P27 Kip1 Protein Research Articles

P57Kip2 Phosphorylation Modulates Its Localization, Stability, and Interactions.

p57Kip2 is a member of the cyclin-dependent kinase (CDK) Interacting Protein/Kinase Inhibitory Protein (CIP/Kip) family that also includes p21Cip1/WAF1 and p27Kip1. Different from its siblings, few data are available about the p57Kip2 protein, especially in humans. Structurally, p57Kip2 is an intrinsically unstructured protein, a characteristic that confers functional flexibility with multiple transient interactions influencing the metabolism and roles of the protein. Being an IUP, its localization, stability, and binding to functional partners might be strongly modulated by post-translational modifications, especially phosphorylation. In this work, we investigated by two-dimensional analysis the phosphorylation pattern of p57Kip2 in different cellular models, revealing how the human protein appears to be extensively phosphorylated, compared to p21Cip1/WAF1 and p27Kip1. We further observed clear differences in the phosphoisoforms distributed in the cytosolic and nuclear compartments in asynchronous and synchronized cells. Particularly, the unmodified form is detectable only in the nucleus, while the more acidic forms are present in the cytoplasm. Most importantly, we found that the phosphorylation state of p57Kip2 influences the binding with some p57Kip2 partners, such as CDKs, LIMK1 and CRM1. Thus, it is necessary to completely identify the phosphorylated residues of the protein to fully unravel the roles of this CIP/Kip protein, which are still partially identified.

Enhancing Clinicopathological Diagnosis of Hydatidiform Mole Through the Combined Application of Histomorphologic Analysis, Immunohistochemical Analysis of p57 Expression, and Short Tandem Repeat Typing Method

This study aims to assess the early histomorphologic characteristics and investigate the role of the p57kip2 protein combined with STR genotyping for pathological diagnosis and typing of the hydatidiform mole (HM). A total of 73 induced abortion tissues were collected for pathological evaluation, including 14 cases with partial HM (PHM), 7 cases with complete HM (CHM), and 52 cases with non-molar pregnancies. Histopathological examination of moles was conducted using hematoxylin and eosin staining. DNA extraction from paraffin sections was performed using Fe3O4 nano-magnetic beads. Molecular diagnosis was performed using STR genotyping. Immunohistochemical analysis was used to determine the distribution and expression level of p57kip2 protein in HM. Significant differences were observed in the morphological indices of villous edema, cistern formation, trophoblastic inclusions, and trophoblastic hyperplasia between the PHM and CHM groups (P < 0.05). The central cistern formation and the trophoblast inclusion showed a significant difference between the HM and non-molar pregnancy (P < 0.05). Moreover, our findings revealed that p57kip2 expression contributed to distinguishing CHM from PHM. However, it could not distinguish PHM from non-mole pregnancy. Furthermore, the results of STR genotyping were consistent with pathological typing. In conclusion, the integration of pathomorphology, immunohistochemical staining, and molecular diagnostics holds great value for the diagnosis and classification of HM.

3D-printed biosensors in biomedical applications exploiting plasmonic phenomena and antibody self-assembled monolayers.

In this work, a 3D-printed plasmonic chip based on a silver-gold bilayer was developed in order to enhance the optical response of the surface plasmon resonance (SPR) probe. More specifically, numerical and experimental results were obtained on the 3D-printed SPR platform based on a silver-gold bilayer. Then, the optimized probe's gold plasmonic interface was functionalized with a specific antibody directed against the p27Kip1 protein (p27), an important cell cycle regulator. The 3D-printed plasmonic biosensor was tested for p27 detection with good selectivity and a detection limit of 55 pM. The biosensor system demonstrated performance similar to commercially available ELISA (enzyme-linked immunoassay) kits, with several advantages, such as a wide detection range and a modular and simple-based architecture. The proposed biosensing technology offers flexible deployment options that are useful in disposable, low-cost, small-size, and simple-to-use biochips, envisaging future applications in experimental and biomedical research.

