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

Non-canonical Wnt co-receptors ROR1/ROR2 are differentially regulated by hypoxia in colon cancer cells

ROR1 and ROR2 co-receptors are transducers of non-canonical Wnt responses that promote an aggressive phenotype in several cancer types, including colon cancer. It has been demonstrated that hypoxia promotes tumor progression through the action of Hypoxia Inducible Factors (HIFs). An in silico analysis revealed that ROR2 is overexpressed in the advanced clinical stages of colon cancer. In line with this, ROR1 and ROR2 were found to be only expressed in malignant colon cells compared to non-malignant ones. The blockade of either ROR1 or ROR2 impaired colon cancer cells' colony formation abilities and the migration capacity of them. Additionally, the silencing of the ROR2 co-receptor blocked the metastatic ability of colon cancer cells in a xenografted mice model. We found that while silencing HIF-1α did not significantly reduce ROR1 or ROR2 expression, inhibiting HIF-2α and HIF-3α expression greatly decreased the protein levels of both co-receptors in colon cancer cells. The HIF-1α subunit expression is induced in acute hypoxia, whereas HIF-2α and HIF-3α show higher activity in chronic hypoxia, which may be functionally relevant since hypoxia induced a decrease in the constitutive active β-catenin transcriptional activity in SW480 cells. While both ROR1 and ROR2 stimulate proliferation and migration under normoxic conditions, the exposure of cells to hypoxia increased the expression of ROR1 or ROR2, depending on the Wnt cellular context, Thus, our results indicate that hypoxia partially represses β-catenin transcriptional activity and activates non-canonical Wnt signaling by regulating ROR1/ROR2 expression to induce an aggressive migrating and metastatic phenotype in colon cancer cells.

A prodrug nanodevice co-delivering docetaxel and ROR1 siRNA for enhanced triple negative breast cancer therapy

Triple-negative breast cancer (TNBC) has been a clinical challenge due to its high recurrence and metastasis rates. Chemotherapy remains the primary treatment for TNBC after surgery ablation, but it lacks targeted specificity and causes side effects in normal tissues. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is significantly expressed in TNBC cells, and small interference RNA (siRNA) targeting ROR1 can effectively suppress ROR1 gene expression, thereby inhibiting proliferation and metastasis. However, clinical application of ROR1 siRNA is limited by susceptibility to clearance and difficulty in endosomal escape. In this study, the docetaxel (DTX) prodrug nanoparticle BBRM delivering ROR1 siRNA was constructed. The BBRM could be effectively internalized by tumor cells and endosomal escape to release DTX and ROR1 siRNA. In 4T1 tumor-bearing mice, BBRM could be targeting delivered to tumor and lung tissues, with good biosafety, achieving a tumor inhibition rate of 74.1 % and inhibiting lung metastasis. By integrating chemotherapy and RNA interference therapy, BBRM successfully co-delivered chemotherapeutic agents and siRNA to improve the therapeutic efficacy of triple-negative breast cancer and provided a promising strategy for clinical transformation. STATEMENT OF SIGNIFICANCE: Chemotherapy is still the primary treatment for triple-negative breast cancer (TNBC) after surgery ablation, but it causes side effects without targeting capacity. ROR1 is significantly expressed in TNBC cells, and RNA interference for ROR1 can suppress ROR1 gene expression to inhibit tumor proliferation. However, as oligonucleotides, effect of ROR1 siRNA is limited by susceptibility to clearance and difficulty in endosomal escape. In this work, we designed a nanodevice based on a docetaxel (DTX) prodrug that targets ROR1 for the synergistic therapy of TNBC. We constructed a nanoparticle (BBRM) for co-delivery of the DTX and ROR1 siRNA. The BBRM could be effectively internalized by tumor cells and endosomal escape. The ROR1 siRNA downregulated ROR1 protein expression and improved the anti-proliferative and anti-metastatic effects. In addition, BBRM reversed the immunosuppressive tumor microenvironment, thus improving breast cancer therapeutic efficacy. It was a pioneering investigation in synergistic chemo-gene therapy by co-delivering DTX and ROR1 siRNA for TNBC treatment.

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.

