Dyslipidemia is described as a hallmark of metabolic syndrome, promoting a stage of metabolic inflammation (metainflammation) that could lead to misbalances in energetic metabolism, contributing to insulin resistance, and modifying intracellular cholesterol pathways and the renin–angiotensin system (RAS) in pancreatic islets. Low-density lipoprotein (LDL) hypercholesterolemia could disrupt the tissue communication between Langerhans β-cells and hepatocytes, wherein extracellular vesicles (EVs) are secreted by β-cells, and exposition to LDL can impair these phenomena. β-cells activate compensatory mechanisms to maintain insulin and metabolic homeostasis; therefore, the work aimed to characterize the impact of LDL on β-cell cholesterol metabolism and the implication on insulin secretion, connected with the regulation of cellular communication mediated by EVs on hepatocytes. Our results suggest that β-cells can endocytose LDL, promoting an increase in de novo cholesterol synthesis targets. Notably, LDL treatment increased mRNA levels and insulin secretion; this hyperinsulinism condition was associated with the transcription factor PDX-1. However, a compensatory response that maintains basal levels of intracellular calcium was described, mediated by the overexpression of calcium targets PMCA1/4, SERCA2, and NCX1, together with the upregulation of the unfolded protein response (UPR) through the activation of IRE1 and PERK arms to maintain protein homeostasis. The LDL treatment induced metainflammation by IL-6, NF-κB, and COX-2 overexpression. Furthermore, LDL endocytosis triggered an imbalance of the RAS components. LDL treatment increased the intracellular levels of cholesterol on lipid droplets; the adaptive β-cell response was portrayed by the overexpression of cholesterol transporters ABCA1 and ABCG1. Therefore, lipotoxicity and hyperinsulinism induced by LDL were regulated by the natural compound auraptene, a geranyloxyn coumarin modulator of cholesterol-esterification by ACAT1 enzyme inhibition. EVs isolated from β-cells impaired insulin signaling via mTOR/p70S6Kα in hepatocytes, a phenomenon regulated by auraptene. Our results show that LDL overload plays a novel role in hyperinsulinism, mechanisms associated with a dysregulation of intracellular cholesterol, lipotoxicity, and the adaptive UPR, which may be regulated by coumarin-auraptene; these conditions explain the affectations that occur during the initial stages of insulin resistance.

Cells employ several adaptive mechanisms under conditions of accelerated cell division, such as the unfolded protein response (UPR). The UPR is composed of a tripartite signaling system that involves ATF6, PERK, and IRE1, which maintain protein homeostasis (proteostasis). However, deregulation of protein translation initiation could be associated with breast cancer (BC) chemoresistance. Specifically, eukaryotic initiation factor-4A (eIF4A) is involved in the unfolding of the secondary structures of several mRNAs at the 5′ untranslated region (5′-UTR), as well as in the regulation of targets involved in chemoresistance. Importantly, the tumor suppressor gene PDCD4 could modulate this process. This regulation might be disrupted in chemoresistant triple negative-BC (TNBC) cells. Therefore, we characterized the effect of doxorubicin (Dox), a commonly used anthracycline medication, on human breast carcinoma MDA-MB-231 cells. Here, we generated and characterized models of Dox chemoresistance, and chemoresistant cells exhibited lower Dox internalization levels followed by alteration of the IRE1 and PERK arms of the UPR and triggering of the antioxidant Nrf2 axis. Critically, chemoresistant cells exhibited PDCD4 downregulation, which coincided with a reduction in eIF4A interaction, suggesting a sophisticated regulation of protein translation. Likewise, Dox-induced chemoresistance was associated with alterations in cellular migration and invasion, which are key cancer hallmarks, coupled with changes in focal adhesion kinase (FAK) activation and secretion of matrix metalloproteinase-9 (MMP-9). Moreover, eIF4A knockdown via siRNA and its overexpression in chemoresistant cells suggested that eIF4A regulates FAK. Pro-atherogenic low-density lipoproteins (LDL) promoted cellular invasion in parental and chemoresistant cells in an MMP-9-dependent manner. Moreover, Dox only inhibited parental cell invasion. Significantly, chemoresistance was modulated by cryptotanshinone (Cry), a natural terpene purified from the roots of Salvia brandegeei. Cry and Dox co-exposure induced chemosensitization, connected with the Cry effect on eIF4A interaction. We further demonstrated the Cry binding capability on eIF4A and in silico assays suggest Cry inhibition on the RNA-processing domain. Therefore, strategic disruption of protein translation initiation is a druggable pathway by natural compounds during chemoresistance in TNBC. However, plasmatic LDL levels should be closely monitored throughout treatment.

