Regulation of cancer stem cells by CXCL1, a chemokine whose secretion is controlled by MCM2.

BACKGROUND: A high expression pattern of minichromosome maintenance 2 (MCM2) has been observed in various cancers. MCM2 is a protein involved in the cell cycle and plays a role in cancer growth and differentiation by binding to six members of the MCM subfamily. The MCM protein family includes MCM2 through MCM7. METHODS: MCM2 has shown high expression in both lung cancer stem cells (LCSCs) and glioma stem cells (GSCs). We investigated the characteristics of CSCs and the regulation of the epithelial-to-mesenchymal transition (EMT) phenomenon in LCSCs and GSCs by MCM2. Additionally, we explored secreted factors regulated by MCM2. RESULTS: There was a significant difference in survival rates between lung cancer patients and brain cancer patients based on MCM2 expression. MCM2 was found to regulate both markers and regulatory proteins in LCSCs. Moreover, MCM2 is thought to be involved in cancer metastasis by regulating cell migration and invasion, not limited to lung cancer but also identified in glioma. Among chemokines, chemokine (C-X-C motif) ligand 1 (CXCL1) was found to be regulated by MCM2. CONCLUSIONS: MCM2 not only participates in the cell cycle but also affects cancer cell growth by regulating the external microenvironment to create a favorable environment for cells. MCM2 is highly expressed in malignant carcinomas, including CSCs, and contributes to the malignancy of various cancers. Therefore, MCM2 may represent a crucial target for cancer therapeutics.

Impact of KIF4A on Cancer Stem Cells and EMT in Lung Cancer and Glioma.

Kinesin family member 4A (KIF4A) belongs to the kinesin 4 subfamily of kinesin-related proteins and is involved in the regulation of chromosome condensation and segregation during mitotic cell division. The expression of KIF4A in various types of cancer, including lung, breast, and colon cancer, has been found to be associated with poor prognosis in cancer patients. However, the exact mechanism by which it promotes tumorigenesis is not yet understood. In osteosarcoma, the expression of KIF4A has been shown to be associated with cancer stem cells (CSCs), whereas in breast cancer, it is not associated with the maintenance of CSCs but regulates the migratory ability of cells. In this light, we identified phenotypic phenomena affecting the malignancy of cancer in lung cancer and glioma, and investigated the mechanisms promoting tumorigenesis. As a result, we demonstrated that KIF4A affected lung cancer stem cells (LCSCs) and glioma stem cells (GSCs) and regulated CSC signaling mechanisms. In addition, the migratory ability of cells was regulated by KIF4A, and epithelial-to-mesenchymal transition (EMT) marker proteins were controlled. KIF4A regulated the expression of the secretory factor plasminogen activator inhibitor-1 (PAI-1), demonstrating that it sustains cancer malignancy through an autocrine loop. Taken together, these findings suggest that KIF4A regulates CSCs and EMT, which are involved in cancer recurrence and metastasis, indicating its potential value as a novel therapeutic target and prognostic marker in lung cancer and glioma.

A Novel Anticancer Peptide Derived from Bryopsis plumosa Regulates Proliferation and Invasion in Non-Small Cell Lung Cancer Cells.

The discovery of new highly effective anticancer drugs with few side effects is a challenge for drug development research. Natural or synthetic anticancer peptides (ACPs) represent a new generation of anticancer agents with high selectivity and specificity. The rapid emergence of chemoradiation-resistant lung cancer has necessitated the discovery of novel anticancer agents as alternatives to conventional therapeutics. In this study, we synthesized a peptide containing 22 amino acids and characterized it as a novel ACP (MP06) derived from green sea algae, Bryopsis plumosa. Using the ACP database, MP06 was predicted to possess an alpha-helical secondary structure and functionality. The anti-proliferative and apoptotic effects of the MP06, determined using the cytotoxicity assay and Annexin V/propidium iodide staining kit, were significantly higher in non-small-cell lung cancer (NSCLC) cells than in non-cancerous lung cells. We confirmed that MP06 suppressed cellular migration and invasion and inhibited the expression of N-cadherin and vimentin, the markers of epithelial-mesenchymal transition. Moreover, MP06 effectively reduced the metastasis of tumor xenografts in zebrafish embryos. In conclusion, we suggest considering MP06 as a novel candidate for the development of new anticancer drugs functioning via the ERK signaling pathway.

BIRC5: A novel therapeutic target for lung cancer stem cells and glioma stem cells.

