Cytoskeleton disruption by the metabolic inhibitor 3-bromopyruvate: implications in cancer therapy

The small molecule 3-bromopyruvate (3BP), is an anticancer molecule that acts by hindering glycolysis and mitochondrial function leading to energy depletion and consequently, to cell death. In this work we have focused on understanding how the glycolytic inhibition affects cancer cell structural features. We showed that 3BP leads to a drastic decrease in the levels of β-actin and α-tubulin followed by disorganization and shrinkage of the cytoskeleton in breast cancer cells. 3BP inhibits cell migration and colony formation independently of the activity of metalloproteinases. To disclose if these structural alterations occurred prior to 3BP toxic effect, non-toxic concentrations of 3BP were used and we could observe that 3BP was able to inhibit energy production and induce loss of β-actin and α-tubulin proteins. This was accompanied with alterations in cytoskeleton organization and an increase in E-cadherin levels which may indicate a decrease in cancer cells aggressiveness. In this study we demonstrate that 3BP glycolytic inhibition of breast cancer cells is accompanied by cytoskeleton disruption and consequently loss of migration ability, suggesting that 3BP can potentially be explored for metastatic breast cancer therapy.

In vitro Evaluation of ASCs and HUVECs Co-cultures in 3D Biodegradable Hydrogels on Neurite Outgrowth and Vascular Organization

Vascular disruption following spinal cord injury (SCI) decisively contributes to the poor functional recovery prognosis facing patients with the condition. Using a previously developed gellan gum hydrogel to which the adhesion motif GRGDS was grafted (GG-GRGDS), this work aimed to understand the ability of adipose-derived stem cells (ASCs) to impact vascular organization of human umbilical vein endothelial cells (HUVECs), and how this in turn affects neurite outgrowth of dorsal root ganglia (DRG) explants. Our data shows that culturing these cells together lead to a synergistic effect as showed by increased stimulation of neuritogenesis on DRG. Importantly, HUVECs were only able to assemble into vascular-like structures when cultured in the presence of ASCs, which shows the capacity of these cells in reorganizing the vascular milieu. Analysis of selected neuroregulatory molecules showed that the co-culture upregulated the secretion of several neurotrophic factors. On the other hand, ASCs, and ASCs + HUVECs presented a similar profile regarding the presence of angiotrophic molecules herein analyzed. Finally, the implantation of GG-GRGDS hydrogels encapsulating ASCs in the chick chorioallantoic membrane (CAM) lead to increases in vascular recruitment toward the hydrogels in comparison to GG-GRGDS alone. This indicates that the combination of ASCs with GG-GRGDS hydrogels could promote re-vascularization in trauma-related injuries in the central nervous system and thus control disease progression and induce functional recovery.

The expression of monocarboxylate transporters in thyroid carcinoma can be associated with the morphological features of BRAF V600E mutation

BRAF ^V600E mutation, usually performed by DNA techniques, is one of the most common diagnostic markers in papillary thyroid carcinoma. Few papers have demonstrated that plump cells (eosinophilic cytoplasms and papillary thyroid carcinoma nuclei) and peculiar sickle-shaped nuclei represent morphological features of BRAF ^V600E on papillary thyroid carcinomas. These features seem to be linked to glycolytic phenotype whereby monocarboxylate transporters 1-4 are hypothesized to have a dominant role as lactate transporters. We investigated the association between these morphological features and monocarboxylate transporters 1 and 4 in 48 cyto-histological samples diagnosed as "positive for malignancy-favoring papillary thyroid carcinoma". These cases were processed with liquid-based cytology and underwent BRAF ^V600E mutational analysis (pyrosequencing) on liquid-based cytology and monocarboxylate transporters immunostaining on histology. The expression of monocarboxylate transporter 1, monocarboxylate transporter 4, glucose trasporter-1 and carbonic anhidrase were scored semi-quantitatively with expression from 0 to 3+ (strong positivity). The 33 mutated and 15 wild type cases showed 100 % cyto-histological concordance. The cytological evaluation revealed plump cells and sickle nuclear shape in 100 % mutated cases. Monocarboxylate transporter 1 yielded 76 % positivity in the mutated cases especially in both the plump cells and sickle-shaped nuclei, whereas the wild types showed 13.3 % positive monocarboxylate transporter 1 (p = 0.00013). Monocarboxylate transporter 4 resulted in 100 % positivity in mutated and 40 % in wild types (p < 0.005). Furthermore, 20 % of the wild types showed weak monocarboxylate transporter 1 nuclear expression associated to a less aggressive behavior. The analysis of glucose trasporter-1 and carbonic anhidrase did not highlight any statistical significance (p > 0.05). This is the first report analyzing the association between monocarboxylate transporter expression and the morphological features of BRAF ^V600E mutated papillary thyroid carcinomas suggesting the possible involvement of lactate in the morphological features.

