Broad-spectrum Delta-BA.2 tandem-fused heterodimer mRNA vaccine delivered by lipopolyplex.

Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, continues to mutate and generates new variants with increasingly severe immune escape, urging the upgrade of COVID-19 vaccines. Here, based on a similar dimeric RBD design as our previous ZF2001 vaccine, we developed a novel broad-spectrum COVID-19 mRNA vaccine, SWIM516, with chimeric Delta-BA.2 RBD dimer delivered by lipopolyplex (LPP). Unlike the popular lipid nanoparticle (LNP), this LPP-delivered mRNA expresses only in the injection site, which avoids potential toxicity to the liver. We demonstrated the broad-spectrum humoral and cellular immunogenicity of this vaccine to Delta and Omicron sub-variants in naïve mice and as booster shots. When challenged with Delta or Omicron live virus, vaccinated human angiotensin-converting enzyme (hACE2) transgenic mice and rhesus macaques were both protected, displaying significantly reduced viral loads and markedly relieved pathological damages. We believe the SWIM516 vaccine qualifies as a candidate for the next-generation broad-spectrum COVID-19 vaccine.

Safety, immunogenicity, and efficacy of a modified COVID-19 mRNA vaccine, SW-BIC-213, in healthy people aged 18 years and above: a phase 3 double-blinded, randomized, parallel controlled clinical trial in Lao PDR (Laos).

Background: The mRNA vaccine has demonstrated significant effectiveness in protecting against SARS-CoV-2 during the pandemic, including against severe forms of the disease caused by emerging variants. In this study, we examined safety, immunogenicity, and relative efficacy of a heterologous booster of the lipopolyplex (LPP)-based mRNA vaccine (SW-BIC-213) versus a homologous booster of an inactivated vaccine (BBIBP) in Laos. Methods: In this phase 3 clinical trial, which was randomized, parallel controlled and double-blinded, healthy adults aged 18 years and above were recruited from the Southern Savannakhet Provincial Hospital and Champhone District Hospital. The primary outcomes were safety and immunogenicity, with efficacy as an exploratory endpoint. Participants who were fully immunized with a two-dose inactivated vaccine for more than 6 months were assigned equally to either the SW-BIC-213 group (25 µg) or BBIBP group. The primary safety endpoint was to describe the safety profile of all participants in each group up to 6 months post-booster immunization. The primary immunogenic outcome was to demonstrate the superiority of the neutralizing antibody response, in terms of geometric mean titers (GMTs) of SW-BIC-213, compared with BBIBP 28 days after the booster dose. The exploratory efficacy endpoint aimed to assess the relative efficacy of SW-BIC-213 compared to BBIBP against virologically confirmed symptomatic COVID-19 over a 6-month period. The trial was registered with ClinicalTrials.gov (NCT05580159). Findings: Between October 10, 2022, and January 13, 2023, 1200 participants were assigned to SW-BIC-213 group and 1203 participants in the BBIBP group. All adverse reactions observed during the study were tolerable, transient, and resolved spontaneously. Solicited local reactions were the main adverse reactions in both the SW-BIC-213 group (43.8%) and BBIBP group (14.8%) (p < 0.001). Heterologous boosting with SW-BIC-213 induced higher live virus neutralizing antibodies to SARS-CoV-2 wildtype and BA.5 strains with GMTs reaching 750.1 and 192.9 than homologous boosting with BBIBP with GMTs of 131.5 (p < 0.001) and 47.5 (p < 0.001) on day 29. The statistical findings revealed that, following a period of 14-day to 6-month after booster vaccination, the SW-BIC-213 group exhibited a relative vaccine efficacy (VE) of 70.1% (95% CI: 34.2-86.4) against symptomatic COVID-19 when compared to the BBIBP group. Interpretation: A heterologous booster with the COVID-19 mRNA vaccine SW-BIC-213 manifests a favorable safety profile and proves highly immunogenic and efficacious in preventing symptomatic COVID-19 in individuals who have previously received two doses of inactivated vaccine. Funding: Shanghai Strategic Emerging Industries Development Special Fund, Biomedical Technology Support Special Project of Shanghai "Science and Technology Innovation Action Plan", Shanghai Municipal Science and Technology Commission.

