An Intricate Connection between Alternative Splicing and Phenotypic Plasticity in Development and Cancer

During tumor progression, hypoxia, nutrient deprivation or changes in the extracellular environment (i.e., induced by anti-cancer drugs) elicit adaptive responses in cancer cells. Cellular plasticity increases the chance that tumor cells may survive in a challenging microenvironment, acquire new mechanisms of resistance to conventional drugs, and spread to distant sites. Re-activation of stem pathways appears as a significant cause of cellular plasticity because it promotes the acquisition of stem-like properties through a profound phenotypic reprogramming of cancer cells. In addition, it is a major contributor to tumor heterogeneity, depending on the coexistence of phenotypically distinct subpopulations in the same tumor bulk. Several cellular mechanisms may drive this fundamental change, in particular, high-throughput sequencing technologies revealed a key role for alternative splicing (AS). Effectively, AS is one of the most important pre-mRNA processes that increases the diversity of transcriptome and proteome in a tissue- and development-dependent manner. Moreover, defective AS has been associated with several human diseases. However, its role in cancer cell plasticity and tumor heterogeneity remains unclear. Therefore, unravelling the intricate relationship between AS and the maintenance of a stem-like phenotype may explain molecular mechanisms underlying cancer cell plasticity and improve cancer diagnosis and treatment.

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Application of Single-Cell Multi-Omics in Dissecting Cancer Cell Plasticity and Tumor Heterogeneity

Frontiers in Molecular Biosciences ◽

10.3389/fmolb.2021.757024 ◽

2021 ◽

Vol 8 ◽

Author(s):

Deshen Pan ◽

Deshui Jia

Keyword(s):

Single Cell ◽

Cancer Cell ◽

Tumor Heterogeneity ◽

Recent Progress ◽

Molecular Mechanisms ◽

High Throughput Sequencing ◽

Tumor Development ◽

Cell Plasticity ◽

Translational Cancer Research ◽

Cellular Components

Tumor heterogeneity, a hallmark of cancer, impairs the efficacy of cancer therapy and drives tumor progression. Exploring inter- and intra-tumoral heterogeneity not only provides insights into tumor development and progression, but also guides the design of personalized therapies. Previously, high-throughput sequencing techniques have been used to investigate the heterogeneity of tumor ecosystems. However, they could not provide a high-resolution landscape of cellular components in tumor ecosystem. Recently, advance in single-cell technologies has provided an unprecedented resolution to uncover the intra-tumoral heterogeneity by profiling the transcriptomes, genomes, proteomes and epigenomes of the cellular components and also their spatial distribution, which greatly accelerated the process of basic and translational cancer research. Importantly, it has been demonstrated that some cancer cells are able to transit between different states in order to adapt to the changing tumor microenvironment, which led to increased cellular plasticity and tumor heterogeneity. Understanding the molecular mechanisms driving cancer cell plasticity is critical for developing precision therapies. In this review, we summarize the recent progress in dissecting the cancer cell plasticity and tumor heterogeneity by use of single-cell multi-omics techniques.

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Xanthohumol Induces Growth Inhibition and Apoptosis in Ca Ski Human Cervical Cancer Cells

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2015/921306 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 13

Author(s):

Wai Kuan Yong ◽

Sri Nurestri Abd Malek

Keyword(s):

