The integration of small interfering RNA (siRNA) with traditional cancer therapies represents a promising frontier in oncology aimed at enhancing treatment effectiveness, reducing side effects, and overcoming drug resistance. This review highlights the potential of siRNA to selectively silence genes that are overexpressed or uniquely expressed in cancer cells, thereby disrupting critical pathways that support tumor growth and survival. Key target genes discussed include survivin, VEGF, EGFR, c-MET, HER2, MUC1, and Bcl-2, all of which play vital roles in tumor proliferation, angiogenesis, and resistance to therapies. Clinical trials investigating various siRNA candidates, such as EZN-3042 and ALN-VSP, indicate that these therapies are generally well-tolerated; however, significant challenges persist, including the effective delivery and stability of siRNA. Recent advancements in nanoparticle-based delivery systems have shown promise in addressing these issues. Future research will focus on optimizing siRNA delivery methods, personalizing therapies based on individual genetic profiles, and establishing clearer regulatory guidelines for approval. As the field evolves, siRNA-based combination therapies are poised to become an integral part of precision oncology, offering new therapeutic options and hope for patients with difficult-to-treat cancers.

MicroRNAs (miRNAs) are small non-coding RNAs that mainly act by binding to target genes to regulate their expression. Due to the multitude of genes regulated by miRNAs they have been subject of extensive research in the past few years. This state-of-the-art review summarizes the current knowledge about miRNAs and illustrates their role as powerful regulators of physiological processes. Moreover, it highlights their aberrant expression in disease, including specific cancer types and the differential hosting-metastases preferences that influence several steps of tumorigenesis. Considering the incidence of breast cancer and that the metastatic disease is presently the major cause of death in women, emphasis is put in the role of miRNAs in breast cancer and in the regulation of the different steps of the metastatic cascade. Furthermore, we depict their involvement in the cascade of events underlying breast cancer brain metastasis formation and development. Collectively, this review shall contribute to a better understanding of the uniqueness of the biologic roles of miRNAs in these processes, to the awareness of miRNAs as new and reliable biomarkers and/or of therapeutic targets, which can change the landscape of a poor prognosis and low survival rates condition of advanced breast cancer patients.

With breast cancer (BC) therapy improvements, the appearance of brain metastases has been increasing, representing a life-threatening condition. Brain metastasis formation involves BC cell (BCC) extravasation across the blood–brain barrier (BBB) and brain colonization by unclear mechanisms. We aimed to disclose the actors involved in BC brain metastasis formation, focusing on BCCs’ phenotype, growth factor expression, and signaling pathway activation, correlating with BBB alterations and intercellular communication. Hippocampi of female mice inoculated with 4T1 BCCs were examined over time by hematoxylin-eosin, immunohistochemistry and immunofluorescence. Well-established metastases were observed at seven days, increasing thereafter. BCCs entering brain parenchyma presented mesenchymal, migratory, and proliferative features; however, with time, they increasingly expressed epithelial markers, reflecting a mesenchymal–epithelial transition. BCCs also expressed platelet-derived growth factor-B, β₄ integrin, and focal adhesion kinase, suggesting autocrine and/or paracrine regulation with adhesion signaling activation, while balance between Rac1 and RhoA was associated with the motility status. Intercellular communication via gap junctions was clear among BCCs, and between BCCs and endothelial cells. Thrombin accumulation, junctional protein impairment, and vesicular proteins increase reflect BBB alterations related with extravasation. Expression of plasmalemma vesicle-associated protein was increased in BCCs, along with augmented vascularization, whereas pericyte contraction indicated mural cells’ activation. Our results provide further understanding of BC brain metastasis formation, disclosing potential therapeutic targets.

The high incidence and modest therapeutic outcomes of lung cancer have prompted the identification of cell molecular targets/biomarkers within the complex networks of interactions involved in cell malignancy. Most of the EMT-related regulatory mediators underline patients’ biologic variations, therapeutic refractory events, and tumor cell heterogeneity. Patient stratification based on the understanding of the relevant pathways, such as the PI3K/Akt axis crucial in EMT initiation, could favorably alter disease management. Significant clinical advantage could be expected when overexpressed Akt tyrosine kinase (Akt2) is addressed as a malignant biomarker to guide clinical management decisions, improving prognosis in lung cancer patients. Moreover, one should not miss the opportunity of using it as a druggable target aiming at the inhibition of the downstream complexity that underlies cell proliferation and survival, expression of stemness markers and drug resistance. The value of mTOR, as a downstream target of Akt, and the further activation of EMT transcription factors Twist, Snail and Zeb1 are revisited in this review. An in-depth state-of-the-art assessment provides evidence of its role in the mechanistic inhibition of epithelial markers, such as E-cadherin and miR-200, while inducing the expression of the mesenchymal ones, such as vimentin, N-cadherin, and miR-21. Lastly, evidence suggesting another transcription factor, FOXM1, as the link between the PI3K/Akt and Wnt/β-catenin pathways, prompting cell metabolism through the regulation of p70S6K, is analyzed. A more realistic approach is advised to address unmet clinical needs and support decision making at a clinical level. Taking into consideration several complex intracellular interactions might further improve patient stratification and result in better outcomes.

Hypericum foliosum Aiton is an endemic Azorean Hypericum species. Even though the aerial parts of Hypericum foliosum are not described in any official pharmacopoeia, they are utilized in local traditional medicine due to their diuretic, hepatoprotective, and antihypertensive properties. This plant has previously been the subject of phytochemical characterization and has been studied for its antidepressant activity, showing significant results in animal models. The lack of a description of the main characteristics of the aerial parts, which would be necessary to properly identify this medicinal plant species, contributes to the possibility of misidentification events. We performed macroscopic and microscopic analyses that identified specific differential characteristics, such as the absence of dark glands, the dimensions of the secretory pockets in the leaf, and the presence of translucent glands in the powder. To continue our previous work on the biological activity of Hypericum foliosum, ethanol, dichloromethane/ethanol, and water extracts were prepared and studied for their antioxidant and cytotoxic activity. Extracts showed in vitro selective cytotoxic activity in human lung cancer cell line A549, colon cancer cell line HCT 8, and breast cancer cell line MDA-MB-231, with dichloromethane/ethanol showing higher activity against all cell lines (IC₅₀ values of 71.49, 27.31, and 9.51 µg/mL, respectively). All extracts also showed significant antioxidant activity.