Baculoviral inhibitor of apoptosis repeat containing 5 (BIRC5) is also known as survivin. BIRC5, a member of the apoptosis inhibitor (IAP) family, negatively regulates apoptosis or programmed cell death by inhibiting caspase activation. Due to these properties, overexpression of BIRC5 enables specific survival and division associated with cancer malignancies. In addition, BIRC5 is highly expressed in stem cells, but not present at all in terminally differentiated cells. On this basis, there is speculation that BIRC5 may be involved in the regulation of cancer stem cells (CSCs), but few study results have been reported. In addition, the molecular mechanisms of BIRC5 regulation are not yet well understood. Through the present study, it was confirmed that BIRC5 is a key factor regulating CSCs and epithelial to mesenchymal transition (EMT). BIRC5 was simultaneously overexpressed in lung cancer stem cells (LCSCs) and glioma stem cells (GSCs), and when the expression was suppressed, the characteristics of CSCs disappeared. In addition, plasminogen activator inhibitor-1 (PAI-1), a secreted factor regulated by BIRC5, is involved in signaling mechanisms that regulate cancer stem cells and EMT, and PAI-1 forms an autocrine chain. Based on these results, BIRC5 is proposed as a novel therapeutic target protein for LCSCs and GSCs.

Regulation of Cancer Stem Cells and Epithelial-Mesenchymal Transition by CTNNAL1 in Lung Cancer and Glioblastoma.

CTNNAL1 is a protein known to be involved in cell-cell adhesion and cell adhesion. Alterations in the expression or function of CTNNAL1 have been reported to contribute to the development and progression of various types of cancer. In breast cancer, CTNNAL1 has been reported as a cancer suppressor gene, and in melanoma and lung cancer, it has been reported as a cancer driver gene. However, due to a lack of research, its function remains unclear. In this study, it is shown that CTNNAL1 regulates cancer stem cells (CSCs) in lung cancer and glioblastoma and modulates their migration and invasion abilities. CSCs are known to play an important role in the malignant transformation of cancer. They have the ability to resist chemotherapeutic drugs and irradiation, which is a known obstacle to cancer treatment. We found that CTNNAL1 regulates the ability to resist irradiation. In addition, we observed that CTNNAL1 regulates the ability of cells to migrate and invade, a key feature of the epithelial to mesenchymal transition phenomenon associated with cancer metastasis. CTNNAL1 was also involved in the secretion of C-C motif chemokine ligand 2 (CCL2), one of the chemokines. CCL2 plays a role in the recruitment of immune cells to the tumor microenvironment, but in cancer, it is known to influence malignancy and metastasis. CTNNAL1 may be a novel target for treating lung CSCs and glioma stem cells and may be used as a marker of malignancy.

RanBP1: A Potential Therapeutic Target for Cancer Stem Cells in Lung Cancer and Glioma.

Cancer stem cells (CSCs) are known to be one of the factors that make cancer treatment difficult. Many researchers are thus conducting research to efficiently destroy CSCs. Therefore, we sought to suggest a new target that can efficiently suppress CSCs. In this study, we observed a high expression of Ran-binding protein 1 (RanBP1) in lung cancer stem cells (LCSCs) and glioma stem cells (GSCs). Upregulated RanBP1 expression is strongly associated with the expression of CSC marker proteins and CSC regulators. In addition, an elevated RanBP1 expression is strongly associated with a poor patient prognosis. CSCs have the ability to resist radiation, and RanBP1 regulates this ability. RanBP1 also affects the metastasis-associated epithelial-mesenchymal transition (EMT) phenomenon. EMT marker proteins and regulatory proteins are affected by RanBP1 expression, and cell motility was regulated according to RanBP1 expression. The cancer microenvironment influences cancer growth, metastasis, and cancer treatment. RanBP1 can modulate the cancer microenvironment by regulating the cytokine IL-18. Secreted IL-18 acts on cancer cells and promotes cancer malignancy. Our results reveal, for the first time, that RanBP1 is an important regulator in LCSCs and GSCs, suggesting that it holds potential for use as a potential therapeutic target.

Effect of Copper Chelators via the TGF-ß Signaling Pathway on Glioblastoma Cell Invasion.

