BCL2 interaction with actin in vitro may inhibit cell motility by enhancing actin polymerization

Jasplakinolide Attenuates Cell Migration by Impeding Alpha-1-syntrophin Protein Phosphorylation in Breast Cancer Cells

BACKGROUND

Alpha-1-syntrophin (SNTA1) is emerging as a novel modulator of the actin cytoskeleton. SNTA1 binds to F-actin and regulates intracellular localization and activity of various actin organizing signaling molecules. Aberration in syntrophin signaling has been closely linked with deregulated growth connected to tumor development/metastasis and its abnormal over expression has been observed in breast cancer. In the present work the effect of jasplakinolide, an actin-binding cyclodepsipeptide, on the SNTA1 protein activity and SNTA1 mediated downstream cellular events was studied in MDA-MB-231 breast cancer cell line.

METHODS

SNTA1 protein levels and phosphorylation status were determined in MDA-MB-231 cells post jasplakinolide exposure using western blotting and immunoprecipitation techniques respectively. MDA-MB-231 cells were transfected with WT SNTA1 and DM SNTA1 (Y^215/229 phospho mutant) and simultaneously treated with jasplakinolide. The effect of jasplakinolide and SNTA1 protein on cell migration was determined using the boyden chamber assay.

RESULTS

Jasplakinolide treatment decreases proliferation of MDA-MB-231 cells in both dose and time dependent manner. Results suggest that subtoxic doses of jasplakinolide induce morphological changes in MDA-MB-231 cells from flat spindle shape adherent cells to round weakly adherent forms. Mechanistically, jasplakinolide treatment was found to decrease SNTA1 protein levels and its tyrosine phosphorylation status. Moreover, migratory potential of jasplakinolide treated cells was significantly inhibited in comparison to control cells.

CONCLUSION

Our results demonstrate that jasplakinolide inhibits cell migration by impairing SNTA1 functioning in breast cancer cells.

Loss of exosomal miR-3188 in cancer-associated fibroblasts contributes to HNC progression

BACKGROUND

Head and neck cancer (HNC) is one of the most common deadly diseases worldwide. An increasing number of studies have recently focused on the malignant functions of cancer-associated fibroblasts (CAFs) in numerous cancers. However, the underlying mechanisms by which CAF-derived exosomes promote tumor progression need to be further elucidated. This study aims to determine whether the loss of specific miRNAs in CAF-derived exosomes may be involved in the malignant transformation of HNC.

METHODS

MiRNA array and real-time PCR assays were used to analyze the differential expression of miRNAs in exosomes from normal fibroblasts (NFs) and CAFs. Cell proliferation, EdU incorporation, colony formation, apoptosis, cell cycle distribution and xenograft assays were performed to examine the effects of miR-3188 on HNC in vitro and in vivo. Real-time PCR, western blotting and luciferase reporter assays were used to identify the target genes of miR-3188. Furthermore, tumor-bearing mouse models were used to prove the potential therapeutic value of miR-3188-loaded exosomes in HNC.

RESULTS

Our results showed that miR-3188 expression is reduced in exosomes and their parental CAFs from HNC tissues. In addition, miR-3188 can be transferred from fibroblasts to HNC cells by exosomes. Further exploration demonstrated that exosomal miR-3188 can influence the proliferation and apoptosis of HNC cells by directly targeting B-cell lymphoma 2 (BCL2) in vitro and in vivo. More importantly, we also found that miR-3188-loaded exosomes significantly inhibited tumor growth in vivo.

CONCLUSIONS

Our findings revealed that CAF-derived exosomes contain lower miR-3188 levels than NFs, and the loss of miR-3188 in exosomes contributes to the malignant phenotypes of HNC cells through the derepression of BCL2. Furthermore, these data suggest the potential therapeutic value of exosomal miR-3188 for inhibiting HNC growth.

E-cadherin-mediated impairment increases anti-apoptotic mechanism through upregulation of Bcl-2: An immunohistochemical study in various patterns of invasion of oral squamous cell carcinoma

BACKGROUND

Bcl-2 and E-cadherin proteins are known to be involved in the control of apoptotic cell death and invasive potential, respectively, which is an important hallmark of tumor regulation that influences their biologic behavior.

AIM

This study investigates the relationship of Bcl-2 and E-cadherin immunoexpression in various Bryne's patterns of invasion.