Characterization of acetate transport in colorectal cancer cells and potential therapeutic implications

Acetate, together with other short chain fatty acids has been implicated in colorectal cancer (CRC) prevention/therapy. Acetate was shown to induce apoptosis in CRC cells. The precise mechanism underlying acetate transport across CRC cells membrane, that may be implicated in its selectivity towards CRC cells, is not fully understood and was addressed here. We also assessed the effect of acetate in CRC glycolytic metabolism and explored its use in combination with the glycolytic inhibitor 3-bromopyruvate (3BP). We provide evidence that acetate enters CRC cells by the secondary active transporters MCT1 and/or MCT2 and SMCT1 as well as by facilitated diffusion via aquaporins. CRC cell exposure to acetate upregulates the expression of MCT1, MCT4 and CD147, while promoting MCT1 plasma membrane localization. We also observed that acetate increases CRC cell glycolytic phenotype and that acetate-induced apoptosis and anti-proliferative effect was potentiated by 3BP. Our data suggest that acetate selectivity towards CRC cells might be explained by the fact that aquaporins and MCTs are found overexpressed in CRC clinical cases. Our work highlights the importance that acetate transport regulation has in the use of drugs such as 3BP as a new therapeutic strategy for CRC.

Prognostic significance of monocarboxylate transporter expression in oral cavity tumors

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of cancer. The majority of patients present advanced stage disease and has poor survival. Therefore, it is imperative to search for new biomarkers and new alternative and effective treatment options. Most cancer cells rely on aerobic glycolysis to generate energy and metabolic intermediates. This phenotype is a hallmark of cancer, characterized by an increase in glucose consumption and production of high amounts of lactate. Consequently, cancer cells need to up-regulate many proteins and enzymes related with the glycolytic metabolism. Thus, the aim of this study was to characterize metabolic phenotype of oral cavity cancers (OCC) by assessing the expression pattern of monocarboxylate transporters (MCTs) 1, 2 and 4 and other proteins related with the glycolytic phenotype.

MATERIAL AND METHODS

We evaluated the immunohistochemical expression of MCT1, MCT4, CD147, GLUT1 and CAIX in 135 human samples of OCC and investigated the correlation with clinicopathological parameters and the possible association with prognosis.

RESULTS

We observed that all proteins analyzed presented significantly higher plasma membrane expression in neoplastic compared to non-neoplastic samples. MCT4 was significantly associated with T-stage and advanced tumoral stage, while CD147 was significantly correlated with histologic differentiation. Interestingly, tumors expressing both MCT1 and MCT4 but negative for MCT2 were associated with shorter overall survival.

CONCLUSION

Overexpression of MCT1/4, CD147, GLUT1 and CAIX, supports previous findings of metabolic reprograming in OCC, warranting future studies to explore the hyper-glycolytic phenotype of these tumors. Importantly, MCT expression revealed to have a prognostic value in OCC survival.

Absence of microsatellite instability and BRAF (V600E) mutation in testicular germ cell tumors

Testicular germ cell tumors (TGCT) are the most common malignant neoplasm in young men. DNA mismatch repair deficiency can lead to microsatellite instability (MSI), an important mechanism of genetic instability. A mutation of the BRAF gene has been implicated in the pathogenesis of several solid tumors and has recently become an important therapeutic target. The role of MSI and BRAF gene mutation in TGCT, particularly in refractory disease, is poorly understood and reported findings are controversial. In this study, we aimed to determine the frequency and clinical impact of MSI status and BRAF mutations in TGCT. DNA was isolated from formalin-fixed paraffin embedded (FFPE) tissue from 150 TGCT cases. The MSI phenotype was evaluated using multiplex PCR for five quasimonomorphic mononucleotide repeat markers. Exon 15 of the BRAF oncogene (V600E) was analyzed by PCR, followed by direct sequencing. Sixteen percent of cases were considered to have refractory disease. In a small subset of cases (17 for MSI and 18 for BRAF), the quantity and quality of DNA recovery were poor and therefore, were unable to be analyzed. The remaining 133 TGCT cases showed a complete absence of MSI. Of the 132 cases successfully evaluated for BRAF mutations, all were V600E wild-type. In conclusion, despite a distinct response of testicular germ cell tumors to therapy, microsatellite instability, and the BRAF V600E mutation were absent in all testicular germ cell tumors tested in this study.

