Letizia Polito

The second edition of the “Women’s Special Issue Series: Biomedicines” brings together a series of articles that reflect both the scientific excellence of women researchers and the growing complexity of contemporary biomedical research

Background/Objectives: Ribosome-inactivating proteins (RIPs) are plant-derived enzymes with potent cytotoxic activity, widely studied as anticancer agents, particularly as toxic payloads in immunoconjugates. Despite numerous encouraging results reported, their clinical application has been limited by their immunogenicity. RIPs from edible plants have been proposed as potentially more suitable candidates due to their possible improved tolerability. However, this aspect still requires validation in vivo in animal models. This study investigated the cytotoxic activity, mechanisms of action and translational potential of sodin 5 (a recently characterized type 1 RIP derived from the edible plant Salsola soda L.) in human colon cancer models, comparing it to the well-known type 1 RIP saporin-S6. Methods: The effects of sodin 5 and saporin-S6 on cell viability, cell death mechanisms and epithelial barrier integrity were assessed on HT29 and Caco-2 cell lines. Sodin 5 cross-reactivity with other anti-type 1 RIP sera was evaluated by ELISA. Finally, its structural characteristics were analyzed. Results: Sodin 5 showed a cytotoxic effect comparable to that of saporin-S6 in HT29 and Caco-2 colon cancer cells, with time- and concentration-dependent reductions in viability. Both type 1 RIPs disrupted the integrity of the intestinal epithelial barrier in mono- and co-culture models and predominantly activated the apoptotic pathway, without inducing necrosis. Sodin 5 exhibited limited immunological cross-reactivity and a conserved catalytic core, supporting its potential relevance as a therapeutic payload for intestinal cancer therapy. Conclusions: Our results indicate that sodin 5 possesses promising characteristics for anticancer applications, particularly in the treatment of intestinal malignancies, where local exposure and repeated administration are often required.

Porcini ( Boletus edulis Bull.) are a reservoir of pharmacological biomolecules with health‐promoting properties. Here, we investigated the cytotoxic activity of edulitin 2, a ribotoxin‐like protein purified from B. edulis fruiting bodies, against two human colon cancer cell lines (Caco‐2 and HT29), and assessed its potential impact on gut microbiota. Edulitin 2 exhibited marked cytotoxicity toward both cell lines in a dose‐ and time‐dependent manner. The effect was particularly evident after 72‐h, with EC ₅₀ values in the 10 ^{− 7} M range for both cell lines. Moreover, edulitin 2 significantly affected barrier integrity in Caco‐2 monolayer models. Edulitin 2 kills cells mainly by triggering apoptotic mechanisms, with limited involvement of necroptosis and absence of necrosis. These results support edulitin 2 as a potential therapeutic agent due to the reduced risk of inducing inflammation‐related damage. Furthermore, this toxin proved to be harmless to microbial consortia simulating the gut microbiota. Overall, these findings make edulitin 2 a promising bioactive compound that combines cytotoxicity toward colorectal tumor cells with microbiota compatibility. This dual profile supports its further exploration in preclinical models (for loco‐regional treatment and as payload of immunotoxins) and highlights the potential of edible mushrooms as a source of novel ribotoxin‐like proteins with biomedical relevance.

Background/Objectives: Momordica charantia L. (Cucurbitaceae) (MC), commonly known as bitter melon, is a prominent therapeutic and edible species deeply rooted in traditional medicine for the management of diverse metabolic and infectious pathologies. Increasing evidence suggests that MC is a significant source of antiviral compounds that could act against many different types of viruses in humans. This narrative review summarizes the current knowledge regarding the antiviral properties of MC, with a focus on molecular mechanisms and therapeutic perspectives. Methods: A comprehensive literature search was conducted across the PubMed, Scopus and Web of Science databases, using the keywords “Momordica charantia”, “bitter melon”, “antiviral” and “MAP30”. Original in vitro, in vivo, in silico and mechanistic studies were included. Results: MC harbors diverse antiviral molecules acting through conserved and virus-specific mechanisms. Ribosome-inactivating proteins (RIPs) purified from MC display potent antiviral activity by catalyzing the depurination of viral RNA and DNA, inactivating host ribosomes and blocking protein synthesis. RIPs, especially MAP30, are among the most potent natural antiviral proteins described to date. Cucurbitane-type triterpenoids and other phytochemicals from MC also show antiviral activity. Conclusions: MC emerges as a promising candidate for the prevention/treatment of viral diseases through nutraceutical, topical and pharmaceutical applications. MC extracts could represent a resource to support the immune system and provide broad-spectrum benefits against viral infections or a tool for local treatments. Moreover, MC is a valuable source of various bioactive compounds that, after thorough pharmacological characterization, could be further developed into specific antiviral agents.

