Expression of lncRNA PVT1 in colorectal cancer tissues and cells and its effect on chemo-sensitivity to cisplatin and the possible mechanisms / 中国肿瘤生物治疗杂志

@#Objective: To study the regulatory effects and possible mechanism of long non-coding RNA plasmacytoma variant translocation 1 (lncRNA PVT1) on chemotherapy sensitivity to cisplatin (DDP) of colorectal cancer (CRC)．Methods: A total of 112 pairs of matched cancer and adjacent non-cancerous tissues were obtained from the CRC patients who underwent surgical resection in the First Affiliated Hospital of Xinxiang Medical University betweenApril 2006 and March 2011.All specimens were confirmed by pathological examinations. Tumor tissues and corresponding adjacent non-cancerous tissues from 30 cisplatin-sensitive CRC patients and 30 cisplatin-resistant patients were selected. Human CRC cell lines (HT29, SW480, HCT116, RKO and LoVo) and normal colonic epithelial cell line NCM460 were also collected for this study; and DDP-resistant RKO/DDP and LoVo/DDP cell lines were constructed. siPVT1, siNC, LV-PVT1 and LV-NC were transfected into LoVo and RKO cells or LoVo/DDP and RKO/DDP cells using lipofectamineTM2000. The expression of lncRNA PVT1 in CRC tissues and cells was tested by Real-time qPCR. CCK-8 assay, flow cytometry and WB were performed to test the effect of PTV1 knockout or enforcement on cell proliferation, apoptosis and expressions of apoptosis-related proteins, respectively. The CRC subcutaneous transplanted xenograft model was established on athymic nude mice to study the effect of PVT1 over-expression on tumor growth and DDP resistance. Results: PVT1 was highly expressed in the cancer tissues and CRC cells, and its expression was positively associated with cisplatin resistance of CRC. After knockdown of PVT1, the proliferation of cisplatinresistant CRC cells was significantly suppressed, while the apoptosis was significantly enhanced (P<0.05 or P<0.01); Mechanically, the levels of drug resistance-associated molecules, including MDR1 and MRP1, as well as the expression of anti-apoptotic Bcl-2 were significantly downregulated whereas the levels of pro-apoptotic Bax and cleaved caspase-3 were increased in PVT1-silenced DDP-resistant CRC cells. Over-expression of PVT1 reversely increased proliferation and decreased apoptosis of CRC cells (P<0.05 or P<0.01). In addition, PVT1 over-expression in CRC cells significantly promoted DDP-resistance in vivo (P<0.05). Conclusion: Collectively, knockdown of PVT1 expression can significantly suppress cell proliferation and promote apoptosis of DDP-resistant CRC cells. Overexpression of PVT1 can significantly promote the growth of CRC cells in vitro and transplanted xenograft in vivo. PVT1 regulates endogenous apoptosis pathways and further promotes the sensitivity of CRC cells to cisplatin chemotherapy via inhibiting the expressions of MDR1 and MRP1.

Interplay between long noncoding RNA ZEB1-AS1 and miR-101/ZEB1 axis regulates proliferation and migration of colorectal cancer cells.

Long noncoding RNAs (lncRNAs) are dysregulated in many diseases. MicroRNA-101 (miR-101) functions as a tumor suppressor by directly targeting ZEB1 in various cancers. However, the potential mechanism of lncRNA ZEB1-AS1 and miR-101/ZEB1 axis in CRC remains unknown. In this study, we further investigated the potential interplay between miR-101/ZEB1 axis and lncRNA ZEB1-AS1 in colorectal cancer (CRC). Results showed that ZEB1-AS1 was upregulated in CRC tissues and cells. MiR-101 was downregulated in CRC tissues and negatively correlated with ZEB1-AS1 and ZEB1 expression levels in CRC. Functional experiments showed that, consistent with ZEB1-AS1 depletion, miR-101 overexpression and ZEB1 depletion inhibited the proliferation and migration of CRC cells. Overexpression of miR-101 partially abolished the effects of ZEB1-AS1 on the proliferation and migration of these cells. Moreover, combined ZEB1-AS1 depletion and miR-101 overexpression significantly inhibited cell proliferation and migration of the CRC cells. Hence, ZEB1-AS1 functioned as a molecular sponge for miR-101 and relieved the inhibition of ZEB1 caused by miR-101. This study revealed a novel regulatory mechanism between ZEB1-AS1 and miR-101/ZEB1 axis. The interplay between ZEB1-AS1 and miR-101/ZEB1 axis contributed to the proliferation and migration of CRC cells, and targeting this interplay could be a promising strategy for CRC treatment.