Colon Cancer Chemoprevention by Sage Tea Drinking: Decreased DNA Damage and Cell Proliferation

Salvia officinalis and some of its isolated compounds have been found to be preventive of DNA damage and increased proliferation in vitro in colon cells. In the present study, we used the azoxymethane model to test effects of S. officinalis on colon cancer prevention in vivo. The results showed that sage treatment reduced the number of ACF formed only if administered before azoxymethane injection, demonstrating that sage tea drinking has a chemopreventive effect on colorectal cancer. A decrease in the proliferation marker Ki67 and in H2 O2 -induced and azoxymethane-induced DNA damage to colonocytes and lymphocytes were found with sage treatment. This confirms in vivo the chemopreventive effects of S. officinalis. Taken together, our results show that sage treatment prevented initiation phases of colon carcinogenesis, an effect due, at least in part, to DNA protection, and reduced proliferation rates of colon epithelial cell that prevent mutations and their fixation through cell replication. These chemopreventive effects of S. officinalis on colon cancer add to the many health benefits attributed to sage and encourage its consumption.

A glycolytic phenotype is associated with prostate cancer progression and aggressiveness: a role for monocarboxylate transporters as metabolic targets for therapy

Metabolic adaptation is considered an emerging hallmark of cancer, whereby cancer cells exhibit high rates of glucose consumption with consequent lactate production. To ensure rapid efflux of lactate, most cancer cells express high levels of monocarboxylate transporters (MCTs), which therefore may constitute suitable therapeutic targets. The impact of MCT inhibition, along with the clinical impact of altered cellular metabolism during prostate cancer (PCa) initiation and progression, has not been described. Using a large cohort of human prostate tissues of different grades, in silico data, in vitro and ex vivo studies, we demonstrate the metabolic heterogeneity of PCa and its clinical relevance. We show an increased glycolytic phenotype in advanced stages of PCa and its correlation with poor prognosis. Finally, we present evidence supporting MCTs as suitable targets in PCa, affecting not only cancer cell proliferation and survival but also the expression of a number of hypoxia-inducible factor target genes associated with poor prognosis. Herein, we suggest that patients with highly glycolytic tumours have poorer outcome, supporting the notion of targeting glycolytic tumour cells in prostate cancer through the use of MCT inhibitors.

Monocarboxylate transporters as targets and mediators in cancer therapy response

Monocarboxylate transporters (MCTs) belong to a family of transporters, encoded by the SLC16 gene family, which is presently composed by 14 members, but only MCT1 to 4 have been biochemically characterized. They have important functions in healthy tissues, being involved in the transmembrane transport of lactic acid and other monocarboxylic acids in human cells. One of the recently recognized hallmarks of cancer is altered metabolism, with high rates of glucose consumption and consequent lactate production. To maintain this metabolic phenotype, cancer cells upregulate a series of plasma membrane proteins, including MCTs. MCT1 and MCT4, in particular, play a dual role in the maintenance of the metabolic phenotype of tumour cells. On one hand, they facilitate the efflux of lactate and, on the other hand, they contribute to the preservation of the intracellular pH, by co-transporting a proton. Thus, MCTs are attractive targets in cancer therapy, especially in cancers with a hyper-glycolytic and acid-resistant phenotype. Recent evidence demonstrates that MCTs are involved in cancer cell uptake of chemotherapeutic agents, including 3-bromopyruvate. In this way MCTs can act as "Trojan horses", as their elevated expression in cancer cells can mediate the entry of this chemotherapeutic agent into the cells and selectively kill cancer cells. As a result, MCTs will be mediators of chemotherapeutic response, and their expression can be used as a molecular marker to predict response to chemotherapy.

GLUT1 and CAIX expression profiles in breast cancer correlate with adverse prognostic factors and MCT1 overexpression

The goal of the present work was to evaluate the correlation of glucose transporter 1 (GLUT1) and carbonic anhydrase IX (CAIX) with the monocarboxylate transporters 1 (MCT1) and 4 (MCT4) and their chaperone, CD147, in breast cancer. The clinico-pathological value of GLUT1 and CAIX was also evaluated. For that, we analysed the immunohistochemical expression of GLUT1 and CAIX, in a large series of invasive breast carcinoma samples (n=124), previously characterized for MCT1, MCT4 and CD147 expression. GLUT1 expression was found in 46% of the cases (57/124), while CAIX was found in 18% of the cases (22/122). Importantly, both MCT1 and CD147, but not MCT4, were associated with GLUT1 and CAIX expression. Also, GLUT1 and CAIX correlated with each other. Concerning the clinico-pathological values, GLUT1 was associated with high grade tumours, basal-like subtype, absence of progesterone receptor, presence of vimentin and high proliferative index as measured by Ki-67. Additionally, CAIX was associated with large tumour size, high histological grade, basal-like subtype, absence of estrogen and progesterone receptors and presence of basal cytokeratins and vimentin expression. Finally, patients with CAIX positive tumours had a significantly shorter disease-free survival. The association between MCT1 and both GLUT1 and CAIX may result from hypoxia-mediated metabolic adaptations, which confer a glycolytic, acid-resistant and more aggressive phenotype to cancer cells.