ALDH1A1 as a marker for metastasis initiating cells: A mechanistic insight

Since metastasis accounts for the majority of cancer morbidity and mortality, attempts are focused to block metastasis and metastasis initiating cellular programs. It is generally believed that hypoxia, reactive oxygen species (ROS) and the dysregulated redox pathways regulate metastasis. Although induction of epithelial to mesenchymal transition (EMT) can initiate cell motility to different sites other than the primary site, the initiation of a secondary tumor at a distant site depends on self-renewal property of cancer stem cell (CSC) property. That subset of metastatic cells possessing CSC property are referred to as metastasis initiating cells (MICs). Among the different cellular intermediates regulating metastasis in response to hypoxia by inducing EMT and self-renewal property, ALDH1A1 is a critical molecule, which can be used as a marker for MICs in a wide variety of malignancies. The cytosolic ALDHs can irreversibly convert retinal to retinoic acid (RA), which initiates RA signaling, important for self-renewal and EMT. The metastasis permissive tumor microenvironment increases the expression of ALDH1A1, primarily through HIF1α, and leads to metabolic reprograming through OXPHOS regulation. The ALDH1A1 expression and its high activity can reprogram the cancer cells with the transcriptional upregulation of several genes, involved in EMT through RA signaling to manifest hybrid EMT or Hybrid E/M phenotype, which is important for acquiring the characteristics of MICs. Thus, the review on this topic highlights the use of ALDH1A1 as a marker for MICs, and reporters for the marker can be effectively used to trace the population in mouse models, and to screen drugs that target MICs.

Extracellular vesicles miR-31-5p promotes pancreatic cancer chemoresistance via regulating LATS2-Hippo pathway and promoting SPARC secretion from pancreatic stellate cells

Pancreatic cancer remains one of the most lethal malignant diseases. Gemcitabine-based chemotherapy is still one of the first-line systemic treatments, but chemoresistance occurs in the majority of patients. Recently, accumulated evidence has demonstrated the role of the tumour microenvironment in promoting chemoresistance. In the tumour microenvironment, pancreatic stellate cells (PSCs) are among the main cellular components, and extracellular vesicles (EVs) are common mediators of cell‒cell communication. In this study, we showed that SP1-transcribed miR-31-5p not only targeted LATS2 in pancreatic cancer cells but also regulated the Hippo pathway in PSCs through EV transfer. Consequently, PSCs synthesized and secreted protein acidic and rich in cysteins (SPARC), which was preferentially expressed in stromal cells, stimulating Extracellular Signal regulated kinase (ERK) signalling in pancreatic cancer cells. Therefore, pancreatic cancer cell survival and chemoresistance were improved due to both the intrinsic Hippo pathway regulated by miR-31-5p and external SPARC-induced ERK signalling. In mouse models, miR-31-5p overexpression in pancreatic cancer cells promoted the chemoresistance of coinjected xenografts. In a tissue microarray, pancreatic cancer patients with higher miR-31-5p expression had shorter overall survival. Therefore, miR-31-5p regulates the Hippo pathway in multiple cell types within the tumour microenvironment via EVs, ultimately contributing to the chemoresistance of pancreatic cancer cells.

Variant Transcript of ROR1 ENST00000545203 Does Not Encode ROR1 Protein

Drs. John and Ford reported in biomedicines that a variant transcript encoding receptor tyrosine kinase-like orphan receptor 1 (ROR1), namely ENST00000545203 or variant 3 (ROR1V3), was a predominant ROR1 transcript of neoplastic or normal cells in the Bioinformatic database, including GTEx and the 33 datasets from TCGA. Unlike the full-length ROR1 transcript, Drs. John and Ford deduced that ROR1V3 encoded a cytoplasmic ROR1 protein lacking an apparent signal peptide necessary for transport to the cell surface, which they presumed made it unlikely to function as a surface receptor for Wingless/Integrated (Wnt) factors. Moreover, they speculated that studies evaluating ROR1 via immunohistochemistry using any one of several anti-ROR1 mAbs actually may have detected cytoplasmic protein encoded by ROR1V3 and that anti-cancer therapies targeting surface ROR1 thus would be ineffective against "cytoplasmic ROR1-positive" cancers that express predominately ROR1V3. We generated lentivirus vectors driving the expression of full-length ROR1 or the ROR1v3 upstream of an internal ribosome entry site (IRES) of the gene encoding a red fluorescent reporter protein. Although we find that cells that express ROR1 have surface and cytoplasmic ROR1 protein, cells that express ROR1v3 neither have surface nor cytoplasmic ROR1, which is consistent with our finding that ROR1v3 lacks an in-frame initiation codon for ribosomal translation into protein. We conclude that the detection of ROR1 protein in various cancers cannot be ascribed to the expression of ROR1v3.