An inoculation site-retained mRNA vaccine induces robust immune responses against SARS-CoV-2 variants.

mRNA-based vaccines and therapeutic agents hold great promise in prevention and treatment of human diseases, yet high percentage of systemic adverse effect in clinic remains a big safety concern. One major potential cause is a high level of leakage of the locally inoculated mRNA vaccine nanoparticles into circulation. We have screened and optimized a core-shell structured lipopolyplex (LPP) formulation for mRNA with a tissue-retention property. Upon intramuscular inoculation, the mRNA-encapsulated LPP nanoparticles were preferentially taken up by the phagocytic antigen-presentation cells, and potently promoted dendritic cell maturation. We applied the new formulation to prepare a prophylactic vaccine for SARS-CoV-2, and observed potent humoral and cellular immune responses from the vaccine in both murine models and non-human primates. More importantly, the vaccine demonstrated a benign safety profile in non-human primates, with limited side effects after repeated treatment with high dosages of LPP/mRNA. Taken together, the inoculation site-retained vaccine formulation serves as a promising vehicle for mRNA vaccines and therapeutic agents.

A single immunization with core-shell structured lipopolyplex mRNA vaccine against rabies induces potent humoral immunity in mice and dogs.

The persistence and clinical consequences of rabies virus (RABV) infection have prompted global efforts to develop a safe and effective vaccines against rabies. mRNA vaccines represent a promising option against emerging and re-emerging infectious diseases, gaining particular interest since the outbreak of COVID-19. Herein, we report the development of a highly efficacious rabies mRNA vaccine composed of sequence-modified mRNA encoding RABV glycoprotein (RABV-G) packaged in core-shell structured lipopolyplex (LPP) nanoparticles, named LPP-mRNA-G. The bilayer structure of LPP improves protection and delivery of RABV-G mRNA and allows gradual release of mRNA molecules as the polymer degrades. The unique core-shell structured nanoparticle of LPP-mRNA-G facilitates vaccine uptake and demonstrates a desirable biodistribution pattern with low liver targeting upon intramuscular immunization. Single administration of low-dose LPP-mRNA-G in mice elicited potent humoral immune response and provided complete protection against intracerebral challenge with lethal RABV. Similarly, single immunization of low-dose LPP-mRNA-G induced high levels of virus-neutralizing antibody titers in dogs. Collectively, our data demonstrate the potential of LPP-mRNA-G as a promising next-generation rabies vaccine used in human and companion animals.

Algorithm for optimized mRNA design improves stability and immunogenicity.

Messenger RNA (mRNA) vaccines are being used to combat the spread of COVID-19 (refs. 1-3), but they still exhibit critical limitations caused by mRNA instability and degradation, which are major obstacles for the storage, distribution and efficacy of the vaccine products4. Increasing secondary structure lengthens mRNA half-life, which, together with optimal codons, improves protein expression5. Therefore, a principled mRNA design algorithm must optimize both structural stability and codon usage. However, owing to synonymous codons, the mRNA design space is prohibitively large-for example, there are around 2.4 × 10632 candidate mRNA sequences for the SARS-CoV-2 spike protein. This poses insurmountable computational challenges. Here we provide a simple and unexpected solution using the classical concept of lattice parsing in computational linguistics, where finding the optimal mRNA sequence is analogous to identifying the most likely sentence among similar-sounding alternatives6. Our algorithm LinearDesign finds an optimal mRNA design for the spike protein in just 11 minutes, and can concurrently optimize stability and codon usage. LinearDesign substantially improves mRNA half-life and protein expression, and profoundly increases antibody titre by up to 128 times in mice compared to the codon-optimization benchmark on mRNA vaccines for COVID-19 and varicella-zoster virus. This result reveals the great potential of principled mRNA design and enables the exploration of previously unreachable but highly stable and efficient designs. Our work is a timely tool for vaccines and other mRNA-based medicines encoding therapeutic proteins such as monoclonal antibodies and anti-cancer drugs7,8.

Long-Term Cross Immune Response in Mice following Heterologous Prime-Boost COVID-19 Vaccination with Full-Length Spike mRNA and Recombinant S1 Protein.

