STK899704 inhibits stemness of cancer stem cells and migration via the FAK-MEK-ERK pathway in HT29 cells

Inhibition of colon cancer K-RasG13D mutation reduces cancer cell proliferation but promotes stemness and inflammation via RAS/ERK pathway

K-Ras is a well-studied oncogene, and its mutation is frequently found in epithelial cancers like pancreas, lung, and colorectal cancers. Cancer cells harboring K-Ras mutations are difficult to treat due to the drug resistance and metastasis properties. Cancer stem cells (CSCs) are believed the major cause of chemotherapeutic resistance and responsible for tumor recurrence and metastasis. But how K-Ras mutation affects CSCs and inflammation is not clear. Here, we compared two colon cancer cell lines, HCT-116 and HT-29, with the former being K-Ras^G13D mutant and the latter being wildtype. We found that HCT-116 cells treated with a K-Ras mutation inhibitor S7333 formed significantly more tumor spheroids than the untreated control, while the wild type of HT-29 cells remained unchanged. However, the size of tumor spheroids was smaller than the untreated controls, indicating their proliferation was suppressed after S7333 treatment. Consistent with this, the expressions of stem genes Lgr5 and CD133 significantly increased and the expression of self-renewal gene TGF-β1 also increased. The flow cytometry analysis indicated that the expression of stem surface marker CD133 increased in the treated HCT-116 cells. To understand the pathway through which the G13D mutation induced the effects, we studied both RAS/ERK and PI3K/Akt pathways using specific inhibitors SCH772984 and BEZ235. The results indicated that RAS/ERK rather than PI3K/Akt pathway was involved. As CSCs play the initial role in cancer development and the inflammation is a vital step during tumor initiation, we analyzed the correlation between increased stemness and inflammation. We found a close correlation of increased Lgr5 and CD133 with proinflammatory factors like IL-17, IL-22, and IL-23. Together, our findings suggest that K-Ras^G13D mutation promotes cancer cell growth but decreases cancer stemness and inflammation thus tumorigenesis and metastasis potential in colon cancer. Inhibition of this mutation reverses the process. Therefore, care needs be taken when employing targeted therapies to K-Ras^G13D mutations in clinics.

Altered protein profile of plasma extracellular vesicles in oral squamous cell carcinoma development

Extracellular vesicles (EVs) are involved in a wide range of pathological processes and recognized as potential and novel biomarkers for oral squamous cell carcinoma (OSCC). Here, we describe the plasma EV proteome of rats with 4-nitroquinoline-1-oxide (4NQO)-induced OSCC or moderate dysplasia (MD), which can progress to OSCC, by tandem mass tag (TMT)-labeled mass spectrometry. The proteomic profiles suggest the differential expression of various proteins in MD and OSCC, some well-recognized pathological changes (e.g., translation, ATP metabolism, and mesenchymal transition), and some novel pathological changes (e.g., podosome, focal adhesion, and S100 binding). We re-examined the presence of traditional exosomal markers and the reported novel pan-EV markers. In summary, these results suggest potential EV biomarkers and underlying pathological changes in early OSCC as well as the presence of oral-derived EVs in plasma and the need for pan-EV markers. SIGNIFICANCE: This research suggests potential EV biomarkers and underlying pathological changes in early OSCC as well as the presence of oral-derived EVs in plasma and the need for pan-EV markers.

Overexpression of Eukaryotic translation initiation factor 3D induces stem cell-like properties and metastasis in cervix cancer by activating FAK through inhibiting degradation of GRP78

Cervix cancer (CC) is the most common gynecological malignancy and the leading cause of morbidity among women worldwide. Previous study indicated that cancer stem cells (CSCs) existed in cervix cancer, and suppressing CSC characteristics of cervix cancer is needed to combat this disease. Eukaryotic translation initiation factor 3 (EIF3) is one of the most complex eukaryotic translation initiation factors containing 13 subunits (EIF3A-EIF3M) and it regulates eukaryotic translation. One member of EIF3, EIF3D, plays a role in the progression and development of multiple tumors. However, its possible role in cervix cancer progression is still unclear. In this study, we found the high EIF3D expression in human cervix cancer tissues. We further found that downregulation of EIF3D suppressed the proliferation and motility of cervix cancer cells. Furthermore, its downregulation restrained the stem cell-like properties of cervix cancer cells. Mechanically, we found that EIF3D promoted FAK activation through GRP78 in cervix cancer cells, thus contributing to the progression of cervix cancer. Therefore our results suggested that EIF3D could serve as a promising target of cervix cancer.

