LncRNA maternally expressed gene 3 (MEG3) is a potential prognostic and diagnostic biomarker in colorectal carcinoma (CC). However, its cellular functions and mechanism remain not fully uncovered. Relative expression of MEG3, miRNA (miR)-103a-3p, and pyruvate dehydrogenase E1 subunit beta (PDHB) was detected by RT-qPCR and western blotting. Cell proliferation was measured by CCK-8 assay, colony formation assay, and flow cytometry, as well as xenograft tumor assay. Transwell assay examined cell invasion. Endoplasmic reticulum (ER) stress was eva luated by western blotting. Dual-luciferase reporter assay and RNA immunoprecipitation determined the relationship between miR-103a-3p and MEG3 or PDHB. Expression of MEG3 was downregulated in human CC tumor tissues and cells (SW620 and HCT116), accompanied by higher miR-103a-3p and lower PDHB. Restoring MEG3 suppressed cell viability, colony formation ability, and invasion, 2 arrested cell cycle, and induced apoptosis rate in SW620 and HCT116 cells, as well as promoted expression of ER stress-related proteins (GRP78, ATF6, CHOP, caspase-3, and caspase-9). Furthermore, MEG3 overexpression hindered tumor growth and facilitated ER stress in vivo. Molecularly, miR-103a-3p was a target of MEG3, and further targeted PDHB. Similarly, in function, blocking miR-103a-3p suppressed CC in vitro by affecting proliferation, invasion, and ER stress; in addition, restoring miR-103a-3p partially counteracted the suppressive role of MEG3 in CC cells. MEG3 sponged miR-103a-3p to suppress CC malignancy by inducing ER stress and inhibiting cell proliferation and invasion via upregulating PDHB, suggesting a novel MEG3/miR-103a-3p/PDHB ceRNA pathway. Key words : MEG3; ER stress; miR-103a-3p; pyruvate dehydrogenase E1 subunit beta (PDHB); colorectal carcinoma Endoplasmic reticulum (ER) stress, caused by the accumulation of unfolded or misfolded proteins, plays a dual role in tumorigenesis and development [1], by linking to fundamental biological processes, such as proliferation, apoptosis, migration, invasion and autophagy [2-4]. In response to ER stress, unfolded protein response (UPR) is activated to promote tumor-survival response or anti-tumor response [5, 6]. Not surprisingly, ER stress and UPR are associated with intestinal diseases, including colorectal carcinoma (CC) [7, 8]. CC is the third most common cancer according to global cancer statistics 2018 of the International Agency for Research on Cancer [9], and its incidence and mortality are expected to be rapidly increasing in many low-income and middle-income countries [10]. The survival of CC patients is closely related to the stage of CC [11], thus it is essential to identify more efficient mole cular targets for better understanding of the mechanism underlying CC progression, as well as seeking early diagnostic markers. Recently, it has been well-documented that long noncoding RNAs (lncRNAs) as key regulators mediate competing endogenous RNA (ceRNA) network to regulate carcinogenesis, progression and treatment of CC [12, 13]. LncRNA...
Purpose: Increasing evidence suggests that microRNAs (miRNAs) may be involved in the occurrence and progression of non-small cell lung cancer (NSCLC). In the present study, we used serum-starved A549 cells emulating tumor under a nutrient depletion stress in the microenvironment. Patients and methods: We first detected the expression level of miR-224 between tumor tissues and the adjacent normal tissues. We analyzed the expression levels of miR-224 and its predicted target phosphatase and tensin homolog (PTEN) using quantitative real-time PCR (qRT-PCR) in starved A549 cells. Following transfection with miR-224 mimic or inhibitor in starved A549 cells, MTT assay, Annexin V FITC/PI staining, and LC-3 immunofluorence staining were performed to investigate the roles of miR-224 on proliferation, apoptosis, and autophagy. Next, the expression of apoptosis-related protein Bax and Bcl-2, autophagy-related proteins LC3, PI3K signaling, and target PTEN were measured using qRT-PCR and Western blot assays. The direct interaction between miR-224 and PTEN was validated with a dual luciferase assay. Results: We found that the expression level of miR-224 in tumor tissues was significantly higher when compared with the adjacent normal tissues. We discovered a reciprocal expression pattern between miR-224 and PTEN in starved A549 cells, and transfection with miR-224 mimic led to down-regulation of PTEN. A dual luciferase assay further confirmed the direct interaction between miR-224 and 3ʹUTR of PTEN. Transfection with miR-224 mimic in starved A549 cells resulted in enhanced cell proliferation, reduced apoptosis, and autophagy, accompanied by increased expression of anti-apoptotic protein Bcl-2, decreased expression of pro-apoptotic protein Bax, and autophagy-related protein LC3. Activation of PI3K was observed in miR-224 mimic transfected cells. The reverse effects by the miR-224 inhibitor in all experiments were observed. Conclusion: Taken together, we proved that miR-224 might play essential roles in cellular functions of nutrient-depleted A549 cells possibly through regulating the target PTEN and downstream signal PI3K, suggesting the potential of miR-224 to be a therapeutic target for NSCLC therapy.
The current study aims to investigate the anticancer effects of zapotin flavone in human gastric carcinoma cells. MTT assay was performed to determine the cytotoxicity effects of zapotin against the gastric cancer cells (SNU-1) and normal gastric cells (GES-1). SNU-1 cell morphology was analyzed through phase-contrast microscopy. Apoptosis was identified through DAPI staining assay and quantified through annexin V/propidium iodide (PI) staining. The effects on cell migration and invasion were carried out through transwell assay. Apoptosis and m-TOR/PI3K/AKT signalling pathway related proteins were analysed through western blotting. Proliferation rate of gastric cancer SNU-1 cell line declined with enhanced zapotin concentrations in comparison to normal GES-1 cells. Substantial morphological changes after zapotin exposure, including nuclear condensation and membrane rupture was observed. Further, increasing number of apoptotic cells, suppression of both cell migration and invasion was observed with increased zapotin concentrations. Finally, western blotting indicated significant blocking of m-TOR/PI3K/AKT signalling pathway. We conclude that zapotin can act as a potential drug against the gastric cancer.
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