Reprogramming Factors Remodel Melanoma Cell Phenotype by Changing Stat3 Expression

Unveiling the Dynamic Interplay between Cancer Stem Cells and the Tumor Microenvironment in Melanoma: Implications for Novel Therapeutic Strategies

Cutaneous melanoma still represents a significant health burden worldwide, being responsible for the majority of skin cancer deaths. Key advances in therapeutic strategies have significantly improved patient outcomes; however, most patients experience drug resistance and tumor relapse. Cancer stem cells (CSCs) are a small subpopulation of cells in different tumors, including melanoma, endowed with distinctive capacities of self-renewal and differentiation into bulk tumor cells. Melanoma CSCs are characterized by the expression of specific biomarkers and intracellular pathways; moreover, they play a pivotal role in tumor onset, progression and drug resistance. In recent years, great efforts have been made to dissect the molecular mechanisms underlying the protumor activities of melanoma CSCs to provide the basis for novel CSC-targeted therapies. Herein, we highlight the intricate crosstalk between melanoma CSCs and bystander cells in the tumor microenvironment (TME), including immune cells, endothelial cells and cancer-associated fibroblasts (CAFs), and its role in melanoma progression. Specifically, we discuss the peculiar capacities of melanoma CSCs to escape the host immune surveillance, to recruit immunosuppressive cells and to educate immune cells toward an immunosuppressive and protumor phenotype. We also address currently investigated CSC-targeted strategies that could pave the way for new promising therapeutic approaches for melanoma care.

Epigenetic regulation and factors that influence the effect of iPSCs-derived neural stem/progenitor cells (NS/PCs) in the treatment of spinal cord injury

Spinal cord injury (SCI) is a severe neurological disorder that causes neurological impairment and disability. Neural stem/progenitor cells (NS/PCs) derived from induced pluripotent stem cells (iPSCs) represent a promising cell therapy strategy for spinal cord regeneration and repair. However, iPSC-derived NS/PCs face many challenges and issues in SCI therapy; one of the most significant challenges is epigenetic regulation and that factors that influence this mechanism. Epigenetics refers to the regulation of gene expression and function by DNA methylation, histone modification, and chromatin structure without changing the DNA sequence. Previous research has shown that epigenetics plays a crucial role in the generation, differentiation, and transplantation of iPSCs, and can influence the quality, safety, and outcome of transplanted cells. In this study, we review the effects of epigenetic regulation and various influencing factors on the role of iPSC-derived NS/PCs in SCI therapy at multiple levels, including epigenetic reprogramming, regulation, and the adaptation of iPSCs during generation, differentiation, and transplantation, as well as the impact of other therapeutic tools (e.g., drugs, electrical stimulation, and scaffolds) on the epigenetic status of transplanted cells. We summarize our main findings and insights in this field and identify future challenges and directions that need to be addressed and explored.

"Reprogram Enablement" as an Assay for Identifying Early Oncogenic Pathways by Their Ability to Allow Neoplastic Cells to Reacquire an Epiblast State

One approach to understanding how tissue-specific cancers emerge is to determine the requirements for “reprograming” such neoplastic cells back to their developmentally normal primordial pre-malignant epiblast-like pluripotent state and then scrutinizing their spontaneous reconversion to a neoplasm, perhaps rendering salient the earliest pivotal oncogenic pathway(s) (before other aberrations accumulate in the adult tumor). For the prototypical malignancy anaplastic thyroid carcinoma (ATC), we found that tonic RAS reduction was obligatory for reprogramming cancer cells to a normal epiblast-emulating cells, confirmed by changes in their transcriptomic and epigenetic profiles, loss of neoplastic behavior, and ability to derive normal somatic cells from their “epiblast organoids.” Without such suppression, ATCs re-emerged from the clones. Hence, for ATC, RAS inhibition was its “reprogram enablement” (RE) factor. Each cancer likely has its own RE factor; identifying it may illuminate pre-malignant risk markers, better classifications, therapeutic targets, and tissue-specification of a previously pluripotent, now neoplastic, cell.