Abstract B018: Triple CDK2/4/6 inhibition via p27 modulation: A novel approach to targeting cell cycle dysregulation

Abstract The dysregulation of cell cycle control is a hallmark of cancer and targeting cyclin-dependent kinases (CDKs) has emerged as a promising strategy in advanced breast cancer. The G1 CDKs are the recipients of the oncogenic signals that travel from the cell surface to the nucleus, and as such, selective inhibition of CDK2, CDK4 and CDK6 has been a goal in oncology for several decades. We present a novel approach involving modulation of the CDK interacting protein p27Kip1, to simultaneously inhibit CDK2/4/6. p27 is responsible for turning the G1 CDKs ON and OFF during periods of proliferation and quiescence, respectively, and this transition is mediated by a specific modification to p27 itself, by the tyrosine kinase BRK (Breast tumor Related Kinase). A naturally occurring ALTernatively spliced form of BRK, named ALT, can bind to p27, blocking BRK's association with and phosphorylation of p27. The binding of ALT to p27 locks both CDK4/6 and CDK2 into the OFF conformation, inhibiting activity of both kinases. p27’s association with CDK2 also prevents p27’s degradation. In in vitro kinase assays, inducible ALT expression in ER+ breast cancer cells, inhibited CDK4/6 and CDK2 activities simultaneously, resulting in durable growth arrest. As p27 associates preferentially with the G1 CDKs, the specificity of ALT for these kinases is achieved by p27 itself, thus avoiding off-target kinase interactions with the rest of the CDK kinome. We engineered IpY.20, a smaller, more stable variant of ALT, formulated within a liposome to increase its serum residence time and facilitate delivery into tumor cells. IpY.20 inhibits cell proliferation of HR+ and triple negative (TN) breast cancer, ovarian, uterine and NSCLC, preferentially over non-tumor cells, supporting its clinical utility. Unlike CDK4/6i and CDK2i which only cause cytostasis, IpY.20 arrests proliferation and induces cell death, demonstrating that p27 inhibition is a viable therapeutic approach to combat CDK4/6i-dependent drug resistance. In vivo, IpY.20 reduces tumor volume in palbociclib-resistant ER+ xenografts, TN xenografts and the MMTV-ErbB2 spontaneous breast cancer model. IpY.20 does not cause the adverse effects seen in the presence of CDK4/6i or CDK2i: IpY.20 does not cause neutropenia, and in combination with palbociclib, IpY.20 rescues the CDK4/6i-dependent decrease in neutrophils, suggesting better tolerability in patients. IpY.20 is detected in tumors within 15 min. of single dose I.V. administration and continues to be detectable for 24 h. IpY.20 is currently completing CMC process optimization, batch-to-batch consistency, and stability as it moves into the IND program. These findings underscore the significance of targeting CDK2, CDK4, and CDK6 simultaneously via p27 modulation as a potential therapy. Given the difficulties in inhibiting the CDK2/4/6 hub with small molecule CDKi (off-target kinase selectivity, adverse effects, lack of tumor cell killing), targeting p27 may provide advantages to the post-CDK4/6i setting. Citation Format: Grace Chen, Natalia Zisman, Krishna Allamneni, Stacy W Blain. Triple CDK2/4/6 inhibition via p27 modulation: A novel approach to targeting cell cycle dysregulation [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B018.

Identification of a Panel of miRNAs Associated with Resistance to Palbociclib and Endocrine Therapy.

We investigated whether we could identify a panel of miRNAs associated with response to treatment in tumor tissues of patients with Hormone Receptor-positive/HER2-negative metastatic breast cancer treated with endocrine therapy (ET) and the CDK4/6 inhibitor (CDK4/6i)i palbociclib. In total, 52 patients were evaluated, with 41 receiving treatment as the first line. The overall median PFS was 20.8 months (range 2.5-66.6). In total, 23% of patients experienced early progression (<6 months). Seven miRNAs (miR-378e, miR-1233, miR-99b-5p, miR-1260b, miR-448, -miR-1252-5p, miR-324-3p, miR-1233-3p) showed a statistically significant negative association with PFS. When we considered PFS < 6 months, miR-378e, miR-99b-5p, miR-877-5p, miR-1297, miR-455-5p, and miR-4536-5p were statistically associated with a poor outcome. In the multivariate analysis, the first three miRNAs confirmed a significant and independent impact on PFS. The literature data and bioinformatic tools provide an underlying molecular rationale for most of these miRNAs, mainly involving the PI3K/AKT/mTOR pathway and cell-cycle machinery as cyclin D1, CDKN1B, and protein p27Kip1 and autophagy. Our findings propose a novel panel of miRNAs associated with a higher likelihood of early progression in patients treated with ET and Palbociclib and may contribute to shed some light on the mechanisms of de novo resistance to CDK4/6i, but this should be considered exploratory and evaluated in larger cohorts.

Elucidating Differences in Early-Stage Centrosome Amplification in Primary and Immortalized Mouse Cells.

