Graphical Schematic diagram of tumor-derived exosomes induced organotropism and immunosuppression.

Background: Benzo[a]pyrene (B[a]P), a carcinogen pollutant produced by combustion processes, is present in the western diet with grilled meats. Chronic exposure of B[a]P in hepatocellular carcinoma (HCC) cells promotes metastasis rather than primary proliferation, implying an unknown mechanism of B[a]P‐induced malignancy. Given that exosomes carry bioactive molecules to distant sites, we investigated whether and how exosomes mediate cancer‐stroma communications for a toxicologically associated microenvironment. Method: Exosomes were isolated from B[a]P stimulated BEL7404 HCC cells (7404‐100Bap Exo) at an environmental relevant dose (100 nmol/L). Lung pre‐education animal model was prepared via injection of exosomes and cytokines. The inflammatory genes of educated lungs were evaluated using quantitative reverse transcription PCR array. HCC LM3 cells transfected with firefly luciferase were next injected to monitor tumor burdens and organotropic metastasis. Profile of B[a]P‐exposed exosomes were determined by ceRNA microarray. Interactions between circular RNA (circRNA) and microRNAs (miRNAs) were detected using RNA pull‐down in target lung fibroblasts. Fluorescence in situ hybridization and RNA immunoprecipitation assay was used to evaluate the “on‐off” interaction of circRNA‐miRNA pairs. We further developed an adeno‐associated virus inhalation model to examine mRNA expression specific in lung, thereby exploring the mRNA targets of B[a]P induced circRNA‐miRNA cascade. Results: Lung fibroblasts exert activation phenotypes, including focal adhesion and motility were altered by 7404‐100Bap Exo. In the exosome‐educated in vivo model, fibrosis factors and pro‐inflammatory molecules of are up‐regulated when injected with exosomes. Compared to non‐exposed 7404 cells, circ_0011496 was up‐regulated following B[a]P treatment and was mainly packaged into 7404‐100Bap Exo. Exosomal circ_0011496 were delivered and competitively bound to miR‐486‐5p in recipient fibroblasts. The down‐regulation of miR‐486‐5p converted fibroblast to cancer‐associated fibroblast via regulating the downstream of Twinfilin‐1 (TWF1) and matrix metalloproteinase‐9 (MMP9) cascade. Additionally, increased TWF1, specifically in exosomal circ_0011496 educated lungs, could promote cancer‐stroma crosstalk via activating vascular endothelial growth factor (VEGF). These modulated fibroblasts promoted endothelial cells angiogenesis and recruited primary HCC cells invasion, as a consequence of a pre‐metastatic niche formation. Conclusion: We demonstrated that B[a]P‐induced tumor exosomes can deliver circ_0011496 to activate miR‐486‐5p/TWF1/MMP9 cascade in the lung fibroblasts, generating a feedback loop that promoted HCC metastasis.

Metastasis is the main cause of high pancreatic cancer (PaCa) mortality and trials dampening PaCa mortality rates are not satisfying. Tumor progression is driven by the crosstalk between tumor cells, predominantly cancer-initiating cells (CIC), and surrounding cells and tissues as well as distant organs, where tumor-derived extracellular vesicles (TEX) are of major importance. A strong stroma reaction, recruitment of immunosuppressive leukocytes, perineural invasion, and early spread toward the peritoneal cavity, liver, and lung are shared with several epithelial cell-derived cancer, but are most prominent in PaCa. Here, we report on the state of knowledge on the PaCIC markers Tspan8, alpha6beta4, CD44v6, CXCR4, LRP5/6, LRG5, claudin7, EpCAM, and CD133, which all, but at different steps, are engaged in the metastatic cascade, frequently via PaCIC-TEX. This includes the contribution of PaCIC markers to TEX biogenesis, targeting, and uptake. We then discuss PaCa-selective features, where feedback loops between stromal elements and tumor cells, including distorted transcription, signal transduction, and metabolic shifts, establish vicious circles. For the latter particularly pancreatic stellate cells (PSC) are responsible, furnishing PaCa to cope with poor angiogenesis-promoted hypoxia by metabolic shifts and direct nutrient transfer via vesicles. Furthermore, nerves including Schwann cells deliver a large range of tumor cell attracting factors and Schwann cells additionally support PaCa cell survival by signaling receptor binding. PSC, tumor-associated macrophages, and components of the dysplastic stroma contribute to perineural invasion with signaling pathway activation including the cholinergic system. Last, PaCa aggressiveness is strongly assisted by the immune system. Although rich in immune cells, only immunosuppressive cells and factors are recovered in proximity to tumor cells and hamper effector immune cells entering the tumor stroma. Besides a paucity of immunostimulatory factors and receptors, immunosuppressive cytokines, myeloid-derived suppressor cells, regulatory T-cells, and M2 macrophages as well as PSC actively inhibit effector cell activation. This accounts for NK cells of the non-adaptive and cytotoxic T-cells of the adaptive immune system. We anticipate further deciphering the molecular background of these recently unraveled intermingled phenomena may turn most lethal PaCa into a curatively treatable disease.

