A 2024 Update on Menin Inhibitors. A New Class of Target Agents against KMT2A-Rearranged and NPM1-Mutated Acute Myeloid Leukemia.

Menin inhibitors are new and promising agents currently in clinical development that target the HOX/MEIS1 transcriptional program which is critical for leukemogenesis in histone-lysine N-methyltransferase 2A-rearranged (KMT2Ar) and in NPM1-mutated (NPM1mut) acute leukemias. The mechanism of action of this new class of agents is based on the disruption of the menin-KMT2A complex (consisting of chromatin remodeling proteins), leading to the differentiation and apoptosis of AML cells expressing KMT2A or with mutated NPM1. To date, this new class of drugs has been tested in phase I and II clinical trials, both alone and in combination with synergistic drugs showing promising results in terms of response rates and safety in heavily pre-treated acute leukemia patients. In this brief review, we summarize the key findings on menin inhibitors, focusing on the mechanism of action and preliminary clinical data on the treatment of acute myeloid leukemia with this promising new class of agents, particularly revumenib and ziftomenib.

Directing in Vitro Selection towards G-quadruplex-forming Aptamers to Inhibit HMGB1 Pathological Activity.

In the search for novel, effective inhibitors of High-Mobility Group Box1 (HMGB1)-a protein involved in various inflammatory and autoimmune diseases as well as in cancer-we herein discovered a set of anti-HMGB1 G-quadruplex(G4)-forming aptamers by using an in vitro selection procedure applied to a doped library of guanine-rich oligonucleotides. The selected DNA sequences were then studied in a pseudo-physiological buffer mimicking the extracellular medium, where HMGB1 exerts its pathological activity, using spectroscopic, electrophoretic, and chromatographic techniques. All the oligonucleotides proved to fold into monomeric G4s and in some cases also dimeric species, stable at physiological temperature. Remarkably, the protein preferentially recognized the sequences forming dimeric parallel G4 structures, as evidenced by a properly designed chemiluminescent binding assay which also highlighted a good selectivity of these aptamers for HMGB1. Moreover, all aptamers showed anti-HMGB1 activity, inhibiting protein-induced cell migration. The acquired data allowed identifying L12 as the best anti-HMGB1 aptamer, featured by high thermal and enzymatic stability, no toxicity at least up to 5 µM concentration on healthy cells, along with potent anti-HMGB1 activity (IC50 ca. 28 nM) and good binding affinity for the protein, thus indicating it as a very promising lead candidate for in vivo studies.

STAT3 silencing by an aptamer-based strategy hampers the crosstalk between NSCLC cells and cancer-associated fibroblasts.

The identification of new effective therapeutic options for non-small-cell lung cancer (NSCLC) represents a crucial challenge in oncology. Recent studies indicate that cancer-associated fibroblasts (CAFs) participate in tumor progression by establishing a favorable microenvironment that promotes cancer progression. Therefore, the development of strategies inhibiting the interplay between CAFs and cancer cells is considered a winning approach for the development of effective anti-cancer drugs. Among other factors, the signal transducer and activator of transcription-3 (STAT3) has been reported as a key mediator of CAF oncogenic actions, representing a promising therapeutic target. Here, we applied an aptamer-based conjugate (named Gint4.T-STAT3), containing a STAT3 siRNA linked to an aptamer binding and inhibiting the platelet-derived growth factor receptor (PDGFR)ß, to obtain STAT3-specific silencing and interfere with CAF pro-tumorigenic functions. We demonstrated that this molecule effectively delivers the STAT3 siRNA in NSCLC cells, and blocks CAF-induced cancer cell growth and migration and reduced spheroid dimension. In addition, we found that Gint4.T-STAT3 alters CAF phenotype, thus functioning as a double-acting molecule able to inhibit the entire tumor bulk. Our data provide a proof of principle for the targeting of CAF pro-tumor functions through an aptamer-based drug, and can open innovative horizons in NSCLC therapy.

The Small RNA Landscape in NSCLC: Current Therapeutic Applications and Progresses.

Non-small-cell lung cancer (NSCLC) is the second most diagnosed type of malignancy and the first cause of cancer death worldwide. Despite recent advances, the treatment of choice for NSCLC patients remains to be chemotherapy, often showing very limited effectiveness with the frequent occurrence of drug-resistant phenotype and the lack of selectivity for tumor cells. Therefore, new effective and targeted therapeutics are needed. In this context, short RNA-based therapeutics, including Antisense Oligonucleotides (ASOs), microRNAs (miRNAs), short interfering (siRNA) and aptamers, represent a promising class of molecules. ASOs, miRNAs and siRNAs act by targeting and inhibiting specific mRNAs, thus showing an improved specificity compared to traditional anti-cancer drugs. Nucleic acid aptamers target and inhibit specific cancer-associated proteins, such as "nucleic acid antibodies". Aptamers are also able of receptor-mediated cell internalization, and therefore, they can be used as carriers of secondary agents giving the possibility of producing very highly specific and effective therapeutics. This review provides an overview of the proposed applications of small RNAs for NSCLC treatment, highlighting their advantageous features and recent advancements in the field.

The pattern of expression of Notch protein members in normal and pathological endometrium.

