A Multiscale Map of the Stem Cell State in Pancreatic Adenocarcinoma.

Drug resistance and relapse remain key challenges in pancreatic cancer. Here, we have used RNA sequencing (RNA-seq), chromatin immunoprecipitation (ChIP)-seq, and genome-wide CRISPR analysis to map the molecular dependencies of pancreatic cancer stem cells, highly therapy-resistant cells that preferentially drive tumorigenesis and progression. This integrated genomic approach revealed an unexpected utilization of immuno-regulatory signals by pancreatic cancer epithelial cells. In particular, the nuclear hormone receptor retinoic-acid-receptor-related orphan receptor gamma (RORγ), known to drive inflammation and T cell differentiation, was upregulated during pancreatic cancer progression, and its genetic or pharmacologic inhibition led to a striking defect in pancreatic cancer growth and a marked improvement in survival. Further, a large-scale retrospective analysis in patients revealed that RORγ expression may predict pancreatic cancer aggressiveness, as it positively correlated with advanced disease and metastasis. Collectively, these data identify an orthogonal co-option of immuno-regulatory signals by pancreatic cancer stem cells, suggesting that autoimmune drugs should be evaluated as novel treatment strategies for pancreatic cancer patients.

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.

Oncogenic translation directs spliceosome dynamics revealing an integral role for SF3A3 in breast cancer.

Splicing is a central RNA-based process commonly altered in human cancers; however, how spliceosomal components are co-opted during tumorigenesis remains poorly defined. Here we unravel the core splice factor SF3A3 at the nexus of a translation-based program that rewires splicing during malignant transformation. Upon MYC hyperactivation, SF3A3 levels are modulated translationally through an RNA stem-loop in an eIF3D-dependent manner. This ensures accurate splicing of mRNAs enriched for mitochondrial regulators. Altered SF3A3 translation leads to metabolic reprogramming and stem-like properties that fuel MYC tumorigenic potential in vivo. Our analysis reveals that SF3A3 protein levels predict molecular and phenotypic features of aggressive human breast cancers. These findings unveil a post-transcriptional interplay between splicing and translation that governs critical facets of MYC-driven oncogenesis.

Targeting KDM4A epigenetically activates tumor-cell-intrinsic immunity by inducing DNA replication stress.

Developing strategies to activate tumor-cell-intrinsic immune response is critical for improving tumor immunotherapy by exploiting tumor vulnerability. KDM4A, as a histone H3 lysine 9 trimethylation (H3K9me3) demethylase, has been found to play a critical role in squamous cell carcinoma (SCC) growth and metastasis. Here we report that KDM4A inhibition promoted heterochromatin compaction and induced DNA replication stress, which elicited antitumor immunity in SCC. Mechanistically, KDM4A inhibition promoted the formation of liquid-like HP1γ puncta on heterochromatin and stall DNA replication, which activated tumor-cell-intrinsic cGAS-STING signaling through replication-stress-induced cytosolic DNA accumulation. Moreover, KDM4A inhibition collaborated with PD1 blockade to inhibit SCC growth and metastasis by recruiting and activating CD8+ T cells. In vivo lineage tracing demonstrated that KDM4A inhibition plus PD1 blockade efficiently eliminated cancer stem cells. Altogether, our results demonstrate that targeting KDM4A can activate anti-tumor immunity and enable PD1 blockade immunotherapy by aggravating replication stress in SCC cells.

Epigenetic escape of immunosurveillance by malignant cell precursors.

Newly formed malignant cells must escape immunosurveillance to generate progressing neoplastic lesions of clinical relevance. Recent data indicate that the immunogenicity of nascent cancer cells, at least in some settings, is dictated by inherent epigenetic mechanisms rather than by immunoediting and the consequent Darwinian selection of poorly immunogenic phenotypes.

AI identifies potent inducers of breast cancer stem cell differentiation based on adversarial learning from gene expression data.

Cancer stem cells (CSCs) are a subpopulation of cancer cells within tumors that exhibit stem-like properties and represent a potentially effective therapeutic target toward long-term remission by means of differentiation induction. By leveraging an artificial intelligence approach solely based on transcriptomics data, this study scored a large library of small molecules based on their predicted ability to induce differentiation in stem-like cells. In particular, a deep neural network model was trained using publicly available single-cell RNA-Seq data obtained from untreated human-induced pluripotent stem cells at various differentiation stages and subsequently utilized to screen drug-induced gene expression profiles from the Library of Integrated Network-based Cellular Signatures (LINCS) database. The challenge of adapting such different data domains was tackled by devising an adversarial learning approach that was able to effectively identify and remove domain-specific bias during the training phase. Experimental validation in MDA-MB-231 and MCF7 cells demonstrated the efficacy of five out of six tested molecules among those scored highest by the model. In particular, the efficacy of triptolide, OTS-167, quinacrine, granisetron and A-443654 offer a potential avenue for targeted therapies against breast CSCs.

