A truncated form of the p27 CDK inhibitor translated from pre-mRNA causes cell cycle arrest at G2 phase

Pre-mRNA splicing is indispensable for eukaryotic gene expression. Splicing inhibition causes cell cycle arrest and cell death, which are the reasons of potent anti-tumor activity of splicing inhibitors. Here, we found that truncated proteins are involved in cell cycle arrest and cell death upon splicing inhibition. We analyzed pre-mRNAs accumulated in the cytoplasm where translation occurs, and found that a truncated form of the p27 CDK inhibitor, named p27*, is translated from pre-mRNA and accumulated in G2 arrested cells. Overexpression of p27* caused G2 phase arrest through inhibiting CDK-cyclin complexes. Conversely, knockout of p27* accelerated resumption of cell proliferation after washout of splicing inhibitor. Interestingly, p27* was resistant to proteasomal degradation. We propose that cells produce truncated proteins with different nature to the original proteins via pre-mRNA translation only under splicing deficient conditions to response to the splicing deficient conditions.

Screening of Apoptosis Pathway-Mediated Anti-Proliferative Activity of the Phytochemical Compound Furanodienone against Human Non-Small Lung Cancer A-549 Cells

Furanodienone (FDN), a major bioactive component of sesquiterpenes produced from Rhizoma curcumae, has been repeatedly acknowledged for its intrinsic anticancer efficacy against different types of cancer. In this study, we aimed to investigate the cytotoxic potential of furanodienone against human lung cancer (NSCLC A549) cells in vitro, as well as its underlying molecular mechanisms in the induction of apoptosis. Herein, we found that FDN significantly inhibited the proliferation of A549 cells in a dose-dependent manner. In addition, treatment with FDN potentially triggered apoptosis in A549 cells via not only disrupting the nuclear morphology, but by activating capsase-9 and caspase-3 with concomitant modulation of the pro- and antiapoptotic gene expression as well. Furthermore, FDN revealed its competence in inducing cell cycle arrest at G0/G1 phase in A549 cells, which was associated with decreased expression of cyclin D1 and cyclin-dependent kinase 4 (CDK4), along with increased expression of CDK inhibitor p21Cip1. Intriguingly, FDN treatment efficiently downregulated the Wnt signaling pathway, which was correlated with increased apoptosis, as well as cell cycle arrest, in A549 cells. Collectively, FDN might represent a promising adjuvant therapy for the management of lung cancer.

Berberine and Evodiamine Synergically Exert Anti-colorectal Cancer Effeccts via P38/MAPK/MAPKAPK2/HSP27 Signaling Pathway

Objective: Combinatorial natural products have high application potential for treatment of complex diseases owing to their synergistic effects and multi-targeting effect. However, studies have not explored the therapeutic effect and the synergetic mechanisms of action combinations of natural products. The present study aimed sought to evaluate the synergistic antitumor effects of a combination of Berberine and Evodiamine, and explore the drug effect on proliferation, migration, invasion of HCT116 and RKO human colorectal cancer cells. Results: The effect of berberine and evodiamine at a specific paired dose (BER30μM, EVO 0.8μM) was explored. A combination of berberine and evodiamine had no effect on activity and proliferation of HCT116 and RKO cells. The combination regulates the cell cycle of HCT116 and RKO cells at different cell phases. Berberine mainly blocked the cell cycle at G0/G1 phase, whereas evodiamine induced cell cycle arrest at G2/M phase. The results showed that the combined effect of berberine and evodiamine does not offset each other, but plays a synergistic role in regulation of colon cancer cell cycle. Western blot analysis showed that the combination of berberine and evodiamine regulated cell cycle by downregulating expression of cdc25c and upregulating expression of p21. The combination significantly inhibited cell migration and invasion by regulating EMT related proteins, upregulating expression of E-cadherin and downregulating expression of N-cadherin. The combination of berberine and evodiamine significantly inhibited phosphorylation of P38 MAPK in HCT116 and RKO cells, and further inhibited phosphorylation of the downstream MAPKAPK2 and HSP27, thus playing a synergistic anti-colon cancer role.Conclusion: Berberine and Evodiamine exhibit synergistic antitumor effects by suppressing cell proliferation, inducing cell cycle arrest and inhibiting EMT by modulating P38MAPK /MAPKAPK2/HSP27 pathway.Significance of the study: To illustrate the potential mechanism of formula-based combination of natural products, and explore the potential applications of the combination and possible antitumor therapeutic targets.

Knockout of caspase-7 gene improves the expression of recombinant protein in CHO cell line through the cell cycle arrest in G2/M phase

Background Chinese hamster ovary cell line has been used routinely as a bioproduction factory of numerous biopharmaceuticals. So far, various engineering strategies have been recruited to improve the production efficiency of this cell line such as apoptosis engineering. Previously, it is reported that the caspase-7 deficiency in CHO cells reduces the cell proliferation rate. But the effect of this reduction on the CHO cell productivity remained unclear. Hence, in the study at hand the effect of caspase-7 deficiency was assessed on the cell growth, viability and protein expression. In addition, the enzymatic activity of caspase-3 was investigated in the absence of caspase-7. Results Findings showed that in the absence of caspase-7, both cell growth and cell viability were decreased. Cell cycle analysis illustrated that the CHO knockout (CHO-KO) cells experienced a cell cycle arrest in G2/M phase. This cell cycle arrest resulted in a 1.7-fold increase in the expression of luciferase in CHO-KO cells compared to parenteral cells. Furthermore, in the apoptotic situation the enzymatic activity of caspase-3 in CHO-KO cells was approximately 3 times more than CHO-K1 cells. Conclusions These findings represented that; however, caspase-7 deficiency reduces the cell proliferation rate but the resulted cell cycle arrest leads to the enhancement of recombinant protein expression. Moreover, increasing in the caspase-3 enzymatic activity compensates the absence of caspase-7 in the caspase cascade of apoptosis.

