Tumor Microenvironment Role in Pancreatic Cancer Stem Cells

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a majority of patients presenting with unresectable or metastatic disease, resulting in a poor 5-year survival rate. This, in turn, is due to a highly complex tumor microenvironment and the presence of cancer stem cells, both of which induce therapy resistance and tumor relapse. Therefore, understanding and targeting the tumor microenvironment and cancer stem cells may be key strategies for designing effective PDAC therapies. In the present review, we summarized recent advances in the role of tumor microenvironment in pancreatic neoplastic progression.

Transcriptome-Wide Analysis of Low-Concentration Exposure to Bisphenol A, S, and F in Prostate Cancer Cells

Bisphenol A (BPA) is a ubiquitous synthetic compound used as a monomer in the production of polycarbonate plastics and epoxy resins. Even at low doses, BPA has been associated with the molecular progression of diseases such as obesity, metabolic syndrome, and hormone-regulated cancers due to its activity as an endocrine-disrupting chemical (EDC). Consequently, the use of BPA has been regulated worldwide by different health agencies. BPA structural analogs such as bisphenol S and bisphenol F (BPS and BPF) have emerged as industrial alternatives, but their biological activity in the molecular progression of cancer remains unclear. Prostate cancer (PCa) is a hormone-dependent cancer, and the role of BPA structural analogs in PCa progression is still undescribed. In this work, we use an in vitro model to characterize the transcriptomic effect of low-concentration exposure to bisphenol A, S, or F in the two main stages of the disease: androgen dependency (LNCaP) and resistance (PC-3). Our findings demonstrated that the low concentration exposure to each bisphenol induced a differential effect over PCa cell lines, which marks the relevance of studying the effect of EDC compounds through all the stages of the disease.

Gene Expression Behavior of a Set of Genes in Platelet and Tissue Samples from Patients with Breast Cancer

The tumor microenvironment (TME) is constituted by a great diversity of highly dynamic cell populations, each of which contributes ligands, receptors, soluble proteins, mRNAs, and miRNAs, in order to regulate cellular activities within the TME and even promote processes such as angiogenesis or metastasis. Intravasated platelets (PLT) undergo changes in the TME that convert them into tumor-educated platelets (TEP), which supports the development of cancer, angiogenesis, and metastasis through the degranulation and release of biomolecules. Several authors have reported that the deregulation of PF4, VEGF, PDGF, ANG-1, WASF3, LAPTM4B, TPM3, and TAC1 genes participates in breast cancer progression, angiogenesis, and metastasis. The present work aimed to analyze the expression levels of this set of genes in tumor tissues and platelets derived from breast cancer patients by reverse transcription-quantitative polymerase chain reaction (RTqPCR) assays, in order to determine if there was an expression correlation between these sources and to take advantage of the new information to be used in possible diagnosis by liquid biopsy. Data from these assays showed that platelets and breast cancer tumors present similar expression levels of a subset of these genes' mRNAs, depending on the molecular subtype, comorbidities, and metastasis presence.

Role of lncRNAs into Mesenchymal Stromal Cell Differentiation

Currently, findings support that 75% of the human genome is actively transcribed, but only 2% is translated into a protein, according to databases such as ENCODE (Encyclopedia of DNA Elements) [1]. The development of high-throughput sequencing technologies, computational methods for genome assembly and biological models have led to the realization of the importance of the previously unconsidered non-coding fraction of the genome. Along with this, noncoding RNAs have been shown to be epigenetic, transcriptional and post-transcriptional regulators in a large number of cellular processes [2]. Within the group of non-coding RNAs, lncRNAs represent a fascinating field of study, given the functional versatility in their mode of action on their molecular targets. In recent years, there has been an interest in learning about lncRNAs in MSC differentiation. The aim of this review is to address the signaling mechanisms where lncRNAs are involved, emphasizing their role in either stimulating or inhibiting the transition to differentiated cell. Specifically, the main types of MSC differentiation are discussed: myogenesis, osteogenesis, adipogenesis and chondrogenesis. The description of increasingly new lncRNAs reinforces their role as players in the well-studied field of MSC differentiation, allowing a step towards a better understanding of their biology and their potential application in the clinic.