Microplastics (MPs), as emerging environmental pollutants, not only possess inherent toxicity but also adsorb or carry other hazardous substances, such as the carcinogen cadmium (Cd), leading to more complex public health issues. Exposure to MPs and Cd has been shown to induce liver injury, with each pollutant triggering distinct toxicological pathways and pathological processes. In this study, Cd and MPs were selected as "stressors" to simulate the transformation from inflammation to tumorigenesis, including non-alcoholic fatty liver disease (NAFLD), liver cirrhosis, and hepatocellular carcinoma (HCC), based on data from the ^Comparative Toxicogenomics Database (CTD) and Genecards. A comprehensive molecular spectrum of the precancerous-lesion-to-cancer cycles induced by individual and combined exposures was established. We also performed in vivo and in vitro experiments to validate these predicted molecular networks. Our findings demonstrated that Cd specifically induces the activation of ECM and cell proliferation-related genes ITGB5, COL3A1, and JUN, thereby driving liver cirrhosis and tumorigenesis. Conversely, MPs were found to predominantly regulate cell death-associated genes BAX and CASP8, which are involved in NAFLD and inflammation. More importantly, co-exposure of Cd and MPs exacerbates and accelerates hepatotoxicity, encompassing fibrosis and carcinogenesis. Therefore, we introduce regulatory cascades as novel initiating and key events within the Adverse Outcome Pathway (AOP) framework, revealing for the first time the precise mechanisms underlying the inflammation-to-cancer transition driven by Cd-MP co-exposure. Our study aligns with the FDA's newly announced alternative approaches to toxicology, demonstrating how the integration of computational and experimental methods can enhance regulatory frameworks for assessing complex pollutant exposures.

Tumor cell-derived extracellular vesicles (TEX) expressing tetraspanin Tspan8-alpha4/beta1 support angiogenesis. Tspan8-alpha6/beta4 facilitates lung premetastatic niche establishment. TEX-promoted target reprogramming is still being disputed, we explored rat endothelial cell (EC) and lung fibroblast (Fb) mRNA and miRNA profile changes after coculture with TEX. TEX were derived from non-metastatic BSp73AS (AS) or metastatic BSp73ASML (ASML) rat tumor lines transfected with Tspan8 (AS-Tspan8) or Tspan8-shRNA (ASML-Tspan8kd). mRNA was analyzed by deep sequencing and miRNA by array analysis of EC and Fb before and after coculture with TEX. EC and Fb responded more vigorously to AS-Tspan8- than AS-TEX. Though EC and Fb responses differed, both cell lines predominantly responded to membrane receptor activation with upregulation and activation of signaling molecules and transcription factors. Minor TEX-initiated changes in the miRNA profile relied, at least partly, on long noncoding RNA (lncRNA) that also affected chromosome organization and mRNA processing. These analyses uncovered three important points. TEX activate target cell autonomous programs. Responses are initiated by TEX targeting units and are target cell-specific. The strong TEX-promoted lncRNA impact reflects lncRNA shuttling and location-dependent distinct activities. These informations urge for an in depth exploration on the mode of TEX-initiated target cell-specific remodeling including, as a major factor, lncRNA.