Unveiling stem-like traits and chemoresistance mechanisms in ovarian cancer cells through the TGFß1-PITX2A/B signaling axis.

Ovarian cancer (OC) is the deadliest gynecological malignancy, having a high mortality rate due to its asymptomatic nature, chemoresistance, and recurrence. However, the proper mechanistic knowledge behind these phenomena is still inadequate. Cancer recurrence is commonly observed due to cancer stem cells which also show chemoresistance. We aimed to decipher the molecular mechanism behind chemoresistance and stemness in OC. Earlier studies suggested that PITX2, a homeobox transcription factor and, its different isoforms are associated with OC progression upon regulating different signaling pathways. Moreover, they regulate the expression of drug efflux transporters in kidney and colon cancer, rendering chemoresistance properties in the tumor cell. Considering these backgrounds, we decided to look for the role of PITX2 isoforms in promoting stemness and chemoresistance in OC cells. In this study, PITX2A/B has been shown to promote stemness and to enhance the transcription of ABCB1. PITX2 has been discovered to augment ABCB1 gene expression by directly binding to its promoter. To further investigate the regulatory mechanism of PITX2 gene expression, we found that TGFß signaling could augment the PITX2A/B expression through both SMAD and non-SMAD signaling pathways. Collectively, we conclude that TGFß1-activated PITX2A/B induces stem-like features and chemoresistance properties in the OC cells.

Phytochemicals modulate cancer aggressiveness: A review depicting the anticancer efficacy of dietary polyphenols and their combinations.

Cancer is referred to as the "Emperor of all maladies" accounting for the second-highest mortality rates worldwide. Major factors associated with cancer lethality are uncontrolled proliferation, metastasis, and frequent recurrence. The conventional therapeutic drugs used in cancer therapy have been associated with numerous damaging side-effects that call for the use of alternative therapeutic options. The natural plant compounds (NPCs) have been found to be effective against diverse groups of diseases including cancer. Among the different types, the polyphenolic phytochemicals like curcumin, (-)epigallocatechin-3-gallate, Resveratrol, and nimbolide which are predominant parts of daily dietary intake have proved their potency in reducing the aggressive properties of cancer. Here, we have highlighted the mechanisms through which these NPCs influence growth, metastatic potential, and the drug-resistant behavior of different cancer types. Moreover, we have also emphasized on their function as modulators of the immune system as well as the metabolic properties of the tumor. The role of these phytochemicals in reducing cancer progression has been highlighted when administered unaided or in combination with similar group of compounds. Moreover, their ability to enhance the drug-sensitivity of cancer cells which accounts for their use in combination with conventional chemotherapeutics has also been discussed in this article. Therefore, co-administration of these phytochemicals with chemically similar group members or with conventional chemotherapeutics may prove to be an effective treatment strategy for cancer.

Mesenchymal splice isoform of CD44 (CD44s) promotes EMT/invasion and imparts stem-like properties to ovarian cancer cells.

Increased metastasis and a precipitous recurrence contribute to the lethality of ovarian cancer (OC). Several molecular mechanisms including aberrant-splicing have been closely associated with the extent of cancer progression. Numerous gene transcripts are differentially spliced in cancer cells, CD44 being one of them. CD44 splice isoforms contribute to the aggressiveness and gain of stem-like properties in different cancer types, but their role in ovarian cancer remains to be elucidated. We observed augmented CD44 levels in human ovarian cancer patient samples correlated with enhanced expression of the mesenchymal spliced variant CD44s (standard) and a concurrent decrease in the epithelial variants (CD44v). Moreover, CD44s was upregulated upon TGFß1-induced EMT, which was mediated through the downregulation of the splicing factor, ESRP1. Furthermore, overexpression of this mesenchymal isoform in the OC cells induced EMT and invasion, followed by the gain of stem-like characteristics and chemoresistance. Since all these phenomena render lethality to this disease type, CD44s can be attributed for playing a major role in deregulated-splicing mediated ovarian cancer progression.

Stemness and chemoresistance are imparted to the OC cells through TGFß1 driven EMT.

Ovarian cancer (OC) is the fourth most common gynecological malignancy due to its highly aggressive, recurrent, and drug-resistant nature. The last two features are rendered by the presence of cancer stem cells (CSCs). Factors like TGFß1 and their downstream signaling pathways are upregulated in most cancers and are known to induce EMT and stemness, but the exact mechanisms underlying the process remain unelucidated. In our study, TGFß1 induced enhanced stem-like properties like high expression of the pluripotent markers SOX2, OCT4a, and NANOG, along with CD44, and CD117 in the OC cells. In addition, increased activity of the aldehyde dehydrogenase enzyme, formation of compact spheroids, and a quiescent phenotype were observed. In deciphering the mechanism behind it, our data propose ZEB1 transcription factor to play a substantial role in inducing the EMT-mediated stemness and chemoresistance. Further, in our study, we elucidated the significant contribution of both Smad and non-Smad pathways like ERK, JNK, and P38 MAPK pathways in the induction of stem-like characteristics. The novelty of the study also resides with the fact in the expression of different lineage-specific markers, like CD31, CD45, and CD117 along with CD44 in the TGFß1-induced epithelial ovarian cancer spheroids. This suggests a tendency of the spheroidal cells towards differentiating into heterogenic populations, which is a distinctive feature of a stem cell. Taken together, the present study provides an insight to the molecular cues involved in the acquisition of stemness and chemoresistance along with tumor heterogeneity in TGFß1-induced OC cells.