A Review of the Bromodomain and Extraterminal Domain Epigenetic Reader Proteins: Function on Virus Infection and Cancer

The BET (bromodomain and extraterminal domain) family of proteins, particularly BRD4 (bromodomain-containing protein 4), plays a crucial role in transcription regulation and epigenetic mechanisms, impacting key cellular processes such as proliferation, differentiation, and the DNA damage response. BRD4, the most studied member of this family, binds to acetylated lysines on both histones and non-histone proteins, thereby regulating gene expression and influencing diverse cellular functions such as the cell cycle, tumorigenesis, and immune responses to viral infections. Given BRD4's involvement in these fundamental processes, it is implicated in various diseases, including cancer and inflammation, making it a promising target for therapeutic development. This review comprehensively explores the roles of the BET family in gene transcription, DNA damage response, and viral infection, discussing the potential of targeted small-molecule compounds and highlighting BET proteins as promising candidates for anticancer therapy.

Role of Wnt5b-Ror1 signaling in the proliferation of pancreatic ductal adenocarcinoma cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the most refractory cancers with the worst prognosis. Although several molecules are known to be associated with the progression of PDAC, the molecular mechanisms underlying the progression of PDAC remain largely elusive. The Ror-family receptors, Ror1 and Ror2, which act as a receptor(s) for Wnt-family ligands, particularly Wnt5a, are involved in the progression of various types of cancers. Here, we show that higher expression of Ror1 and Wnt5b, but not Ror2, are associated with poorer prognosis of PDAC patients, and that Ror1 and Wnt5b are expressed highly in a type of PDAC cell lines, PANC-1 cells. Knockdown of either Ror1 or Wnt5b in PANC-1 cells inhibited their proliferation significantly in vitro, and knockout of Ror1 in PANC-1 cells resulted in a significant inhibition of tumor growth in vivo. Furthermore, we show that Wnt5b-Ror1 signaling in PANC-1 cells promotes their proliferation in a cell-autonomous manner by modulating our experimental setting in vitro. Collectively, these findings indicate that Wnt5b-Ror1 signaling might play an important role in the progression of some if not all of PDAC by promoting proliferation.

Receptor tyrosine kinase-like orphan receptor 1: A novel antitumor target in gastrointestinal cancers

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a member of the type I receptor tyrosine kinase family. ROR1 is pivotal in embryonic development and cancer, and serves as a biomarker and therapeutic target. It has soluble and membrane-bound subtypes, with the latter highly expressed in tumors. ROR1 is conserved throughout evolution and may play a role in the development of gastrointestinal cancer through multiple signaling pathways and molecular mechanisms. Studies suggest that overexpression of ROR1 may increase tumor invasiveness and metastasis. Additionally, ROR1 may regulate the cell cycle, stem cell characteristics, and interact with other signaling pathways to affect cancer progression. This review explores the structure, expression and role of ROR1 in the development of gastrointestinal cancers. It discusses current antitumor strategies, outlining challenges and prospects for treatment.

Exosomal ROR1 in peritoneal fluid identifies peritoneal disseminated PDAC and is associated with poor survival

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest forms of cancer and peritoneal dissemination is one major cause for this poor prognosis. Exosomes have emerged as promising biomarkers for gastrointestinal cancers and can be found in all kinds of bodily fluids, also in peritoneal fluid (PF). This is a unique sample due to its closeness to gastrointestinal malignancies. The receptor tyrosine kinase-like orphan receptor 1 (ROR1) has been identified as a potential biomarker in human cancers and represents a promising target for an immunotherapy approach, which could be considered for future treatment strategies. Here we prospectively analyzed the exosomal surface protein ROR1 (exo-ROR1) in PF in localized PDAC patients (PER-) on the one hand and peritoneal disseminated tumor stages (PER+) on the other hand followed by the correlation of exo-ROR1 with clinical-pathological parameters.

Methods

Exosomes were isolated from PF and plasma samples of non-cancerous (NC) (n = 15), chronic pancreatitis (CP) (n = 4), localized PDAC (PER-) (n = 18) and peritoneal disseminated PDAC (PER+) (n = 9) patients and the surface protein ROR1 was detected via FACS analysis. Additionally, soluble ROR1 in PF was analyzed. ROR1 expression in tissue was investigated using western blots (WB), qPCR, and immunohistochemistry (IHC). Exosome isolation was proven by Nano Tracking Analysis (NTA), WB, Transmission electron microscopy (TEM), and BCA protein assay. The results were correlated with clinical data and survival analysis was performed.