Silencing long noncoding RNA PVT1 inhibits tumorigenesis and cisplatin resistance of colorectal cancer.

Long noncoding RNA plasmacytoma variant translocation 1 (PVT1) plays pivotal roles in tumorigenesis of many cancers, including colorectal cancer (CRC). However, the clinical significance and the biological functions of PVT1 in CRC remain largely unknown. In this study, we found that PVT1 was highly expressed in CRC tissues and cell lines compared with the corresponding non-cancerous samples and normal colon epithelial cells. Clinically, increased expression of PVT1 was positively correlated with tumor size, advanced histological stages, metastases, poor prognosis, and cisplatin resistance of CRC patients. In vitro studies showed that PVT1 silencing inhibited the proliferation, migration, invasion, and apoptosis escape of CRC cells. Knockdown of PVT1 in cisplatin-resistant CRC cells induced proliferation inhibition and apoptosis, whereas overexpression of PVT1 increased proliferation and decreased apoptosis of CRC cells. Mechanically, the levels of drug resistance-associated molecules, including multidrug resistance 1 and multidrug resistance protein 1, as well as the expression of anti-apoptotic Bcl-2 were significantly downregulated whereas the levels of pro-apoptotic Bax and cleaved caspase-3 were increased in PVT1-silenced cisplatin-resistant CRC cells. However, ectopic expression of PVT1 in CRC cells reversed the expressions of the molecules mentioned above. In addition, PVT1 overexpression in CRC cells significantly promoted cisplatin resistance in vivo. Collectively, these results demonstrated that PVT1 is a significant regulator in tumorigenesis and cisplatin resistance of CRC and provided evidence that PVT1 may be a promising target for CRC therapy.

microRNA-9 functions as a tumor suppressor in colorectal cancer by targeting CXCR4.

MicroRNAs (miRs) dysregulation has been proven to play a crucial role in the initiation and progression of colorectal cancer (CRC). miR-9 functions as a tumor suppressor in many cancer types, including CRC. However, the precise role of miR-9 and the underlying molecular mechanisms that miR-9 involves in CRC progression remain largely unknown. In this study, it was reported that miR-9 had lower expression in CRC tissue samples than in those matched adjacent non-tumor tissues. Deregulated miR-9 expression was inverse correlated with the TNM stage, lymph node metastasis, and prognosis of CRC patients. Ectopic miR-9 expression suppressed CRC cell proliferation, migration, and invasion. Dual-Luciferase Reporter Assay confirmed that C-X-C Motif Chemokine Receptor 4 (CXCR4) was a direct miR-9 target, and the effects of miR-9 were mimicked through CXCR4 depletion in vitro. CXCR4 rescue experiments further verified that CXCR4 is a functional target of miR-9. Animal xenograft assays also provided evidence that miR-9 functions as a tumor suppressor via targeting CXCR4 in vivo. Mechanistically, miR-9 overexpression or CXCR4 knockdown influenced cell proliferation and epithelial-mesenchymal transition (EMT). Results suggest that miR-9 acts as a tumor suppressor in CRC progression by regulating CXCR4.

Design of amphiphilic PCL-PEG-PCL block copolymers as vehicles of Ginkgolide B and their brain-targeting studies.