MATERIAL AND METHODS

Immunohistochemical analyses for Bcl-2 and E-cadherin were performed on paraffin-embedded tissue sections on 40 cases (32 cases of Oral squamous cell carcinoma and eight cases of controls) and were scored using qualitative and quantitative (percentage positive) analysis.

STATISTICAL ANALYSIS

The resulting data were analyzed using SPSS software version 19. Correlation between patterns of invasion and qualitative scores of Bcl-2 and E-cadherin was calculated using Spearman rho correlation. Difference of mean percentage of positive cells of Bcl-2 and E-cadherin in different patterns of invasion was tested by ANOVA followed by Tukey HSD test.

RESULTS

Bcl-2 and E-cadherin immunoreactivity was positively correlated with Bryne's pattern of invasion (P value<.05). An inverse relation was found between Bcl-2 and E-cadherin expression with Bryne's patterns 1-5 of invasion.

CONCLUSIONS

The results pointed to the antagonistic role of E-cadherin and Bcl-2 and thus provide the opportunity for cell survival along with increased invasive potential.

Evaluating Cell Processes, Quality, and Biomarkers in Pluripotent Stem Cells Using Video Bioinformatics

There is a foundational need for quality control tools in stem cell laboratories engaged in basic research, regenerative therapies, and toxicological studies. These tools require automated methods for evaluating cell processes and quality during in vitro passaging, expansion, maintenance, and differentiation. In this paper, an unbiased, automated high-content profiling toolkit, StemCellQC, is presented that non-invasively extracts information on cell quality and cellular processes from time-lapse phase-contrast videos. Twenty four (24) morphological and dynamic features were analyzed in healthy, unhealthy, and dying human embryonic stem cell (hESC) colonies to identify those features that were affected in each group. Multiple features differed in the healthy versus unhealthy/dying groups, and these features were linked to growth, motility, and death. Biomarkers were discovered that predicted cell processes before they were detectable by manual observation. StemCellQC distinguished healthy and unhealthy/dying hESC colonies with 96% accuracy by non-invasively measuring and tracking dynamic and morphological features over 48 hours. Changes in cellular processes can be monitored by StemCellQC and predictions can be made about the quality of pluripotent stem cell colonies. This toolkit reduced the time and resources required to track multiple pluripotent stem cell colonies and eliminated handling errors and false classifications due to human bias. StemCellQC provided both user-specified and classifier-determined analysis in cases where the affected features are not intuitive or anticipated. Video analysis algorithms allowed assessment of biological phenomena using automatic detection analysis, which can aid facilities where maintaining stem cell quality and/or monitoring changes in cellular processes are essential. In the future StemCellQC can be expanded to include other features, cell types, treatments, and differentiating cells.

The H1047R point mutation in p110 alpha changes the morphology of human colon HCT116 cancer cells

The class IA phosphatidylinositol 3-kinases (PI3K) is involved in controlling changes in cell morphology, which is a highly coordinated cellular event. This event is powered by actin filament polymerization and remodeling. The gain-of-function mutations in the catalytic subunit of p110α of class IA PI3K, which occur in up to one-third of human colorectal cancers (CRCs), are capable of causing dysregulation of cell signaling and thus may result in the alteration in cell morphology and motility and in turn cause cancer metastasis. In vivo studies have demonstrated that cell lines bearing the H1047R point mutation, the most frequent cancer-specific mutation in the kinase domain of p110α, are more metastatic than cells carrying wild-type p110α. In the current study, we show that the H1047R in p110α of PI3K decreases F-actin polymerization, increases the formation of filopodia and significantly changes the cell morphology in HCT116 cancer cells. The anti-apoptotic protein B-cell lymphoma 2 (Bcl-2), which is also involved in actin polymerization and cell migration, is downregulated by the H1047R mutation in p110α. Our data suggest that the H1047R mutation in PI3K is responsible for the rearrangement of the cytoskeleton, alteration in cell morphology and enhancing cell motility, and that Bcl-2 may be involved in the H1047R mutation-mediated morphological changes and increased migratory capability.

