Ectopic expression of E3 ubiquitin-protein ligase 2 in glioma and enhances resistance to apoptosis through activating nuclear factor κ-light-chain-enhancer of B cells

MIB2 promotes the progression of non-small cell lung cancer by regulating cell cycle control pathways

BACKGROUND

Although numerous measures have been used to improve the outcome of lung cancer patients, lung cancer, as the second most common diagnosed cancer, is still the main cause of cancer death. It becomes increasingly urgent for us to deeply deplore the molecular mechanism of lung cancer and to discover the potential therapeutic targets. In our study, we are dedicated to discovering the role of MIB2 in lung cancer development.

METHODS

The public databases were used to compare the expression level of MIB2 in cancer and non-cancer tissue. We analyzed the expression of MIB2 in lung cancer samples by performing Rt-PCR and western blot. We carried out CCK8 and clone assays to study the influence of MIB2 in lung cancer proliferation. The transwell assays and wound healing assays were implemented to study the function of MIB2 in metastasis and invasion. Proteins of cell cycle control pathways are detected to verify the potential mechanism of MIB2 in lung cancer progression.

RESULTS

MIB2 is up regulated in lung cancer tissue compared to adjacent normal lung tissue according to both public databases and our clinical lung cancer samples. Knockdown of MIB2 inhibits proliferation, metastasis, and invasion of lung cancer cell lines. Cyclins and cyclin dependent kinases (CDK) including CDK2, CDK4, and cyclinB1 were down regulated in MIB2 knockdown cells.

CONCLUSION

Our results prove that MIB2 acts as a driver in NSCLC tumorigenesis by regulating cell cycle control pathways.

Role of Ubiquitination in PTEN Cellular Homeostasis and Its Implications in GB Drug Resistance

Glioblastoma (GB) is the most common and aggressive brain malignancy, characterized by heterogeneity and drug resistance. PTEN, a crucial tumor suppressor, exhibits phosphatase-dependent (PI3K-AKT-mTOR pathway)/independent (nucleus stability) activities to maintain the homeostatic regulation of numerous physiological processes. Premature and absolute loss of PTEN activity usually tends to cellular senescence. However, monoallelic loss of PTEN is frequently observed at tumor inception, and absolute loss of PTEN activity also occurs at the late stage of gliomagenesis. Consequently, aberrant PTEN homeostasis, mainly regulated at the post-translational level, renders cells susceptible to tumorigenesis and drug resistance. Ubiquitination-mediated degradation or deregulated intracellular localization of PTEN hijacks cell growth rheostat control for neoplastic remodeling. Functional inactivation of PTEN mediated by the overexpression of ubiquitin ligases (E3s) renders GB cells adaptive to PTEN loss, which confers resistance to EGFR tyrosine kinase inhibitors and immunotherapies. In this review, we discuss how glioma cells develop oncogenic addiction to the E3s-PTEN axis, promoting their growth and proliferation. Antitumor strategies involving PTEN-targeting E3 ligase inhibitors can restore the tumor-suppressive environment. E3 inhibitors collectively reactivate PTEN and may represent next-generation treatment against deadly malignancies such as GB.