Machine Learning Identifies Stemness Features Associated with Oncogenic Dedifferentiation.

Cancer progression involves the gradual loss of a differentiated phenotype and acquisition of progenitor and stem-cell-like features. Here, we provide novel stemness indices for assessing the degree of oncogenic dedifferentiation. We used an innovative one-class logistic regression (OCLR) machine-learning algorithm to extract transcriptomic and epigenetic feature sets derived from non-transformed pluripotent stem cells and their differentiated progeny. Using OCLR, we were able to identify previously undiscovered biological mechanisms associated with the dedifferentiated oncogenic state. Analyses of the tumor microenvironment revealed unanticipated correlation of cancer stemness with immune checkpoint expression and infiltrating immune cells. We found that the dedifferentiated oncogenic phenotype was generally most prominent in metastatic tumors. Application of our stemness indices to single-cell data revealed patterns of intra-tumor molecular heterogeneity. Finally, the indices allowed for the identification of novel targets and possible targeted therapies aimed at tumor differentiation.

The Epigenetic Modifiers HDAC2 and HDAC7 Inversely Associate with Cancer Stemness and Immunity in Solid Tumors.

Dysregulation of histone deacetylases (HDACs) is closely associated with cancer development and progression. Here, we comprehensively analyzed the association between all HDAC family members and several clinicopathological and molecular traits of solid tumors across 22 distinct tumor types, focusing primarily on cancer stemness and immunity. To this end, we used publicly available TCGA data and several bioinformatic tools (i.e., GEPIA2, TISIDB, GSCA, Enrichr, GSEA). Our analyses revealed that class I and class II HDAC proteins are associated with distinct cancer phenotypes. The transcriptomic profiling indicated that class I HDAC members, including HDAC2, are positively associated with cancer stemness, while class IIA HDAC proteins, represented by HDAC7, show a negative correlation to cancer stem cell-like phenotypes in solid tumors. In contrast to tumors with high amounts of HDAC7 proteins, the transcriptome signatures of HDAC2-overexpressing cancers are significantly enriched with biological terms previously determined as stemness-associated genes. Moreover, high HDAC2-expressing tumors are depleted with immune-related processes, and HDAC2 expression correlates with tumor immunosuppressive microenvironments. On the contrary, HDAC7 upregulation is significantly associated with enhanced immune responses, followed by enriched infiltration of CD4+ and CD8+ T cells. This is the first comprehensive report demonstrating robust and versatile associations between specific HDAC family members, cancer dedifferentiation, and anti-tumor immune statuses in solid tumors.

Bromodomain (BrD) Family Members as Regulators of Cancer Stemness-A Comprehensive Review.

Epigenetic mechanisms involving DNA methylation and chromatin modifications have emerged as critical facilitators of cancer heterogeneity, substantially affecting cancer development and progression, modulating cell phenotypes, and enhancing or inhibiting cancer cell malignant properties. Not surprisingly, considering the importance of epigenetic regulators in normal stem cell maintenance, many chromatin-related proteins are essential to maintaining the cancer stem cell (CSC)-like state. With increased tumor-initiating capacities and self-renewal potential, CSCs promote tumor growth, provide therapy resistance, spread tumors, and facilitate tumor relapse after treatment. In this review, we characterized the epigenetic mechanisms that regulate the acquisition and maintenance of cancer stemness concerning selected epigenetic factors belonging to the Bromodomain (BrD) family of proteins. An increasing number of BrD proteins reinforce cancer stemness, supporting the maintenance of the cancer stem cell population in vitro and in vivo via the utilization of distinct mechanisms. As bromodomain possesses high druggable potential, specific BrD proteins might become novel therapeutic targets in cancers exhibiting de-differentiated tumor characteristics.

The association between bromodomain proteins and cancer stemness in different solid tumor types.