Melatonin Induces Cell Cycle Arrest, Inhibits Cell Proliferation and Accelerates Apoptosis by Modulation of CDK4 in NSCLC

Purpose To explore whether melatonin affect the progression of cell cycle and exert anticancer activities via the modulation of CDK4 in NSCLC . Methods Cells treated with melatonin were used for assessing the anticancer effect of melatonin. Cells transfected with lentivirus for CDK4 upregulation or downregulation was constructed to evaluate the role of CDK4 in melatonin-induced anticancer effect. The protein and mRNA level of CDK4, PCNA and Bax were detected by western blotting and qRT-PCR. The application of flow cytometry was used for analyzing the distribution of cell cycle and apoptosis. Animal model of subcutaneous tumor was constructed and used for further study in vivo. Results We found that melatonin inhibited cell viability, colony formation, downregulated the expression of CDK4 and PCNA while upregulated the level of Bax. Besides, melatonin decreased the phosphorylation of ERK. Importantly, inhibition of ERK activation by PD98059 particapated in melatonin-induced downregulation of CDK4. Furthermore, melatonin led to G1 arrest and cell apoptosis. CDK4 knockdown enhanced melatonin-induced cell cycle arrest while CDK4 overexpression reversed the effect. Additionally, the animal experiment showed that melatonin decreased the level of CDK4 and inhibited tumor growth. However, the anti-tumor effect of melatonin was reversed by CDK4 overexpression. Conclusion Taken together, CDK4 involved in anti-cancer activities of melatonin. Melatonin led to G1 arrest, blocked G1-to-S transition, as a result, inhibited cell proliferation and accelerates apoptosis via suppressing CDK4 signaling. Targeting CDK4 inhibition and combining it with melatonin has protential to be a novel strategy for NSCLC.

Toward Tumor Fight and Tumor Microenvironment Remodeling: PBA Induces Cell Cycle Arrest and Reduces Tumor Hybrid Cells’ Pluripotency in Bladder Cancer

Bladder cancer (BC) is the second most frequent cancer of the genitourinary system. The most successful therapy since the 1970s has consisted of intravesical instillations of Bacillus Calmette–Guérin (BCG) in which the tumor microenvironment (TME), including macrophages, plays an important role. However, some patients cannot be treated with this therapy due to comorbidities and severe inflammatory side effects. The overexpression of histone deacetylases (HDACs) in BC has been correlated with macrophage polarization together with higher tumor grades and poor prognosis. Herein we demonstrated that phenylbutyrate acid (PBA), a HDAC inhibitor, acts as an antitumoral compound and immunomodulator. In BC cell lines, PBA induced significant cell cycle arrest in G1, reduced stemness markers and increased PD-L1 expression with a corresponding reduction in histone 3 and 4 acetylation patterns. Concerning its role as an immunomodulator, we found that PBA reduced macrophage IL-6 and IL-10 production as well as CD14 downregulation and the upregulation of both PD-L1 and IL-1β. Along this line, PBA showed a reduction in IL-4-induced M2 polarization in human macrophages. In co-cultures of BC cell lines with human macrophages, a double-positive myeloid–tumoral hybrid population (CD11b+EPCAM+) was detected after 48 h, which indicates BC cell–macrophage fusions known as tumor hybrid cells (THC). These THC were characterized by high PD-L1 and stemness markers (SOX2, NANOG, miR-302) as compared with non-fused (CD11b−EPCAM+) cancer cells. Eventually, PBA reduced stemness markers along with BMP4 and IL-10. Our data indicate that PBA could have beneficial properties for BC management, affecting not only tumor cells but also the TME.

Naringenin Induces ROS-Mediated ER Stress, Autophagy, and Apoptosis in Human Osteosarcoma Cell Lines

Osteosarcoma, a primary bone tumor, responds poorly to chemotherapy and radiation therapy in children and young adults; hence, as the basis for an alternative treatment, this study investigated the cytotoxic and antiproliferative effects of naringenin on osteosarcoma cell lines, HOS and U2OS, by using cell counting kit-8 and colony formation assays. DNA fragmentation and the increase in the G2/M phase in HOS and U2OS cells upon treatment with various naringenin concentrations were determined by using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay and Annexin V/propidium iodide double staining, respectively. Flow cytometry was performed, and 2′,7′-dichlorodihydrofluorescein diacetate, JC-1, and Fluo-4 AM ester probes were examined for reactive oxygen species (ROS) generation, mitochondrial membrane potential, and intracellular calcium levels, respectively. Caspase activation, cell cycle, cytosolic and mitochondrial, and autophagy-related proteins were determined using with western blotting. The results indicated that naringenin significantly inhibited the viability and proliferation of osteosarcoma cells in a dose-dependent manner. In addition, naringenin induced cell cycle arrest in osteosarcoma cells by inhibiting cyclin B1 and cyclin-dependent kinase 1 expression and upregulating p21 expression. Furthermore, naringenin significantly inhibited the growth of osteosarcoma cells by increasing the intracellular ROS level. Naringenin induced endoplasmic reticulum (ER) stress-mediated apoptosis through the upregulation of ER stress markers, GRP78 and GRP94. Naringenin caused acidic vesicular organelle formation and increased autophagolysosomes, microtubule-associated protein-light chain 3-II protein levels, and autophagy. The findings suggest that the induction of cell apoptosis, cell cycle arrest, and autophagy by naringenin through mitochondrial dysfunction, ROS production, and ER stress signaling pathways contribute to the antiproliferative effect of naringenin on osteosarcoma cells.