Search

African lungfishes are ammonotelic in water. They can aestivate for long periods on land during drought. During aestivation, the gills are covered with dried mucus and ammonia excretion ceases. In fishes, ammonia excretion through the gills involves Rhesus glycoproteins (RhGP/Rhgp). This study aimed to obtain the complete cDNA coding sequences of rhgp from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Three isoforms of rhgp (rhag, rhbg and rhcg) were obtained in the gills of P. annectens. Their complete cDNA coding sequences ranged between 1311 and 1398 bp, coding for 436 to 465 amino acids with estimated molecular masses between 46.8 and 50.9 kDa. Dendrogramic analyses indicated that Rhag was grouped closer to fishes, while Rhbg and Rhcg were grouped closer to tetrapods. During the induction phase, the protein abundance of Rhag, but not its transcript level, was down-regulated in the gills, suggesting that there could be a decrease in the release of ammonia from the erythrocytes to the plasma. Furthermore, the branchial transcript levels of rhbg and rhcg decreased significantly, in preparation for the subsequent shutdown of gill functions. During the maintenance phase, the branchial expression levels of rhag/Rhag, rhbg/Rhbg and rhcg/Rhcg decreased significantly, indicating that their transcription and translation were down-regulated. This could be part of an overall mechanism to shut down branchial functions and save metabolic energy used for transcription and translation. It could also be regarded as an adaptive response to stop ammonia excretion. During the arousal phase, it is essential for the lungfish to regain the ability to excrete ammonia. Indeed, the protein abundance of Rhag, Rhbg and Rhcg recovered to the corresponding control levels after 1 day or 3 days of recovery from 6 months of aestivation. [ABSTRACT FROM AUTHOR]

The JAK2/STAT3 signaling pathway plays a critical role in tumorigenesis, and has been suggested as a potential molecular target for anti-melanoma therapeutics. However, few JAK2 inhibitors were being tested for melanoma therapy. In this study, eight amentoflavone analogues were evaluated for their activity against human malignant melanoma cells. The most potent analogue, compound 1, inhibited the phosphorylation of JAK2 and STAT3 in human melanoma cells, but had no discernible effect on total JAK2 and STAT3 levels. A cellular thermal shift assay was performed to identify that JAK2 is engaged by 1 in cell lysates. Moreover, compound 1 showed higher antiproliferative activity against human melanoma A375 cells compared to a panel of cancer and normal cell lines. Compound 1 also activated caspase-3 and cleaved PARP, which are markers of apoptosis, and suppressed the anti-apoptotic Bcl-2 level. Finally, compound 1 induced apoptosis in 80% of treated melanoma cells. To our knowledge, compound 1 is the first amentoflavone-based JAK2 inhibitor to be investigated for use as an anti-melanoma agent. [ABSTRACT FROM AUTHOR]

Vascular calcification is an active process of osteoblastic differentiation of vascular smooth muscle cells; however, its definite mechanism remains unknown. Vinpocetine, a derivative of the alkaloid vincamine, has been demonstrated to inhibit the high glucose-induced proliferation of vascular smooth muscle cells; however, it remains unknown whether vinpocetine can affect the osteoblastic differentiation of vascular smooth muscle cells. We hereby investigated the effect of vinpocetine on vascular calcification using a beta-glycerophosphate-induced cell model. Our results showed that vinpocetine significantly reduced the osteoblast-like phenotypes of vascular smooth muscle cells including ALP activity, osteocalcin, collagen type I, Runx2 and BMP-2 expression as well as the formation of mineralized nodule. Vinpocetine, binding to translocation protein, induced phosphorylation of extracellular signal-related kinase and Akt and thus inhibited the translocation of nuclear factor-kappa B into the nucleus. Silencing of translocator protein significantly attenuated the inhibitory effect of vinpocetine on osteoblastic differentiation of vascular smooth muscle cells. Taken together, vinpocetine may be a promising candidate for the clinical therapy of vascular calcification. [ABSTRACT FROM AUTHOR]

