Integrin-linked kinase regulates senescence in an Rb-dependent manner in cancer cell lines

Combination Effects of Integrin-linked Kinase and Abelson Kinase Inhibition on Aberrant Mitosis and Cell Death in Glioblastoma Cells

In cancer cells, inhibition of integrin-linked kinase (ILK) increases centrosome declustering causing mitotic arrest and cell death. Yet, not all cancer cells are susceptible to anti-ILK treatment alone. We investigate a combination drug strategy targeting ILK and another oncogenic kinase, Abelson kinase (ABL). Drug-concentration viability assays (i.e., MTT assays) indicate that ILK and ABL inhibitors in combination decreased the viability of glioblastoma cells over the ILK drug QLT-0267 alone. Combination strategies also increased aberrant mitoses and cell death over QLT-0267 alone. This was evident from an increase in mitotic arrest, apoptosis and a sub-G1 peak following FAC analysis. In vitro, ILK and ABL localized to the centrosome and the putative ILK kinase domain was important for this localization. Increased levels of cytosolic ABL are associated with its transformative abilities. ILK inhibitor effects on survival correlated with its ability to decrease cytosolic ABL levels and inhibit ABL's localization to mitotic centrosomes in glioblastoma cells. ILK inhibitor effects on ABL's centrosomal localization were reversed by the proteasomal inhibitor MG132 (a drug that inhibits ABL degradation). These results indicate that ILK regulates ABL at mitotic centrosomes and that combination treatments targeting ILK and ABL are more effective then QLT-0267 alone at decreasing the survival of dividing glioblastoma cells.

The kinase activity of integrin-linked kinase regulates cellular senescence in gastric cancer

The activity of integrin-linked kinase (ILK) in cancerous cells is often oncogenic and associated with malignant properties, such as uncontrolled cell cycle progression and evasion from senescence. However, the role of ILK in cellular senescence in gastric cancer (GC) has not been previously examined. We generated single-cell clones of ILK knock-out using CRISPR-Cas9 in human GC lines with mesenchymal or epithelial histology. Cells with no residual ILK expression exhibited strong cellular senescence with diminished clathrin-mediated endocytosis, Surprisingly, ILK loss-induced cellular senescence appeared to be independent of its function in integrin signaling. The low dose of CPD22, a small molecule inhibitor of ILK activity-induced senescence in three GC cell lines with different histologies. Furthermore, senescent cells with ILK depletion transfected with N-terminal truncated ILK mutant remaining catalytic domains displayed the reduction of senescent phenotypes. RNA sequencing and cytokine array results revealed the enrichment of multiple pro-inflammatory signaling pathways in GC lines in the absence of ILK. Our study identified the important role and the potential mechanism of ILK in the cellular senescence of cancerous epithelial cells. The inhibition of ILK activity using small molecule compounds could have a pro-senescent effect as a therapeutic option for GC.

A Potential Role for Integrin-Linked Kinase in Colorectal Cancer Growth and Progression via Regulating Senescence and Immunity

Integrin-linked kinase (ILK) has been implicated as a molecular driver and mediator in both inflammation and tumorigenesis of the colon. ILK functions as an adaptor and mediator protein linking the extracellular matrix with downstream signaling pathways. ILK is broadly expressed in many human tissues and cells. It is also overexpressed in many cancers, including colorectal cancer (CRC). Inflammation, as evidenced by inflammatory bowel disease (IBD), is one of the highest risk factors for initiating CRC. This has led to the hypothesis that targeting ILK therapeutically could have potential in CRC, as it regulates different cellular processes associated with CRC development and progression as well as inflammation in the colon. A number of studies have indicated an ILK function in senescence, a cellular process that arrests the cell cycle while maintaining active metabolism and transcription. Senescent cells produce different secretions collectively known as the senescence-associated secretory phenotype (SASP). The SASP secretions influence infiltration of different immune cells, either positively for clearing senescent cells or negatively for promoting tumor growth, reflecting the dual role of senescence in cancer. However, a role for ILK in senescence and immunity in CRC remains to be determined. In this review, we discuss the possible role for ILK in senescence and immunity, paying particular attention to the relevance of ILK in CRC. We also examine how activating Toll-like receptors (TLRs) and their agonists in CRC could trigger immune responses against cancer, as a combination therapy with ILK inhibition.

Bufalin inhibits glycolysis-induced cell growth and proliferation through the suppression of Integrin β2/FAK signaling pathway in ovarian cancer

Bufalin is the major digoxin-like component of the traditional Chinese medicine Chansu and has obvious anti-tumor effect in major malignancies, but the role of bufalin in glucose metabolism in ovarian cancer remains illustrated. Here, we sought to elucidate the regulatory function of bufalin on cell glucose metabolism in ovarian cancer. The treatment of bufalin on ovarian cancer cells effectively inhibited glucose uptake and lactate production in ovarian cancer cells. The expression levels of glycolysis-related proteins, including GLUT4, LDHB and HK2, were decreased by the treatment of bufalin detected by qRT-PCR and immunoblotting. Mechanistically, bufalin exerted its anti-tumor effect by targeting ITGB2/FAK signaling pathway in vitro and in vivo, which could be rescued by the introduction of ITGB2 cDNA in ovarian cancer cells. These findings provide evidence that bufalin inhibited cellular glycolysis-induced cell growth and proliferation through repression of the ITGB2/FAK pathway, indicating that bufalin may be developed as a chemotherapeutic agent to treat ovarian cancer.

Integrin-linked kinase: A new actor in the ageing process?