Mesenchymal stem cell-derived exosomes block malignant behaviors of hepatocellular carcinoma stem cells through a lncRNA C5orf66-AS1/microRNA-127-3p/DUSP1/ERK axis

Mesenchymal stem cell (MSCs)-derived exosomes have been frequently used as useful tools in disease control. This research aimed to study the function of MSC-derived exosomes (Exo) in the stemness of cancer stem cells (CSCs) of hepatocellular carcinoma (HCC) and the molecular mechanism. Exo from the procured human bone marrow-MSCs were extracted and identified. CSCs from HCC cell lines were collected. The CSCs were treated with Exo, and then the proliferation, migration, invasion, angiogenesis-stimulating and self-renewal abilities of the Hep3B-CSCs and HuH7-CSCs were significantly reduced. C5orf66-AS1 was found as the most upregulated long noncoding RNAs (lncRNAs) in CSCs after Exo treatment. The integrated bioinformatic analyses and luciferase assays suggested that C5orf66-AS1 upregulated DUSP1 expression through sequestering microRNA-127-3p (miR-127-3p). Either artificial overexpression of miR-127-3p or silencing of DUSP1 blocked the inhibitory functions of Exo in the CSCs. DUSP1 inhibition increased the phosphorylation of ERK. Similar results were reproduced in vivo where Exo reduced the growth of xenograft formed by CSCs in nude mice, and this reduction was blocked upon miR-127-3p overexpression or DUSP1 silencing. To conclude, this research reported that MSC-derived Exo block malignant behaviors of HCC-sourced CSCs through a C5orf66-AS1/miR-127-3p/DUSP1/ERK axis.

Pleckstrin homology domain of phospholipase D2 is a negative regulator of focal adhesion kinase

Phospholipase D2 (PLD2) has been implicated in the tyrosine kinase-mediated signaling pathways, but the regulation events are yet to be identified. Herein, we demonstrate that pleckstrin homology (PH) domain of PLD2 (PLD2-PH) exerts an antitumorigenic effect via the suppression of PLD2 and focal adhesion kinase (FAK). The kinase domain of FAK interacts with PLD2-PH and induces tyrosine phosphorylation and activation of PLD2. Furthermore, PLD2 increased tyrosine phosphorylation of FAK. However, ectopic expression of the PLD2-PH competes for binding to FAK and reduces the interaction between PLD2 and FAK, thereby suppressing FAK-induced PLD activation and tyrosine phosphorylation of FAK. The PLD2-PH suppressed the migration and invasion of glioblastoma cells, as well as tumor formation in a xenograft mouse model. This study uncovers a novel role of PLD2-PH as a negative regulator of PLD2 and FAK.

Role of Focal Adhesion Kinase in Small-Cell Lung Cancer and Its Potential as a Therapeutic Target

Small-cell lung cancer (SCLC) represents 15% of all lung cancers and it is clinically the most aggressive type, being characterized by a tendency for early metastasis, with two-thirds of the patients diagnosed with an extensive stage (ES) disease and a five-year overall survival (OS) as low as 5%. There are still no effective targeted therapies in SCLC despite improved understanding of the molecular steps leading to SCLC development and progression these last years. After four decades, the only modest improvement in OS of patients suffering from ES-SCLC has recently been shown in a trial combining atezolizumab, an anti-PD-L1 immune checkpoint inhibitor, with carboplatin and etoposide, chemotherapy agents. This highlights the need to pursue research efforts in this field. Focal adhesion kinase (FAK) is a non-receptor protein tyrosine kinase that is overexpressed and activated in several cancers, including SCLC, and contributing to cancer progression and metastasis through its important role in cell proliferation, survival, adhesion, spreading, migration, and invasion. FAK also plays a role in tumor immune evasion, epithelial-mesenchymal transition, DNA damage repair, radioresistance, and regulation of cancer stem cells. FAK is of particular interest in SCLC, being known for its aggressiveness. The inhibition of FAK in SCLC cell lines demonstrated significative decrease in cell proliferation, invasion, and migration, and induced cell cycle arrest and apoptosis. In this review, we will focus on the role of FAK in cancer cells and their microenvironment, and its potential as a therapeutic target in SCLC.

Novel Antrodia cinnamomea Extract Reduced Cancer Stem-Like Phenotype Changes and Resensitized KRAS-Mutant Colorectal Cancer via a MicroRNA-27a Pathway

Colorectal cancer (CRC) is one of the most common causes of death in Taiwan. Previous studies showed that Antrodia cinnamomea (AC) can treat poisoning, diarrhea, and various types of cancer. Therefore, we purified a novel ubiquinone derivative, AC009, and investigated its antitumor effects. Cell viability assays revealed that AC009 reduced the viability of several human CRC cell lines. AC009 treatment resulted in cell-cycle arrest/apoptosis, and these effects may occur via caspase and Bcl-2 signaling pathways. We demonstrated that AC009 could significantly inhibit in vivo tumor growth in xenograft mouse models. Using messenger RNA (mRNA) and microRNA (miRNA) microarrays, we found that KRAS gene expression was also regulated by AC009, possibly through specific miRNAs. AC009 also reduced cancer stem-cell marker CD44⁺/CD24⁺ expression and restored the tumor inhibition effect of cetuximab in KRAS-mutant CRC. Moreover, we found that miRNA-27a could restore the tumor inhibition effect of cetuximab in KRAS-mutant CRC cells. Taken together, our results suggest that AC009 has therapeutic potential against human wild-type and KRAS-mutant CRC.