Cancer stemness, which covers the stem cell-like molecular traits of cancer cells, is essential for tumor development, progression and relapse. Both transcriptional and epigenetic aberrations are essentially connected with cancer stemness. The engagement of bromodomain (BrD) proteins-a family of epigenetic factors-has been presented in the pathogenesis of several tumor types, although their association with cancer stemness remains largely unknown. Here, we harnessed TCGA and GEO databases and used several bioinformatic tools (ie, Oncomine, PrognoScan, GEPIA2, TIMER2.0, TISIDB, GSEA, R2 platform) to characterize the association between the BrD family members' expression and cancer stemness in solid tumors. Our results demonstrate that significant upregulation of ATAD2 and SMARCA4, and downregulation of SMARCA2 is consistently associated with enriched cancer stem cell-like phenotype, respectively. Especially, higher-grade tumors that display stem cell-like properties overexpress ATAD2. In contrast to most BrD members, the gene expression profiles of ATAD2HIGH expressing tumors are strongly enriched with known markers of stem cells and with specific targets for c-Myc transcription factor. For other BrD proteins, the association with cancer de-differentiation status is rather tumor-specific. Our results demonstrate for the first time the relation between distinct BrD family proteins and cancer stemness across 27 solid tumor types. Specifically, our approach allowed us to discover a robust association of high ATAD2 expression with cancer stemness and reveal its' versatility in tumors. As bromodomains are attractive targets from a chemical and structural perspective, we propose ATAD2 as a novel druggable target for de-differentiated tumors, especially those overexpressing MYC.

Mining Transcriptomic Data to Uncover the Association between CBX Family Members and Cancer Stemness.

Genetic and epigenetic changes might facilitate the acquisition of stem cell-like phenotypes of tumors, resulting in worse patients outcome. Although the role of chromobox (CBX) domain proteins, a family of epigenetic factors that recognize specific histone marks, in the pathogenesis of several tumor types is well documented, little is known about their association with cancer stemness. Here, we have characterized the relationship between the CBX family members' expression and cancer stemness in liver, lung, pancreatic, and uterine tumors using publicly available TCGA and GEO databases and harnessing several bioinformatic tools (i.e., Oncomine, GEPIA2, TISIDB, GSCA, UALCAN, R2 platform, Enrichr, GSEA). We demonstrated that significant upregulation of CBX3 and downregulation of CBX7 are consistently associated with enriched cancer stem-cell-like phenotype across distinct tumor types. High CBX3 expression is observed in higher-grade tumors that exhibit stem cell-like traits, and CBX3-associated gene expression profiles are robustly enriched with stemness markers and targets for c-Myc transcription factor regardless of the tumor type. Similar to high-stemness tumors, CBX3-overexpressing cancers manifest a higher mutation load. On the other hand, higher-grade tumors are characterized by the significant downregulation of CBX7, and CBX7-associated gene expression profiles are significantly depleted with stem cell markers. In contrast to high-stemness tumors, cancer with CBX7 upregulation exhibit a lower mutation burden. Our results clearly demonstrate yet unrecognized association of high CBX3 and low CBX7 expression with cancer stem cell-like phenotype of solid tumors.

It Runs in the Bromodomain Family: Speckled Proteins (SP) Play a Role in the Antitumor Immune Response in Solid Tumors.

Cells and immune cells in the extracellular matrix: Depending on the tumor type and variety of TAAs (tumor-associated antigens), immune infiltrates are composed of many different subpopulations of immune cells. Epigenetic changes are also considered to be characteristic of cancer. Epigenetic factors taking part in the regulation of gene expression include the VII group of bromodomain proteins (BrD)-SP-family proteins. Here, we used transcriptomic data from the TCGA database, as well as immunological evidence from ESTIMATE, TIP, and TIMER2.0 databases for various solid tumor types and harnessed several publicly available bioinformatic tools (such as GSEA and GSCA) to demonstrate mechanisms and interactions between BrD proteins and immune infiltrates in cancer. We present a consistently positive correlation between the SP-family genes and immune score regardless of the tumor type. The SP-family proteins correlate positively with T cells' trafficking and infiltration into tumor. Our results also show an association between the high expression of SP family genes and enriched transcriptome profiles of inflammatory response and TNF-α signaling via NF-κß. We also show that the SP-family proteins could be considered good predictors of high immune infiltration phenotypes.

