved in LIC progression and maintenance in T- and B-cell leukemias, (iii) novel epigenetic and age-related mechanisms of LIC propagation, and (iv) ongoing efforts in immunotherapy to eradicate LIC-enriched cell subsets in relapsed and refractory ALL cases. Current conventional treatments do not efficiently eliminate LICs. Therefore, innovative therapeutics that exclusively target LICs hold great promise for developing an effective cure for ALL.

The involvement of noncanonical Wnt signaling in cancers

Wnt signaling is one of the key cascades regulating normal tissue development and has been tightly associated with cancer. The Wnt signaling can be subdivided into two categories: canonical & noncanonical. Noncanonical Wnt signaling pathways mainly include Wnt/PCP (planar cell polarity) signaling and Wnt-cGMP (cyclic guanosine monophosphate) /Ca2+ signaling. It has been well studied by previous researches that noncanonical Wnt signaling regulates multiple cell functions including proliferation, differentiation, adhesion, polarity, motility, and migration. The aberrant activation or inhibition of noncanonical Wnt signaling is crucial in cancer progression, exerting both oncogenic and tumor-suppressive effects. Recent studies show the involvement of noncanonical Wnt in regulating cancer cell invasion, metastasis, metabolism, and inflammation. Here, we review current insights into novel components of non-canonical signalings and describe their involvement in various cancer types. We also summarize recent biological and clinical discoveries that outline non-canonical Wnt signaling in tumorigenesis. Finally, we provide an overview of current strategies to target non-canonical Wnt signaling in cancer and challenges that are associated with such approaches.

SNORA72 Activates the Notch1/c-Myc Pathway to Promote Stemness Transformation of Ovarian Cancer Cells

Cancer stem cells (CSCs) are responsible for the migration and recurrence of cancer progression. Small nucleolar RNAs (snoRNAs) play important roles in tumor development. However, how snoRNAs contribute to the regulation of the stemness of ovarian CSCs (OCSCs) remains unclear. In the present study, we found that SNORA72 was significantly upregulated in OVCAR-3 spheroids (OS) and CAOV-3 spheroids (CS) with the OCSC characteristics attained by serum-free culture in a suspension of OVCAR-3 (OV) and CAOV-3 (CA) cells. The overexpression of SNORA72 increased self-renewal abilities and migration abilities in OV and CA cells and upregulated the expressions of the stemness markers Nanog, Oct4, and CD133. In addition, the ectopic expression of SNORA72 can elevate the messenger RNA (mRNA) and protein expression levels of Notch1 and c-Myc in parental cells. The opposite results were observed in SNORA72-silenced OCSCs. Moreover, we found that Notch1 knockdown inversed the migration abilities and self-renewal abilities raised by overexpressing SNORA72. In summary, stemness transformation of ovarian cancer cells can be activated by SNORA72 through the Notch1/c-Myc pathway. This study introduces a novel therapeutic strategy for improving the treatment efficiency of ovarian cancer.

The cross-talk between methylation and phosphorylation in lymphoid-specific helicase drives cancer stem-like properties

Posttranslational modifications (PTMs) of proteins, including chromatin modifiers, play crucial roles in the dynamic alteration of various protein properties and functions including stem-cell properties. However, the roles of Lymphoid-specific helicase (LSH), a DNA methylation modifier, in modulating stem-like properties in cancer are still not clearly clarified. Therefore, exploring PTMs modulation of LSH activity will be of great significance to further understand the function and activity of LSH. Here, we demonstrate that LSH is capable to undergo PTMs, including methylation and phosphorylation. The arginine methyltransferase PRMT5 can methylate LSH at R309 residue, meanwhile, LSH could as well be phosphorylated by MAPK1 kinase at S503 residue. We further show that the accumulation of phosphorylation of LSH at S503 site exhibits downregulation of LSH methylation at R309 residue, which eventually promoting stem-like properties in lung cancer. Whereas, phosphorylation-deficient LSH S503A mutant promotes the accumulation of LSH methylation at R309 residue and attenuates stem-like properties, indicating the critical roles of LSH PTMs in modulating stem-like properties. Thus, our study highlights the importance of the crosstalk between LSH PTMs in determining its activity and function in lung cancer stem-cell maintenance.

