microRNA-873 inhibits self-renewal and proliferation of pancreatic cancer stem cells through pleckstrin-2-dependent PI3K/AKT pathway

Recent studies have emphasized microRNAs (miRs) as crucial regulators in the occurrence and development of pancreatic cancer that continues to be one of the deadliest malignancies with few effective therapies. The study aimed to investigate the functional role of miR-873 and its associated mechanism to unravel the biological characteristics of pancreatic cancer stem cells in tumor growth. The expression patterns of pleckstrin-2 (PLEK2) and miR-873 were detected in the pancreatic cancer tissues. Then to further investigate specific role of miR-873, the pancreatic cancer stem cells were treated with miR-873 mimic, PLEK2, small interfering RNA against PLEK2, LY294002 (inhibitor of phosphatidylinositol 3-kinase/protein kinase B [PI3K/AKT] pathway) to detect the relative gene expression as well as their effects on cell self-renewal, proliferation and apoptosis. Finally, the tumor formation in nude mice was measured to verify the preceding results in vivo. Pancreatic cancer tissues exhibited a decline of miR-873 expression and an enhancement of PLEK2 expression. miR-873 targeted PLEK2 and downregulated its expression, leading to inhibition of PI3K/AKT pathway. Overexpressed miR-873 or silenced PLEK2 inhibited the self-renewal and proliferation while promoting the apoptosis of pancreatic cancer stem cells. Tumor formation was inhibited by overexpressed miR-873 or silenced PLEK2 in nude mice. Overall, miR-873 can suppress the self-renewal and proliferation of pancreatic cancer stem cells by blocking PLEK2-dependent PI3K/AKT pathway. Hence, this study contributes to understanding the role of miR-873 in pancreatic cancer stem cells and its underlying molecular mechanisms to aid in the development of effective pancreatic cancer therapeutics.     

Itraconazole inhibits proliferation of pancreatic cancer cells through activation of Bak-1

Itraconazole is an FDA-approved antifungal agent, which has been reported to possess promising anticancer activities in recent years. This study investigates the antiproliferative effects of itraconazole on pancreatic cancer cells and the molecular mechanism of its apoptosis-inducing effects. In this study, our results showed that itraconazole inhibited the growth of pancreatic cancer cells in vitro, and it also significantly inhibited the tumor growth of CFPAC-1 xenografts in vivo. Itraconazole induced apoptosis through ROS generation and mitochondrial membrane depolarization. A Bak-1 activation dependent apoptosis was identified in CFPAC-1 cells. These data suggested that itraconazole exhibited antiproliferative effects in pancreatic cancer cells by inducing apoptosis through Bak-1 activation.     

BMP-6 inhibits cell proliferation by targeting microRNA-192 in breast cancer

Although bone morphogenetic protein-6 (BMP-6) has been identified as a tumor suppressor associated with breast cancer differentiation and metastasis, the potential roles of BMP-6 in regulating cell cycle progression have not been fully examined. In the present study, we provide the novel finding that induction of BMP-6 in MDA-MB-231 breast cancer cells significantly inhibits cell proliferation by decreasing the number of cells in S phase of the cell cycle, resulting in inhibition of tumorigenesis in a nude mouse xenograft model. Further investigation indicated that BMP-6 up-regulates the expression of microRNA-192 (miR-192) in MDA-MB-231 cells. Elevated expression of miR-192 caused cell growth arrest, which is similar to the effect of BMP-6 induction. Importantly, depletion of endogenous miR-192 by miRNA inhibition significantly attenuated BMP-6-mediated repression of cell cycle progression. In breast cancer tissue, miR-192 expression is significantly down-regulated in tumor samples and positively correlates with the expression of BMP-6, demonstrating the inhibitory effect of BMP-6 on cell proliferation through miR-192 regulation. Additionally, using the RT² Profiler PCR Array, retinoblastoma 1 (RB1) was identified as a direct target of the BMP-6/miR-192 pathway in regulating cell proliferation in breast cancer. In conclusion, we have identified an important role for BMP-6/miR-192 signaling in the regulation of cell cycle progression in breast cancer. Furthermore, BMP-6/miR-192 was expressed at low levels in breast cancer specimens, indicating that this pathway might represent a promising therapeutic target for breast cancer treatment.     