Three-focal-spot terahertz diffractive optical element-iterative design and neural network approach.

The redistribution of an incoming radiation into several beams is necessary in telecommunication to demultiplex data signals. In the terahertz spectral range, it can be realized by easy-to-manufacture diffractive optical elements (DOEs) allowing to focus the radiation into multiple focal spots in a single plane. In this article, we present diffractive optical elements focusing THz radiation into three focal spots. Different focal spot distributions (symmetric and asymmetric) are designed using an iterative algorithm. The phase distribution forming asymmetric focal spots can be realized by iterative design, which is a novel approach, to our knowledge. Then, the structures are manufactured using a sintering-based 3D-printing method from polyamide 12 (PA 12) and measured in an experimental setup for 150 GHz frequency. A novel approach based on neural networks (NNs) is proposed to optimize the phase delay maps of the structures to further improve their performance - the higher efficiency and the lower unwanted background noise.

The role of TRIM family proteins in the regulation of cancer stem cell self-renewal.

The tripartite-motif (TRIM) family of proteins represents one of the largest classes of putative single protein RING-finger E3 ubiquitin ligases. The members of this family are characterized by an N-terminal TRIM motif containing one RING-finger domain, one or two zinc-finger domains called B boxes (B1 box and B2 box), and a coiled-coil region. The TRIM motif can be found in isolation or in combination with a variety of C-terminal domains, and based on C-terminus, TRIM proteins are classified into 11 distinct groups. Because of the complex nature of TRIM proteins, they are implicated in a variety of cellular functions and biological processes, including regulation of cell proliferation, cell division and developmental processes, cancer transformation, regulation of cell metabolism, autophagocytosis, modification of chromatin status, regulation of gene transcription, post-translational modifications, and interactions with pathogens. Here, we demonstrate the specific activities of TRIM family proteins that contribute to the cancer stem cell phenotype. A growing body of evidence demonstrates that several TRIM members guarantee the acquisition of stem cell properties and the ability to sustain stem-like phenotype by cancer cells using distinct mechanisms. For other members, further work is needed to understand their full contribution to stem cell self-renewal. Identification of TRIM proteins that possess the potential to serve as therapeutic targets may result in the development of new therapeutic strategies. Finally, these strategies may result in the disruption of the machinery of stemness acquisition, which may prevent tumor growth, progression, and overcome the resistance to anticancer therapies.

Gene delivery methods and genome editing of human pluripotent stem cells.

Induced pluripotent stem cells derived from normal somatic cells could be utilized to study tumorigenesis through overexpression of specific oncogenes, downregulation of tumor suppressors and dysregulation of other factors thought to promote tumorigenesis. Therefore, effective approaches that provide direct modifications of induced pluripotent stem cell genome are extremely needed. Emerging strategies are expected to provide the ability to more effectively introduce diverse genetic alterations, from as small as single-nucleotide modifications to whole gene amplification or deletion, all with a high degree of target specificity. To date, several techniques have been applied in stem cell studies to directly edit cell genome (ZFNs, TALENs or CRISPR/Cas9). In this review, we summarize specific gene delivery strategies that were applied to stem cell studies together with genome editing techniques, which enable a direct modification of endogenous DNA sequences in the context of cancer studies.

Application of induced pluripotency in cancer studies.

As soon as induced pluripotent stem cells (iPSCs) reprogramming of somatic cells were developed, the discovery attracted the attention of scientists, offering new perspectives for personalized medicine and providing a powerful platform for drug testing. The technology was almost immediately applied to cancer studies. As presented in this review, direct reprogramming of cancer cells with enforced expression of pluripotency factors have several basic purposes, all of which aim to explain the complex nature of cancer development and progression, therapy-resistance and relapse, and ultimately lead to the development of novel anti-cancer therapies. Here, we briefly present recent advances in reprogramming methodologies as well as commonalities between cell reprogramming and carcinogenesis and discuss recent outcomes from the implementation of induced pluripotency into cancer research.