The Role of Intestinal Fatty Acid Binding Proteins in Protecting Cells from Fatty Acid Induced Impairment of Mitochondrial Dynamics and Apoptosis.

BACKGROUND/AIMS: The conformation, folding and lipid binding properties of the intestinal fatty acid binding proteins (IFABP) have been extensively investigated. In contrast, the functional aspects of these proteins are not understood and matter of debates. In this study, we aim to address the deleterious effects of FA overload on cellular components, particularly mitochondria; and how IFABP helps in combating this stress by restoring the mitochondrial dynamics. METHODS: In the present study the functional aspect of IFABP under conditions of lipid stress was studied by a string of extensive in-cell studies; flow cytometry by fluorescence-activated cell sorting (FACS), confocal imaging, western blotting and quantitative real time PCR. We deployed ectopic expression of IFABP in rescuing cells under the condition of lipid stress. Again in order to unveil the mechanistic insights of functional traits, we arrayed extensive computational approaches by means of studying centrality calculations along with protein-protein association and ligand induced cluster dissociation. While addressing its functional importance, we used FCS and in-silico computational analyses, to show the structural distribution and the underlying mechanism of IFABP's action. RESULTS: Ectopic expression of IFABP in HeLa cells has been found to rescue mitochondrial morphological dynamics and restore membrane potential, partially preventing apoptotic damage induced by the increased FAs. These findings have been further validated in the functionally relevant intestinal Caco-2 cells, where the native expression of IFABP protects mitochondrial morphology from abrogation induced by FA overload. However, this native level expression is insufficient to protect against apoptotic cell death, which is rescued, at least partially in cells overexpressing IFABP. In addition, shRNA mediated IFABP knockdown in Caco-2 cells compromises mitochondrial dynamics and switches on intrinsic apoptotic pathways under FA-induced metabolic stress. CONCLUSION: To summarize, the present study implicates functional significance of IFABP in controlling ligand-induced damage in mitochondrial dynamics and apoptosis.

Co-Activation of TGFß and Wnt Signalling Pathways Abrogates EMT in Ovarian Cancer Cells.

BACKGROUND/AIMS: The aggressive property of ovarian cancer (OC) in terms of epithelial-mesenchymal transition (EMT), proliferation and metastasis are of major concern. Different growth factors including TGFß are associated with regulating these molecular events but the underlying mechanisms remain unclear. The aim of this report is to decipher the regulation of EMT by co-activation of TGFß and Wnt signalling cascades in gaining malignancy. METHODS: The expression of the different components of signalling events were analyzed by QPCR, Western blot, Immunofluorescence microscopy and flow cytometry. ß-catenin promoter activity was checked by luciferase assay. RESULTS: We observed reduced EMT in ovarian cancer cells upon co-activation with TGFß1 and LiCl as shown by the expressions of epithelial/mesenchymal markers and the EMT promoting factor, Snail1, accompanied by decrease in the invasion and migration of the cells compared to individual pathway activation. A detailed study of the mechanism suggested reduction in the ß-catenin and p-GSK3b (Ser 9) levels to be the driving cause of this phenomenon, which was reversed upon co-activation with higher concentrations of LiCl. CONCLUSIONS: Therefore, tumourigenesis might be affected by the concentration of ligand/ growth factors for the respective signalling pathways activated in the tumour microenvironment and interaction between them might alter tumourigenesis.

Protein Fibril-Templated Biomimetic Synthesis of Highly Fluorescent Gold Nanoclusters and Their Applications in Cysteine Sensing.

Biomimetic synthesis of multifunctional fluorescent gold nanoclusters (Au NCs) is of great demand because of their ever-increasing applications. In this study, we have used self-assembled bovine serum albumin (BSA) amyloid-like nanofibers as the bioinspired scaffold for the synthesis of Au NCs. The amyloid fibril stabilized gold nanocluster (Fib-Au NC) has been found to have appreciable enhancement of fluorescence emission and a large 25 nm red shift in its emission maxima when compared to its monomeric protein counterpart (BSA-Au NC). The underlying mechanism accountable for the fluorescence behavior and its spectral shift has been thoroughly investigated by a combined use of spectroscopic and microscopic techniques. We have subsequently demonstrated the use of Fib-Au NCs for cysteine (Cys) sensing both in vitro and inside live cells. Additionally, cellular uptake and postpermeation effect of Fib-Au NCs have also been ascertained by detailed flow cytometry analysis, viability assay, and real-time apoptotic gene expression profiling.