CD147 overexpression allows an accurate discrimination of bladder cancer patients' prognosis

BACKGROUND

Urothelial bladder carcinoma (UBC) is a chemo-sensitive tumour, but the response to treatment is heterogeneous. CD147 has been associated with chemotherapy resistance. We aimed to define tumours with an aggressive phenotype by the combined analysis of clinicopathological and biological parameters.

METHODS

77 patients with T1G3 or muscle-invasive UBC treated by radical cystectomy were studied. Immunohistochemistry was performed to detect CD147, heparanase, CD31 (blood vessels identification) and D2-40 (lymphatic vessels identification) expressions. The immunohistochemical reactions were correlated with the clinicopathological and the outcome parameters. 5-year disease-free survival (DFS) and overall survival (OS) rates were estimated using the Kaplan-Meier method. Multivariate analysis was performed by Cox proportional hazards analysis.

RESULTS

The 5-year DFS and OS rates were significantly influenced by the classical clinicopathological parameters, and by the occurrence of lymphovascular invasion. CD147 and heparanase immunoexpression did not affect patients' outcome. However, patients with pT3/pT4 tumours had a median OS time of 14.7 months (95% CI 7.1-22.3, p = 0.003), which was reduced to 9.2 months (95% CI 1.5-17.0, p = 0.008) if the tumours were CD147 positive. We developed a model of tumour aggressiveness using parameters as stage, grade, lymphovascular invasion and CD147 immunoexpression, which separated a low aggressiveness from a high aggressiveness group, remaining as an independent prognostic factor of DFS (HR 3.746; 95% CI 1.244-11.285; p = 0.019) and OS (HR 3.247; 95% CI 1.015-10.388, p = 0.047).

CONCLUSION

CD147 overexpression, included in a model of UBC aggressiveness, may help surgeons to identify patients who could benefit from a personalized therapeutic regimen. Additional validation is needed.

Immunohistochemical expression of VEGF-A and its ligands in non-neoplastic lesions of the breast sampling-assisted by dynamic angiothermography

The aim of this study was to investigate the expression of angiogenic markers, vascular endothelial growth factor A (VEGF-A) ligand and its receptors, VEGFR-1 and -2, in a series of biopsy-proven non-neoplastic lesions of the breast detected by dynamic angiothermography. We have also studied the vascular density demonstrated by CD31 immunoreactivity, in order to assess the potential of the imaging method to recognize lesions with an enhanced vascular network of clinical importance in routine breast examination. The lesions were classified as non-proliferative, proliferative without atypia and proliferative with atypia. VEGF was diffusely expressed in the epithelial cells of proliferative lesions in almost all cases. Similarly, VEGFR-1 and -2 also exhibited epithelial positive reactions in the majority of cases. VEGF-A and its receptors were also present in blood vessels. CD31 showed an increase in vascular proliferation at the periphery of proliferative epithelial lesions, but not in non-proliferative lesions. Our results, showing marked expression of VEGF by the epithelial proliferative lesions and neoangiogenesis at their periphery, confirm that these lesions can be detected by dynamic angiothermography.

EGFR amplification and lack of activating mutations in metaplastic breast carcinomas

Metaplastic breast carcinomas are reported to harbour epidermal growth factor receptor (EGFR) overexpression in up to 80% of the cases, but EGFR gene amplification is the underlying genetic mechanism in around one-third of these. In this study, EGFR gene amplification as defined by chromogenic in situ hybridization and protein overexpression was examined in a cohort of 47 metaplastic breast carcinomas. Furthermore, the presence of activating EGFR mutations in exons 18, 19, 20, and 21 was investigated. Thirty-two cases showed EGFR overexpression and of these, 11 (34%) harboured EGFR gene amplification. In addition, EGFR amplification showed a statistically significant association with EGFR overexpression (p < 0.0094) and was restricted to carcinomas with homologous metaplasia. Ten cases, five with and five without EGFR amplification, were subjected to microarray-based CGH, which demonstrated that EGFR copy number gain may occur by amplification of a discrete genomic region or by gains of the short arm of chromosome 7 with a breakpoint near the EGFR gene locus, the minimal region of amplification mapping to EGFR, LANCL2, and SEC61G. No activating EGFR mutations were identified, suggesting that this is unlikely to be a common alternative underlying genetic mechanism for EGFR expression in metaplastic breast carcinomas. Given that metaplastic breast carcinomas are resistant to conventional chemotherapy or hormone therapy regimens and that tumours with EGFR amplification are reported to be sensitive to EGFR tyrosine kinase inhibitors, these findings indicate that further studies are warranted to explore EGFR tyrosine kinase inhibitors as potential therapeutic agents for metaplastic breast carcinomas harbouring amplification of 7p11.2.