Nucleophosmin (NPM1) is a mainly nucleolar protein that shuttles between nucleoli, nucleoplasm and cytoplasm to fulfill its many functions. It is a chaperone of both nucleic acids and proteins and plays a role in cell cycle control, centrosome duplication, ribosome maturation and export, as well as the cellular response to a variety of stress stimuli. NPM1 is a hub protein in nucleoli where it contributes to nucleolar organization through heterotypic and homotypic interactions. Furthermore, several alterations, including overexpression, chromosomal translocations and mutations are present in solid and hematological cancers. Recently, novel germline mutations that cause dyskeratosis congenita have also been described. This review focuses on NPM1 interactions and inhibition. Indeed, the list of NPM1 binding partners is ever-growing and, in recent years, many studies contributed to clarifying the structural basis for NPM1 recognition of both nucleic acids and several proteins. Intriguingly, a number of natural and synthetic ligands that interfere with NPM1 interactions have also been reported. The possible role of NPM1 inhibitors in the treatment of multiple cancers and other pathologies is emerging as a new therapeutic strategy.

KDEL receptors (KDELRs) are ubiquitous seven-transmembrane domain proteins encoded by three mammalian genes. They bind to and retro-transport endoplasmic reticulum (ER)-resident proteins with a C-terminal Lys-Asp-Glu-Leu (KDEL) sequence or variants thereof. In doing this, KDELR participates in the ER quality control of newly synthesized proteins and the unfolded protein response. The binding of KDEL proteins to KDELR initiates signaling cascades involving three alpha subunits of heterotrimeric G proteins, Src family kinases, protein kinases A (PKAs), and mitogen-activated protein kinases (MAPKs). These signaling pathways coordinate membrane trafficking flows between secretory compartments and control the degradation of the extracellular matrix (ECM), an important step in cancer progression. Considering the basic cellular functions performed by KDELRs, their association with various diseases is not surprising. KDELR mutants unable to bind the collagen-specific chaperon heat-shock protein 47 (HSP47) cause the osteogenesis imperfecta. Moreover, the overexpression of KDELRs appears to be linked to neurodegenerative diseases that share pathological ER-stress and activation of the unfolded protein response (UPR). Even immune function requires a functional KDELR1, as its mutants reduce the number of T lymphocytes and impair antiviral immunity. Several studies have also brought to light the exploitation of the shuttle activity of KDELR during the intoxication and maturation/exit of viral particles. Based on the above, KDELRs can be considered potential targets for the development of novel therapeutic strategies for a variety of diseases involving proteostasis disruption, cancer progression, and infectious disease. However, no drugs targeting KDELR functions are available to date; rather, KDELR has been leveraged to deliver drugs efficiently into cells or improve antigen presentation.

Objective: Cold atmospheric plasma (CAP) is a novel approach for cancer treatment. It can be used to treat liquids—plasma‐activated media (PAM)—which are then transferred to the target as an exogenous source of reactive oxygen and nitrogen species (RONS). The present study aimed at chemically characterizing different PAM and assessing their in vitro selectivity against head and neck cancer cells (HNC).Methods: PAM were obtained by exposing 2 and 5 mL of cell culture medium to CAP for 5, 10 and 20 min at a 6 mm working distance. Anions kinetics was evaluated by ion chromatography. Cell proliferation inhibition, apoptosis occurrence, and cell cycle modifications were assessed by MTS and flow cytometry, on human epidermal keratinocyte (HaCaT) and HNC cell lines HSC3, HSC4 and A253.Results: The 2 mL conditions showed a significant reduction in cell proliferation whereas for the 5 mL the effect was milder, but the time‐dependence was more evident. HaCaT were unaffected by the 5 mL PAM, indicating a selectivity for cancer cells.Conclusions: The media chemical composition modified by CAP exposure influenced cell proliferation by modulating cell cycle and inducing apoptosis in cancer cells, without affecting normal cells.

Objective: The aim of the present study was to evaluate the expression of intracellular and vesicular LGALS3BP in oral squamous cell carcinoma (OSCC) patients and available cell lines to explore its potential as a target for antibody‐drug conjugate (ADC) therapy.Methods: Free and vesicular LGALS3BP expression levels were evaluated in cancer tissues from a cohort of OSCC patients as well as in a panel of OSCC cell lines through immunohistochemistry, qRT‐PCR, Western Blot analysis, and ELISA.Results: LGALS3BP resulted in being highly expressed in the cytoplasm of tumour cells in OSCC patient tissues. A strong correlation was found between high LGALS3BP expression levels and aggressive histological features of OSCC. Biochemistry analysis performed on OSCC cell lines showed that LGALS3BP is expressed in all the tested cell lines and highly enriched in cancer‐derived extracellular vesicles. Moreover, LGALS3BP high‐expressing HOC621 and CAL27 OSCC cell lines showed high sensitivity to the ADC‐payload DM4, with an IC₅₀ around 0.3 nM.Conclusions: The present study highlights that LGALS3BP is highly expressed in OSCC suggesting a role as a potential diagnostic biomarker and therapeutic target for ADC‐based therapy.

Survival rate of head and neck squamous cell carcinomas (HNSCC) patients are still to date very poor, and the application of innovative clinical approaches are urgently needed. Cold atmospheric plasmas (CAPs) are partially ionized gases that have shown anti-tumor effectiveness over a wide range of cancer types with potential application into clinics. However, the comprehension of the mechanisms underlying indirect CAP effects plays a key role for the prediction of treatment outcomes. In our work, we assessed the potential application of indirect CAP, by using plasma activated media (PAM) and plasma-treated liquids (PTL), as therapeutic strategies for HNSCC treatment. The impact of PAM obtained from exposure to CAP for different times was evaluated in three head and neck cancer (HNC) cell lines (HSC3, FaDu, CAL-27). Cytotoxic effects as inhibition of proliferation, apoptosis rate and cell cycle modifications were tested for the different PAM, showing a time- and cell culture media-dependence tightly related to the chemical composition of PAM considered. In addition, cytotoxic effects were also observed on HNC, two bladder cancer models and one breast cancer cell line when considering PTL, paving the way for their application into a clinical setting.

Nucleostemin (NS; a product of the GNL3 gene) is a nucleolar–nucleoplasm shuttling GTPase whose levels are high in stem cells and rapidly decrease upon differentiation. NS levels are also high in several solid and hematological neoplasms, including acute myeloid leukaemia (AML). While a role in telomere maintenance, response to stress stimuli and favoring DNA repair has been proposed in solid cancers, little or no information is available as to the role of nucleostemin in AML. Here, we investigate this issue via a proteomics approach. We use as a model system the OCI-AML 3 cell line harboring a heterozygous mutation at the NPM1 gene, which is the most frequent driver mutation in AML (approximately 30% of total AML cases). We show that NS is highly expressed in this cell line, and, contrary to what has previously been shown in other cancers, that its presence is dispensable for cell growth and viability. However, proteomics analysis of the OCI-AML 3 cell line before and after nucleostemin (NS) silencing showed several effects on different biological functions, as highlighted by ingenuity pathway analysis (IPA). In particular, we report an effect of down-regulating DNA repair through homologous recombination, and we confirmed a higher DNA damage rate in OCI-AML 3 cells when NS is depleted, which considerably increases upon stress induced by the topoisomerase II inhibitor etoposide. The data used are available via ProteomeXchange with the identifier PXD034012.