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The factors for reprogramming a cancer cell to an epiblast-like cell can be assayed

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“Reprogram enablement” can yield insights into the earliest pivotal oncogenic steps

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For anaplastic thyroid carcinoma, RAS inhibition was obligatory for reprograming

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Each tissue-specific cancer will have its own reprogramming enablement requirement

Modulating cancer stemness provides luminal a breast cancer cells with HER2 positive-like features

Breast cancers can be classified into luminal A, luminal B, HER2 positive and triple-negative subtypes, each with a distinct therapeutic response. Tumor stemness drives cancer malignancy that challenges cancer control. Understanding the revolutionary relationships driven by tumor stemness among breast cancer subtypes is fundamental to identifying feasible therapeutic modalities for each breast cancer subtype. Utilizing the endogenous tRNA-processing system, we established a multiplexing CRISPR/dCas9 system in breast cancer cells, and applied it to a four-gene panel controlling cell potency, i.e., OCT4, KLF, MYC, SOX2. The stable cell strain, OKMS#1 was obtained through concomitantly over-expressing these genes in luminal A breast cancer cells. OKMS#1 cells showed increased invasion, proliferation and cancer stemness, shared similar drug response pattern with HER2 positive cells, and exhibited altered MAPK and enhanced NFkB signaling. This study contributes in providing an efficient multiplexing CRISPR/dCas9 system that enriches our genetic modulation tool box, and suggests that HER2 positive cells are potential progenitors of luminal A cells and that these two breast cancer subtypes may share similar treatment strategies once rewired between the two states. Our results also implicate that triple negative breast cancer cells, though sharing similar cancer stemness with HER2 positive cells, represent a distinct type of disease and require unique treatment solutions.

STAT3 and STAT5 Targeting for Simultaneous Management of Melanoma and Autoimmune Diseases

Melanoma is a skin cancer which can become metastatic, drug-refractory, and lethal if managed late or inappropriately. An increasing number of melanoma patients exhibits autoimmune diseases, either as pre-existing conditions or as sequelae of immune-based anti-melanoma therapies, which complicate patient management and raise the need for more personalized treatments. STAT3 and/or STAT5 cascades are commonly activated during melanoma progression and mediate the metastatic effects of key oncogenic factors. Deactivation of these cascades enhances antitumor-immune responses, is efficient against metastatic melanoma in the preclinical setting and emerges as a promising targeting strategy, especially for patients resistant to immunotherapies. In the light of the recent realization that cancer and autoimmune diseases share common mechanisms of immune dysregulation, we suggest that the systemic delivery of STAT3 or STAT5 inhibitors could simultaneously target both, melanoma and associated autoimmune diseases, thereby decreasing the overall disease burden and improving quality of life of this patient subpopulation. Herein, we review the recent advances of STAT3 and STAT5 targeting in melanoma, explore which autoimmune diseases are causatively linked to STAT3 and/or STAT5 signaling, and propose that these patients may particularly benefit from treatment with STAT3/STAT5 inhibitors.

Systems analysis of barrier molecule and ARNT-related gene expression regulation in melanoma

Background: We have identified, in melanomas, a set of genes encoding proteins that mediate mechanical barrier function in normal skin (barrier molecule genes, BMGs) and whose overexpression is associated with decreased immune signatures and shorter patient survival. The most overexpressed of these, filaggrin (FLG), is expressed on chromosome 1q21.3, which also encodes genes of the epidermal differentiation complex (EDC). EDC genes may be regulated by the transcription factors (TFs) AHR and ARNT. We hypothesized that ARNT-related genes would be expressed concordantly with BMG and EDC genes, inversely associated with immune signatures, and enhanced by 1q21.3 copy gain. Methods: Gene expression data from human melanomas in the Cancer Genome Atlas (TCGA), and a validation GEO dataset were evaluated, with copy number profiles from TCGA. Expression of Th1 immune genes and BMG/EDCs at 1q21.3 was visualized using clustered copy number and mRNA profiles. Associations of clusters and 1q21.3 copy number with patient survival and mRNA expression were assessed using Kaplan Meier curves, log-rank tests, and Wilcoxon rank sum tests. Results: BMGs are concordantly expressed with EDC genes. Clustering divided tumors into 4 categories: (1) Immune^HI, (2) BMG/EDC^HI, (3) ARNT^HI, (4) Mixed. Both ARNT^HI and BMG/EDC^HI tumors had low immune signatures and significantly shortened survival. KLF4 and FOXF2 are putative TFs that may regulate these genes. Conclusions: ARNT^HI tumors may represent another subset of tumors, in addition to BMG/EDC^HI tumors, with barriers to immune infiltrates, likely with different mechanisms. These genes have prognostic significance and may be relevant targets for future therapy.

Knockdown of STAT3 targets a subpopulation of invasive melanoma stem-like cells

Transcription factor signal transducer and activator of transcription 3 (STAT3) is constitutively activated in many cancers, including melanomas. Active, phosphorylated STAT3 contributes to tumor growth and formation of the immunosuppressive tumor microenvironment. Recent evidence suggests an important role of STAT3 in self-renewal of cancer stem-like cells (CSCs). In the present study, we aimed to determine the expression and role of active STAT3 in melanoma CSCs. We found the increased levels of phosphorylated (Y705) STAT3 in CSC sphere cultures derived from three human and murine melanoma cells. Knockdown of STAT3 did not affect basal proliferation, but reduced sphere forming capacity of two human melanoma cell lines. Moreover, the level of active STAT3 was elevated in rhodamine 123 negative subpopulations of CSCs sorted from three melanoma cell lines. We found that focal adhesion kinase (FAK) and AKT signaling pathways, implicated in the regulation of cell migration and invasion, were up-regulated in melanoma CSCs. Moreover, expression of SERPINA3, which regulates melanoma invasion, was increased in melanoma CSCs sphere cultures, which correlated with augmented cell invasion in Matrigel. Our findings show that STAT3 is activated and supports maintenance of melanoma CSCs. It suggests that STAT3 could serve as a potential target to impair tumor progression or recurrence.