The amphiphilic PEG-b-PCL block copolymers were synthesized by ring-opening polymerization. The specific and selective antagonists of platelet activating factor, Ginkgolide B (GB), was successfully encapsulated in the synthesized PEG-PCL nanoparticles (NPs) with high Encapsulation Efficiency and Drug Loading. The synthesis of different PEG-PCL copolymers were confirmed with FTIR and 1H NMR spectra. The morphology and particles size distribution of cargo-free PEG-PCL NPs were studied by transmission electron microscope (TEM) analysis and Malvern laser particle analyzer. The bio-distribution and pharmacodynamics studies of GB were studied with Wistar mice as the animal models via tail injecting of GB-PEG-PCL NPs. Results from Malvern laser particle analyzer and TEM analysis illustrated that the cargo-free NPs showed narrow distribution and well separated particles size of about 60 nm in diameter. The in vitro experiment of GB-PEG-PCL NPs exhibited an extended release behavior. The bio-distribution data suggested that Tween-80 covered GB-PEG-PCL NPs showed a brain-targeting behavior. The pharmacodynamics results confirmed that the GB-PEG-PCL NPs had an obvious cerebral protection effect.

PQ401, an IGF-1R inhibitor, induces apoptosis and inhibits growth, proliferation and migration of glioma cells.

Growth factor signalling pathways transduce extra-cellular physiological cues to guide cells to maintain critical cellular functions, including cell proliferation, survival and metabolism. Dysregulation of certain growth factor signalling pathways has been shown as a major route to promote tumourigenesis. Glioma is a type of aggressive malignant tumour with no effective systematic therapy so far. Overexpression or hyperactivation of IGF-1R has been observed to be tightly associated with glioma progression and poor prognosis. Here, we examined the biological effects of a specific IGF-1R inhibitor, PQ401, on suppressing U87MG glioma cell growth and migration. Specifically, we observed that PQ401 not only induced cellular apoptosis in U87MG cells and subsequently reduced cell viability and proliferation but also attenuated cell mobility in vitro. More importantly, through a mouse xenograft model, we observed that administration of PQ401 on mice led to suppression of glioma tumour growth in vivo. In summary, our study suggests that PQ401 may serve as a promising leading drug for treating glioma patients with elevated IGF-1R signalling.

Novel chalcone derivatives as hypoxia-inducible factor (HIF)-1 inhibitor: synthesis, anti-invasive and anti-angiogenic properties.

A novel series of chalcone derivatives were synthesized and their biological activities against HIF-1 were evaluated. Among these compounds, 5d exhibited clearly inhibitory effects on HIF-1 by downregulating the expression of HIF-1α under hypoxic conditions. Meanwhile, it also significantly suppressed VEGF-induced migration and invasion of Hep3B and HUVEC cells in nontoxic concentrations. Additionally, tube formation assay demonstrated its anti-angiogenesis activity. Moreover, the in vivo study indicated that compound 5d could retard tumor growth of Hep3B xenograft models and reduced CD31 and MMP-2 expression in tumor tissues. Finally, in acute intravenous toxicity, 5d was well tolerated and was found to be non-toxic up to 200 mg/kg in Swiss mice. These findings support the further investigation on the anti-invasive and anti-angiogenic potential of this class of compounds as HIF-1 inhibitor.

A novel small-molecule activator of procaspase-3 induces apoptosis in cancer cells and reduces tumor growth in human breast, liver and gallbladder cancer xenografts.

PURPOSE: Procaspase-3, a proenzyme of apoptotic executioner caspase-3, is overexpressed in numerous tumors. We aimed to characterize a novel procaspase-3 activator, WF-210, which may have potential as an anticancer drug. EXPERIMENTAL DESIGN: The procaspase-3 activating ability, antitumor efficacy, mechanisms of action, and toxicity profiles of WF-210 were investigated in vitro and in vivo, using normal cells, cancer cells, and mouse xenograft models. The role of procaspase-3 in WF-210-induced apoptosis was explored by manipulating procaspase-3 expression in cultured cells. RESULTS: WF-210 activated procaspase-3 with an EC50 of 0.95 µM, less than half that of its mother compound PAC-1 (2.08 µM). The mechanism involved the chelation of inhibitory zinc ions, subsequently resulting in an auto-activation of procaspase-3. WF-210 was more cytotoxic than PAC-1 to human cancer cells, but less cytotoxic to normal cells. Cancer cells with high procaspase-3 expression, like HL-60 and U-937, were particularly sensitive. WF-210-induced the apoptosis of HL-60 and U-937 cells by activating procaspases and promoting proteasome-dependent degradation of XIAP and Survivin. The level of WF-210-induced apoptosis in cultured cells was related to the level of procaspase-3 expression. Finally, WF-210 was superior to PAC-1 in retarding the in vivo growth of breast, liver and gallbladder xenograft tumors which overexpress procaspase-3, and induced no substantial weight loss or neurotoxicity. WF-210 and PAC-1 had no effect on the growth of MCF-7 xenograft tumors, which do not express procaspase-3. CONCLUSION: We identified WF-210 as a potent small-molecule activator of procaspase-3. The favorable antitumor activity and acceptable toxicity profile of WF-210 provide a strong rationale for its clinical evaluation in the treatment of tumors with high procaspase-3 expression.