A dual-action niclosamide-based prodrug that targets cancer stem cells and inhibits TNBC metastasis.

Chemotherapy typically destroys the tumor mass but rarely eradicates the cancer stem cells (CSCs) that can drive metastatic recurrence. A key current challenge is finding ways to eradicate CSCs and suppress their characteristics. Here, we report a prodrug, Nic-A, created by combining a carbonic anhydrase IX (CAIX) inhibitor, acetazolamide, with a signal transducer and transcriptional activator 3 (STAT3) inhibitor, niclosamide. Nic-A was designed to target triple-negative breast cancer (TNBC) CSCs and was found to inhibit both proliferating TNBC cells and CSCs via STAT3 dysregulation and suppression of CSC-like properties. Its use leads to a decrease in aldehyde dehydrogenase 1 activity, CD44high/CD24low stem-like subpopulations, and tumor spheroid-forming ability. TNBC xenograft tumors treated with Nic-A exhibited decreased angiogenesis and tumor growth, as well as decreased Ki-67 expression and increased apoptosis. In addition, distant metastases were suppressed in TNBC allografts derived from a CSC-enriched population. This study thus highlights a potential strategy for addressing CSC-based cancer recurrence.

Exploiting transcription factors to target EMT and cancer stem cells for tumor modulation and therapy.

Transcription factors (TFs) are essential in controlling gene regulatory networks that determine cellular fate during embryogenesis and tumor development. TFs are the major players in promoting cancer stemness by regulating the function of cancer stem cells (CSCs). Understanding how TFs interact with their downstream targets for determining cell fate during embryogenesis and tumor development is a critical area of research. CSCs are increasingly recognized for their significance in tumorigenesis and patient prognosis, as they play a significant role in cancer initiation, progression, metastasis, and treatment resistance. However, traditional therapies have limited effectiveness in eliminating this subset of cells, allowing CSCs to persist and potentially form secondary tumors. Recent studies have revealed that cancer cells and tumors with CSC-like features also exhibit genes related to the epithelial-to-mesenchymal transition (EMT). EMT-associated transcription factors (EMT-TFs) like TWIST and Snail/Slug can upregulate EMT-related genes and reprogram cancer cells into a stem-like phenotype. Importantly, the regulation of EMT-TFs, particularly through post-translational modifications (PTMs), plays a significant role in cancer metastasis and the acquisition of stem cell-like features. PTMs, including phosphorylation, ubiquitination, and SUMOylation, can alter the stability, localization, and activity of EMT-TFs, thereby modulating their ability to drive EMT and stemness properties in cancer cells. Although targeting EMT-TFs holds potential in tackling CSCs, current pharmacological approaches to do so directly are unavailable. Therefore, this review aims to explore the role of EMT- and CSC-TFs, their connection and impact in cellular development and cancer, emphasizing the potential of TF networks as targets for therapeutic intervention.

Chondroitin sulfate modification of CSPG4 regulates the maintenance and differentiation of glioma-initiating cells via integrin-associated signaling.