Exosomes can transport regulatory biomolecules and are mediators of cellular signaling among metabolic tissues through endocrine mechanisms. Understanding the pathways and processes underlying exosome-mediated inter-tissue communication is critical for elucidating the molecular pathophysiology of metabolic diseases such as obesity, type 2 diabetes mellitus (T2DM), and cardiovascular disorders. Consequently, these mechanisms represent novel and promising targets for pharmacological regulation. We examined the current knowledge regarding exosome physiology, the mechanisms of interaction with target tissues, and its role in metabolic tissue communication. We also analyzed the secretory profiles of exosomes in metabolic tissues, emphasizing their regulatory roles in adipose tissue, liver, pancreas, skeletal muscle, and the small intestine, while discussing their association with metabolic diseases. In this sense, we propose the exosomal pentad as a novel framework highlighting exosome-mediated inter-organ communication, where exosomes may regulate a metabolic axis involving these tissues. This model aligns with the ominous octet in type 2 diabetes but emphasizes exosomes as key regulators of metabolic homeostasis and potential therapeutic targets. The role of exosomes for the treatment of metabolic diseases emerges as a critical area of pharmacologic exploration. For instance, therapeutic strategies that prevent target tissue binding or expression of cargo molecules such as miRNAs could be designed, using antagomiRs or nanoparticles. Additionally, integrins like αvβ5 on the exosomal membrane can be blocked with monoclonal antibodies or engineered for targeted delivery of therapeutic molecules. Exosomes, critical mediators of inter-organ communication and metabolic regulation, hold potential to design precise molecular-level therapies while minimizing systemic side effects.

Resistance to HER2 tyrosine-kinase inhibitor Lapatinib (Lap) is one of the leading causes of cancer treatment failure in HER2+ breast cancer (BC), associated with an aggressive tumor phenotype. Cryptotanshinone (Cry) is a natural terpene molecule that could function as a chemosensitizer by disturbing estrogen receptor (ERα) signaling and inhibiting the protein translation factor-4A, eIF4A. Therefore, we evaluated Cry dual regulation on eIF4A and ERα. This study aimed to elucidate the underlying mechanisms of Lap chemoresistance and the impact of Cry on them. We generated two Lap-resistant BT474 cell HER2+ variants named BT474^LapRV1 and BT474^LapRV2 with high chemoresistance levels, with 7- and 11-fold increases in EC₅₀, respectively, compared to BT474 parental cells. We found a PDCD4-p70S6Kβ axis association with Lap chemoresistance. However, a concomitant down-regulation of the RAF-MEK-ERK cell survival pathway and NF-κB was found in the chemoresistant cell variants; this phenomenon was exacerbated by joint treatment of Cry and Lap under a Lap plasmatic reported concentration. Optimized calcium management was identified as a compensatory mechanism contributing to chemoresistance, as determined by the higher expression of calcium pumps PMCA1/4 and SERCA2. Contrary to expectations, a combination of Lap and Cry did not affect the chemoresistance despite the ERα down-regulation; Cry-eIF4A binding possibly dampens this condition. Results indicated the pro-survival eIF4A/STAT/Bcl-xl pathway and that the down-regulation of the MAPK-NF-κB might function as an adaptive mechanism; this response may be compensated by calcium homeostasis in chemoresistance, highlighting new adaptations in HER2+ cells that lead to chemoresistance.

Approximately 80% of breast cancer (BC) cases are estrogen receptor positive (ER+) and sensitive to hormone treatment; Tamoxifen is a prodrug, and its main plasmatic active metabolites are 4-hydroxytamoxifen (4-OH Tam) and endoxifen. Despite the effectiveness of tamoxifen therapy, resistance can be developed. An increment in eukaryotic initiation factor-4A complex (eIF4A) activity can result in tamoxifen-resistant tumor cells. For this work, we developed a cell variant resistant to 4-OH Tam and endoxifen, denominated MCF-7^{Var E}; then, the aim of this research was to reverse the acquired resistance of this variant to tamoxifen metabolites by incorporating the natural compound auraptene. Combination treatments of tamoxifen derivatives and auraptene successfully sensitized the chemoresistant MCF-7^{Var E}. Our data suggest a dual regulation of eIF4A and ER by auraptene. Joint treatments of 4-OH Tam and endoxifen with auraptene identified a novel focus for chemoresistance disruption. Synergy was observed using the auraptene molecule and tamoxifen-derived metabolites, which induced a sensitization in MCF-7^{Var E} cells and ERα parental cells that was not observed in triple-negative breast cancer cells (TNBC). Our results suggest a synergistic effect between auraptene and tamoxifen metabolites in a resistant ER+ breast cancer model, which could represent the first step to achieving a pharmacologic strategy.

Obesity is a multifactorial health condition influenced by genetic predisposition and environmental factors, identified as a condition of persistent, mild systemic inflammation marked by an abnormal buildup of fat tissue, becoming clinical when accompanied by functional impairment of organs. This review explores the role of hyperinsulinemia and hypertriglyceridemia in driving the transition from a preclinical to a clinical state of obesity. Insulin resistance leads to compensatory hyperinsulinemia, impairing glucose homeostasis in skeletal muscle, liver, and adipose tissue. Concurrently, excessive dietary fat intake contributes to elevated triglyceride levels, which promote systemic inflammation and facilitate the onset of endocrine and cardio vascular disorders. Early risk factors, such as childhood obesity, as well as other contributors, including chronic psychological stress, alterations in gut microbiota, sleep disturbances, and vitamin D deficiency, are discussed in the context of their role in disease progression. Critically, the concept of a ‘borderline’ stage is introduced–a transitional phase characterized by elevated triglycerides, insulin resistance, and low-grade chronic inflammation–representing a critical point in the progression toward clinical obesity. Identifying this intermediary stage, even present in other pathologies, offers a valuable window for early interven tion, potentially preventing the establishment of chronic degenerative diseases associated with advanced obesity. Current strategies aimed at controlling hyperinsulinemia and hypertriglyceridemia, including dietary interventions, physical activity, and pharmacological approaches such as GLP-1 receptor agonists and SGLT2 inhibitors, should be considered.