(1) Background: As the COVID-19 pandemic enters its fourth year, it continues to cause significant morbidity and mortality worldwide. Although various vaccines have been approved and the use of homologous or heterologous boost doses is widely promoted, the impact of vaccine antigen basis, forms, dosages, and administration routes on the duration and spectrum of vaccine-induced immunity against variants remains incompletely understood. (2) Methods: In this study, we investigated the effects of combining a full-length spike mRNA vaccine with a recombinant S1 protein vaccine, using intradermal/intramuscular, homologous/heterologous, and high/low dosage immunization strategies. (3) Results: Over a period of seven months, vaccination with a mutant recombinant S1 protein vaccine based on the full-length spike mRNA vaccine maintained a broadly stable humoral immunity against the wild-type strain, a partially attenuated but broader-spectrum immunity against variant strains, and a comparable level of cellular immunity across all tested strains. Furthermore, intradermal vaccination enhanced the heterologous boosting of the protein vaccine based on the mRNA vaccine. (4) Conclusions: This study provides valuable insights into optimizing vaccination strategies to address the ongoing challenges posed by emerging SARS-CoV-2 variants.

Safety and immunogenicity of a modified COVID-19 mRNA vaccine, SW-BIC-213, as a heterologous booster in healthy adults: an open-labeled, two-centered and multi-arm randomised, phase 1 trial.

BACKGROUND: We assessed the safety and immunogenicity of a core-shell structured lipopolyplex (LPP) based COVID-19 mRNA vaccine, SW-BIC-213, as a heterologous booster in healthy adults. METHODS: We conducted an open-labeled, two-centered, and three-arm randomised phase 1 trial. Healthy adults, who had completed a two-dose of inactivated COVID-19 vaccine for more than six months, were enrolled and randomized to receive a booster dose of COVILO (inactivated vaccine) (n = 20) or SW-BIC-213-25µg (n = 20), or SW-BIC-213-45µg (n = 20). The primary study endpoint was adverse events within 30 days post-boosting. The secondary endpoint was the titers of binding antibodies and neutralizing antibodies against the wild-type (WT) of SARS-CoV-2 as well as variants of concern in serum. The exploratory endpoint was the cellular immune responses. This trial was registered with http://www.chictr.org.cn (ChiCTR2200060355). FINDINGS: Between Jun 6 and Jun 22, 2022, 60 participants were enrolled and randomized to receive a booster dose of SW-BIC-213 (25 µg, n = 20, or 45 µg, n = 20) or COVILO (n = 20). The baseline demographic characteristics of the participants at enrollment were similar among the treatment groups. For the primary outcome, injection site pain and fever were more common in the SW-BIC-213 groups (25 µg and 45 µg). Grade 3 fever was reported in 25% (5/20) of participants in the SW-BIC-213-45µg group but was resolved within 48 h after onset. No fatal events or adverse events leading to study discontinuation were observed. For secondary and exploratory outcomes, SW-BIC-213 elicited higher and longer humoral and cellular immune responses than that in the COVILO group. INTERPRETATION: SW-BIC-213, a core-shell structured lipopolyplex (LPP) based mRNA vaccine, was safe, tolerable, and immunogenic as a heterologous booster in healthy Chinese adults. FUNDING: Shanghai Municipal Government, the Science and Technology and Economic Commission of Shanghai Pudong New Area, and mRNA Innovation and Translation Center of Shanghai.

An mRNA vaccine elicits STING-dependent antitumor immune responses.

Lipid-formulated RNA vaccines have been widely used for disease prevention and treatment, yet their mechanism of action and individual components contributing to such actions remain to be delineated. Here, we show that a therapeutic cancer vaccine composed of a protamine/mRNA core and a lipid shell is highly potent in promoting cytotoxic CD8+ T cell responses and mediating anti-tumor immunity. Mechanistically, both the mRNA core and lipid shell are needed to fully stimulate the expression of type I interferons and inflammatory cytokines in dendritic cells. Stimulation of interferon-ß expression is exclusively dependent on STING, and antitumor activity from the mRNA vaccine is significantly compromised in mice with a defective Sting gene. Thus, the mRNA vaccine elicits STING-dependent antitumor immunity.

Single-cell transcriptome atlas reveals protective characteristics of COVID-19 mRNA vaccine.