Results

PDAC (PER+) patients have the highest exo-ROR1 values in PF and can be discriminated from NC (p <0.0001), PDAC (PER-) (p <0.0001), and CP (p = 0.0112). PDAC (PER-) can be discriminated from NC (p = 0.0003). In plasma, exo-ROR1 is not able to distinguish between the groups. While there is no expression of ROR1 in the exocrine pancreatic tissue, PDAC and peritoneal metastasis show expression of ROR1. High exo-ROR1 expression in PF is associated with lower overall survival (p = 0.0482).

Conclusion

With exo-ROR1 in PF we found a promising diagnostic and prognostic biomarker possibly discriminating between NC, PDAC (PER-) and PDAC (PER+) and might shed light on future diagnostic and therapeutic concepts in PDAC.

Molecular pathology of small cell lung cancer: Overview from studies on neuroendocrine differentiation regulated by ASCL1 and Notch signaling

Pulmonary neuroendocrine (NE) cells are rare airway epithelial cells. The balance between Achaete-scute complex homolog 1 (ASCL1) and hairy and enhancer of split 1, one of the target molecules of the Notch signaling pathway, is crucial for NE differentiation. Small cell lung cancer (SCLC) is a highly aggressive lung tumor, characterized by rapid cell proliferation, a high metastatic potential, and the acquisition of resistance to treatment. The subtypes of SCLC are defined by the expression status of NE cell-lineage transcription factors, such as ASCL1, which roles are supported by SRY-box 2, insulinoma-associated protein 1, NK2 homeobox 1, and wingless-related integration site signaling. This network reinforces NE differentiation and may induce the characteristic morphology and chemosensitivity of SCLC. Notch signaling mediates cell-fate decisions, resulting in an NE to non-NE fate switch. The suppression of NE differentiation may change the histological type of SCLC to a non-SCLC morphology. In SCLC with NE differentiation, Notch signaling is typically inactive and genetically or epigenetically regulated. However, Notch signaling may be activated after chemotherapy, and, in concert with Yes-associated protein signaling and RE1-silencing transcription factor, suppresses NE differentiation, producing intratumor heterogeneity and chemoresistance. Accumulated information on the molecular mechanisms of SCLC will contribute to further advances in the control of this recalcitrant cancer.

Inhibition of Bromodomain Proteins Enhances Oncolytic HAdVC5 Replication and Efficacy in Pancreatic Ductal Adenocarcinoma (PDAC) Models

Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive type of pancreatic cancer, which rapidly develops resistance to the current standard of care. Several oncolytic Human AdenoViruses (HAdVs) have been reported to re-sensitize drug-resistant cancer cells and in combination with chemotherapeutics attenuate solid tumour growth. Obstacles preventing greater clinical success are rapid hepatic elimination and limited viral replication and spread within the tumour microenvironment. We hypothesised that higher intratumoural levels of the virus could be achieved by altering cellular epigenetic regulation. Here we report on the screening of an enriched epigenetics small molecule library and validation of six compounds that increased viral gene expression and replication. The greatest effects were observed with three epigenetic inhibitors targeting bromodomain (BRD)-containing proteins. Specifically, BRD4 inhibitors enhanced the efficacy of Ad5 wild type, Ad∆∆, and Ad-3∆-A20T in 3-dimensional co-culture models of PDAC and in vivo xenografts. RNAseq analysis demonstrated that the inhibitors increased viral E1A expression, altered expression of cell cycle regulators and inflammatory factors, and attenuated expression levels of tumour cell oncogenes such as c-Myc and Myb. The data suggest that the tumour-selective Ad∆∆ and Ad-3∆-A20T combined with epigenetic inhibitors is a novel strategy for the treatment of PDAC by eliminating both cancer and associated stromal cells to pave the way for immune cell access even after systemic delivery of the virus.

ROR2 regulates cellular plasticity in pancreatic neoplasia and adenocarcinoma

Cellular plasticity is a hallmark of pancreatic ductal adenocarcinoma (PDAC) starting from the conversion of normal cells into precancerous lesions to the progression of carcinoma subtypes associated with aggressiveness and therapeutic response. We discovered that normal acinar cell differentiation, maintained by the transcription factor Pdx1, suppresses a broad gastric cell identity that is maintained in metaplasia, neoplasia, and the classical subtype of PDAC in mouse and human. We have identified the receptor tyrosine kinase Ror2 as marker of a gastric metaplasia (SPEM)-like identity in the pancreas. Ablation of Ror2 in a mouse model of pancreatic tumorigenesis promoted a switch to a gastric pit cell identity that largely persisted through progression to the classical subtype of PDAC. In both human and mouse pancreatic cancer, ROR2 activity continued to antagonize the gastric pit cell identity, strongly promoting an epithelial to mesenchymal transition, conferring resistance to KRAS inhibition, and vulnerability to AKT inhibition.