Overexpression of p53 protein is a marker of poor prognosis in Mexican women with breast cancer

Breast cancer (BC) is a disease with different clinical, histological and molecular characteristics, frequently presenting mutated tumour-suppressing genes and oncogenes. P53 is a known tumour suppressor that is often mutated in BC; several mutations in p53 inhibit its role as a transcriptional repressor of several oncogenes. Topoisomerase 2α (TOP2α) is a gene target of p53, and it is also a known target for anthracyclines. The aim of the present study, was to analyse the genetic alterations of p53 and TOP2α genes and their levels of protein expression, as well as their association with survival in Mexican women with BC. A total of 102 biopsies were collected (tumour and adjacent tissues) from patients with BC. To identify point mutations and deletions in the p53 gene, the Sanger sequencing method was carried out. Deletions or amplifications for TOP2α gene were determined using quantitative polymerase chain reaction (qPCR). In addition, the expression of the TOP2α and p53 proteins was evaluated by western blotting. Furthermore, p53 protein expression was analysed by proximity ligation assay (PLA)-qPCR. Only 28.5% of the patients were found to have triple-negative breast cancer (TNBC); the average age at the time of diagnosis of these patients was 50 years, and Scarff-Bloom-Richardson (SBR) histological grade III (p=0.0089). No differences in point mutations or deletions in p53, and deletions or amplifications as well as protein expression level of TOP2α were observed between patients with TNBC and non-TNBC patients. However, patients with TNBC showed p53 protein overexpression as determined by PLA-qPCR and western blotting (p<0.0001). Furthermore, we found an association between TOP2α amplification and overexpression of its protein in patients with TNBC (p<0.0001). Concerning p53, overexpression resulted in a lower survival in patients with BC.

Overexpression of MEOX2 and TWIST1 is associated with H3K27me3 levels and determines lung cancer chemoresistance and prognosis

Lung cancer is the leading cause of death from malignant diseases worldwide, with the non-small cell (NSCLC) subtype accounting for the majority of cases. NSCLC is characterized by frequent genomic imbalances and copy number variations (CNVs), but the epigenetic aberrations that are associated with clinical prognosis and therapeutic failure remain not completely identify. In the present study, a total of 55 lung cancer patients were included and we conducted genomic and genetic expression analyses, immunohistochemical protein detection, DNA methylation and chromatin immunoprecipitation assays to obtain genetic and epigenetic profiles associated to prognosis and chemoresponse of NSCLC patients. Finally, siRNA transfection-mediated genetic silencing and cisplatinum cellular cytotoxicity assays in NSCLC cell lines A-427 and INER-37 were assessed to describe chemoresistance mechanisms involved. Our results identified high frequencies of CNVs (66–51% of cases) in the 7p22.3–p21.1 and 7p15.3–p15.2 cytogenetic regions. However, overexpression of genes, such as MEOX2, HDAC9, TWIST1 and AhR, at 7p21.2–p21.1 locus occurred despite the absence of CNVs and little changes in DNA methylation. In contrast, the promoter sequences of MEOX2 and TWIST1 displayed significantly lower/decrease in the repressive histone mark H3K27me3 and increased in the active histone mark H3K4me3 levels. Finally these results correlate with poor survival in NSCLC patients and cellular chemoresistance to oncologic drugs in NSCLC cell lines in a MEOX2 and TWIST1 overexpression dependent-manner. In conclusion, we report for the first time that MEOX2 participates in chemoresistance irrespective of high CNV, but it is significantly dependent upon H3K27me3 enrichment probably associated with aggressiveness and chemotherapy failure in NSCLC patients, however additional clinical studies must be performed to confirm our findings as new probable clinical markers in NSCLC patients.