Glioma stem cell/glioma-initiating cell (GIC) and their niches are considered responsible for the therapeutic resistance and recurrence of malignant glioma. To clarify the molecular mechanisms of GIC maintenance/differentiation, we performed a unique integrated proteogenomics utilizing GIC clones established from patient tumors having the potential to develop glioblastoma. After the integration and extraction of the transcriptomics/proteomics data, we found that chondroitin sulfate proteoglycan 4 (CSPG4) and its glycobiosynthetic enzymes were significantly upregulated in GICs. Glyco-quantitative PCR array revealed that chondroitin sulfate (CS) biosynthetic enzymes, such as xylosyltransferase 1 (XYLT1) and carbohydrate sulfotransferase 11, were significantly downregulated during serum-induced GIC differentiation. Simultaneously, the CS modification on CSPG4 was characteristically decreased during the differentiation and also downregulated by XYLT1 knockdown. Notably, the CS degradation on CSPG4 by ChondroitinaseABC treatment dramatically induced GIC differentiation, which was significantly inhibited by the addition of CS. GIC growth and differentiation ability were significantly suppressed by CSPG4 knockdown, suggesting that CS-CSPG4 is an important factor in GIC maintenance/differentiation. To understand the molecular function of CS-CSPG4, we analyzed its associating proteins in GICs and found that CSPG4, but not CS-CSPG4, interacts with integrin αV during GIC differentiation. This event sequentially upregulates integrin-extracellular signal-regulated kinase signaling, which can be inhibited by cyclic-RGD (Arg-Gly-Asp) integrin αV inhibitor. These results indicate that CS-CSPG4 regulates the GIC microenvironment for GIC maintenance/differentiation via the CS moiety, which controls integrin signaling. This study demonstrates a novel function of CS on CSPG4 as a niche factor, so-called "glyco-niche" for GICs, and suggests that CS-CSPG4 could be a potential target for malignant glioma.

Cancer cell plasticity, stem cell factors, and therapy resistance: how are they linked?

Cellular plasticity can occur naturally in an organism and is considered an adapting mechanism during the developmental stage. However, abnormal cellular plasticity is observed in different diseased conditions, including cancer. Cancer cell plasticity triggers the stimuli of epithelial-mesenchymal transition (EMT), abnormal epigenetic changes, expression of stem cell factors and implicated signaling pathways, etc., and helps in the maintenance of CSC phenotype. Conversely, CSC maintains the cancer cell plasticity, EMT, and epigenetic plasticity. EMT contributes to increased cell migration and greater diversity within tumors, while epigenetic changes, stem cell factors (OCT4, NANOG, and SOX2), and various signaling pathways allow cancer cells to maintain various phenotypes, giving rise to intra- and inter-tumoral heterogeneity. The intricate relationships between cancer cell plasticity and stem cell factors help the tumor cells adopt drug-tolerant states, evade senescence, and successfully acquire drug resistance with treatment dismissal. Inhibiting molecules/signaling pathways involved in promoting CSCs, cellular plasticity, EMT, and epigenetic plasticity might be helpful for successful cancer therapy management. This review discussed the role of cellular plasticity, EMT, and stem cell factors in tumor initiation, progression, reprogramming, and therapy resistance. Finally, we discussed how the intervention in this axis will help better manage cancers and improve patient survivability.

Dynamic interplay of nuclear receptors in tumor cell plasticity and drug resistance: Shifting gears in malignant transformations and applications in cancer therapeutics.

Recent advances have brought forth the complex interplay between tumor cell plasticity and its consequential impact on drug resistance and tumor recurrence, both of which are critical determinants of neoplastic progression and therapeutic efficacy. Various forms of tumor cell plasticity, instrumental in facilitating neoplastic cells to develop drug resistance, include epithelial-mesenchymal transition (EMT) alternatively termed epithelial-mesenchymal plasticity, the acquisition of cancer stem cell (CSC) attributes, and transdifferentiation into diverse cell lineages. Nuclear receptors (NRs) are a superfamily of transcription factors (TFs) that play an essential role in regulating a multitude of cellular processes, including cell proliferation, differentiation, and apoptosis. NRs have been implicated to play a critical role in modulating gene expression associated with tumor cell plasticity and drug resistance. This review aims to provide a comprehensive overview of the current understanding of how NRs regulate these key aspects of cancer biology. We discuss the diverse mechanisms through which NRs influence tumor cell plasticity, including EMT, stemness, and metastasis. Further, we explore the intricate relationship between NRs and drug resistance, highlighting the impact of NR signaling on chemotherapy, radiotherapy and targeted therapies. We also discuss the emerging therapeutic strategies targeting NRs to overcome tumor cell plasticity and drug resistance. This review also provides valuable insights into the current clinical trials that involve agonists or antagonists of NRs modulating various aspects of tumor cell plasticity, thereby delineating the potential of NRs as therapeutic targets for improved cancer treatment outcomes.

Cancer cell plasticity: from cellular, molecular, and genetic mechanisms to tumor heterogeneity and drug resistance.