Messenger RNA (mRNA) vaccines are promising alternatives to conventional vaccines in many aspects. We previously developed a lipopolyplex (LPP)-based mRNA vaccine (SW0123) that demonstrated robust immunogenicity and strong protective capacity against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in mice and rhesus macaques. However, the immune profiles and mechanisms of pulmonary protection induced by SW0123 remain unclear. Through high-resolution single-cell analysis, we found that SW0123 vaccination effectively suppressed SARS-CoV-2-induced inflammatory responses by inhibiting the recruitment of proinflammatory macrophages and increasing the frequency of polymorphonuclear myeloid-derived suppressor cells. In addition, the apoptotic process in both lung epithelial and endothelial cells was significantly inhibited, which was proposed to be one major mechanism contributing to vaccine-induced lung protection. Cell-cell interaction in the lung compartment was also altered by vaccination. These data collectively unravel the mechanisms by which the SW0123 protects against lung damage caused by SARS-CoV-2 infection.

Advances in Development of mRNA-Based Therapeutics.

Recently, mRNA-based therapeutics have been greatly boosted since the development of novel technologies of both mRNA synthesis and delivery system. Promising results were showed in both preclinical and clinical studies in the field of cancer vaccine, tumor immunotherapy, infectious disease prevention and protein replacement therapy. Recent advancements in clinical trials also encouraged scientists to attempt new applications of mRNA therapy such as gene editing and cell programming. These studies bring mRNA therapeutics closer to real-world application. Herein, we provide an overview of recent advances in mRNA-based therapeutics.

Virus-Mimic mRNA Vaccine for Cancer Treatment.

An effective therapeutic cancer vaccine should be empowered with the capacity to overcome the immunosuppressive tumor microenvironment. Here, the authors describe a mRNA virus-mimicking vaccine platform that is comprised of a phospholipid bilayer encapsulated with a protein-nucleotide core consisting of antigen-encoding mRNA molecules, unmethylated CpG oligonucleotides and positively charged proteins. In cell culture, VLVP potently stimulated bone marrow-derived dendritic cells (BMDCs) to express inflammatory cytokines that facilitated dendritic cell (DC) maturation and promoted antigen processing and presentation. In tumor-bearing mice, VLVP treatment stimulated proliferation of antigen-specific CD8+T cells in the lymphatic organs and T cell infiltration into the tumor bed, resulting in potent anti-tumor immunity. Cytometry by time of flight (CyTOF) analysis revealed that VLVP treatment stimulated a 5-fold increase in tumor-associated CD8+DCs and a 4-fold increase in tumorinfiltrated CD8+T cells, with concurrent decreases in tumor-associated bone marrow-derived suppressor cells and arginase 1- expressing suppressive DCs. Finally, CpG oligonucleotide is an essential adjuvant for vaccine activity. Inclusion of CpG not only maximized vaccine activity but also prevented PD-1 expression in T cells, serving the dual roles as a potent adjuvant and a checkpoint blockade agent.

Antibody-dependent cellular cytotoxicity response to SARS-CoV-2 in COVID-19 patients.

Antibody-dependent cellular cytotoxicity (ADCC) responses to viral infection are a form of antibody regulated immune responses mediated through the Fc fragment. Whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) triggered ADCC responses contributes to COVID-19 disease development is currently not well understood. To understand the potential correlation between ADCC responses and COVID-19 disease development, we analyzed the ADCC activity and neutralizing antibody response in 255 individuals ranging from asymptomatic to fatal infections over 1 year post disease. ADCC was elicited by 10 days post-infection, peaked by 11-20 days, and remained detectable until 400 days post-infection. In general, patients with severe disease had higher ADCC activities. Notably, patients who had severe disease and recovered had higher ADCC activities than patients who had severe disease and deceased. Importantly, ADCC activities were mediated by a diversity of epitopes in SARS-COV-2-infected mice and induced to comparable levels against SARS-CoV-2 variants of concern (VOCs) (B.1.1.7, B.1.351, and P.1) as that against the D614G mutant in human patients and vaccinated mice. Our study indicates anti-SARS-CoV-2 ADCC as a major trait of COVID-19 patients with various conditions, which can be applied to estimate the extra-neutralization level against COVID-19, especially lethal COVID-19.

A core-shell structured COVID-19 mRNA vaccine with favorable biodistribution pattern and promising immunity.