Metformin inhibits RANKL and sensitizes cancer stem cells to denosumab

The increased propensity of BRCA1 mutation carriers to develop aggressive breast tumors with stem-like properties begins to be understood in terms of osteoprotegerin (OPG)-unrestricted cross-talk between RANKL-overproducing progesterone-sensor cells and cancer-initiating RANK⁺ responder cells that reside within pre-malignant BRCA1^mut/+ breast epithelial tissue. We recently proposed that, in the absence of hormone influence, cancer-initiating cells might remain responsive to RANKL stimulation, and hence to the therapeutic effects of the anti-RANKL antibody denosumab because genomic instability induced by BRCA1 haploinsufficiency might suffice to cell-autonomously hyperactivate RANKL gene expression. Here we report that the biguanide metformin prevents BRCA1 haploinsufficiency-driven RANKL gene overexpression, thereby disrupting an auto-regulatory feedback control of RANKL-addicted cancer stem cell-like states within BRCA1^mut/? cell populations. Moreover, metformin treatment elicits a synergistic decline in the breast cancer-initiating cell population and its self-renewal capacity in BRCA1-mutated basal-like breast cancer cells with bone metastasis-initiation capacity that exhibit primary resistance to denosumab in mammosphere assays. The specific targeting of RANKL/RANK signaling with denosumab is expected to revolutionize prevention and treatment strategies currently available for BRCA1 mutation carriers. Our findings provide a rationale for new denosumab/metformin combinatorial strategies to clinically manage RANKL-related breast oncogenesis and metastatic progression.     

microRNA-203 suppresses bladder cancer development by repressing bcl-w expression

It is increasingly clear that microRNAs (miRNAs) play an important role in many diseases, including tumorigenesis. However, the mechanisms by which miRNAs regulate bladder cancer development remain poorly understood. Here, we evaluated the expression of microRNA-203 (miR-203) in bladder cancer tissues using real-time PCR, and defined the target genes and biologically functional effect using luciferase reporter assay, flow cytometry and western blot analysis. We first verified that the expression of miR-203 was decreased in bladder cancer tissues. Moreover, ectopic expression of miR-203 promoted the apoptosis of human bladder cancer cell lines and inhibited cell proliferation, whereas its depletion increased cell growth. We further verified that miR-203 directly targeted 3'-untranslated region of the bcl-w gene, and decreased its expression in vitro and in vivo. Western blot analysis also showed that the expression level of miR-203 was negatively correlated with bcl-w level in tumor tissues. These data suggest an important role for miR-203 in the molecular etiology of bladder cancer and implicate the potential application of miR-203 in bladder cancer therapy.     

miR-126 inhibits non-small cell lung cancer cells proliferation by targeting EGFL7

MicroRNAs (miRNAs) represent an abundant group of small non-coding RNAs that regulate gene expression, and have been demonstrated to play roles as tumor suppressor genes (oncogenes), and affect homeostatic processes such as development, cell proliferation, and cell death. Subsequently, epidermal growth factor-like domain 7 (EGFL7), which is confirmed to be involved in cellular responses such as cell migration and blood vessel formation, is identified as a potential miR-126 target by bioinformatics. However, there is still no evidence showing EGFL7’s relationship with miR-126 and the proliferation of lung cancer cells. The aim of this work is to investigate whether miR-126, together with EGFL7, have an effect on non-small cell lung cancer (NSCLC) cells’ proliferation. Therefore, we constructed overexpressed miR-126 plasmid to target EGFL7 and transfected them into NSCLC cell line A549 cells. Then, we used methods like quantitative RT-PCR, Western blot, flow cytometry assay, and immunohistochemistry staining to confirm our findings. The result was that overexpression of miR-126 in A549 cells could increase EGFL7 expression. Furthermore, the most notable finding by cell proliferation related assays is that miR-126 can inhibit A549 cells proliferation in vitro and inhibit tumor growth in vivo by targeting EGFL7. As a result, our study demonstrates that miR-126 can inhibit proliferation of non-small cell lung cancer cells through one of its targets, EGFL7.     

The putative tumor suppressor microRNA-497 modulates gastric cancer cell proliferation and invasion by repressing eIF4E

Accumulating evidence has shown that microRNAs are involved in multiple processes in gastric cancer (GC) development and progression. Aberrant expression of miR-497 has been frequently reported in cancer studies; however, the role and mechanism of its function in GC remains unknown. Here, we reported that miR-497 was frequently downregulated in GC tissues and associated with aggressive clinicopathological features of GC patients. Further in vitro observations showed that the enforced expression of miR-497 inhibited cell proliferation by blocking the G1/S transition and decreased the invasion of GC cells, implying that miR-497 functions as a tumor suppressor in the progression of GC. In vivo study indicated that restoration of miR-497 inhibited tumor growth and metastasis. Luciferase assays revealed that miR-497 inhibited eIF4E expression by targeting the binding sites in the 3′-untranslated region of eIF4E mRNA. qRT-PCR and Western blot assays verified that miR-497 reduced eIF4E expression at both the mRNA and protein levels. A reverse correlation between miR-497 and eIF4E expression was noted in GC tissues. Taken together, our results identify a crucial tumor suppressive role of miR-497 in the progression of GC and suggest that miR-497 might be an anticancer therapeutic target for GC patients.     