Glioblastoma multiforme (GBM) is a fast-growing and aggressive type of brain cancer. Unlike normal brain cells, GBM cells exhibit epithelial-mesenchymal transition (EMT), which is a crucial biological process in embryonic development and cell metastasis, and are highly invasive. Copper reportedly plays a critical role in the progression of a variety of cancers, including brain, breast, and lung cancers. However, excessive copper is toxic to cells. D-penicillamine (DPA) and triethylenetetramine (TETA) are well-known copper chelators and are the mainstay of treatment for copper-associated diseases. Following treatment with copper sulfate and DPA, GBM cells showed inhibition of proliferation and suppression of EMT properties, including reduced expression levels of N-cadherin, E-cadherin, and Zeb, which are cell markers associated with EMT. In contrast, treatment with copper sulfate and TETA yielded the opposite effects in GBM. Genes, including TGF-ß, are associated with an increase in copper levels, implying their role in EMT. To analyze the invasion and spread of GBM, we used zebrafish embryos xenografted with the GBM cell line U87. The invasion of GBM cells into zebrafish embryos was markedly inhibited by copper treatment with DPA. Our findings suggest that treatment with copper and DPA inhibits proliferation and EMT through a mechanism involving TGF-ß/Smad signaling in GBM. Therefore, DPA, but not TETA, could be used as adjuvant therapy for GBM with high copper concentrations.

Epithelial membrane protein 3 regulates lung cancer stem cells via the TGF­ß signaling pathway.

Epithelial membrane protein 3 (EMP3) is a transmembrane glycoprotein that contains a peripheral myelin protein 22 domain. EMP3 first received attention as a tumor suppressor, but accumulating evidence has since suggested that it may exhibit a tumor­promoting function. Nonetheless, the biological function of EMP3 remains largely unclear with regards to its role in cancer. Herein, it was shown that EMP3 expression is upregulated in non­small cell lung cancer (NSCLC) cells overexpressing aldehyde dehydrogenase 1 (ALDH1). EMP3 was shown to be involved in cell proliferation, the formation of cancer stem cells (CSCs) and in epithelial­mesenchymal transition (EMT). The ability to resist irradiation, one of the characteristics of CSCs, decreased when the EMP3 mRNA expression was knocked down using small interfering RNA. In addition, when EMP3 knockdown reduced the migratory ability of cells, a characteristic of EMT. Additionally, it was shown that the TGF­ß/Smad signaling axis was a target of EMP3. EMP3 was found to interact with TGF­ß receptor type 2 (TGFBR2) upon TGF­ß stimulation in lung CSCs (LCSC). As a result, binding of EMP3­TGFBR2 regulates TGF­ß/Smad signaling activation and consequently affects CSCs and EMT. Kaplan­Meier analysis results confirmed that patients with high expression of EMP3 had poor survival rates. Taken together, these findings showed that EMP3 may be a potential target for management of LCSCs with high expression of ALDH1, and that EMP3 is involved in TGF­ß/Smad signaling activation where it promotes acquisition of cancerous properties in tumors.

HSPA1L Enhances Cancer Stem Cell-Like Properties by Activating IGF1Rß and Regulating ß-Catenin Transcription.

Studies have shown that cancer stem cells (CSCs) are involved in resistance and metastasis of cancer; thus, therapies targeting CSCs have been proposed. Here, we report that heat shock 70-kDa protein 1-like (HSPA1L) is partly involved in enhancing epithelial-mesenchymal transition (EMT) and CSC-like properties in non-small cell lung cancer (NSCLC) cells. Aldehyde dehydrogenase 1 (ALDH1) is considered a CSC marker in some lung cancers. Here, we analyzed transcriptional changes in genes between ALDH1high and ALDH1low cells sorted from A549 NSCLC cells and found that HSPA1L was highly expressed in ALDH1high cells. HSPA1L played two important roles in enhancing CSC-like properties. First, HSPA1L interacts directly with IGF1Rß and integrin αV to form a triple complex that is involved in IGF1Rß activation. HSPA1L/integrin αV complex-associated IGF1Rß activation intensified the EMT-associated cancer stemness and γ-radiation resistance through its downstream AKT/NF-κB or AKT/GSK3ß/ß-catenin activation pathway. Secondly, HSPA1L was also present in the nucleus and could bind directly to the promoter region of ß-catenin to function as a transcription activator of ß-catenin, an important signaling protein characterizing CSCs by regulating ALDH1 expression. HSPA1L may be a novel potential target for cancer treatment because it both enhances IGF1Rß activation and regulates γß-catenin transcription, accumulating CSC-like properties.