Although inoculation of COVID-19 vaccines has rolled out globally, there is still a critical need for safe and effective vaccines to ensure fair and equitable supply for all countries. Here, we report on the development of a highly efficacious mRNA vaccine, SW0123 that is composed of sequence-modified mRNA encoding the full-length SARS-CoV-2 Spike protein packaged in core-shell structured lipopolyplex (LPP) nanoparticles. SW0123 is easy to produce using a large-scale microfluidics-based apparatus. The unique core-shell structured nanoparticle facilitates vaccine uptake and demonstrates a high colloidal stability, and a desirable biodistribution pattern with low liver targeting effect upon intramuscular administration. Extensive evaluations in mice and nonhuman primates revealed strong immunogenicity of SW0123, represented by induction of Th1-polarized T cell responses and high levels of antibodies that were capable of neutralizing not only the wild-type SARS-CoV-2, but also a panel of variants including D614G and N501Y variants. In addition, SW0123 conferred effective protection in both mice and non-human primates upon SARS-CoV-2 challenge. Taken together, SW0123 is a promising vaccine candidate that holds prospects for further evaluation in humans.

Cellular determinants and microenvironmental regulation of prostate cancer metastasis.

Metastasis causes more than 90% of cancer-related deaths and most prostate cancer (PCa) patients also die from metastasis. The 'metastatic cascade' is a complex biological process that encompasses tumor cell dissociation (from the primary tumor), local invasion, intravasation, transport in circulation, extravasation, colonization, and overt growth in end organs. It has become clear that successful metastasis not only involves many tumor cell-intrinsic properties but also depends on productive interactions between cancer cells and the tumor microenvironment. In this Review, we begin with a general summary on cancer metastasis and a specific discussion on PCa metastasis. We then discuss recent advances in our knowledge of the cellular determinants of PCa metastasis and the importance of tumor microenvironment, especially an immunosuppressive tumor microenvironment, in shaping metastatic propensities. We conclude with a presentation of current and future therapeutic options for patients with PCa metastasis, emphasizing the development of novel, mechanism-based combinatorial strategies for treating metastatic and castration-resistant PCa.

Inhibition of the hexosamine biosynthetic pathway promotes castration-resistant prostate cancer.

The precise molecular alterations driving castration-resistant prostate cancer (CRPC) are not clearly understood. Using a novel network-based integrative approach, here, we show distinct alterations in the hexosamine biosynthetic pathway (HBP) to be critical for CRPC. Expression of HBP enzyme glucosamine-phosphate N-acetyltransferase 1 (GNPNAT1) is found to be significantly decreased in CRPC compared with localized prostate cancer (PCa). Genetic loss-of-function of GNPNAT1 in CRPC-like cells increases proliferation and aggressiveness, in vitro and in vivo. This is mediated by either activation of the PI3K-AKT pathway in cells expressing full-length androgen receptor (AR) or by specific protein 1 (SP1)-regulated expression of carbohydrate response element-binding protein (ChREBP) in cells containing AR-V7 variant. Strikingly, addition of the HBP metabolite UDP-N-acetylglucosamine (UDP-GlcNAc) to CRPC-like cells significantly decreases cell proliferation, both in-vitro and in animal studies, while also demonstrates additive efficacy when combined with enzalutamide in-vitro. These observations demonstrate the therapeutic value of targeting HBP in CRPC.

Systematic dissection of phenotypic, functional, and tumorigenic heterogeneity of human prostate cancer cells.

Human cancers are heterogeneous containing stem-like cancer cells operationally defined as cancer stem cells (CSCs) that possess great tumor-initiating and long-term tumor-propagating properties. In this study, we systematically dissect the phenotypic, functional and tumorigenic heterogeneity in human prostate cancer (PCa) using xenograft models and >70 patient tumor samples. In the first part, we further investigate the PSA-/lo PCa cell population, which we have recently shown to harbor self-renewing long-term tumor-propagating cells and present several novel findings. We show that discordant AR and PSA expression in both untreated and castration-resistant PCa (CRPC) results in AR+PSA+, AR+PSA-, AR-PSA-, and AR-PSA+ subtypes of PCa cells that manifest differential sensitivities to therapeutics. We further demonstrate that castration leads to a great enrichment of PSA-/lo PCa cells in both xenograft tumors and CRPC samples and systemic androgen levels dynamically regulate the relative abundance of PSA+ versus PSA-/lo PCa cells that impacts the kinetics of tumor growth. We also present evidence that the PSA-/lo PCa cells possess distinct epigenetic profiles. As the PSA-/lo PCa cell population is heterogeneous, in the second part, we employ two PSA- (Du145 and PC3) and two PSA+ (LAPC9 and LAPC4) PCa models as well as patient tumor cells to further dissect the clonogenic and tumorigenic subsets. We report that different PCa models possess distinct tumorigenic subpopulations that both commonly and uniquely express important signaling pathways that could represent therapeutic targets. Our results have important implications in understanding PCa cell heterogeneity, response to clinical therapeutics, and cellular mechanisms underlying CRPC.