The complexity of TRIM28 contribution to cancer.

Since the first discovery in 1996, the engagement of TRIM28 in distinct aspects of cellular biology has been extensively studied resulting in identification of a complex nature of TRIM28 protein. In this review, we summarize core biological functions of TRIM28 that emerge from TRIM28 multi-domain structure and possessed enzymatic activities. Moreover, we will discuss whether the complexity of TRIM28 engagement in cancer biology makes TRIM28 a possible candidate for targeted anti-cancer therapy. Briefly, we will demonstrate the role of TRIM28 in regulation of target gene transcription, response to DNA damage, downregulation of p53 activity, stimulation of epithelial-to-mesenchymal transition, stemness sustainability, induction of autophagy and regulation of retrotransposition, to provide the answer whether TRIM28 functions as a stimulator or inhibitor of tumorigenesis. To date, number of studies demonstrate significant upregulation of TRIM28 expression in cancer tissues which correlates with worse overall patient survival, suggesting that TRIM28 supports cancer progression. Here, we present distinct aspects of TRIM28 involvement in regulation of cancer cell homeostasis which collectively imply pro-tumorigenic character of TRIM28. Thorough analyses are further needed to verify whether TRIM28 possess the potential to become a new anti-cancer target.

Oncogenic BRAF mutations and p16 expression in melanocytic nevi and melanoma in the Polish population.

INTRODUCTION: Twenty-five - fifty percent of skin melanomas arise from nevi. Melanocyte proliferation is activated by BRAFV600E, then is arrested, but single nevi transform to melanomas. p16 controls arrest, and p16 loss may promote transformation. AIM: To analyze BRAFV600E, p16 expression and melanocyte proliferation in dermal, compound and dysplastic nevi, cells of primary and metastatic melanoma in the Polish population. MATERIAL AND METHODS: One hundred and thirty-two nevi (dermal, compound, dysplastic) and 41 melanomas (in situ, primary, metastatic) were studied. BRAF was assessed by cobas® 4800 BRAFV600 Mutation Test, High Resolution Melting Assay validated with: pyrosequencing and immunohistochemistry. p16 and Ki67 expression was analyzed by IHC. RESULTS: Eighty-two percent of nevi and 57% of melanomas display BRAFV600E expression. Most dermal and compound nevi had > 50% of p16(+) cells. BRAFV600E dysplastic nevi had a low number of p16(+) cells. Nevi without BRAFV600E (WT), had 90% of cells p16(+). In 60% of in situ and primary melanomas, there was a low number of cells of p16(+). Fifty percent of WT metastatic melanoma and 33% of BRAFV600E showed a high level of p16. The number of Ki67(+) cells in dysplastic nevi was very low. In 25% of BRAFV600E melanomas in situ and 55% of WT, > 10% cells were Ki67(+). All BRAFV600E primary melanomas and 66% of WT had > 10% Ki67(+) cells. Twenty percent of BRAFV600E and WT metastases had > 10% of Ki67(+), however, 62% of BRAFV600E and 32% of WT samples had > 50% of Ki67(+) cells. CONCLUSIONS: BRAFV600E and p16 are more frequent in nevi than in melanoma in vivo. A significantly higher p16 expression was observed in mutated nevi than in WT, while in melanoma it was just the opposite. The proliferation rate of melanoma cells negatively correlated with p16 expression.

Regulation of breast cancer stem cell features.