Gelsolin inhibits the proliferation and invasion of the 786-0 clear cell renal cell carcinoma cell line in vitro

The aim of the present study was to investigate the effect of gelsolin (GSN) on the proliferation and invasion of the 786-0 clear cell renal cell carcinoma (ccRCC) cell line in vitro. A GSN overexpression lentiviral vector was constructed and transfected into 786‑0 ccRCC cells in vitro. A 3-(4,5-dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) assay was conducted to detect the effect of GSN on the proliferation and adhesion ability of the 786‑0 ccRCC cells, and a Transwell invasion assay was used to determine the effect of GSN on the invasion of 786‑0 ccRCC cells. In addition, the expression levels of invasion‑associated proteins, matrix metalloproteinase (MMP)2, MMP9 and E‑cadherin were analyzed by ELISA and western blotting. The MTT assay demonstrated a significantly lower optical density value for the 786‑0/GSN cells compared with that of the 786‑0/green fluorescent protein (GFP) and 786‑0 cells following 24‑ and 48‑h culture (P<0.05). The mean penetration rate of the 786‑0/GSN cells was significantly lower than that of the 786‑0/GFP and 786‑0 cells (P<0.05) according to the Transwell invasion assay. The expression levels of MMP2 and MMP9 were significantly decreased in the 786‑0/GSN cells, when compared with the 786‑0/GFP and 786‑0 cells following a 48‑h transfection, according to ELISA (P<0.001). Furthermore, in the 786‑0/GSN cells, the expression levels of MMP2 and MMP9 were markedly decreased, while the expression of E‑cadherin was markedly increased. Thus, the overexpression of GSN may inhibit the proliferation, adhesion ability and invasion of 786‑0 ccRCC cells. Additionally, GSN downregulated the expression of MMP2 and MMP9, and upregulated the expression of E‑cadherin in the 786‑0 ccRCC cells, which may have suppressed the invasion ability of the 786-0 ccRCC cells.

BH3 Inhibitor Sensitivity and Bcl-2 Dependence in Primary Acute Lymphoblastic Leukemia Cells

BH3 mimetic drugs may be useful to treat acute lymphoblastic leukemia (ALL) but the sensitivity of primary tumor cells has not been fully evaluated. Here, B-lineage ALL cell cultures derived from a set of primary tumors were studied with respect to sensitivity to the BH3 mimetics ABT-263 and ABT-199 and to Bcl-2 dependence and function. These ALL cells each expressed high levels of Bcl-2 and exhibited great sensitivity to ABT-263 and ABT-199, which induced rapid apoptotic cell death. BH3 profiling indicated that the ALL cultures were Bcl-2 dependent. Coimmunoprecipitation studies revealed a multifaceted role for Bcl-2 in binding proapoptotic partners including Bax, Bak, Bik, and Bim. ABT-263 disrupted Bcl-2:Bim interaction in cells. Mcl-1 overexpression rendered ALL cells resistant to ABT-263 and ABT-199, with Mcl-1 assuming the role of Bcl-2 in binding Bim. Freshly isolated pediatric ALL blasts also expressed high levels of Bcl-2 and exhibited high sensitivity to Bcl-2 inhibition by the BH3 mimetic compounds. Overall, our results showed that primary ALL cultures were both more sensitive to BH3 mimetics and more uniform in their response than established ALL cell lines that have been evaluated previously. Furthermore, the primary cell model characterized here offers a powerful system for preclinical testing of novel drugs and drug combinations to treat ALL.

An Integrated Bioinformatics and Computational Biology Approach Identifies New BH3-Only Protein Candidates

In this study, we utilized an integrated bioinformatics and computational biology approach in search of new BH3-only proteins belonging to the BCL2 family of apoptotic regulators. The BH3 (BCL2 homology 3) domain mediates specific binding interactions among various BCL2 family members. It is composed of an amphipathic α-helical region of approximately 13 residues that has only a few amino acids that are highly conserved across all members. Using a generalized motif, we performed a genome-wide search for novel BH3-containing proteins in the NCBI Consensus Coding Sequence (CCDS) database. In addition to known pro-apoptotic BH3-only proteins, 197 proteins were recovered that satisfied the search criteria. These were categorized according to α-helical content and predictive binding to BCL-xL (encoded by BCL2L1) and MCL-1, two representative anti-apoptotic BCL2 family members, using position-specific scoring matrix models. Notably, the list is enriched for proteins associated with autophagy as well as a broad spectrum of cellular stress responses such as endoplasmic reticulum stress, oxidative stress, antiviral defense, and the DNA damage response. Several potential novel BH3-containing proteins are highlighted. In particular, the analysis strongly suggests that the apoptosis inhibitor and DNA damage response regulator, AVEN, which was originally isolated as a BCL-xL-interacting protein, is a functional BH3-only protein representing a distinct subclass of BCL2 family members.