Cell Cycle ◽

Cervical Cancer ◽

Cancer Cells ◽

Cancer Cell ◽

Morphological Changes ◽

S Phase ◽

Phase Cell ◽

Cervical Cancer Cell Line ◽

Dependent Manner ◽

Cervical Cancer Cells

We investigate induction of apoptosis by xanthohumol on Ca Ski cervical cancer cell line. Xanthohumol is a prenylated chalcone naturally found in hop plants, previously reported to be an effective anticancer agent in various cancer cell lines. The present study showed that xanthohumol was effective to inhibit proliferation of Ca Ski cells based on IC50values using sulforhodamine B (SRB) assay. Furthermore, cellular and nuclear morphological changes were observed in the cells using phase contrast microscopy and Hoechst/PI fluorescent staining. In addition, 48-hour long treatment with xanthohumol triggered externalization of phosphatidylserine, changes in mitochondrial membrane potential, and DNA fragmentation in the cells. Additionally, xanthohumol mediated S phase arrest in cell cycle analysis and increased activities of caspase-3, caspase-8, and caspase-9. On the other hand, Western blot analysis showed that the expression levels of cleaved PARP, p53, and AIF increased, while Bcl-2 and XIAP decreased in a dose-dependent manner. Taken together, these findings indicate that xanthohumol-induced cell death might involve intrinsic and extrinsic apoptotic pathways, as well as downregulation of XIAP, upregulation of p53 proteins, and S phase cell cycle arrest in Ca Ski cervical cancer cells. This work suggests that xanthohumol is a potent chemotherapeutic candidate for cervical cancer.

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ATP Inhibits Breast Cancer Migration and Bone Metastasis through Down-Regulation of CXCR4 and Purinergic Receptor P2Y11

Cancers ◽

10.3390/cancers13174293 ◽

2021 ◽

Vol 13 (17) ◽

pp. 4293

Author(s):

Xiaowen Liu ◽

Manuel A. Riquelme ◽

Yi Tian ◽

Dezhi Zhao ◽

Francisca M. Acosta ◽

...

Keyword(s):

Breast Cancer ◽

Cell Migration ◽

Bone Metastasis ◽

Cancer Cells ◽

Cancer Cell ◽

Breast Cancer Cells ◽

Cxcr4 Expression ◽

Dependent Manner ◽

Cancer Cell Migration ◽

Dose Dependent

ATP released by bone osteocytes is shown to activate purinergic signaling and inhibit the metastasis of breast cancer cells into the bone. However, the underlying molecular mechanism is not well understood. Here, we demonstrate the important roles of the CXCR4 and P2Y11 purinergic receptors in mediating the inhibitory effect of ATP on breast cancer cell migration and bone metastasis. Wound-healing and transwell migration assays showed that non-hydrolysable ATP analogue, ATPγS, inhibited migration of bone-tropic human breast cancer cells in a dose-dependent manner. BzATP, an agonist for P2X7 and an inducer for P2Y11 internalization, had a similar dose-dependent inhibition on cell migration. Both ATPγS and BzATP suppressed the expression of CXCR4, a chemokine receptor known to promote breast cancer bone metastasis, and knocking down CXCR4 expression by siRNA attenuated the inhibitory effect of ATPγS on cancer cell migration. While a P2X7 antagonist A804598 had no effect on the impact of ATPγS on cell migration, antagonizing P2Y11 by NF157 ablated the effect of ATPγS. Moreover, the reduction in P2Y11 expression by siRNA decreased cancer cell migration and abolished the impact of ATPγS on cell migration and CXCR4 expression. Similar to the effect of ATPγS on cell migration, antagonizing P2Y11 inhibited bone-tropic breast cancer cell migration in a dose-dependent manner. An in vivo study using an intratibial bone metastatic model showed that ATPγS inhibited breast cancer growth in the bone. Taken together, these results suggest that ATP inhibits bone-tropic breast cancer cells by down-regulating the P2Y11 purinergic receptor and the down-regulation of CXCR4 expression.

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Nuclear upregulation of PI3K p110β correlates with increased rRNA transcription in endometrial cancer cells

10.1101/2019.12.20.884122 ◽

2019 ◽

Author(s):

Fatemeh Mazloumi Gavgani ◽

Thomas Karlsson ◽

Ingvild L Tangen ◽

Andrea Papdiné Morovicz ◽

Victoria Smith Arnesen ◽

...

Keyword(s):