Cancer is a complex disease displaying a variety of cell states and phenotypes. This diversity, known as cancer cell plasticity, confers cancer cells the ability to change in response to their environment, leading to increased tumor diversity and drug resistance. This review explores the intricate landscape of cancer cell plasticity, offering a deep dive into the cellular, molecular, and genetic mechanisms that underlie this phenomenon. Cancer cell plasticity is intertwined with processes such as epithelial-mesenchymal transition and the acquisition of stem cell-like features. These processes are pivotal in the development and progression of tumors, contributing to the multifaceted nature of cancer and the challenges associated with its treatment. Despite significant advancements in targeted therapies, cancer cell adaptability and subsequent therapy-induced resistance remain persistent obstacles in achieving consistent, successful cancer treatment outcomes. Our review delves into the array of mechanisms cancer cells exploit to maintain plasticity, including epigenetic modifications, alterations in signaling pathways, and environmental interactions. We discuss strategies to counteract cancer cell plasticity, such as targeting specific cellular pathways and employing combination therapies. These strategies promise to enhance the efficacy of cancer treatments and mitigate therapy resistance. In conclusion, this review offers a holistic, detailed exploration of cancer cell plasticity, aiming to bolster the understanding and approach toward tackling the challenges posed by tumor heterogeneity and drug resistance. As articulated in this review, the delineation of cellular, molecular, and genetic mechanisms underlying tumor heterogeneity and drug resistance seeks to contribute substantially to the progress in cancer therapeutics and the advancement of precision medicine, ultimately enhancing the prospects for effective cancer treatment and patient outcomes.

Glioblastoma stem cell metabolism and immunity.

Despite enormous efforts being invested in the development of novel therapies for brain malignancies, there remains a dire need for effective treatments, particularly for pediatric glioblastomas. Their poor prognosis has been attributed to the fact that conventional therapies target tumoral cells, but not glioblastoma stem cells (GSCs). GSCs are characterized by self-renewal, tumorigenicity, poor differentiation, and resistance to therapy. These characteristics represent the fundamental tools needed to recapitulate the tumor and result in a relapse. The mechanisms by which GSCs alter metabolic cues and escape elimination by immune cells are discussed in this article, along with potential strategies to harness effector immune cells against GSCs. As cellular immunotherapy is making significant advances in a variety of cancers, leveraging this underexplored reservoir may result in significant improvements in the treatment options for brain malignancies.

BRD9-SMAD2/3 Orchestrates Stemness and Tumorigenesis in Pancreatic Ductal Adenocarcinoma.

BACKGROUND & AIMS: The dismal prognosis of pancreatic ductal adenocarcinoma (PDAC) is linked to the presence of pancreatic cancer stem-like cells (CSCs) that respond poorly to current chemotherapy regimens. The epigenetic mechanisms regulating CSCs are currently insufficiently understood, which hampers the development of novel strategies for eliminating CSCs. METHODS: By small molecule compound screening targeting 142 epigenetic enzymes, we identified that bromodomain-containing protein BRD9, a component of the BAF histone remodeling complex, is a key chromatin regulator to orchestrate the stemness of pancreatic CSCs via cooperating with the TGFß/Activin-SMAD2/3 signaling pathway. RESULTS: Inhibition and genetic ablation of BRD9 block the self-renewal, cell cycle entry into G0 phase and invasiveness of CSCs, and improve the sensitivity of CSCs to gemcitabine treatment. In addition, pharmacological inhibition of BRD9 significantly reduced the tumorigenesis in patient-derived xenografts mouse models and eliminated CSCs in tumors from pancreatic cancer patients. Mechanistically, inhibition of BRD9 disrupts enhancer-promoter looping and transcription of stemness genes in CSCs. CONCLUSIONS: Collectively, the data suggest BRD9 as a novel therapeutic target for PDAC treatment via modulation of CSC stemness.

Cancer Stem Cells as a Therapeutic Target: Current Clinical Development and Future Prospective.

The key role of cancer stem cells (CSCs) in tumor development and therapy resistance makes them essential biomarkers and therapeutic targets. Numerous agents targeting CSCs, either as monotherapy or as part of combination therapy, are currently being tested in clinical trials to treat solid tumors and hematologic malignancies. Data from ongoing and future clinical trials testing novel approaches to target tumor stemness-related biomarkers and pathways may pave the way for further clinical development of CSC-targeted treatments and CSC-guided selection of therapeutic regimens. In this concise review, we discuss recent progress in developing CSC-directed treatment approaches, focusing on clinical trials testing CSC-directed therapies. We also consider the further development of CSC-assay-guided patient stratification and treatment personalization.

Stem cell dynamics and cellular heterogeneity across lineage subtypes of castrate-resistant prostate cancer.