Epigenetic control of pancreatic cancer metastasis

Surgical resection, when combined with chemotherapy, has been shown to significantly improve the survival rate of patients with pancreatic ductal adenocarcinoma (PDAC). However, this treatment option is only feasible for a fraction of patients, as more than 50% of cases are diagnosed with metastasis. The multifaceted process of metastasis is still not fully understood, but recent data suggest that transcriptional and epigenetic plasticity play significant roles. Interfering with epigenetic reprogramming can potentially control the adaptive processes responsible for metastatic progression and therapy resistance, thereby enhancing treatment responses and preventing recurrence. This review will focus on the relevance of histone-modifying enzymes in pancreatic cancer, specifically on their impact on the metastatic cascade. Additionally, it will also provide a brief update on the current clinical developments in epigenetic therapies.

Transcriptional co-activators: emerging roles in signaling pathways and potential therapeutic targets for diseases

Specific cell states in metazoans are established by the symphony of gene expression programs that necessitate intricate synergic interactions between transcription factors and the co-activators. Deregulation of these regulatory molecules is associated with cell state transitions, which in turn is accountable for diverse maladies, including developmental disorders, metabolic disorders, and most significantly, cancer. A decade back most transcription factors, the key enablers of disease development, were historically viewed as 'undruggable'; however, in the intervening years, a wealth of literature validated that they can be targeted indirectly through transcriptional co-activators, their confederates in various physiological and molecular processes. These co-activators, along with transcription factors, have the ability to initiate and modulate transcription of diverse genes necessary for normal physiological functions, whereby, deregulation of such interactions may foster tissue-specific disease phenotype. Hence, it is essential to analyze how these co-activators modulate specific multilateral processes in coordination with other factors. The proposed review attempts to elaborate an in-depth account of the transcription co-activators, their involvement in transcription regulation, and context-specific contributions to pathophysiological conditions. This review also addresses an issue that has not been dealt with in a comprehensive manner and hopes to direct attention towards future research that will encompass patient-friendly therapeutic strategies, where drugs targeting co-activators will have enhanced benefits and reduced side effects. Additional insights into currently available therapeutic interventions and the associated constraints will eventually reveal multitudes of advanced therapeutic targets aiming for disease amelioration and good patient prognosis.

Extracellular vesicle-associated tyrosine kinase-like orphan receptors ROR1 and ROR2 promote breast cancer progression

BACKGROUND

Extracellular vesicles (EVs) harbor a plethora of different biomolecules, which they can transport across cells. In cancer, tumor-derived EVs thereby support the creation of a favorable tumor microenvironment. So far, EV uptake and cargo delivery into target cells have been regarded as the main mechanisms for the pro-tumoral function of EVs. To test this hypothesis, we investigated the fate of the oncogenic transmembrane Wnt tyrosine kinase-like orphan receptor 1 and 2 (ROR1, ROR2) delivered via distinct EV subpopulations to breast cancer cells and aimed to unravel their impact on tumor progression.

METHODS

EVs were isolated by differential ultracentrifugation from cell culture supernatant as well as plasma samples from healthy individuals (n = 27) and breast cancer patients (n = 41). EVs were thoroughly characterized by electron microscopy, nanoparticle tracking analysis, immunoblot, and flow cytometry. ROR transfer to target cells was observed using microscopy-based assays and biodistribution experiments were conducted in syngeneic mice. EV impact on cancer cell migration and invasion was tested in functional assays.

RESULTS

We observed that the supernatant of ROR-overexpressing cells was sufficient for transferring the receptors to ROR-negative cells. Analyzing the secretome of the ROR-overexpressing cells, we detected a high enrichment of ROR1/2 on large and small EVs, but not on large oncosomes. Interestingly, the majority of ROR-positive EVs remained attached to the target cell surface after 24 h of stimulation and was quickly removed by treatment with trypsin. Nonetheless, ROR-positive EVs increased migration and invasion of breast cancer cells, even after chemically inhibiting EV uptake, in dependence of RhoA downstream signaling. In vivo, ROR-depleted EVs tended to distribute less into organs prone for the formation of breast cancer metastases. ROR-positive EVs were also significantly elevated in the plasma of breast cancer patients and allowed to separate them from healthy controls.

CONCLUSIONS

The oncogenic Wnt receptors ROR1/2 are transferred via EVs to the surface of ROR-negative cancer cells, in which they induce an aggressive phenotype supporting tumor progression. Video Abstract.