Cancer stem cells (CSCs) are rare, tumour-initiating cells that exhibit stem cell properties: capacity of self-renewal, pluripotency, highly tumorigenic potential, and resistance to therapy. Cancer stem cells have been characterised and isolated from many cancers, including breast cancer. Developmental pathways, such as the Wnt/ß-catenin, Notch/γ-secretase/Jagged, Shh (sonic hedgehog), and BMP signalling pathways, which direct proliferation and differentiation of normal stem cells, have emerged as major signalling pathways that contribute to the self-renewal of stem and/or progenitor cells in a variety of organs and cancers. Deregulation of these signalling pathways is frequently linked to an epithelial-mesenchymal transition (EMT), and breast CSCs often possess properties of cells that have undergone the EMT process. Signalling networks mediated by microRNAs and EMT-inducing transcription factors tie the EMT process to regulatory networks that maintain "stemness". Recent studies have elucidated epigenetic mechanisms that control pluripotency and stemness, which allows an assessment on how embryonic and normal tissue stem cells are deregulated during cancerogenesis to give rise to CSCs. Epigenetic-based mechanisms are reversible, and the possibility of "resetting" the abnormal cancer epigenome by applying pharmacological compounds targeting epigenetic enzymes is a promising new therapeutic strategy. Chemoresistance of CSCs is frequently driven by various mechanisms, including aberrant expression/activity of ABC transporters, aldehyde dehydrogenase and anti-oncogenic proteins (i.e. BCL2, B-cell lymphoma-2), enhanced DNA damage response, activation of pro-survival signalling pathways, and epigenetic deregulations. Despite controversy surrounding the CSC hypothesis, there is substantial evidence for their role in cancer, and a number of drugs intended to specifically target CSCs have entered clinical trials.

The Cancer Genome Atlas (TCGA): an immeasurable source of knowledge.

The Cancer Genome Atlas (TCGA) is a public funded project that aims to catalogue and discover major cancer-causing genomic alterations to create a comprehensive "atlas" of cancer genomic profiles. So far, TCGA researchers have analysed large cohorts of over 30 human tumours through large-scale genome sequencing and integrated multi-dimensional analyses. Studies of individual cancer types, as well as comprehensive pan-cancer analyses have extended current knowledge of tumorigenesis. A major goal of the project was to provide publicly available datasets to help improve diagnostic methods, treatment standards, and finally to prevent cancer. This review discusses the current status of TCGA Research Network structure, purpose, and achievements.

Low Levels of TRIM28-Interacting KRAB-ZNF Genes Associate with Cancer Stemness and Predict Poor Prognosis of Kidney Renal Clear Cell Carcinoma Patients.

Krüppel-associated box zinc finger (KRAB-ZNF) proteins are known to regulate diverse biological processes, such as embryonic development, tissue-specific gene expression, and cancer progression. However, their involvement in the regulation of cancer stemness-like phenotype acquisition and maintenance is scarcely explored across solid tumor types, and to date, there are no data for kidney renal clear cell cancer (KIRC). We have harnessed The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) database transcriptomic data and used several bioinformatic tools (i.e., GEPIA2, GSCALite, TISIDB, GSEA, CIBERSORT) to verify the relation between the expression and genomic alterations in KRAB-ZNFs and kidney cancer, focusing primarily on tumor dedifferentiation status and antitumor immune response. Our results demonstrate a significant negative correlation between KRAB-ZNFs and kidney cancer dedifferentiation status followed by an attenuated immune-suppressive response. The transcriptomic profiles of high KRAB-ZNF-expressing kidney tumors are significantly enriched with stem cell markers and show a depletion of several inflammatory pathways known for favoring cancer stemness. Moreover, we show for the first time the prognostic role for several KRAB-ZNFs in kidney cancer. Our results provide new insight into the role of selected KRAB-ZNF proteins in kidney cancer development. We believe that our findings may help better understand the molecular basis of KIRC.

The Association between TIF1 Family Members and Cancer Stemness in Solid Tumors.