Endometrial Cancer ◽

Cancer Cells ◽

Cell Lines ◽

Molecular Mechanisms ◽

Pi3k Pathway ◽

Clinical Samples ◽

Mrna Levels ◽

Dependent Manner ◽

Cytoplasmic Staining ◽

Ec Cells

AbstractGenes encoding for components of the phosphoinositide 3-kinase (PI3K) pathway are frequently mutated in cancer, including inactivating mutations of PTEN and activating mutations of PIK3CA, encoding the PI3K catalytic subunit p110α. PIK3CB, encoding p110β, is rarely mutated, but can contribute to tumourigenesis in some PTEN-deficient tumours. The underlying molecular mechanisms are however poorly understood. By analysing cell lines and annotated clinical samples, we have previously found that p110β is highly expressed in endometrial cancer (EC) cell lines and that PIK3CB mRNA levels increase early in primary tumours correlating with lower survival. Selective inhibition of p110α and p110β led to different effects on cell signalling and cell function, p110α activity being correlated to cell survival in PIK3CA mutant cells and p110β with cell proliferation in PTEN-deficient cells. To understand the mechanisms governing the differential roles of these isoforms, we assessed their sub-cellular localisation. p110α was cytoplasmic whereas p110β was both cytoplasmic and nuclear with increased levels in both compartments in cancer cells. Immunohistochemistry of p110β in clinically annotated patient tumour sections revealed high nuclear/cytoplasmic staining ratio, which correlated significantly with higher grades. Consistently, the presence of high levels of p110β in the nuclei of EC cells, correlated with high levels of its product phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) in the nucleus. Using immunofluorescence labelling, we observed both p110β and PtdIns(3,4,5)P3 in the nucleoli of EC cell lines. The production of nucleolar PtdIns(3,4,5)P3 was dependent upon p110β activity. EC cells with high levels of nuclear PtdIns(3,4,5)P3 and p110β showed elevated nucleolar activity as assessed by the increase in 47S pre-rRNA transcriptional levels in a p110β-dependent manner. Altogether, these results present a nucleolar role for the PI3K pathway that may contribute to tumour progression in endometrial cancer.

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Betulinic Acid Suppresses Ovarian Cancer Cell Proliferation through Induction of Apoptosis

Biomolecules ◽

10.3390/biom9070257 ◽

2019 ◽

Vol 9 (7) ◽

pp. 257 ◽

Cited By ~ 1

Author(s):

Dahae Lee ◽

Seoung Rak Lee ◽

Ki Sung Kang ◽

Yuri Ko ◽

Changhyun Pang ◽

...

Keyword(s):

Ovarian Cancer ◽

Cancer Cell ◽

Betulinic Acid ◽

Molecular Mechanisms ◽

Underlying Mechanism ◽

Nuclear Staining ◽

Dependent Manner ◽

Meoh Extract ◽

Concentration Dependent Manner ◽

Induction Of Apoptosis

Ovarian cancer is one of the leading causes of cancer deaths worldwide in women, and the most malignant cancer among the different gynecological cancers. In this study, we explored potentially anticancer compounds from Cornus walteri (Cornaceae), the MeOH extract of which has been reported to show considerable cytotoxicity against several cancer cell lines. Phytochemical investigations of the MeOH extract of the stem and stem bark of C. walteri by extensive application of chromatographic techniques resulted in the isolation of 14 compounds (1–14). The isolated compounds were evaluated for inhibitory effects on the viability of A2780 human ovarian carcinoma cells and the underlying molecular mechanisms were investigated. An 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was employed to assess the anticancer effects of compounds 1–14 on A2780 cells, which showed that compound 11 (betulinic acid) reduced the viability of these cells in a concentration-dependent manner and had an half maximal (50%) inhibitory concentration (IC50) of 44.47 μM at 24 h. Nuclear staining and image-based cytometric assay were carried out to detect the induction of apoptosis by betulinic acid. Betulinic acid significantly increased the condensation of nuclei and the percentage of apoptotic cells in a concentration-dependent manner in A2780 cells. Western blot analysis was performed to investigate the underlying mechanism of apoptosis. The results indicated that the expression levels of cleaved caspase-8, -3, -9, and Bax were increased in A2780 cells treated with betulinic acid, whereas those of Bcl-2 were decreased. Thus, we provide the experimental evidence that betulinic acid can induce apoptosis in A2780 cells through both mitochondria-dependent and -independent pathways and suggest the potential use of betulinic acid in the development of novel chemotherapeutics for ovarian cancer therapy.