Following the invitation from Biomedicines, we launched a second edition of the Special Issue “Advances in Cancer Biology and Experimental Anticancer Therapies”, as we believe it is truly important to continue focusing on advances in cancer biology and experimental antitumor therapies

Indicitin is an atypical ribosome-targeting enzyme isolated from the edible mushroom Calocybe indica , structurally classified as thaumatin-like protein. This toxin has low toxicity toward several cell types and is non-harmful to the gut microbiota.

Ricin, a type 2 ribosome-inactivating protein, is a lethal toxin found in castor bean seeds. Although the systemic toxicity of ricin has been extensively studied, its localized effect on the gastrointestinal tract remains a critical concern, particularly in the case of oral ingestion. This study investigates the cytotoxic effects of ricin on human intestinal epithelial cell lines and its impact on epithelial barrier integrity. Ricin cytotoxicity was assessed on the intestinal-derived HT29 and Caco-2 cell lines using dose– and time–response assays, while the epithelial integrity was evaluated via Trans-Epithelial Electrical Resistance (TEER) measurements in Caco-2 monolayers. Cell death was determined through flow cytometry analysis, and the protective effects of cell death inhibitors and antioxidant scavengers were investigated on ricin-intoxicated cells. Ricin showed high cytotoxicity on HT29 and Caco-2 cells, with EC₅₀ values in the nM range after 24–72 h of intoxication. Moreover, ricin strongly reduced TEER values in Caco-2 cells at 0.1–1 nM after 24 h of treatment. At a 1 nM concentration, ricin cytotoxicity can be significantly prevented by pre-incubating cells with the cell death inhibitors Z-VAD or necrostatin-1 and the antioxidant scavenger catalase, butylated hydroxyanisole or sodium pyruvate, demonstrating the involvement of apoptosis/necroptosis and oxidative stress in ricin cell death pathways and mechanisms.

Sarcomas are very complex and clinically challenging mesenchymal tumors. Although the standard therapeutic approach has improved the 5-year survival rate, many patients experience local relapses and/or distant metastases. To improve patient outcome, new strategies need to be investigated. Immunotoxins (ITs) based on rRNA N-glycosylases (also named ribosome-inactivating proteins, RIPs) are promising tools for cancer therapy because, by combining rRNA-glycosylase’s high cytotoxicity with carrier selectivity, they can specifically eliminate target neoplastic cells. In the last few years, 3D models have been extensively used in cancer research, particularly for target-specific drug screening. This study aimed to evaluate the possibility of utilizing ribosome-inactivating protein (RIP)-containing ITs to selectively target TfR1-, EGFR1- and Her2-expressing sarcoma adherent cells (ACs), spheroids (SSs) and organoids (ORs). To compare Its’ efficacy and ability to induce apoptosis, we performed dose–response viability and caspase 3/7 activation assays on rhabdomyosarcoma and osteosarcoma ACs, SSs and ORs treated with Tf-IT, αEGFR1-IT and αHer2-IT. Our results indicate that, compared to the corresponding unconjugated RIPs, all ITs showed increased cytotoxicity in sarcoma ACs. Despite the increased complexity characterizing 3D models, the higher IC₅₀ differences between ITs and unconjugated RIPs were obtained in ORs, which appeared more resistant to the nonspecific killing of the RIPs than either the ACs or SSs, thus augmenting the therapeutic window between unconjugated and conjugated RIPs. IT induced a more delayed apoptosis in 3D compared to 2D models. Our results provide essential outcomes for the potential use of these RIP-based ITs as a therapeutic strategy to treat sarcoma.

Non-communicable neurological disorders are the second leading cause of death, and their burden continues to increase as the world population grows and ages. Oxidative stress and inflammation are crucially implicated in the triggering and progression of multiple sclerosis, Alzheimer’s disease, amyotrophic lateral sclerosis, Huntington’s disease, Parkinson’s disease, and even stroke. In this narrative review, we examine the role of xanthine oxidoreductase (XOR) activities and products in all the above-cited neurological diseases. The redox imbalance responsible for oxidative stress could arise from excess reactive oxygen and nitrogen species resulting from the activities of XOR, as well as from the deficiency of its main product, uric acid (UA), which is the pivotal antioxidant system in the blood. In fact, with the exception of stroke, serum UA levels are inversely related to the onset and progression of these neurological disorders. The inverse correlation observed between the level of uricemia and the presence of neurological diseases suggests a neuroprotective role for UA. Oxidative stress and inflammation are also caused by ischemia and reperfusion, a condition in which XOR action has been recognized as a contributing factor to tissue damage. The findings reported in this review could be useful for addressing clinical decision-making and treatment optimization.