SerpinA3g participates in the antiadipogenesis and insulin-resistance induced by tumor necrosis factor-α in 3T3-F442A cells

Tumor necrosis factor alpha (TNF-α) is a proven modulator of adipose metabolism, but the mechanisms by which this cytokine affects the development and function of adipose tissue have not been fully elucidated to date. Using differential display analysis, in this study, we demonstrate that gene expression of the serine protease inhibitor A3g (SerpinA3g) is specifically induced in 3T3-F442A preadipocytes by TNF-α but not by other adipogenic inhibitors, such as retinoic acid (RA) or transforming growth factor type beta (TGF-β). The specific induction of SerpinA3g by TNF-α was confirmed by RT-PCR in both preadipose and terminally differentiated 3T3-F442A cells. The knockdown of SerpinA3g using small interfering RNA prevented the antiadipogenesis elicited by TNF-α in 3T3-F442A cells but not the antiadipogenesis induced by RA or TGF-β. SerpinA3g-silenced 3T3-F442A cells also did not display TNF-α-induced insulin resistance. Our results demonstrate that SerpinA3g is specifically induced by TNF-α in 3T3-F442A cells, regardless of their stage of differentiation, and participates in the antiadipogenesis and insulin resistance induced by this cytokine. Our results suggest that SerpinA3g plays a role in the TNF-α modulation of adipose tissue development and metabolism. Additional studies are warranted regarding the mechanisms mediating adipose SerpinA3g effects.

Energy metabolism transition in multi-cellular human tumor spheroids

It is thought that glycolysis is the predominant energy pathway in cancer, particularly in solid and poorly vascularized tumors where hypoxic regions develop. To evaluate whether glycolysis does effectively predominate for ATP supply and to identify the underlying biochemical mechanisms, the glycolytic and oxidative phosphorylation (OxPhos) fluxes, ATP/ADP ratio, phosphorylation potential, and expression and activity of relevant energy metabolism enzymes were determined in multi-cellular tumor spheroids, as a model of human solid tumors. In HeLa and Hek293 young-spheroids, the OxPhos flux and cytochrome c oxidase protein content and activity were similar to those observed in monolayer cultured cells, whereas the glycolytic flux increased two- to fourfold; the contribution of OxPhos to ATP supply was 60%. In contrast, in old-spheroids, OxPhos, ATP content, ATP/ADP ratio, and phosphorylation potential diminished 50-70%, as well as the activity (88%) and content (3 times) of cytochrome c oxidase. Glycolysis and hexokinase increased significantly (both, 4 times); consequently glycolysis was the predominant pathway for ATP supply (80%). These changes were associated with an increase (3.3 times) in the HIF-1alpha content. After chronic exposure, both oxidative and glycolytic inhibitors blocked spheroid growth, although the glycolytic inhibitors, 2-deoxyglucose and gossypol (IC(50) of 15-17 nM), were more potent than the mitochondrial inhibitors, casiopeina II-gly, laherradurin, and rhodamine 123 (IC(50) > 100 nM). These results suggest that glycolysis and OxPhos might be considered as metabolic targets to diminish cellular proliferation in poorly vascularized, hypoxic solid tumors.

Proliferation and apoptosis of HeLa cells induced by in vitro stimulation with digitalis

In the HeLa tumor cell line, we studied the characteristics of the dual effect of digitalis compounds on cell growth (proliferation and death). In addition, we explored whether both effects occur by means of the same mechanism. HeLa cell cultures were exposed to increasing concentrations (0.01 nM-10 microM) of ouabain, strophantidin, digoxin, and digoxigenin at 24-96 h intervals. Cell growth in treated cultures was compared with cell growth under nontreated conditions. Additionally, we studied changes in nuclear morphology, as well as in genomic DNA degradation, cytochrome c release, and caspase-9 and -3 presence and processing induced by toxic concentrations of digitalis. Digitalis compounds increased HeLa cell number when exposed to concentrations <10 nM during a 48 h period. Ethacrynic acid (a nonsteroid inhibitor for Na+/K+-ATPase) did not induce cell growth at these concentrations. Digitalis concentrations >10 nM induced cell death in a concentration- and exposure period-dependent fashion. Changes in nuclear morphology, DNA fragmentation, mitochondrial cytochrome c release, and proteolytic processing of caspases-9 and -3, suggest apoptotic cell death. The IC50 for the inducing effect of apoptosis by ouabain at 96 h was 18 nM and corresponds with the IC50 for the Na+/K+-ATPase inhibition in HeLa cells. In conclusion, the dual effect of digitalis compounds on HeLa cells growth is concentration and time-dependent. The apoptosis-inducing effect correlates with inhibition of Na+/K+-ATPase. Proliferation does not appear to be mediated through this pathway. The apoptosis-induction pathway is possibly cytochrome c-dependent.