The objective of this study was to investigate the pattern of expression and the localization of Notch-1, Notch-4 and Jagged-1 in physiological and pathological human endometrium and to evaluate the expression levels of two major regulators of the G1 checkpoint, namely cyclin D1 and p21. Sixty samples of physiological endometrium and 60 samples of pathological endometrium were used for the study. Evaluation of the expression level and the distribution of Notch pathway members and cell-cycle proteins was performed by immunohistochemistry. In the physiological endometrium we observed an increase of Notch-1 and Jagged-1 from proliferative to secretory phase and an opposite trend for Notch-4. In menopause, the level of expression of all three members of the Notch pathway decreased. We also observed a cyclin D1 increase from proliferative to secretory phase. By contrast, p21 showed a slight increase from proliferative to secretory phase. In the pathological endometrium, we observed an increase of Notch-1 expression from polyps to carcinoma and decrease for Notch-4 and Jagged-1. Moreover, we observed a higher expression of cyclin D1 in all the endometrial pathologies. By contrast, the expression level of p21 slightly increased from polyps to carcinoma. We concluded that in human endometrium Notch-4 seems to be more involved in controlling proliferation, whereas Notch-1 seems to be more involved in differentiation programming. Deregulation of these functions may induce the onset of several endometrial pathologies from polyps to cancer.

Modulation of Bax expression in physiological and pathological human placentas throughout pregnancy.

Apoptosis is intimately involved in placental homeostasis, growth and remodelling, and apoptotic rates increase progressively during normal pregnancy as part of normal placental development. Moreover, apoptosis increases in pregnancies complicated by some pathologies such as preeclampsia, fetal growth restriction and diabetes. In the present study, we describe differences in the expression of proapoptotic protein Bax, in first trimester voluntary termination of pregnancy, first trimester abortion (reserved abortion), caesarean birth, spontaneous birth, preeclampsia and diabetes. We first observed a strong increase of Bax expression in the cytotrophoblast, stroma, endothelial cells and decidua of placentas of the first trimester abortion compared to the low/moderate Bax immunopositivity in all the placental compartments during the first trimester voluntary termination of pregnancy. Secondly, we showed a more intense immunopositivity for Bax in the third trimester spontaneous birth with respect to the third trimester caesarean birth. Thirdly, we observed an increase of Bax expression in preeclamptic placentas compared to the normal full-term placentas. In contrast, we observed a moderate Bax expression in diabetic placentas only slightly lower than the normal full-term placentas. Our results seem to suggest that deregulation of apoptotic turnover may lead to placental dysfunction and pathologies.

Down-regulation of aquaporin 4 in human placenta throughout pregnancy.

BACKGROUND: The family of mammalian aquaporins (AQP) consists of 12 known members, each with a specific tissue distribution and membrane localization pattern. AQP4 is the first member of this family identified in biological membranes. This water channel protein is primarily expressed in astrocytes but is also localized in ependymocytes and endothelial cells, suggesting its involvement in the movement of water between the blood and brain, and between the brain and cerebrospinal fluid (CSF). To date, the regulation of AQP4 expression in the human placenta has not been studied. The purpose of this work was to investigate AQP4 localization and expression in the human placenta during gestation. MATERIALS AND METHODS: A total of 30 samples, 15 full-term placentae and 15 chorionic villous samples from first trimester, for the immunohistochemical analysis of AQP4 expression were used. The gestation period ranged from 5 to 40 weeks. RESULTS: A decrease of AQP4 expression in the syncytiotiophoblast from the first to the third trimester of gestation, in contrast with an increased expression shown by endothelial cells and stroma of placental villi was found. CONCLUSION: Our results may suggest that AQP4-mediated maternal-fetal fluid exchange could play an important role in the control of ion homeostasis and water balance in the human placenta throughout pregnancy.

Distribution of Notch protein members in normal and preeclampsia-complicated placentas.

Notch proteins are a transmembrane receptor family that is structurally and functionally conserved from worms to humans. The mammalian family of Notch proteins consists of several genes encoding Notch receptors and related Notch ligands. Notch signaling is involved in different aspects of the cell-fate decision tree: differentiation, proliferation, and apoptosis. These three processes are finely regulated in human placenta in order to allow a successful pregnancy and correct fetal growth. Notch and its ligands also participate in vascular remodeling and stabilization. Vasculogenesis and blood regulation are of importance in the human placenta for normal fetal development and growth; any disorder of these systems leads to preeclampsia. Drawing on this background, we have investigated the expression of Notch-1, Notch-4, and Jagged-1, together with two members related to the Notch pathway in angiogenesis: VEGF and p21. Normal and preeclamptic human placentas have been evaluated by immunohistochemistry. In preeclamptic samples, a down-regulation of Notch pathway members occurs with a weak/moderate expression of the Notch protein members in all components of placenta compared with physiological placentas that, at term, exhibit the strong expression of Jagged-1 and a moderate expression of both Notch-1 and Notch-4 in all compartments of the placental villi. Moreover, preeclamptic samples also reveal a down-regulation of VEGF expression, together with a moderate nuclear expression of p21(Cip1) in the syncytiotrophoblast, cytotrophoblast, and endothelial cells. This down-regulation of VEGF in preeclamptic placentas, in turn, probably decreases Notch protein expression in placental compartments and in endothelial cells and could offer an ethiopathogenetic explanation for the onset of this pathology.