Purpose: Chemo-resistance is the leading cause of failure in cancer therapy, however, much remains to be understood about the intrinsic mechanisms. In the present study, we discovered the novel miR-4443 that regulated malignancy of breast cancer both in vitro and in vivo. Methods: We examined the expression of miR-4443 in MDA-MB-231/S and MDA-MB-231 Epirubicin-resistant cell lines with 76 breast cancer formalin-fixed paraffin-embedded tissues by real-time PCR. Also, we investigated the loss- and gain-functions of miR-4443 by MTT assay and flow cytometry. Furthermore, we detected miR-4443 mediated tissue inhibitor of metalloproteinase 2 expression in cells by TargetScan, RT-qPCR and western blot. Results: We identified the up-regulated expression of miR-4443 in Epi-resistant cell lines versus MDA-MB-231/S cell(Epi versus S) and in post-chemotherapy FFPE tissues, along with statistically differential expressions in PR(partial response) versus SD(stable disease)/PD(progressive disease) patients. Overexpression of miR-4443 increased the IC50 value of Epi for the target cells transfected, while inhibition of miR-4443 could restored sensitivity of the target cells to Epi. Besides, down-regulation of endogenous miR-4443 by miRNA-inhibitors significantly enhanced Epi-induced apoptosis while up-regulation of miR-4443 by miRNA-mimics lead to less Epi-induced apoptotic cells. Consequently, changes in TIMP2 mRNA and protein expression revealed that miR-4443 mimics suppressed expression of TIMP2 and induced migration in breast cancer cells. Furthermore, TIMP2 expression associated with better prognosis(HR = 0.721, 95%CI: 0.529–0.983). Conclusions: We revealed that miR-4443 induced malignancy of breast cancer mainly in chemo-resistance aspect for the very first time, providing a novel biomarker in breast cancer diagnosis and therapy. [ABSTRACT FROM AUTHOR]

Acquisition of resistance to docetaxel (Doc) is one of the most important problems in treatment of breast cancer patients, but the underlying mechanisms are still not fully understood. In present study, Doc-resistant MDA-MB-231 and MCF-7 breast cancer cell lines (MDA-MB-231/Doc and MCF-7/Doc) were successfully established in vitro by gradually increasing Doc concentration on the basis of parental MDA-MB-231 and MCF-7 cell lines (MDA-MB-231/S and MCF-7/S). The potential miRNAs relevant to the Doc resistance were screened by miRNA microarray. We selected 5 upregulated miRNAs (has-miR-3646, has-miR-3658, has-miR-4438, has-miR-1246, and has-miR-574-3p) from the results of microarray for RT-qPCR validation. The results showed that expression level of miR-3646 in MDA-MB-231/Doc cells was significantly higher than in MDA-MB-231/S cells. Compared to MCF-7/S cells, miR-3646 expression was up-regulated in MCF-7/Doc cells. Further studies revealed that transfection of miR-3646 mimics into MDA-MB-231/S or MCF-7/S cells remarkably increased their drug resistance, in contrast, transfection of miR-3646 inhibitors into MDA-MB-231/Doc or MCF-7/Doc cells resulted in significant reduction of the drug resistance. By the pathway enrichment analyses for miR-3646, we found that GSK-3β/β-catenin signaling pathway was a significant pathway, in which GSK-3β was an essential member. RT-qPCR and Western blot results demonstrated that miR-3646 could regulate GSK-3β mRNA and protein expressions. Furthermore, a marked increase of both nuclear and cytoplasmic β-catenin expressions (with phosphorylated-β-catenin decrease) was observed in MDA-MB-231/Doc cells compared with MDA-MB-231/S cells, and their expression were positively related to miR-3646 and negatively correlated with GSK-3β. Taken together, our results suggest that miR-3646-mediated Doc resistance of breast cancer cells maybe, at least in part, through suppressing expression of GSK-3β and resultantly activating GSK-3β/β-catenin signaling pathway. [ABSTRACT FROM AUTHOR]

18β-glycyrrhetinic acid (18β-GA) is a bioactive component of licorice. The anti-cancer activity of 18β-GA has been studied in many cancer types, whereas its effects in lung cancer remain largely unknown. We first showed that 18β-GA effectively suppressed cell proliferation and inhibited expression as well as activity of thromboxane synthase (TxAS) in non-small cell lung cancer (NSCLC) cells A549 and NCI-H460. In addition, the administration of 18β-GA did not have any additional inhibitory effect on the decrease of cell proliferation induced by transfection with TxAS small interference RNA (siRNA). Moreover, 18β-GA failed to inhibit cell proliferation in the immortalized human bronchial epithelial cells 16HBE-T and another NSCLC cell line NCI-H23, both of which expressed minimal level of TxAS as compared to A549 and NCI-H460. However, 18β-GA abolished the enhancement of cell proliferation induced by transfection of NCI-H23 with pCMV6-TxAS plasmid. Further study found that the activation of both extracellular signal-regulated kinase (ERK)1/2 and cyclic adenosine monophosphate response element binding protein (CREB) induced by TxAS cDNA transfection could be totally blocked by 18β-GA. Altogether, we have delineated that, through inhibiting TxAS and its initiated ERK/CREB signaling, 18β-GA suppresses NSCLC cell proliferation. Our study has highlighted the significance of 18β-GA with respect to prevention and treatment of NSCLC. [ABSTRACT FROM AUTHOR]