An anilinoquinazoline derivative inhibits tumor growth through interaction with hCAP-G2, a subunit of condensin II

NCAPG2 could be an immunological and prognostic biomarker: From pan-cancer analysis to pancreatic cancer validation

More recently, NCAPG2 has emerged as an intrinsically essential participant of the condensin II complex involved in the process of chromosome cohesion and stabilization in mitosis, and its position in particular tumours is now being highlighted. Simultaneously, the genetic properties of NCAPG2 hint that it might have enormous potential to interpret the malignant progression of tumors in a broader perspective, that is, in pan-cancer. Yet, at present, this recognition remains merely superficial and there is a lack of more detailed studies to explore the underlying pathogenesis. To meet this need, the current study was undertaken to comprehensively elucidate the potential functions of NCAPG2 in pan-cancer, based on a combination of existing databases like TCGA and GTEx. NCAPG2 was identified to be overexpressed in almost every tumor and to exhibit significant prognostic and diagnostic efficacy. Furthermore, the correlation between NCAPG2 and selected immune features, namely immune cell infiltration, immune checkpoint genes, TMB, MSI, etc. also indicates that NCAPG2 could potentially be applied in guidance of immunotherapy. Subsequently, in pancreatic cancer, this study further clarified the utility of NCAPG2 that downregulation of its expression could result in reduced proliferation, invasion and metastasis of pancreatic cancer cells, among such phenotypical changes, the epithelial-mesenchymal transition disruption could be at least one of the possible mechanisms raising or enhancing tumorigenesis. Taken above, NCAPG2, as a member of pan-oncogenes, would serve as a biomarker and potential therapeutic target for a range of malignancies, sharing new insights into precision medicine.

Perspective of Human Condensins Involved in Colorectal Cancer

Although many important roles are played by human condesins in condensation and segregation of mitotic chromosomes, what roles of human condensins play in colorectal cancer are still unclear at present. Recently, abnormal expressions of all eight subunits of human condensins have been found in colorectal cancer and they are expected to become potential biomarkers and therapeutic targets for colorectal cancer in the future. However, there are still no reviews on the significance of abnormal expression of human condensin subunits and colorectal cancer until now. Based on a brief introduction to the discovery and composition of human condensins, the review summarized all abnormally expressed human subunits found in colorectal cancer based on publicly published papers. Moreover, Perspective of application on abnormally expressed human subunits in colorectal cancer is further reviewed.

Homeostasis of soluble proteins and the proteasome post nuclear envelope reformation in mitosis

Upon Nuclear envelope (NE) fragmentation in the prometaphase the nuclear and cytosolic proteomes blend and must be redefined to reinstate homeostasis. Using a molecular GFP ladder, we show that in early mitosis, condensed chromatin excludes cytosolic proteins. When the NE reforms tightly around condensed chromatin in late mitosis, large GFP multimers are automatically excluded from the nucleus. This can be circumvented by limiting DNA condensation with Q15, a Condensin II inhibitor. Soluble small and other NLS-targeted proteins then swiftly enter the expanding nuclear space. We then examined the proteasome, located in cytoplasm and nucleus. A significant fraction of 20S proteasomes is imported by importin IPO5 within 20 minutes following reformation of the nucleus, after which import comes to an abrupt halt. This suggests that maintaining the nuclear-cytosol distribution after mitosis requires chromatin condensation to exclude cytosolic material from the nuclear space and specialized machineries for nuclear import of large protein complexes such as the proteasome.

Small Molecule Condensin Inhibitors

Condensins play a unique role in orchestrating the global folding of the chromosome, an essential cellular process, and contribute to human disease and bacterial pathogenicity. As such, they represent an attractive and as yet untapped target for diverse therapeutic interventions. We describe here the discovery of small molecule inhibitors of the Escherichia coli condensin MukBEF. Pilot screening of a small diversity set revealed five compounds that inhibit the MukBEF pathway, two of which, Michellamine B and NSC260594, affected MukB directly. Computer-assisted docking suggested plausible binding sites for the two compounds in the hinge and head domains of MukB, and both binding sites were experimentally validated using mutational analysis and inspection of NSC260594 analogs. These results outline a strategy for the discovery of condensin inhibitors, identify druggable binding sites on the protein, and describe two small molecule inhibitors of condensins.