Platelet-Synthesized Testosterone in Men with Prostate Cancer Induces Androgen Receptor Signaling.

Platelets have been long postulated to play a critical role in the pathogenesis of prostate cancer, although relatively little is known regarding the precise mechanisms involved. Androgen deprivation therapy (ADT) for prostate cancer eventually fails with relapse occurring in the form of castration-resistant prostate cancer (CRPC). CRPC tumors typically overexpress androgen receptor (AR), demonstrating continued dependence upon AR signaling. Platelets have been previously demonstrated to contain androgens, and we sought to explore the contribution of platelet-derived androgens in CRPC. In this study, we examined the role of platelet-derived androgens in vitro using platelets from men with CRPC, men with high-risk prostate cancer, and healthy male donors. A series of in vitro assays was performed to elucidate the impact of platelet-derived androgens on androgen-sensitive prostate tumor cells. By examining platelet-derived androgen effects on AR signaling in prostate tumor cells, we found that platelets, from men with CRPC and on ADT, strongly induce AR target genes and tumor cell proliferation. Moreover, we show a fully intact testosterone (T) biosynthetic pathway within platelets from its precursor cholesterol and demonstrate that platelets of CRPC patients with ADT resistance are able to generate T. Overall, our findings reveal an unknown capacity of platelets to synthesize T at functionally relevant levels in patients with lethal prostate cancer. Importantly, it suggests a novel paracrine mechanism of T production that may act to sustain CRPC state and potentiate therapeutic resistance.

High throughput quantitative reverse transcription PCR assays revealing over-expression of cancer testis antigen genes in multiple myeloma stem cell-like side population cells.

Multiple myeloma (MM) stem cells, proposed to be responsible for the tumourigenesis, drug resistance and recurrence of this disease, are enriched in the cancer stem cell-like side population (SP). Cancer testis antigens (CTA) are attractive targets for immunotherapy because they are widely expressed in cancers but only in limited types of normal tissues. We designed a high throughput assay, which allowed simultaneous relative quantifying expression of 90 CTA genes associated with MM. In the three MM cell lines tested, six CTA genes were over-expressed in two and LUZP4 and ODF1 were universally up-regulated in all three cell lines. Subsequent study of primary bone marrow (BM) from eight MM patients and four healthy donors revealed that 19 CTA genes were up-regulated in SP of MM compared with mature plasma cells. In contrast, only two CTA genes showed a moderate increase in SP cells of healthy BM. Furthermore, knockdown using small interfering RNA (siRNA) revealed that LUZP4 expression is required for colony-forming ability and drug resistance in MM cells. Our findings indicate that multiple CTA have unique expression profiles in MM SP, suggesting that CTA may serve as targets for immunotherapy that it specific for MM stem cells and which may lead to the long-term cure of MM.

Transcription factors OVOL1 and OVOL2 induce the mesenchymal to epithelial transition in human cancer.

Cell plasticity regulated by the balance between the mesenchymal to epithelial transition (MET) and the opposite program, EMT, is critical in the metastatic cascade. Several transcription factors (TFs) are known to regulate EMT, though the mechanisms of MET remain unclear. We demonstrate a novel function of two TFs, OVOL1 and OVOL2, as critical inducers of MET in human cancers. Our findings indicate that the OVOL-TFs control MET through a regulatory feedback loop with EMT-inducing TF ZEB1, and the regulation of mRNA splicing by inducing Epithelial Splicing Regulatory Protein 1 (ESRP1). Using mouse prostate tumor models we show that expression of OVOL-TFs in mesenchymal prostate cancer cells attenuates their metastatic potential. The role of OVOL-TFs as inducers of MET is further supported by expression analyses in 917 cancer cell lines, suggesting their role as crucial regulators of epithelial-mesenchymal cell plasticity in cancer.