Inverse relationship between p27/Kip.1 and the F-box protein Skp2 in human astrocytic gliomas by immunohistochemistry and Western blot

doi:10.1016/S0304-3940(02)00483-4

Neuroscience Letters

Volume 328, Issue 2, 9 August 2002, Pages 125-128

https://doi.org/10.1016/S0304-3940(02)00483-4 Get rights and content

Abstract

The F-box protein Skp2 regulates G1–S transition by controlling p27/Kip.1. The deregulated expression of p27/Kip.1 plays a critical role in the pathogenesis of many human tumors. Its cellular levels depend on ubiquitin-mediated degradation. Recently, Skp2 has been demonstrated to mediate p27/Kip.1 degradation and to have oncogenic properties. In a series of astrocytic gliomas, immunohistochemistry and Western blot of p27/Kip.1 and Skp2 have been compared. p27/Kip.1 decreased with anaplasia and almost disappeared in glioblastomas (GBM), whereas Skp2 was absent or poorly expressed in well differentiated astrocytomas and it was diffusely or focally expressed in most GBM. Since the expression of Skp2 increases during G1–S transition, the correlation of Skp2 levels with malignancy might simply reflect the highest percentage of proliferating cells in anaplastic gliomas or alternatively be instrumental to p27/Kip.1 degradation.

Section snippets

Acknowledgements

Supported by AIRC, Milan and MURST, Rome.

References (18)

R. Mamillapalli et al.
PTEN regulates the ubiquitin-dependent degradation of the CDK inhibitor p27(KIP1) through the ubiquitin E3 ligase SCF (SKP2)
Curr. Biol.
(2001)
R. Piva et al.
p27/kip1 expression in astrocytic gliomas
Neurosci. Lett.
(1997)
C.H. Alleyne et al.
Analysis of cyclin dependent kinase inhibitors in malignant astrocytomas
Int. J. Oncol.
(1999)
A.C. Carrano et al.
SKP2 is required for ubiquitin-mediated degradation of the CDK inhibitor p27
Nat. Cell Biol.
(1999)
R. Chiarle et al.
CD30 overexpression enhances negative selection in the thymus and mediates programmed cell death via a Bcl-2 pathway
J. Immunol.
(1999)
S. Fredersdorf et al.
High level expression of p27/kip1 and cyclin D1 in some human breast cancer cells: inverse correlation between the expression of p27/Kip1 and degree of malignancy in human breast and colorectal cancers
Proc. Natl. Acad. Sci. USA
(1997)
D. Ganoth et al.
The cell cycle regulatory protein Cks1 is required for SCF(Skp2)-mediated ubiquitination of p27
Nat. Cell Biol.
(2001)
D. Hershko et al.
Inverse relationship between levels of p27^Kip1 and of its ubiquitin ligase subunit Skp2 in colorectal cancer
Cancer
(2001)
E.T. Kipreos et al.
The F-box protein family
Genome Biol.
(2000)

There are more references available in the full text version of this article.

Cited by (40)