The centrosome is involved in cytoplasmic microtubule organization during interphase and in mitotic spindle assembly during cell division. Centrosome amplification (abnormal proliferation of centrosome number) has been observed in several types of cancer and in precancerous conditions. Therefore, it is important to elucidate the mechanism of centrosome amplification in order to understand the early stage of carcinogenesis. Primary cells could be used to better understand the early stage of carcinogenesis rather than immortalized cells, which tend to have various genetic and epigenetic changes. Previously, we demonstrated that a poly(ADP-ribose) polymerase (PARP) inhibitor, 3-aminobenzamide (3AB), which is known to be nontoxic and nonmutagenic, could induce centrosome amplification and chromosomal aneuploidy in CHO-K1 cells. In this study, we compared primary mouse embryonic fibroblasts (MEF) and immortalized MEF using 3AB. Although centrosome amplification was induced with 3AB treatment in immortalized MEF, a more potent PARP inhibitor, AG14361, was required for primary MEF. However, after centrosome amplification, neither 3AB in immortalized MEF nor AG14361 in primary MEF caused chromosomal aneuploidy, suggesting that further genetic and/or epigenetic change(s) are required to exhibit aneuploidy. The DNA-damaging agents doxorubicin and γ-irradiation can cause cancer and centrosome amplification in experimental animals. Although doxorubicin and γ-irradiation induced centrosome amplification and led to decreased p27Kip protein levels in immortalized MEF and primary MEF, the phosphorylation ratio of nucleophosmin (Thr199) increased in immortalized MEF, whereas it decreased in primary MEF. These results suggest that there exists a yet unidentified pathway, different from the nucleophosmin phosphorylation pathway, which can cause centrosome amplification in primary MEF.

Low CDKN1B Expression Associated with Reduced CD8+ T Lymphocytes Predicts Poor Outcome in Breast Cancer in a Machine Learning Analysis.

The cyclin-dependent kinase inhibitor 1B (CDKN1B) gene, which encodes the p27Kip1 protein, is important in regulating the cell cycle process and cell proliferation. Its role in breast cancer prognosis is controversial. We evaluated the significance and predictive role of CDKN1B expression in breast cancer prognosis. We investigated the clinicopathologic factors, survival rates, immune cells, gene sets, and prognostic models according to CDKN1B expression in 3794 breast cancer patients. We performed gene set enrichment analysis (GSEA), in silico cytometry, pathway network analyses, gradient boosting machine (GBM) learning, and in vitro drug screening. High CDKN1B expression levels in breast cancer correlated with high lymphocyte infiltration signature scores and increased CD8+ T cells, both of which were associated with improved prognosis in breast cancer. which were associated with a better prognosis. CDKN1B expression was associated with gene sets for the upregulation of T-cell receptor signaling pathways and downregulation of CD8+ T cells. Pathway network analysis revealed a direct link between CDKN1B and the pathway involved in the positive regulation of the protein catabolic process pathway. In addition, an indirect link was identified between CDKN1B and the T-cell receptor signaling pathway. In in vitro drug screening, BMS-345541 demonstrated efficacy as a therapeutic targeting of CDKN1B, effectively impeding the growth of breast cancer cells characterized by low CDKN1B expression. The inclusion of CDKN1B expression in GBM models increased the accuracy of survival predictions. CDKN1B expression plays a significant role in breast cancer progression, implying that targeting CDKN1B might be a promising strategy for treating breast cancer.

Loss of fragile WWOX gene leads to senescence escape and genome instability

Induction of DNA damage response (DDR) to ensure accurate duplication of genetic information is crucial for maintaining genome integrity during DNA replication. Cellular senescence is a DDR mechanism that prevents the proliferation of cells with damaged DNA to avoid mitotic anomalies and inheritance of the damage over cell generations. Human WWOX gene resides within a common fragile site FRA16D that is preferentially prone to form breaks on metaphase chromosome upon replication stress. We report here that primary Wwox knockout (Wwox−/−) mouse embryonic fibroblasts (MEFs) and WWOX-knockdown human dermal fibroblasts failed to undergo replication-induced cellular senescence after multiple passages in vitro. Strikingly, by greater than 20 passages, accelerated cell cycle progression and increased apoptosis occurred in these late-passage Wwox−/− MEFs. These cells exhibited γH2AX upregulation and microsatellite instability, indicating massive accumulation of nuclear DNA lesions. Ultraviolet radiation-induced premature senescence was also blocked by WWOX knockdown in human HEK293T cells. Mechanistically, overproduction of cytosolic reactive oxygen species caused p16Ink4a promoter hypermethylation, aberrant p53/p21Cip1/Waf1 signaling axis and accelerated p27Kip1 protein degradation, thereby leading to the failure of senescence induction in Wwox-deficient cells after serial passage in culture. We determined that significantly reduced protein stability or loss-of-function A135P/V213G mutations in the DNA-binding domain of p53 caused defective induction of p21Cip1/Waf1 in late-passage Wwox−/− MEFs. Treatment of N-acetyl-l-cysteine prevented downregulation of cyclin-dependent kinase inhibitors and induced senescence in Wwox−/− MEFs. Our findings support an important role for fragile WWOX gene in inducing cellular senescence for maintaining genome integrity during DDR through alleviating oxidative stress.