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Impact of the Tumor Microenvironment on Tumor Heterogeneity and Consequences for Cancer Cell Plasticity and Stemness

Cancers ◽

10.3390/cancers12123716 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3716

Author(s):

Ralf Hass ◽

Juliane von der Ohe ◽

Hendrik Ungefroren

Keyword(s):

Tumor Microenvironment ◽

Cancer Cell ◽

Tumor Heterogeneity ◽

Cancer Therapies ◽

Epigenetic Alterations ◽

Cell Plasticity ◽

Cellular Phenotypes ◽

Therapy Success ◽

Physical And Chemical

Tumor heterogeneity is considered the major cause of treatment failure in current cancer therapies. This feature of solid tumors is not only the result of clonal outgrowth of cells with genetic mutations, but also of epigenetic alterations induced by physical and chemical signals from the tumor microenvironment (TME). Besides fibroblasts, endothelial and immune cells, mesenchymal stroma/stem-like cells (MSCs) and tumor-associated macrophages (TAMs) intimately crosstalk with cancer cells and can exhibit both anti- and pro-tumorigenic effects. MSCs can alter cancer cellular phenotypes to increase cancer cell plasticity, eventually resulting in the generation of cancer stem cells (CSCs). The shift between different phenotypic states (phenotype switching) of CSCs is controlled via both genetic programs, such as epithelial-mesenchymal transdifferentiation or retrodifferentiation, and epigenetic alterations triggered by signals from the TME, like hypoxia, spatial heterogeneity or stromal cell-derived chemokines. Finally, we highlight the role of spontaneous cancer cell fusion with various types of stromal cells. i.e., MSCs in shaping CSC plasticity. A better understanding of cell plasticity and phenotype shifting in CSCs is a prerequisite for exploiting this phenomenon to reduce tumor heterogeneity, thereby improving the chance for therapy success.

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A Novel 3D Model for Visualization and Tracking of Fibroblast-Guided Directional Cancer Cell Migration

Biology ◽

10.3390/biology9100328 ◽

2020 ◽

Vol 9 (10) ◽

pp. 328

Author(s):

Yihe Zhang ◽

Bingjie Jiang ◽

Meng Huee Lee

Keyword(s):

Cell Migration ◽

Cancer Cells ◽

Cancer Cell ◽

Molecular Mechanisms ◽

Cell Mass ◽

Physical Contact ◽

Physical Interaction ◽

Matrix Remodeling ◽

Cancer Cell Migration ◽

Cell Type

Stromal fibroblasts surrounding cancer cells are a major and important constituent of the tumor microenvironment not least because they contain cancer-associated fibroblasts, a unique fibroblastic cell type that promotes tumorigenicity through extracellular matrix remodeling and secretion of soluble factors that stimulate cell differentiation and invasion. Despite much progress made in understanding the molecular mechanisms that underpin fibroblast–tumor cross-talk, relatively little is known about the way the two cell types interact from a physical contact perspective. In this study, we report a novel three-dimensional dumbbell model that would allow the physical interaction between the fibroblasts and cancer cells to be visualized and monitored by microscopy. To achieve the effect, the fibroblasts and cancer cells in 50% Matrigel suspension were seeded as independent droplets in separation from each other. To allow for cell migration and interaction, a narrow passage of Matrigel causeway was constructed in between the droplets, effectively molding the gel into the shape of a dumbbell. Under time-lapse microscopy, we were able to visualize and image the entire process of fibroblast-guided cancer cell migration event, from initial vessel-like structure formation by the fibroblasts to their subsequent invasion across the causeway, attracting and trapping the cancer cells in the process. Upon prolonged culture, the entire population of fibroblasts eventually infiltrated across the passage and condensed into a spheroid-like cell mass, encapsulating the bulk of the cancer cell population within. Suitable for almost every cell type, our model has the potential for a wider application as it can be adapted for use in drug screening and the study of cellular factors involved in cell–cell attraction.