An insight into the ubiquitin-proteasomal axis and related therapeutic approaches towards central nervous system malignancies
2022, Biochimica et Biophysica Acta - Reviews on Cancer
Citation Excerpt :
Another cell-cycle checkpoint inhibitor Rb (retinoblastoma) which negatively regulatestheE2F transcription factor, has been shown to attach with 20s proteasome in GBM via excessive ubiquitinylation by Mdm2 and degraded to promote the cell cycle in an uncontrolled manner [73]. G1-S transition is further regulated by various CKIs like p27, and p21 which are readily eliminated in GBMvia skp2 and APC/C dependent manner and elevated faulty cell cycle to increase tumor mass [74,75]. CNS differentiation and maturation are regulated by NF-ĸβsignaling and in the case of tumor formation this plays an important role to give a favorable environment to the malignant cells; NF-ĸβ is activated by the proteolysis of Iĸβ via β-TrCp in a proteasome-dependent manner and blockade in this pathway leads to decrease of MB cells and senescence of glioma-initiating cells (GIC) [76,77].
The Ubiquitin-Protease system (UPS) is a major destruction system responsible for eliminating dysfunctional/misfolded proteins, thus acting as a pivotal regulator of protein homeostasis in eukaryotic cells. In this review, the UPS system and its various functions in the cell and their detailed impact such as cell cycle control, DNA damage response, apoptosis, and cellular stress regulations have been elucidated with a focus on the central nervous system. Since the Ubiquitin-Protease pathway(UPP) plays a prominent role in the sculpting of the CNS cells and their maintenance, it is naturally deeply involved in many malignancies that develop due to dysregulation of the UPS. Understanding the major disruptive players of the UPS in the development of these malignancies, for example, insoluble protein aggregates or inclusion bodies deposits due to malfunctioning of the UPS has paved the pathway for the development of new therapeutics. Here, the de-regulation of the UPS at various checkpoints in CNS malignancies has been detailed, thus facilitating an easy comprehension of the different targets that remain to be explored yet. The present therapeutic advancements in the field of CNS malignancies management through UPS targeting have also been included thus broadening the scope of drug development. Thus, this review while shedding sufficient light on the details of the UPS system and its connection to CNS malignancies, also opens new avenues for therapeutic advancements in the form of novel targetable UPP proteins and their interactions.
The Skp2 Pathway: A Critical Target for Cancer Therapy
2020, Seminars in Cancer Biology
Citation Excerpt :
Notably, a six-gene signature based genomic copy number alteration including Skp2, Eno1, Fhit, Hyal2, p16 and 14-3-3zeta is identified for sputum-based early detection of NSCLCs with 86.7% sensitivity and 93.9% specificity in distinguishing stage I NSCLC patients from the noncancer individuals [184]. Additionally, high expressions of Skp2 are widely observed in various solid tumors or hematological malignancies including head and neck [185], liver [46,71,186], pancreas [187], esophageal [188], gastric [189], colorectal [190], thyroid [191], brain [192], ovary cancer [193], sarcoma [194,195], leukemia [196], lymphoma [197] and melanoma [198], correlated with disease progression and poor survival. As a putative oncoprotein, Skp2 governs tumor formation and progression in many aspects such as promoting cell cycle, preventing cellular senescence and apoptosis, orchestrating cancer metabolism, maintaining cancer cell stemness, facilitating tumor metastasis, inducing drug resistance and other effects, as summarized in Fig. 4.
Strictly regulated protein degradation by ubiquitin-proteasome system (UPS) is essential for various cellular processes whose dysregulation is linked to serious diseases including cancer. Skp2, a well characterized component of Skp2-SCF E3 ligase complex, is able to conjugate both K48-linked ubiquitin chains and K63-linked ubiquitin chains on its diverse substrates, inducing proteasome mediated proteolysis or modulating the function of tagged substrates respectively. Overexpression of Skp2 is observed in various human cancers associated with poor survival and adverse therapeutic outcomes, which in turn suggests that Skp2 engages in tumorigenic activity. To that end, the oncogenic properties of Skp2 are demonstrated by various genetic mouse models, highlighting the potential of Skp2 as a target for tackling cancer. In this article, we will describe the downstream substrates of Skp2 as well as upstream regulators for Skp2-SCF complex activity. We will further summarize the comprehensive oncogenic functions of Skp2 while describing diverse strategies and therapeutic platforms currently available for developing Skp2 inhibitors.
Styryl-cinnamate hybrid inhibits glioma by alleviating translation, bioenergetics and other key cellular responses leading to apoptosis
2019, Experimental Cell Research
Citation Excerpt :
Along with Cyclins, certain CDKs expression was also evaluated and their expression did not alter much after 36 h insult. Interestingly, accumulation of p27 protein, which is generally degraded in glioma [56] in 36 h indicates a prominent role of 1 in cell cycle arrest. In order to confirm the role of 1 at translational level, we also tried to understand if it had any regulatory role at transcription level as well.
Gliomas are lethal and aggressive form of brain tumors with resistance to conventional radiation and cytotoxic chemotherapies; inviting continuous efforts for drug discovery and drug delivery. Interestingly, small molecule hybrids are one such pharmacophore that continues to capture interest owing to their pluripotent medicinal effects. Accordingly, we earlier reported synthesis of potent Styryl-cinnamate hybrids (analogues of Salvianolic acid F) along with its plausible mode of action (MOA). We explored iTRAQ-LC/MS-MS technique to deduce differentially expressed landscape of native & phospho-proteins in treated glioma cells. Based on this, Protein-Protein Interactome (PPI) was looked into by employing computational tools and further validated in vitro. We hereby report that the Styryl-cinnamate hybrid, an analogue of natural Salvianolic acid F, alters key regulatory proteins involved in translation, cytoskeleton development, bioenergetics, DNA repair, angiogenesis and ubiquitination. Cell cycle analysis dictates arrest at G0/G1 stage along with reduced levels of cyclin D; involved in G1 progression. We discovered that Styryl-cinnamate hybrid targets glioma by intrinsically triggering metabolite-mediated stress. Various oncological circuits alleviated by the potential drug candidate strongly supports the role of such pharmacophores as anticancer drugs. Although, further analysis of SC hybrid in treating xenografts or solid tumors is yet to be explored but their candidature has gained huge impetus through this study. This study equips us better in understanding the shift in proteomic landscape after treating glioma cells with SC hybrid. It also allows us to elicit molecular targets of this potential drug before progressing to preclinical studies.