Human primary myoblasts derived from paraspinal muscle reflect donor age as an experimental model of sarcopenia

BackgroundLow back pain is a general phenomenon of aging, and surgery is an unavoidable choice to relieve severe back pain. The discarded surgical site during surgery is of high value for muscle and muscle-related research. This study investigated the age-dependent properties of patients' paraspinal muscles at the cellular level. MethodsTo define an association of paraspinal muscle degeneration with sarcopenia, we analyzed lumbar paraspinal muscle and myoblasts isolated from donors of various ages (25–77 years). Preoperative evaluations were performed by bioimpedance analysis using the InBody 720, magnetic resonance (MR) imaging of the lumbar spine, and lumbar extension strength using a lumbar extension dynamometer. In addition, the growth and differentiation capacity of myoblasts obtained from the donor was determined using proliferation assay and western blotting. ResultsThe cross-sectional area of the lumbar paraspinal muscle decreased with age and was also correlated with the appendicular skeletal muscle index (ASM/height2). Human primary myoblasts isolated from paraspinal muscle preserved their proliferative capacity in vitro, which tended to decrease with donor age. The age-dependent decline in myoblast proliferation was correlated with levels of cell cycle inhibitory proteins (p16INK4a, p21CIP1, and p27KIP1) associated with cellular senescence. Primary myoblasts isolated from younger donors differentiated into multinucleate myotubes earlier and at a higher rate than those from older donors in vitro. Age-dependent decline in myogenic potential of the isolated primary myoblasts was likely correlated with the inactivation of myogenic transcription factors such as MyoD, myogenin, and MEF2c. ConclusionsMyoblasts isolated from human paraspinal muscle preserve myogenic potential that correlates with donor age, providing an in vitro model of sarcopenia.

A pan-cancer analysis for the oncogenic role of cyclin-dependent kinase inhibitor 1B in human cancers

BackgroundHuman health and life are threatened by cancer with high morbidity and mortality worldwide. In many experiments, CDKN1B level is associated with cancer risk, Nevertheless, no pan-cancer analysis has been conducted on CDKN1B in human cancers.MethodsWith the help of bioinformatics, a pan-cancer analysis was conducted on the expression levels of CDKN1B in cancer tissues and adjacent tissues from the TCGA, CPTAC and GEO databases. The CDKN1B expression levels in tumor patients was further validated using immunohistochemistry (IHC) and quantitative real-time PCR.ResultsIn the study, we first investigated the cancer-related roles of CDKN1B’s in 40 tumors with malignancy. The CDKN1B gene encodes the p27Kip1 protein, which can block the production cyclin-dependent kinase (CDK), which is obviously related to the function and survival of cancer cells and alters the prognosis of cancer patients. Furthermore, CDKN1B function requires both protein processing and RNA metabolism. Additionally, the elevated expression of the CDKN1B gene and protein was validated in several cancer tissues from the patients.ConclusionsThese results showed that the levels of CDKN1B were considerably different in a number of cancer tissues, offering a potential future target for cancer therapy.

Abstract 1441: p27Kip1 is upregulated in UMSCV-4 cells corresponding to entering a state of quiescence when treated with clobetasol