Cancer progression entails a gradual loss of a differentiated phenotype in parallel with the acquisition of stem cell-like features. Cancer de-differentiation and the acquisition of stemness features are mediated by the transcriptional and epigenetic dysregulation of cancer cells. Here, using publicly available data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and harnessing several bioinformatic tools, we characterized the association between Transcriptional Intermediary Factor 1 (TIF1) family members and cancer stemness in 27 distinct types of solid tumors. We aimed to define the prognostic value for TIF1 members in predicting a stem cell-like cancer phenotype and patient outcome. Our results demonstrate that high expression of only one member of the TIF1 family, namely TIF1ß (also known as Tripartite Motif protein 28, TRIM28) is consequently associated with enriched cancer stemness across the tested solid tumor types, resulting in a worse prognosis for cancer patients. TRIM28 is highly expressed in higher grade tumors that exhibit stem cell-like traits. In contrast to other TIF1 members, only TIF1ß/TRIM28-associated gene expression profiles were robustly enriched with stemness markers regardless of the tumor type. Our work demonstrates that TIF1 family members exhibit distinct expression patterns in stem cell-like tumors, despite their structural and functional similarity. Among other TIF1 members, only TRIM28 might serve as a marker of cancer stemness features.

Disruption of RING and PHD Domains of TRIM28 Evokes Differentiation in Human iPSCs.

TRIM28, a multi-domain protein, is crucial in the development of mouse embryos and the maintenance of embryonic stem cells' (ESC) self-renewal potential. As the epigenetic factor modulating chromatin structure, TRIM28 regulates the expression of numerous genes and is associated with progression and poor prognosis in many types of cancer. Because of many similarities between highly dedifferentiated cancer cells and normal pluripotent stem cells, we applied human induced pluripotent stem cells (hiPSC) as a model for stemness studies. For the first time in hiPSC, we analyzed the function of individual TRIM28 domains. Here we demonstrate the essential role of a really interesting new gene (RING) domain and plant homeodomain (PHD) in regulating pluripotency maintenance and self-renewal capacity of hiPSC. Our data indicate that mutation within the RING or PHD domain leads to the loss of stem cell phenotypes and downregulation of the FGF signaling. Moreover, impairment of RING or PHD domain results in decreased proliferation and impedes embryoid body formation. In opposition to previous data indicating the impact of phosphorylation on TRIM28 function, our data suggest that TRIM28 phosphorylation does not significantly affect the pluripotency and self-renewal maintenance of hiPSC. Of note, iPSC with disrupted RING and PHD functions display downregulation of genes associated with tumor metastasis, which are considered important targets in cancer treatment. Our data suggest the potential use of RING and PHD domains of TRIM28 as targets in cancer therapy.

Melanoma Stem Cell-Like Phenotype and Significant Suppression of Immune Response within a Tumor Are Regulated by TRIM28 Protein.

TRIM28 emerged as a guard of the intrinsic "state of cell differentiation", facilitating self-renewal of pluripotent stem cells. Recent reports imply TRIM28 engagement in cancer stem cell (CSC) maintenance, although the exact mechanism remains unresolved. TRIM28 high expression is associated with worse melanoma patient outcomes. Here, we investigated the association between TRIM28 level and melanoma stemness, and aligned it with the antitumor immune response to find the mechanism of "stemness high/immune low" melanoma phenotype acquisition. Based on the SKCM TCGA data, the TRIM28 expression profile, clinicopathological features, expression of correlated genes, and the level of stemness and immune scores were analyzed in patient samples. The biological function for differentially expressed genes was annotated with GSEA. Results were validated with additional datasets from R2: Genomics Analysis and Visualization Platform and in vitro with a panel of seven melanoma cell lines. All statistical analyses were accomplished using GraphPad Prism 8. TRIM28HIGH-expressing melanoma patients are characterized by worse outcomes and significantly different gene expression profiles than the TRIM28NORM cohort. TRIM28 high level related to higher melanoma stemness as measured with several distinct scores and TRIM28HIGH-expressing melanoma cell lines possess the greater potential of melanosphere formation. Moreover, TRIM28HIGH melanoma tumors were significantly depleted with infiltrating immune cells, especially cytotoxic T cells, helper T cells, and B cells. Furthermore, TRIM28 emerged as a good predictor of "stemness high/immune low" melanoma phenotype. Our data indicate that TRIM28 might facilitate this phenotype by direct repression of interferon signaling. TRIM28 emerged as a direct link between stem cell-like phenotype and attenuated antitumor immune response in melanoma, although further studies are needed to evaluate the direct mechanism of TRIM28-mediated stem-like phenotype acquisition.