Amentoflavone suppresses tumor growth in ovarian cancer by modulating Skp2
2017, Life Sciences
Citation Excerpt :
Accumulating evidence has shown that Skp2 plays a vital role in the development and progression of tumor through interacting with its substrates[34]. Clinical data also established the oncogenic role of Skp2 in a variety of human malignancies including ovarian cancer [35–37]. An early study by Ohama et al. has reported a significantly higher detection rate of Skp2 expression in advanced-stage diseases compared with early-stage diseases and Skp2 overexpression was significantly correlated with poor patient survival in ovarian adenocarcinoma [11].
Ovarian cancer is one of most common malignancies in women and is associated with high reoccurrence rate and poor prognosis. This study is designed to investigate the anti-tumor effects of amentoflavone (AF), one of the major active ingredients of S. tamariscina, against ovarian cancer.
Human ovarian cancer cell lines SKOV3 and OVCAR-3 were used in this study. The effect of AF on cell viability was examined by CCK-8 assay. Cell apoptosis and cell cycle distribution was determined by flow cytometry. ROS generation was detected using fluorescent staining. Expression of signaling molecules was determined by western blots. Xenograft model was established to evaluate the therapeutic efficacy of AF in vivo.
Our results showed that AF could significantly suppress cell proliferation, induce apoptosis and block cell cycle progression. Mechanistically, downregulation of S-phase kinase protein 2 (Skp2) by AF contributed to its anti-tumor effect against ovarian cancer. Furthermore, our results showed that AF repressed the expression of Skp2 through ROS/AMPK/mTOR signaling. The anti-tumor effect of AF against ovarian cancer was also confirmed in a xenograft animal model.
Overall, our present findings highlighted the potential of AF in the treatment of ovarian cancer. Moreover, our study also provided a new elucidation regarding the anti-tumor mechanisms of AF.
Physcion 8-O-β-glucopyranosideregulates cell cycle, apoptosis, and invasion in glioblastoma cells through modulating Skp2
2017, Biomedicine and Pharmacotherapy
Glioblastoma multiforme (GBM) is the most common malignant glioma in the central nervous system. This study aimed to investigate the anti-tumor activity of physcion 8-O-β-glucopyranoside (PG) in GBM cells. This showed that PG could significantly block cell cycle progression, induce apoptosis, and suppress invasion in both model GBM cell lines (U87 and U251). At the molecular level, PG repressed the expression of S-phase kinase protein 2 (Skp2), which was responsible for the anti-tumor effect of PG in GBM cells. The ectopic overexpression of Skp2 significantly abrogated the inducing effect of PG on apoptosis as well as the suppressing effect of PG on cell invasion. In contrast, the knockdown of Skp2 by short hairpin RNA enhanced the anti-tumor effect of PG in GBM cells. Moreover, the findings indicated that PG repressed the expression of Skp2 through generating reactive oxygen species and hence modulating AMPK/mTOR signaling.
A genome-wide transcriptome profiling reveals the early molecular events during callus initiation in Arabidopsis multiple organs
2012, Genomics
Citation Excerpt :
In our studies, six genes encoding the F-box protein family were up-regulated with different expression patterns and only one gene (At3g61060) was down-regulated during the incubation time (Supplemental Table 7). Consistently, the previous work showed the F-box protein Skp2 regulates G1/S transition by controlling the degradation of p27/Kip.1, which plays a critical role in the pathogenesis of many human tumors [38]. Activation of genes whose products are involved in the ubiquitin proteolytic pathways during callus induction has been reported previously [4,8,37].
Induction of a pluripotent cell mass termed callus is the first step in an in vitro plant regeneration system, which is required for subsequent regeneration of new organs or whole plants. However, the early molecular mechanism underlying callus initiation is largely elusive. Here, we analyzed the dynamic transcriptome profiling of callus initiation in Arabidopsis aerial and root explants and identified 1342 differentially expressed genes in both explants after incubation on callus-inducing medium. Detailed categorization revealed that the differentially expressed genes were mainly related to hormone homeostasis and signaling, transcriptional and post transcriptional regulations, protein phosphorelay cascades and DNA- or chromatin-modification. Further characterization showed that overexpression of two transcription factors, HB52 or CRF3, resulted in the callus formation in transgenic plants without exogenous auxin. Therefore, our comprehensive analyses provide some insight into the early molecular regulations during callus initiation and are useful for further identification of the regulators governing callus formation.

View all citing articles on Scopus

View full text

Inverse relationship between p27/Kip.1 and the F-box protein Skp2 in human astrocytic gliomas by immunohistochemistry and Western blot

Abstract

Section snippets

Acknowledgements

Curr. Biol.

Neurosci. Lett.

Analysis of cyclin dependent kinase inhibitors in malignant astrocytomas

Int. J. Oncol.

SKP2 is required for ubiquitin-mediated degradation of the CDK inhibitor p27

Nat. Cell Biol.

CD30 overexpression enhances negative selection in the thymus and mediates programmed cell death via a Bcl-2 pathway

J. Immunol.

High level expression of p27/kip1 and cyclin D1 in some human breast cancer cells: inverse correlation between the expression of p27/Kip1 and degree of malignancy in human breast and colorectal cancers

Proc. Natl. Acad. Sci. USA

The cell cycle regulatory protein Cks1 is required for SCF(Skp2)-mediated ubiquitination of p27

Nat. Cell Biol.

Inverse relationship between levels of p27Kip1 and of its ubiquitin ligase subunit Skp2 in colorectal cancer

Cancer

The F-box protein family

Genome Biol.

Inverse relationship between levels of p27^Kip1 and of its ubiquitin ligase subunit Skp2 in colorectal cancer