Abstract Quiescence, the temporary exit from the cell cycle, presents therapeutic challenges to cancer management since it allows evasion of chemotherapy and radiotherapy treatment. Essential to the study of quiescence in carcinogenesis is an established model system. Our studies have found that clobetasol treatment of the vulvar cancer cell line, UMSCV-4 causes these cells to enter a state of dormancy. Subsequent removal of the cells from clobetasol show a return to normal cell proliferation, even after dormancy for 3 months. p27Kip1 protein has been used as marker for entry into quiescence. Using both antibodies against p27Kip1 and transfection of a modified p27Kip1 containing plasmid into the UMSCV-4 cells we found that p27Kip1 is upregulated by addition of clobetasol, reflecting that quiescence is being activated in the treated UMSCV-4 cells. Cells that were incubated in clobetasol for three months and then removed from clobetasol (UMSCV-4 LT), allowing them to reenter the cell cycle, no longer expressed p27Kip1 upon re-exposure to clobetasol. This establishes the UMSCV-4 cells as a good model system for the study of clobetasol induced quiescence in vulvar squamous epithelial cells. The importance of this work is underscored by the observation that clobetasol is often used to treat a common inflammatory disease of the vulva known as vulvar lichen sclerosus (VLS) and up to 65% of vulvar carcinomas arise in the background of VLS. Citation Format: Gianna Minnuto, Luke North, Mack Ogden, Kia Haering, Jani E. Lewis. p27Kip1 is upregulated in UMSCV-4 cells corresponding to entering a state of quiescence when treated with clobetasol [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1441.

Evaluation of p57 expression in early disordered pregnancies with molar status vs non-molar ones

Background: The molar and non-molar lesions are determined during histomorphological examination and treated as inconclusive. The establishing of a marker by immunohistochemical investigations could influence the accuracy of the morphopathological diagnosis. The aim is evaluation of p57 immunoexpression in the trophoblastic germ compartment in molar and non-molar pregnancies. Material and methods: Abortion products from 15 patients with hydatidiform mole, 18 pregnancies solved on social indications and 16 short-term disordered pregnancies were evaluated depending on the immunoexpresion of p57. Results: The hydatidiform mole was classified based on anti-p57 immunoexpression into: complete hydatidiform mole – 8 cases (negative immunoexpression or expression in ˂10% of villous cytotrophoblast) and partial hydatidiform mole – 7 cases (positive expression in ˃10% of the villous cytotrophoblast). Basal deciduous and extravillous cytotrophoblasts were positive in 100% of cases and served as internal control. Hepatocytes were used as negative control. In the control group, the positive immunoexpression was attested in &gt;10% of cases in the villous trophoblast. Conclusions: Differential immunoexpression of p57 protein in the germinal cytotrophoblast allows subclassification of molar pathology into complete and partial forms, while not allowing the differentiation between partial hydatidiform mole and non-molar lesions. Immunohistochemical evaluation of p57kip2 protein in molar and non-molar pathology is useful in differential diagnosis as a complementary method.

Chemical Composition, Antitumor Properties, and Mechanism of the Essential Oil from Plagiomnium acutum T. Kop.

Plagiomnium acutum T. Kop. (P. acutum) has been used as a traditional Chinese medicine for thousands of years to treat cancer but lacks evidence. The objective of this work was to reveal the chemical composition of P. acutum essential oil (PEO) and explore its potential antitumor activity and molecular mechanism. PEO was prepared by the simultaneous distillation-extraction method and characterized by gas chromatography/mass spectroscopy. CCK8 assay, flow cytometry, western blot, and immunofluorescence techniques were used to analyze the effects and mechanism of PEO against cancer cells. A total of 74 constituents of PEO were identified, with diterpenes (26.5%), sesquiterpenes (23.89%), and alcohols (21.81%) being the major constituents. Two terpenoids, selina-6-en-4-ol and dolabella-3,7-dien-18-ol, were detected in PEO for the first time. PEO showed significant cell growth inhibitory activity on HepG2 and A549 cells by blocking the G1 phase and inducing apoptosis, which may be attributed to its upregulation of p21Cip1 and p27Kip1 proteins and interference with mitochondrial membrane potential effect. Dolabella-3,7-dien-18-ol accounts for 25.5% of PEO and is one of the main active components of PEO, with IC50 values in HepG2 and A549 cells of (25.820 ± 0.216) µg/mL and (23.597 ± 1.207) μg/mL, respectively. These results confirmed the antitumor medicinal value of P. acutum and showed great application potential in the pharmaceutical industry.