Glucocorticoids induce differentiation and chemoresistance in ovarian cancer by promoting ROR1-mediated stemness

Glucocorticoids are routinely used in the clinic as anti-inflammatory and immunosuppressive agents as well as adjuvants during cancer treatment to mitigate the undesirable side effects of chemotherapy. However, recent studies have indicated that glucocorticoids may negatively impact the efficacy of chemotherapy by promoting tumor cell survival, heterogeneity, and metastasis. Here, we show that dexamethasone induces upregulation of ROR1 expression in ovarian cancer (OC), including platinum-resistant OC. Increased ROR1 expression resulted in elevated RhoA, YAP/TAZ, and BMI-1 levels in a panel of OC cell lines as well as primary ovarian cancer patient-derived cells, underlining the translational relevance of our studies. Importantly, dexamethasone induced differentiation of OC patient-derived cells ex vivo according to their molecular subtype and the phenotypic expression of cell differentiation markers. High-throughput drug testing with 528 emerging and clinical oncology compounds of OC cell lines and patient-derived cells revealed that dexamethasone treatment increased the sensitivity to several AKT/PI3K targeted kinase inhibitors, while significantly decreasing the efficacy of chemotherapeutics such as taxanes, as well as anti-apoptotic compounds such as SMAC mimetics. On the other hand, targeting ROR1 expression increased the efficacy of taxane drugs and SMAC mimetics, suggesting new combinatorial targeted treatments for patients with OC.

ROR1 is upregulated in endometrial cancer and represents a novel therapeutic target

ROR1 and ROR2 are receptor tyrosine kinases with altered expression in a range of cancers. Silencing ROR1 or ROR2 in different tumour types has been shown to inhibit proliferation and decrease metastatic potential. The aim of this study was to investigate the role of ROR1 and ROR2 in endometrial cancer via immunohistochemistry (IHC) in a large endometrial cancer patient cohort (n = 499) and through in vitro analysis in endometrial cancer cell lines. Correlation was assessed between ROR1/2 expression and clinicopathological parameters. Kaplan Meier curves were produced for 5-year progression free survival (PFS) and overall survival (OS) with low/moderate versus high ROR1/2 intensity. Cox multivariate regression was applied to analyse the effect of selected covariates on the PFS and OS. The effect of ROR1 and/or ROR2 modulation on cell proliferation, adhesion, migration and invasion was analysed in two endometrial cancer cell lines (KLE and MFE-296). We observed a significant decrease in OS and PFS in patients with high ROR1 expression. ROR1 silencing and ROR2 overexpression significantly inhibited proliferation of KLE endometrial cancer cells and decreased migration. This study supports the oncogenic role of ROR1 in endometrial cancer, and warrants investigation of future application of ROR1-targeting therapies in endometrial cancer patients.

Baicalin Attenuates YAP Activity to Suppress Ovarian Cancer Stemness

Purpose

This study aims to reveal the mechanism underlying baicalin-suppressing ovarian cancer stemness.

Methods

OVCAR-3 and the primary ovarian cancer cells were used for cell model. The ovarian cancer stem cells were isolated by suspension culture. Cell viability and clonogenicity were examined by CCK-8 assay and colony formation assay. The self-renewal of the cells was evaluated by the determination of sphere-forming capacity and the frequency of in vitro sphere-forming and in vivo tumor-initiating cells. The mRNA and protein levels were relatively quantified by qRT-PCR and Western blot. The transcription regulation of target genes was tested by luciferase reporter assay and a modified nuclear rn-on qRT-PCR assay.

Results

Treatment with a non-toxic dose of baicalin significantly inhibited the spherogenicity of ovarian cancer cells. Moreover, a non-toxic dose of baicalin treatment suppressed the frequency of sphere-forming and tumor-initiating ovarian cancer cells. Furthermore, the expression of ovarian cancer stem cell markers (CD133 and ALDH1A1) was inhibited by a non-toxic dose of baicalin treatment. Baicalin inhibits YAP activity and suppresses RASSF6, a positive regulator of YAP, at the transcriptional level. Overexpression of both YAP and RASSF6 abolished the inhibitory effect of baicalin on the proliferation and stemness of ovarian cancer cells.

Conclusion

The results in this study demonstrated that baicalin suppresses the stemness of ovarian cancer cells by attenuating YAP activity via inhibiting RASSF6 at the transcriptional level. This finding revealed baicalin as a novel YAP inhibitor that could serve as an anti-cancer drug for eradicating ovarian cancer stem cells.

The Application of Patient-Derived Xenograft Models in Gynecologic Cancers

Recently, due to the limitations of cell line models and animal models in the preclinical research with insufficient reflecting the physiological situation of humans, patient-derived xenograft (PDX) models of many cancers have been widely developed because of their better representation of the tumor heterogeneity and tumor microenvironment with retention of the cellular complexity, cytogenetics, and stromal architecture. PDX models now have been identified as a powerful tool for determining cancer characteristics, developing new treatment, and predicting drug efficacy. An increase in attempts to generate PDX models in gynecologic cancers has emerged in recent years to understand tumorigenesis. Hence, this review summarized the generation of PDX models and engraftment success of PDX models in gynecologic cancers. Furthermore, we illustrated the similarity between PDX model and original tumor, and described preclinical utilization of PDX models in gynecologic cancers. It would help supply better personalized therapy for gynecologic cancer patients.