To resist lineage-dependent therapies such as androgen receptor inhibition, prostate luminal epithelial adenocarcinoma cells often adopt a stem-like state resulting in lineage plasticity and phenotypic heterogeneity. Castrate-resistant prostate adenocarcinoma can transition to neuroendocrine (NE) and occasionally to amphicrine, co-expressed luminal and NE, phenotypes. We developed castrate-resistant prostate cancer (CRPC) patient-derived organoid models that preserve heterogeneity of the originating tumor, including an amphicrine model displaying a range of luminal and NE phenotypes. To gain biological insight and to identify potential treatment targets within heterogeneous tumor cell populations, we assessed the lineage hierarchy and molecular characteristics of various CRPC tumor subpopulations. Transcriptionally similar stem/progenitor (St/Pr) cells were identified for all lineage populations. Lineage tracing in amphicrine CRPC showed that heterogeneity originated from distinct subclones of infrequent St/Pr cells that produced mainly quiescent differentiated amphicrine progeny. By contrast, adenocarcinoma CRPC progeny originated from St/Pr cells and self-renewing differentiated luminal cells. Neuroendocrine prostate cancer (NEPC) was composed almost exclusively of self-renewing St/Pr cells. Amphicrine subpopulations were enriched for secretory luminal, mesenchymal, and enzalutamide treatment persistent signatures that characterize clinical progression. Finally, the amphicrine St/Pr subpopulation was specifically depleted with an AURKA inhibitor, which blocked tumor growth. These data illuminate distinct stem cell (SC) characteristics for subtype-specific CRPC in addition to demonstrating a context for targeting differentiation-competent prostate SCs.

Antitumor efficacy of synthesized Ag-Au nanocomposite loaded with PEG and ascorbic acid in human lung cancer stem cells.

Lung cancer is the leading cause of mortality worldwide of which non-small cell lung carcinoma constitutes majority of the cases. High mortality is attributed to early metastasis, late diagnosis, ineffective treatment and tumor relapse. Chemotherapy and radiotherapy form the mainstay of its treatment. However, their associated side effects involving kidneys, nervous system, gastrointestinal tract, and liver further adds to dismal outcome. These disadvantages of conventional treatment can be circumvented by use of engineered nanoparticles for improved effectiveness with minimal side effects. In this study we have synthesized silver gold nanocomposite (Ag-Au NC) using polyethylene glycol and l-ascorbic acid as surfactant and reducing agent respectively. Synthesized nanocomposite was characterized by ultraviolet-visible absorption, dynamic light scattering, scanning and transmission electron microscopy. Compositional analysis was carried out by energy dispersive X-ray analysis and average pore diameter was estimated using Barrett-Joyner-Halenda method. In-silico molecular docking analysis of the synthesized NC against active regions of epidermal growth factor receptor revealed good binding energy. Subsequently, we investigated the effect of NC on growth and stem cell attributes of A549 lung cancer cells. Results showed that NC was effective in inhibiting A549 cell proliferation, induced DNA damage, G2/M phase arrest and apoptosis. Further, tumor cell migration and spheroid formation were also negatively affected. NC also enhanced reactive oxygen species generation and mitochondrial depolarization. In addition, the effect of NC on putative cancer stem cells in A549 cells was evaluated. We found that Ag-Au NC at IC50 targeted CD44, CD24, CD166, CD133 and CD326 positive cancer stem cells and induced apoptosis. CD166 positive cells were relatively resistance to apoptosis. Together our results demonstrate the anticancer efficacy of Ag-Au NC mediated by a mechanism involving cell cycle arrest and mitochondrial derangement.

The m6A methyltransferase RBM15 affects tumor cell stemness and progression of cervical cancer by regulating the stability of lncRNA HEIH.

Cervical cancer (CC), as a common female malignant tumor in the world, is an important risk factor endangering women's health worldwide. The purpose of this study was to investigate the role of RBM15 in CC. The TCGA database was used to screen differentially expressed m6A genes in normal and tumor tissues. QRT-PCR was used to quantify HEIH, miR-802, EGFR, cell stemness, and epithelial-mesenchymal transition (EMT)-related genes. The interaction between HEIH and miR-802 was verified by dual-luciferase reporter assay and RIP assay. The occurrence of tumor cells after different treatments was detected by CCK-8, transwell and EdU staining. BALB/c nude mice were used to examine the effects of different treatments on tumor growth and cell stemness in vivo. RBM15 was upregulated in tumor tissues and cells. M6A was highly enriched in HEIH and enhances its RNA stability. HEIH acts as an oncogenic lncRNA to promote CC cell proliferation, migration and tumor growth. Mechanistically, HEIH regulates tumor cell stemness and promotes the proliferation and migration of CC cells by competitively adsorbing miR-802 and up-regulating the expression of EGFR. In short, our data shown that the m6A methyltransferase RBM15 could affect tumor cell proliferation, metastasis and cell stemness by stabilizing HEIH expression.