Therapeutic melanoma vaccine with cancer stem cell phenotype represses exhaustion and maintains antigen-specific T cell stemness by up-regulating BCL6.

We developed a therapeutic, gene-modified, allogeneic melanoma vaccine (AGI-101H), which, upon genetic modification, acquired melanoma stem cell-like phenotype. Since its initial clinical trial in 1997, the vaccine has resulted in the long-term survival of a substantial fraction of immunized patients (up to 20 years). Here, we investigated the potential molecular mechanisms underlying the long-lasting effect of AGI-101H using transcriptome profiling of patients' peripheral T lymphocytes. Magnetically-separated T lymphocytes from AGI-101H-immunized long-term survivors, untreated melanoma patients, and healthy controls were subjected to transcriptome profiling using the microarray analyses. Data were analyzed with a multitude of bioinformatics tools (WebGestalt, DAVID, GSEA) and the results were validated with RT-qPCR. We found substantial differences in the transcriptomes of healthy controls and melanoma patients (both untreated and AGI-101H-vaccinated). AGI-101H immunization induced similar profiles of peripheral T cells as tumor residing in untreated patients. This suggests that whole stem cells immunization mobilizes analogous peripheral T cells to the natural adaptive anti-melanoma response. Moreover, AGI-101H treatment activated the TNF-α and TGF-ß signaling pathways and dampened IL2-STAT5 signaling in T cells, which finally resulted in the significant up-regulation of a BCL6 transcriptional repressor, a known amplifier of the proliferative capacity of central memory T cells and mediator of a progenitor fate in antigen-specific T cells. In the present study, high levels of BCL6 transcripts negatively correlated with the expression of several exhaustion markers (CTLA4, KLRG1, PTGER2, IKZF2, TIGIT). Therefore, Bcl6 seems to promote a progenitor fate for cancer-experienced T cells from AGI-101H-vaccinated patients by repressing the exhaustion markers.

Whole cell melanoma vaccine genetically modified to stem cells like phenotype generates specific immune responses to ALDH1A1 and long-term survival in advanced melanoma patients.

Allogeneic whole cell gene modified therapeutic melanoma vaccine (AGI-101H) comprising of two melanoma cell lines transduced with cDNA encoding fusion protein composed of IL-6 linked with the soluble IL-6 receptor (sIL-6R), referred to as H6 was developed. H6 served as a molecular adjuvant, however, it has altered vaccine cells phenotype towards melanoma stem cells (MSC)-like with high activity of aldehyde dehydrogenase isoenzyme (ALDH1A1). AGI-101H was applied in advanced melanoma patients with non-resected and resected disease. In the adjuvant setting, it was combined with surgery in case of recurring metastases, which were surgically removed and vaccination continued. A significant fraction of AGI-101H treated melanoma patients is still alive (11-19 years). Out of 106 living patients, 39 were HLA-A2 positive and were the subject of the study. Immunization of melanoma patients resulted in the generation of cytotoxic CD8+ T cells specific for ALDH1A1, which were detected in circulation by HLA-A0201 MHC dextramers loaded with ALDH1A188-96(LLYKLADLI) peptide. Phenotypically they were central memory CD8+ T cells. Re-stimulation with ALDH1A188-96ex vivo resulted in IFN-γ secretion and cells degranulation. Following each vaccine dose administration, the number of ALDH1A1-CD8+ T cells increased in circulation and returned to the previous level until next dose injection (one month). ALDH1A1-CD8+ T cells were also found, however in the lower number than in vaccinated patients, in the circulation of untreated melanoma with stage IV but were not found in stage II or III and healthy donors. Specific anti-ALDH1 antibodies were present in treated patients. Long-term survival suggests immuno-targeting of MSC in treated patients.