Malignant Melanoma: Autoimmunity and Supracellular Messaging as New Therapeutic Approaches

OPINION STATEMENT

Melanoma is one of the most aggressive forms of cancer, with a high mortality rate in the absence of a safe and curable therapy. As a consequence, several procedures have been tested over time, with the most recent (immunological and targeted) therapies proving to be effective in some patients. Unfortunately, these new treatment options continue to generate debate related to the therapeutic strategy (intended to maximize the long-term results of patients with melanoma), not only about the monotherapy configuration but also regarding association/succession between distinct therapeutic procedures. As an example, targeted therapy with BRAF inhibitors proved to be effective in advanced BRAF-mutant melanoma. However, such treatments with BRAF inhibitors lead to therapy resistance in half of patients after approximately 6 months. Even if most benign nevi incorporate oncogenic BRAF mutations, they rarely become melanoma; therefore, targeted therapy with BRAF inhibitors should be viewed as an incomplete or perfectible therapy. Another example is related to the administration of immune checkpoint inhibitors/ICIs (anti-CTLA-4 antibodies, anti-PD-1/PD-L1 antibodies), which are successfully used in metastatic melanoma. It is currently believed that CTLA-4 and PD-1 blockade would favor a strong immune response against cancer cells. The main side effects of ICIs are represented by the development of immune-related adverse events, which in some cases can be lethal. These ICI side effects would thus be not only therapeutically counterproductive but also potentially dangerous. Surprisingly, a subset of immune-related adverse events (especially autoimmune toxicity) seems to be clearly correlated with better therapeutic results, perhaps due to an additional therapeutic effect (currently insufficiently studied/exploited). Contrary to the classical approach of cancer (considered until now an uncontrolled division of cells), a very recent and comprehensive theory describes malignancy as a supracellular disease. Cancerous disease would therefore be a disturbed supracellular process (embryogenesis, growth, development, regeneration, etc.), which imposes/coordinates an increased rhythm of cell division, angiogenesis, immunosuppression, etc. Melanoma is presented from such a supracellular perspective to be able to explain the beneficial role of autoimmunity in cancer (autoimmune abortion/rejection of the melanoma-embryo phenotype) and to create premises to better optimize the newly emerging therapeutic options. Finally, it is suggested that the supracellular evolution of malignancy implies complex supracellular messaging (between the cells and host organism), which would be interfaced especially by the extracellular matrix and noncoding RNA. Therefore, understanding and manipulating supracellular messaging in cancer could open new treatment perspectives in the form of digitized (supracellular) therapy.

Reprogramming factors induce proliferation and inhibit apoptosis of melanoma cells by changing the expression of particular genes

Uncontrolled proliferation and defective apoptosis are two major factors responsible for maintaining the malignant properties of melanoma cells. Our previous study demonstrated that induced expression of four reprogramming factors remodeled the phenotype of B16‑F10 mouse melanoma cells into melanoma stem cells. The present study was conducted to investigate the effect of the four Yamanaka reprogramming factors, namely Oct4, Sox2, Klf4 and c‑Myc (OSKM), on the proliferation and apoptosis of melanoma cells, and to identify the responsible molecular signals. The results identified that expression of the four reprogramming factors was highly induced by doxycycline treatment in the stable melanoma cell clone that was transfected with a plasmid expressing these factors, driven by the Tet‑On element. It was further confirmed that induced expression of these factors enhanced the proliferation and suppressed the apoptosis of the melanoma cells. In addition, induced OSKM expression increased cell proliferation, accelerated the progression of the cell cycle, and upregulated the mRNA expression levels of Janus kinase 2 (JAK2) and Cyclin‑B1. Induced expression of these factors also decreased the apoptosis, as well as upregulated B‑cell lymphoma 2 (BCL‑2) and downregulated BCL‑2‑associated X (BAX) mRNA expression levels. Taken together, the results suggested that upregulated JAK2 and Cyclin‑B1 may be responsible for the enhanced proliferation of melanoma cells, and that BCL‑2 upregulation and BAX downregulation may account for the suppressed apoptosis of these cells.