Dracorhodin perchlorate inhibits osteoclastogenesis through repressing RANKL-stimulated NFATc1 activity

Osteolytic skeletal disorders are caused by an imbalance in the osteoclast and osteoblast function. Suppressing the differentiation and resorptive function of osteoclast is a key strategy for treating osteolytic diseases. Dracorhodin perchlorate (D.P), an active component from dragon blood resin, has been used for facilitating wound healing and anti-cancer treatments. In this study, we determined the effect of D.P on osteoclast differentiation and function. We have found that D.P inhibited RANKL-induced osteoclast formation and resorbed pits of hydroxyapatite-coated plate in a dose-dependent manner. D.P also disrupted the formation of intact actin-rich podosome structures in mature osteoclasts and inhibited osteoclast-specific gene and protein expressions. Further, D.P was able to suppress RANKL-activated JNK, NF-κB and Ca²⁺ signalling pathways and reduces the expression level of NFATc1 as well as the nucleus translocation of NFATc1. Overall, these results indicated a potential therapeutic effect of D.P on osteoclast-related conditions.     

D-glucosamine inhibits proliferation of human cancer cells through inhibition of p70S6K

Although D-glucosamine has been reported as an inhibitor of tumor growth both in vivo and in vitro, the mechanism for the anticancer effect of D-glucosamine is still unclear. Since there are several reports suggesting D-glucosamine inhibits protein synthesis, we examined whether D-glucosamine affects p70S6K activity, an important signaling molecule involved in protein translation. In the present study, we found D-glucosamine inhibited the activity of p70S6K and the proliferation of DU145 prostate cancer cells and MDA-MB-231 breast cancer cells. D-glucosamine decreased phosphorylation of p70S6K, and its downstream substrates RPS6, and eIF-4B, but not mTOR and 4EBP1 in DU145 cells, suggesting that D-glucosamine induced inhibition of p70S6K is not through the inhibition of mTOR. In addition, D-glucosamine enhanced the growth inhibitory effects of rapamycin, a specific inhibitor of mTOR. These findings suggest that D-glucosamine can inhibit growth of cancer cells through dephosphorylation of p70S6K.     

TMEM106A inhibits cell proliferation,migration, and induces apoptosis of lung cancer cells

Transmembrane protein 106A (TMEM106A) has been found to function as tumor suppressor in gastric and renal cancer. However, the role of TMEM106A in nonsmall-cell lung carcinoma (NSCLC) has not been investigated. In this study, we evaluated the expression profile of TMEM106A in NSCLC tissues and cell line, and explored the roles of TMEM106A in NSCLC cell lines. Our results showed that TMEM106A expression was significantly decreased in human NSCLC tissues. In vitro assays showed that TMEM106A expression in NSCLC cell lines was much lower than that in the bronchial epithelial cell line. Besides, overexpression of TMEM106A reduced cell proliferation, migration, and invasion, while induced cell apoptosis in NSCLC cells. TMEM106A overexpression repressed epithelial-mesenchymal transition (EMT), which was illustrated by increased E-cadherin expression and decreased the expressions of N-cadherin, and vimentin. In addition, TMEM106A overexpression suppressed the activation of phosphoinositide 3-kinase/protein kinase B/nuclear factor-κB (PI3K/Akt/NF-κB) signaling pathway in NSCLC cells. Our results indicated that TMEM106A acted as a tumor suppressor in NSCLC, and could be a therapeutic target for the management of NSCLC.     

MicroRNA-192 targeting retinoblastoma 1 inhibits cell proliferation and induces cell apoptosis in lung cancer cells

microRNAs play an important roles in cell growth, differentiation, proliferation and apoptosis. They can function either as tumor suppressors or oncogenes. We found that the overexpression of miR-192 inhibited cell proliferation in A549, H460 and 95D cells, and inhibited tumorigenesis in a nude mouse model. Both caspase-7 and the PARP protein were activated by the overexpression of miR-192, thus suggesting that miR-192 induces cell apoptosis through the caspase pathway. Further studies showed that retinoblastoma 1 (RB1) is a direct target of miR-192. Over-expression of miR-192 decreased RB1 mRNA and protein levels and repressed RB1-3'-UTR reporter activity. Knockdown of RB1 using siRNA resulted in a similar cell morphology as that observed for overexpression of miR-192. Additionally, RB1-siRNA treatment inhibited cell proliferation and induced cell apoptosis in lung cancer cells. Analysis of miRNA expression in clinical samples showed that miR-192 is significantly downregulated in lung cancer tissues compared to adjacent non-cancerous lung tissues. In conclusion, our results demonstrate that miR-192 is a tumor suppressor that can target the RB1 gene to inhibit cell proliferation and induce cell apoptosis in lung cancer cells. Furthermore, miR-192 was expressed at low levels in lung cancer samples, indicating that it might be a promising therapeutic target for lung cancer treatment.     

miR-126 inhibits proliferation of small cell lung cancer cells by targeting SLC7A5

Despite intensive efforts to improve therapies, small cell lung cancer (SCLC) still has a dismal median survival of 18 months. Since miR-126 is under-expressed in the majority of SCLC tumors, we investigated the effect of miR-126 overexpression on the proliferation and cell cycle distribution of H69 cells. Our results demonstrate that miR-126 inhibits proliferation of H69 cells, by delaying the cells in the G1 phase. Short interfering RNA (siRNA) mediated suppression of SLC7A5, a predicted target of mir-126, has the same effect on H69 cells. We also show for the first time that SLC7A5 is a direct target of miR-126.