Suppression of NF-κB signaling and P-glycoprotein function by gambogic acid synergistically potentiates adriamycin -induced apoptosis in lung cancer.

Gambogic acid (GA) has been approved by the Chinese Food and Drug Administration for the treatment of lung cancer in clinical trials. However, whether GA has chemosensitizing properties when combined with other chemotherapy agents in the treatment of lung cancer is not known. Here we investigated the effects of GA combined with adriamycin (ADM), a common chemotherapy agent, in regard to their activities and the possible mechanisms against lung cancer in vitro and in vivo. Cell viability results showed that sequential GA-ADM treatment was synergistic, while the reverse sequence and simultaneous treatments were antagonistic or additive, in lung cancer cells and ADM resistant cells, but not in normal cells. The combined use of GA and ADM synergistically displayed apoptosis-inducing activities in lung cancer cells. Moreover, GA in combination with ADM could promote PARP cleavage, enhance caspases activation and decrease the expression of anti-apoptotic proteins in lung cancer cells. The combined use of GA and ADM decreased the expression of P-glycoprotein and increased the accumulation of ADM in lung cancer cells. Furthermore, it was found that, prior to ADM treatment, GA could inhibit NF-κB signaling pathways, which have been validated to confer ADM resistance. The critical role of NF-κB was further confirmed by using PDTC, a NF-κB inhibitor, which significantly increased apoptosis induction by the combination of GA and ADM and inhibited ADM-induced ABCB1 upregulation. Importantly, our results indicated that the combination of GA and ADM exerted enhanced anti-tumor effects on A549 xenograft models through inhibiting NF-κB and P-glycoprotein, and attenuated ADM-induced cardiotoxicity. Collectively, these findings indicate that GA sensitizes lung cancer cells to ADM in vitro and in vivo, providing a rationale for the combined use of GA and ADM in lung cancer chemotherapy.

Activated microglia are implicated in cognitive deficits, neuronal death, and successful recovery following intermittent ethanol exposure.

Microglia function as the primary immune effector cells in the brain and play a pivotal role in the neuroinflammatory processes which are critical component of neurodegenerative diseases. Alcohol abuse has been considered as one of the common reasons for neurodegeneration although the causative factors are poorly understood. Here, we investigated whether activated microglia were implicated in neurodegeneration and cognitive dysfunctions in adult rats after intermittent alcohol abuse. Rats were given orally a priming dose of 5 g/kg ethanol and then 3g/kg every 8h for 4 days, followed by a 3-day ethanol-withdrawal period. These 4 days of ethanol treatments were repeated four times intermittently to simulate the binge drinking of human alcoholics. Neurodegeneration and microglial activation were detected by Fluoro-Jade B staining, Golgi staining, immunohistochemistry and ELISA, respectively, while cognitive function was assessed by Morris water maze and novel object recognition. The results showed that microglial activation and inflammatory cytokine expression were obvious in the parietal association cortex, entorhinal cortex and hippocampus accompanied by neurodegeneration following ethanol treatment. Moreover, learning and memory abilities also declined following ethanol treatments. However, the hypertrophied microglia disappeared accompanied by the decrease of inflammatory cytokines levels on day 4, and ramified microglial proliferated significantly on day 14 after ethanol withdrawal, along with a recovery from neuronal damage and cognitive impairment. Thus, the present study indicated that activated microglia might be involved in neurodegeneration and cognitive dysfunctions induced by intermittent ethanol exposure, and neurotrophic microglia appear to have a contribution to the recovery during abstinence.