Subunits of human condensins are potential therapeutic targets for cancers

The main role of condensins is to regulate chromosome condensation and segregation during cell cycles. Recently, it has been suggested in the literatures that subunits of condensin I and condensin II are involved in some human cancers. This paper will first briefly discuss discoveries of human condensins, their components and structures, and their multiple cellular functions. This will be followed by reviews of most recent studies on subunits of human condensins and their dysregulations or mutations in human cancers. It can be concluded that many of these subunits have potentials to be novel targets for cancer therapies. However, hCAP-D2, a subunit of human condensin I, has not been directly documented to be associated with any human cancers to date. This review hypothesizes that hCAP-D2 can also be a potential therapeutic target for human cancers, and therefore that all subunits of human condensins are potential therapeutic targets for human cancers.

NCAPH plays important roles in human colon cancer

Colon cancer (CC) is one of the major malignancies worldwide, whose pathogenesis is complex and requires the accumulated alteration of multiple genes and signaling pathways. Condensins are multi-protein complexes that play pivotal roles in chromosome assembly and segregation during mitosis, meiosis and even tumorigenesis. Using tissue microarrays by immunohistochemistry and hematoxylin–eosin staining, we found that non-SMC condensin I complex subunit H (NCAPH) in colon cancerous tissues was higher than that in all corresponding adjacent non-cancerous tissues. We then characterized the exact function of the NCAPH in CC. We provided evidences showing that NCAPH is highly expressed in colorectal cancer cell lines comparing with normal human colonic epithelial cells, and identified many NCAPH mutations in CC patients. We found that depletion of NCAPH inhibits CC cell proliferation, migration in vitro and xenograft tumor formation in vivo. Furthermore, NCAPH knockdown promotes cell apoptosis and cell cycle arrest at G2/M phase. Interestingly, the NCAPH high expression in tumor tissues of colon patients had a significantly better prognosis and survival rate than low-expression patients, suggesting that NCAPH high expression promotes colonic cancerous cell proliferation; on the other hand, it may also sensitize these cells responding to chemo- or radio-therapies. Collectively, these findings reveal an important role of NCAPH in CC, indicating that NCAPH could be used as a new therapeutic target in future.

The functional role for condensin in the regulation of chromosomal organization during the cell cycle

In all organisms, the control of cell cycle progression is a fundamental process that is essential for cell growth, development, and survival. Through each cell cycle phase, the regulation of chromatin organization is essential for natural cell proliferation and maintaining cellular homeostasis. During mitosis, the chromatin morphology is dramatically changed to have a "thread-like" shape and the condensed chromosomes are segregated equally into two daughter cells. Disruption of the mitotic chromosome architecture physically impedes chromosomal behaviors, such as chromosome alignment and chromosome segregation; therefore, the proper mitotic chromosome structure is required to maintain chromosomal stability. Accumulating evidence has demonstrated that mitotic chromosome condensation is induced by condensin complexes. Moreover, recent studies have shown that condensin also modulates interphase chromatin and regulates gene expression. This review mainly focuses on the molecular mechanisms that condensin uses to exert its functions during the cell cycle progression. Moreover, we discuss the condensin-mediated chromosomal organization in cancer cells.

Hereditary spastic paraplegia protein spartin is an FK506-binding protein identified by mRNA display

Here, we used mRNA display to search for proteins that bind to FK506, a potent immunosuppressant drug, and identified spartin, a hereditary spastic paraplegia protein, from a human brain cDNA library. We demonstrated that FK506 binds to the C-terminal region of spartin and thereby inhibits the interaction of spartin with TIP47, one of the lipid droplet-associated proteins. We further confirmed that FK506 inhibits localization of spartin and its binder, an E3 ubiquitin ligase AIP4, in lipid droplets and increases the protein level of ADRP (adipose differentiation-related protein), which is a regulator of lipid homeostasis. These results strongly suggest that FK506 suppresses the proteasomal degradation of ADRP, a substrate of AIP4, by inhibiting the spartin-TIP47 interaction and thereby blocking the localization of spartin and AIP4 in lipid droplets.

MIP-2A is a novel target of an anilinoquinazoline derivative for inhibition of tumour cell proliferation

We recently identified a novel anilinoquinazoline derivative, Q15, as a potent apoptosis inducer in a panel of human cancer cell lines and determined that Q15 targets hCAP-G2, a subunit of condensin II complex, leading to abnormal cell division. However, whether the defect in normal cell division directly results in cell death remains unclear. Here, we used an mRNA display method on a microfluidic chip to search for other Q15-binding proteins. We identified an additional Q15-binding protein, MIP-2A (MBP-1 interacting protein-2A), which has been reported to interact with MBP-1, a repressor of the c-Myc promoter. Our results indicate that Q15 inhibits the interaction between MIP-2A and MBP-1 as well as the expression of c-Myc protein, thereby inducing cell death. This study suggests that the simultaneous targeting of hCAP-G2 and MIP-2A is a promising strategy for the development of antitumor drugs as a treatment for intractable tumours.