Fbxo22 promotes cervical cancer progression via targeting p57Kip2 for ubiquitination and degradation

F-box only protein 22 (FBXO22) is a key subunit of the Skp1-Cullin 1-F-box protein (SCF) E3 ubiquitin ligase complex. Little is known regarding its biological function and underlying molecular mechanisms in regulating cervical cancer (CC) progression. In this study, we aim to explore the role and mechanism of FBXO22 in CC progression. The correlation between FBXO22 and clinicopathological characteristics of CC was analyzed by tissue microarray. MTT, colony formation, flow cytometry, Western blotting, qRT-PCR, protein half-life, co-immunoprecipitation, ubiquitination, and xenograft experiments were performed to assess the functions of FBXO22 and potential molecular mechanisms of FBXO22-mediated malignant progression in CC. The expression of FBXO22 protein in CC tissues was higher than that in adjacent non-tumor cervical tissues. Notably, high expression of FBXO22 was significantly associated with high histology grades, positive lymph node metastasis, and poor outcomes in CC patients. Functionally, ectopic expression of FBXO22 promoted cell viability in vitro and induced tumor growth in vivo, while knockdown of FBXO22 exhibited opposite effects. In addition, overexpression of FBXO22 promoted G1/S phase progression and inhibited apoptosis in CC cells. Mechanistically, FBXO22 physically interacted with the cyclin-dependent kinase inhibitor p57Kip2 and subsequently mediated its ubiquitination and proteasomal degradation leading to tumor progression. FBXO22 protein level was found negatively associated with p57Kip2 protein levels in patient CC samples. FBXO22 promotes CC progression partly through regulating the ubiquitination and proteasomal degradation of p57Kip2. Our study indicates that FBXO22 might be a novel prognostic biomarker and therapeutic target for CC.

Abstract 668: A MYOD-SKP2 axis boosts oncogenic properties of fusion negative rhabdomyosarcoma and is counteracted by neddylation inhibition in vitro and in vivo

Abstract Rhabdomyosarcoma (RMS) is a pediatric soft tissue sarcoma characterized by an impaired myogenic differentiation despite the expression of myogenic master genes MYOD and MYOG. Therefore, the restoration of differentiation is considered an anti-cancer therapy. SKP2 is an oncogenic E3-ubiquitin ligase that promotes cell proliferation by targeting the CDKi p21Cip1 and p27Kip1. Previous works showed that SKP2 overexpression is induced by the fusion oncoprotein PAX3-FOXO1 expressed in fusion positive (FP)-RMS cells, and promotes tumor cell proliferation through p27kip1 degradation. However, the role of SKP2 in fusion negative (FN)-RMS cells, devoid of any fusion gene, remains unclear. We report here that SKP2 transcript and protein levels are up-regulated in RMS patients and cell lines compared to normal tissue. Accordingly, we observed increased acetylation of H3K27 histone mark in RMS patients and cell lines compared to myoblasts and muscle tissue. We then show that in RMS cell lines SKP2 expression is induced by MYOD, which binds two SKP2 regulatory regions, an intronic and a distal enhancers, identified by Hi-C and 3C experiments. SKP2 knockdown in FN-RMS cells leads to p21Cip1 and p27Kip1 protein levels up-regulation coupled with G1/S cell cycle arrest. Rescue experiments showed that SKP2 promotes cell proliferation directly targeting p27Kip1. Moreover, SKP2 binds and promotes degradation of p57Kip2 and its silencing restores myogenic differentiation associated to MYOG and de novo MyHC expression in FN-RMS cells. SKP2 depletion also induces cell senescence and prevents anchorage-independent growth and stemness in vitro, and tumor growth in vivo. In turn, SKP2 forced expression partially rescued the anti-cancer effects preventing the increase of p21Cip1, p27Kip1, p57Kip2 and MYOG, promoting re-entry into cell cycle, inhibiting human myoblasts cell differentiation and restoring the tumorigenic potential in FN-RMS. Since neddylation is an essential step for the activity of SKP2, we used MLN4924, an inhibitor of the Nedd8 Activating Enzyme (NAE), under clinical investigation, to resume SKP2 knockdown features. MLN4924 induces p21Cip1 and p27Kip2 expression, promotes senescence and apoptosis, and hampers cell growth in vitro and in vivo both in FP- and FN-RMS. These results unveil an unprecedented role for SKP2 in governing both proliferation and myogenic differentiation in RMS, suggesting that targeting SKP2 functions through MLN4924 treatment might have clinical relevance in FP- and FN-RMS. The study has been founded by AIRC and 5xmille 2021/Ministero della Salute to RR. Citation Format: Silvia Pomella, Matteo Cassandri, Doris Phelps, Clara Perrone, Michele Pezzella, Marco Wachtel, Benjamin Sunkel, Antonella Cardinale, Zoe Walters, Cristina Cossetti, Sonia Rodriguez, Nadia Carlesso, Janet Shipley, Lucio Miele, Beat Schafer, Enrico Velardi, Peter Houghton, Berkley Gryder, Benjamin Stanton, Concetta Quintarelli, Biagio De Angelis, Franco Locatelli, Rossella Rota. A MYOD-SKP2 axis boosts oncogenic properties of fusion negative rhabdomyosarcoma and is counteracted by neddylation inhibition in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 668.