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Cisplatin and Paclitaxel Modulated the Cell Survival Potential of Prostate Cancer Cells

Proceedings ◽

10.3390/proceedings2019040042 ◽

2020 ◽

Vol 40 (1) ◽

pp. 42

Author(s):

Kashani ◽

Kilbas ◽

Yerlikaya ◽

Gurkan ◽

Arisan

Keyword(s):

Prostate Cancer ◽

Cell Viability ◽

Cell Survival ◽

Cancer Cells ◽

Cancer Cell ◽

Prostate Cancer Cell ◽

Dependent Manner ◽

Prostate Cancer Cells ◽

Cell Viability Assay ◽

Chemotherapy Drugs

Prostate cancer is the second common cause of death among men worldwide. In the treatment of prostate cancer, conventional chemotherapeutics are commonly used. The plant alkaloid Paclitaxel and platinum-based cisplatin are the most common chemotherapy drugs. The transcription factor p53 has a potential target in the regulation of cell response to DNA damage of prostate cancer. Although the effectiveness of these drugs on prostate cancer cell progression had been proved, the mechanistic action of these drugs on the progression of the disease is not detailed explained. In this study, we aim to examine the function of p53 overexpression in prostate cancer cell survival. Therefore, we treated wild type (wt) and p53 overexpressed PC3 (p53+) prostate cancer cells with cisplatin or paclitaxel. According to the MTT Cell Viability assay, cisplatin (12.5–25–50 µM) was found to be more effective decreasing PC3 and PC3 p53+ cell viability in a dose-dependent manner compared to paclitaxel (12.5–25–50 nM). Colony formation assay showed that treatment of cells with cisplatin or paclitaxel caused the loss of colony forming ability of PC3 and PC3 p53+ cells. In addition, the critical apoptotic markers Caspase-3 and Caspase-9 expressions were altered with cisplatin or paclitaxel treated PC3 wt and p53+ cells.

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DENR promotes translation reinitiation via ribosome recycling to drive expression of oncogenes including ATF4

Nature Communications ◽

10.1038/s41467-020-18452-2 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Jonathan Bohlen ◽

Liza Harbrecht ◽

Saioa Blanco ◽

Katharina Clemm von Hohenberg ◽

Kai Fenzl ◽

...

Keyword(s):

Stress Response ◽

Cancer Cells ◽

Strong Correlation ◽

Molecular Mechanisms ◽

Open Reading Frames ◽

Translation Efficiency ◽

Dependent Manner ◽

Translation Factors ◽

Upstream Open Reading Frames ◽

Reading Frames

Abstract Translation efficiency varies considerably between different mRNAs, thereby impacting protein expression. Translation of the stress response master-regulator ATF4 increases upon stress, but the molecular mechanisms are not well understood. We discover here that translation factors DENR, MCTS1 and eIF2D are required to induce ATF4 translation upon stress by promoting translation reinitiation in the ATF4 5′UTR. We find DENR and MCTS1 are only needed for reinitiation after upstream Open Reading Frames (uORFs) containing certain penultimate codons, perhaps because DENR•MCTS1 are needed to evict only certain tRNAs from post-termination 40S ribosomes. This provides a model for how DENR and MCTS1 promote translation reinitiation. Cancer cells, which are exposed to many stresses, require ATF4 for survival and proliferation. We find a strong correlation between DENR•MCTS1 expression and ATF4 activity across cancers. Furthermore, additional oncogenes including a-Raf, c-Raf and Cdk4 have long uORFs and are translated in a DENR•MCTS1 dependent manner.

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Regulating Methylation at H3K27: A Trick or Treat for Cancer Cell Plasticity

Cancers ◽

10.3390/cancers12102792 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2792

Author(s):

Provas Das ◽

Joseph H. Taube

Keyword(s):

Cell Fate ◽

Cancer Cell ◽

Current Knowledge ◽

Carcinoma Cells ◽

Aberrant Methylation ◽

Cellular Plasticity ◽

Cell Plasticity ◽

Stages Of Development ◽

Histone 3 ◽

Cancer Initiation

Properly timed addition and removal of histone 3 lysine 27 tri-methylation (H3K27me3) is critical for enabling proper differentiation throughout all stages of development and, likewise, can guide carcinoma cells into altered differentiation states which correspond to poor prognoses and treatment evasion. In early embryonic stages, H3K27me3 is invoked to silence genes and restrict cell fate. Not surprisingly, mutation or altered functionality in the enzymes that regulate this pathway results in aberrant methylation or demethylation that can lead to malignancy. Likewise, changes in expression or activity of these enzymes impact cellular plasticity, metastasis, and treatment evasion. This review focuses on current knowledge regarding methylation and de-methylation of H3K27 in cancer initiation and cancer cell plasticity.

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