Salinomycin and IR780-loaded upconversion nanoparticles influence biological behavior of liver cancer stem cells by persistently activating the MAPK signaling pathway.

The combination of chemotherapy and phototherapy has emerged as a promising therapeutic approach for enhancing the efficacy of cancer treatment and mitigating drug resistance. Salinomycin (SAL), a polyether antibiotic, exhibits potent cytotoxicity against chemotherapy-resistant cancer cells. IR780 iodide, a novel photosensitive reagent with excellent near-infrared (NIR) light absorption and photothermal conversion abilities, is suitable for use in photothermal therapy for cancers. However, both SAL and IR780 exhibit hydrophobic properties that limit their clinical applicability. Upconversion nanoparticles (UCNPs) are an emerging class of fluorescent probe materials capable of emitting high-energy photons upon excitation by low-energy NIR light. The UCNPs not only function as nanocarriers for drug delivery but also serve as light transducers to activate photosensitizers for deep-tissue photodynamic therapy. Here, to enhance the targeting and bioavailability of hydrophobic drugs in liver cancer stem cells (LCSCs), we employ distearoyl phosphorethanolamine-polyethylene glycol (DSPE-PEG) to encapsulate SAL and IR780 on the surface of UCNPs. Cell viability was evaluated using the CCK-8 assay. Cell migration was assessed by the Transwell Boyden Chamber. The activation of the mitogen-activated protein kinase (MAPK) signaling pathway was measured via western blot. The results demonstrated successful loading of both IR780 and SAL onto the UCNPs, and the SAL and IR780-loaded UCNPs (UISP) exhibited a robust photothermal effect under NIR light irradiation. The UISP effectively inhibited the viability of HCCLM3 and LCSCs. Under NIR light irradiation, the UISP further suppressed HCCLM3 viability but had no impact on LCSC viability; however, it could further inhibit LCSC migration. Meanwhile, under NIR light irradiation, the UISP persistently activated the MAPK pathway more significantly in LCSCs. These findings suggest that exposure to NIR light results in persistent activation of the MAPK pathway by UISP, thereby influencing the biological behavior of LCSCs and enhancing their therapeutic efficacy against liver cancer.

Interaction of SMAC with a survivin-derived peptide alters essential cancer hallmarks: Tumor growth, inflammation, and immunosuppression.

Second mitochondrial-derived activator of caspase (SMAC), also known as direct inhibitor of apoptosis-binding proteins with low pI (Diablo), is known as a pro-apoptotic mitochondrial protein released into the cytosol in response to apoptotic signals. We recently reported SMAC overexpression in cancers as essential for cell proliferation and tumor growth due to non-apoptotic functions, including phospholipid synthesis regulation. These functions may be associated with its interactions with partner proteins. Using a peptide array with 768 peptides derived from 11 selected SMAC-interacting proteins, we identified SMAC-interacting sequences. These SMAC-binding sequences were produced as cell-penetrating peptides targeted to the cytosol, mitochondria, or nucleus, inhibiting cell proliferation and inducing apoptosis in several cell lines. For in vivo study, a survivin/baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5)-derived peptide was selected, due to its overexpression in many cancers and its involvement in mitosis, apoptosis, autophagy, cell proliferation, inflammation, and immune responses, as a target for cancer therapy. Specifically, a SMAC-targeting survivin/BIRC5-derived peptide, given intratumorally or intravenously, strongly inhibited lung tumor growth, cell proliferation, angiogenesis, and inflammation, induced apoptosis, and remodeled the tumor microenvironment. The peptide promoted tumor infiltration of CD-8+ cells and increased cell-intrinsic programmed cell death protein 1 (PD-1) and programmed cell death ligand 1 (PD-L1) expression, resulting in cancer cell self-destruction and increased tumor cell death, preserving immune cells. Thus, targeting the interaction between the multifunctional proteins SMAC and survivin represents an innovative therapeutic cancer paradigm.