Role of P27kip1 Protein, P45skp2Coactivator, and P38jab1 Coactivator In Preventing Rhabdomyosarcoma (RMS) in Oral Cavity of Children

Rhabdomyosarcoma is a rare malignant tumor that attacks the differentiation of skeletal muscle and usually affects children, contributing to about 60% of all soft tissue sarcomas. The purpose of this study was to examine the relationship between p27Kip1 immunoexpression and p45Skp2 and p38Jab1 coactivators, as well as the relationship between p27Kip1 immunoexpression and p45Skp2 and p38Jab1 coactivators on stages and prognosis of oral RMS in children. This was a restrospective study on the immunoexpression of p27Kip1 and p45Skp2 and p38Jab1 coactivators on RMS cells. The RMS stage was determined according to the American Joint Committee of Cancer/AJCC of stages 1–4, and were divided into group I (stages 1 and 2) and group II (3 and 4). Samples were retrieved fromt he paraffin blocks of patients with embryonal RMS. Each paraffin block was cut, and 6 samples with 5 µm thickness from each block were examined using p27Kip1, p45Skp2, and p38Jab1 proteins. The analysis was performed using a linear regression test on the relationship between p27Kip1 and p45Skp2 and p38Jab1, resulting in a p-value of 0.000 (&lt;0.05) and a coefficient value of b -1.36. Meanwhile, the stage was analyzed using the Wald test of 8.0688, resulting in a p-value of 0.0045 with a significant negative correlation. Analysis on the relationship between p45Skp2 and p38Jab1 and the RMS stage was performed using the Gamma test, resulting in a significant positive correlation (p&lt;0.05).

The ascending aorta of male hypertensive bicuspid aortic valve patients preferentially associated with a cellular aneurysmal phenotype

Male sex and hypertension represent risk factors in the progression of an aortic aneurysm. The present study examined the morphological/cellular phenotype of the ascending aorta (AA) of male and female patients diagnosed with a bicuspid aortic valve (BAV) to test the hypothesis that hypertension‐induced remodeling of male BAV patients preferentially recapitulated the expression of a panel of proteins favoring aneurysm formation. The diameter of the AA of hypertensive male (35 ± 6 mm) and female (39 ± 5 mm) BAV patients was comparable to normotensive patients reflecting an early phase of vessel expansion. Morphological/structural remodeling of the medial region of the AA of male normotensive and hypertensive BAV patients were comparable. Protein levels of non‐muscle myosin IIB, the cell cycle inhibitor p27kip1, tumor suppressor p53 and matrix metalloproteinase‐2 and −9 were significantly upregulated in the AA of male hypertensive BAV patients. In female hypertensive BAV patients, collagen content was significantly increased whereas elastin content and medial width of the AA were similar to normotensive BAV patients. In the AA of female hypertensive BAV patients, matrix metalloproteinase‐9 and p27kip1 protein levels were unchanged whereas p53 and matrix metalloproteinase‐2 protein expression was significantly reduced. Nestin protein levels were diminished in the AA of male and female hypertensive BAV patients. Thus, sexual dimorphic remodeling of the AA was prevalent in hypertensive BAV patients. Moreover, during the early phase of vessel expansion, the AA of male hypertensive BAV patients was preferentially associated with the upregulation of a panel of proteins linked to progressive dilatation and potential aneurysm formation.

Apigenin inhibits growth of melanoma by suppressing miR-512-3p and promoting the G1 phase of cell cycle involving the p27 Kip1 protein.

In the present study, we screened multiple melanoma cell lines for treatment of Apigenin and miRNA expression, also studied the role of miR-512-3p in melanoma. RT-PCR analysis was done for screening miRNA in melanoma cell lines (WM1361B, WM983A, WM1341D, SK-MEL-3, SH-4, SK-MEL-24 and RPMI-7951) compared to normal human epidermal melanocytes. Colony formation assay for cell viability studies, cell cycle by flowcytometry and protein expression by immunoblot analysis. For in vivo analysis tumour xenograft mouse model was created. Immunohistochemistry was done for PCNA positive cells. For expression of miR-512-3p in tumour tissues fluorescence in situ hybridization was done. In silico studies were done by molecular docking studies. The WM1361B and WM983A cell lines showed overexpression of miR-512-3p and increased cell proliferation compared to normal human epidermal melanocytes. Treatment of anti-miR-512-3p to WM1361B and WM983A cells halted cell proliferation and also caused G1-phase arrest. We studied the effect of Apigenin on the expression levels of miR-512-3p and associated molecular targets. Apigenin treatment in WM1361B and WM983A cells showed inhibition in expression of miR-512-3p, arrest of G1 phase of cell cycle, cytotoxicity and revival of p27 Kip1. Apigenin treatment significantly suppressed the growth of WM1361B in tumour induced mice, the activity was associated with decreased levels of miR-512-3p, tumour cell proliferation and increased levels of p27 Kip1 protein. Docking studies confirm potential affinity of Apigenin for p27 Kip1. Apigenin acts as an inhibitor of miR-512-3p by suppressing growth of melanoma both in vitro and in vivo targeting the p27 Kip1 axis.