Integrin-linked kinase (ILK) is a protein located in focal adhesion complexes that is linked to the cytoplasmic domain of integrin receptors. Together with PINCH and parvin, ILK forms the IPP complex, which is associated with conserved intracellular signalling pathways and integrin regulation of the actin cytoskeleton. ILK plays an essential role in a wide variety of cellular functions, including cell migration, differentiation, survival, and division. The present review summarizes recent evidence, suggesting a new role for ILK in organismal ageing and cellular senescence, indicating that ILK is a key regulator of longevity and premature cellular senescence induced by extracellular stressors.

Bufalin enhances antitumor effect of paclitaxel on cervical tumorigenesis via inhibiting the integrin α2/β5/FAK signaling pathway

While Bufalin restrains primary tumorigenesis, the role of Bufalin in cervical cancer remains unclear. Here, we show that Bufalin can inhibit cervical cancer cell proliferation, block cell cycle in G2/M phase, induce cellular apoptosis and reduce cell metastasis through stimulation of p21^waf/cip1, p27^cip/kip, Bax and E-cadherin, and suppression of cyclin A, cyclin B1, CDK2, Bcl-2, Bcl-xl, MMP9 and SNAIL1. Further study suggests that Bufalin has no apparent damage to human normal cervical cells at the low concentration (<20nM), but increases the chemotherapeutic efficacy of paclitaxel. Mechanistic study reveals that Bufalin suppresses the integrin α2/FAK/AKT1/ GSK3β signaling. Finally, in vivo studies show that Bufalin blocks the Siha-induced xenograft tumor growth without detectable toxicity in the animals at the therapeutic doses, and the combination treatment of Bufalin and paclitaxel more efficiently inhibits xenograft tumor growth. Thus, Bufalin may be developed as a potential therapeutic agent to treat cervical cancer.

Loukoumasomes Are Distinct Subcellular Structures from Rods and Rings and Are Structurally Associated with MAP2 and the Nuclear Envelope in Retinal Cells

“Rods and rings” (RR) and loukoumasomes are similarly shaped, subcellular macromolecular structures with as yet unknown function. RR, so named because of their shape, are formed in response to inhibition in the GTP or CTP synthetic pathways and are highly enriched in the two key enzymes of the nucleotide synthetic pathway. Loukoumasomes also occur as linear and toroidal bodies and were initially inferred to be the same as RR, largely due to their shared shape and size and the fact that it was unclear if they shared the same subcomponents. In human retinoblastoma tissue and cells we have observed toroidal, perinuclear, macromolecular structures of similar size and antigenicity to those previously reported in neurons (neuronal-loukoumasomes). To further characterize the subcomponents of the retinal-loukoumasomes, confocal analysis following immunocytochemical staining for alpha-tubulin, beta-III tubulin and detyrosinated tubulin was performed. These studies indicate that retinal-loukoumasomes are enriched for beta-III tubulin and other tubulins associated with microtubules. Immunofluorescence together with the in situ proximity ligation assay (PLA), confirmed that beta-III tubulin colocalized with detyrosinated tubulin within loukoumasomes. Our results indicate that these tissues contain only loukoumasomes because these macromolecular structures are immunoreactive with an anti-tubulin antibody but are not recognized by the prototype anti-RR/inosine monophosphate dehydrogenase (IMPDH) antibody (It2006). To further compare the RR and retinal-loukoumasomes, retinoblastoma cells were exposed to the IMPDH-inhibitor ribavirin, a drug known to induce the formation of RR. In contrast to RR, the production of retinal-loukoumasomes was unaffected. Coimmunostaining of Y79 cells for beta-III tubulin and IMPDH indicate that these cells, when treated with ribavirin, can contain both retinal-loukoumasomes and RR and that these structures are antigenically distinct. Subcellular fractionation studies indicate that ribavirin increased the RR subcomponent, IMPDH, in the nuclear fraction of Y79 cells from 21.3 ± 5.8% (0 mM ribavirin) to 122.8 ± 7.9% (1 mM ribavirin) while the subcellular localization of the retinal-loukoumasome subcomponent tubulin went unaltered. Further characterization of retinal-loukoumasomes in retinoblastoma cells reveals that they are intimately associated with lamin folds within the nuclear envelope. Using immunofluorescence and the in situ PLA in this cell type, we have observed colocalization of beta-III tubulin with MAP2. As MAP2 is a microtubule-associated protein implicated in microtubule crosslinking, this supports a role for microtubule crosslinkers in the formation of retinal-loukoumasomes. Together, these results suggest that loukoumasomes and RR are distinct subcellular macromolecular structures, formed by different cellular processes and that there are other loukoumasome-like structures within retinal tissues and cells.

Expression Profile and Function Analysis of LncRNAs during Priming Phase of Rat Liver Regeneration

Emerging evidences have revealed that long non-coding RNAs (lncRNAs) functioned in a wide range of physiological and pathophysiological processes including rat liver regeneration, and could regulate gene expression in the transcriptional and post-transcriptional levels. However, the underlying mechanism for lncRNAs participation in liver regeneration is largely unknown. To define the mechanisms how the lncRNAs regulate LR, we performed bio-chip technology, high-throughput sequencing and RT-PCR to detect the expression of lncRNAs at 0, 2 and 6 h during LR after 2/3 hepatectomy (PH). The results indicated that 28 lncRNAs were involved in LR. Bioinformatics analysis predicated 465 co-expression target genes including 10 regulatory genes were related to these 28 lncRNAs. Ingenuity Pathway Analysis (IPA) was employed to analyze the signaling pathways and physiological activities that regulated by these genes, and the results suggested that these genes were potentially related to ILK, SAPK/JNK and ERK/MAPK signaling pathways, and possibly regulate many important physiological activities in LR in terms of cell proliferation, cell differentiation, cell survival, apoptosis and necrosis.