Extracts of Musa basjoo induce growth inhibition and changes in the protein expression of cell cycle control molecules in human colorectal cancer cell lines.

Musa basjoo (MB) is a species of the banana plant belonging to the genus Musa that has been used as a folk medicine. However, evidence-based biological activities and the molecular mechanism of action of MB are unknown. Thus, the aim of the present study was to examine whether the crude dried leaf extracts of MB inhibit the growth of colorectal (HT29 and HCT116) and other types (HepG2, MCF-7 and PC-3) of human cancer cell lines. Crude extracts of MB inhibited the growth of cells with IC50 values of 136 µg/ml (acetone extract, HT29), 51 µg/ml (acetone extract, HCT116), 45 µg/ml (acetone extract, HepG2), 40 µg/ml (acetone extract, MCF-7), 29 µg/ml (acetone extract, PC-3), 175 µg/ml (methanol extract, HT29), 137 µg/ml (methanol extract, HCT116), 102 µg/ml (methanol extract, HepG2), 85 µg/ml (methanol extract, MCF-7), and 85 µg/ml (methanol extract, PC-3) in colony formation assays, and 126 µg/ml (acetone extract, HT29), 68 µg/ml (acetone extract, HCT116), 260 µg/ml (methanol extract, HT29), and 216 µg/ml (methanol extract, HCT116) in MTT assays. Thin layer chromatography analysis revealed the potential existence of aromatic compounds in the acetone extract of MB. Flow cytometric analysis indicated that the percentage of cells in G1 increased, and this was associated with a concomitant decrease of cells in the S and/or G2-M phases of the cell cycle. When colorectal cancer cells were treated with acetone extract of MB, there was a marked decrease in the levels of expression of the cyclin D1, cyclin E, cdk2 and cdk4 proteins and a marked increase in the levels of the expression of the p21CIP1, p27KIP1, and p53 proteins, but those of apoptosis-associated protein PARP did not change. There was a tendency for acetone extract of MB to inhibit xenograft tumor growth in mice. Collectively, the crude extracts of MB contain active components that exert growth inhibition of human cancer cells. This is the first systematic study of the anticancer activity of MB and may broaden insights into the possible clinical approach of specific herbal medicines.

Caffeic acid phenethyl ester targets ubiquitin-specific protease 8 and synergizes with cisplatin in endometrioid ovarian carcinoma cells

Deubiquitinases (DUBs) mediate the removal of ubiquitin from diverse proteins that participate in the regulation of cell survival, DNA damage repair, apoptosis and drug resistance. Previous studies have shown an association between activation of cell survival pathways and platinum-drug resistance in ovarian carcinoma cell lines. Among the strategies available to inhibit DUBs, curcumin derivatives appear promising, thus we hypothesized their use to enhance the efficacy of cisplatin in ovarian carcinoma preclinical models. The caffeic acid phenethyl ester (CAPE), inhibited ubiquitin-specific protease 8 (USP8), but not proteasomal DUBs in cell-free assays. When CAPE was combined with cisplatin in nine cell lines representative of various histotypes a synergistic effect was observed in TOV112D cells and in the cisplatin-resistant IGROV-1/Pt1 variant, both of endometrioid type and carrying mutant TP53. In the latter cells, persistent G1 accumulation upon combined treatment associated with p27kip1 protein levels was observed. The synergy was not dependent on apoptosis induction, and appeared to occur in cells with higher USP8 levels. In vivo antitumor activity studies supported the advantage of the combination of CAPE and cisplatin in the subcutaneous model of cisplatin-resistant IGROV-1/Pt1 ovarian carcinoma as well as CAPE activity on intraperitoneal disease. This study reveals the therapeutic potential of CAPE in cisplatin-resistant ovarian tumors as well as in tumors expressing USP8.