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

A molecular and immunohistochemical study of 37 cases of ovarian Sertoli-Leydig cell tumor

This study provides an analysis of 37 ovarian Sertoli-Leydig cell tumors (SLCT), focusing on their morphological, immunohistochemical, and molecular features. The cohort was comprised of 9 well-differentiated, 25 moderately differentiated, and 3 poorly differentiated tumors. The immunohistochemical analysis was performed with 28 markers, including diagnostic markers and markers with possible predictive significance. The results showed high expression of sex cord markers (FOXL2, SF1, inhibin A, CD99, calretinin, ER, PR, AR), and variable expression of other markers such as CKAE1/3 (83%), CAIX (14%), and MUC4 (1%). Loss of PTEN expression was present in 14% of cases, and CTLA4 expression was seen in 43% of cases. All tumors were MMR proficient and HER2 and PD-L1 negative. The molecular analysis showed DICER1 mutations in 54.5% of cases, and a FOXL2 mutation in 6% of tumors. In addition, we detected 2 cases with TERT promoter mutation. RNA NGS sequencing identified significant differences in mRNA expression between DICER1MUT and DICER1WT tumors. The DICER1WT tumors showed increased expression of PRKCA, HNF1A, LDLR, and MAP2K5. On the contrary, the DICER1MUT cases showed increased expression of CDK6, NOTCH2, and FGFR2. The results of our study show that SLCTs exhibit distinct molecular features based on their degree of differentiation. We have confirmed that DICER1 mutations are characteristic of moderately and poorly differentiated SLCTs, while well-differentiated SLCTs may represent a distinct entity. DICER1MUT and DICER1WT tumors showed different mRNA expression profiles. The FOXL2 mutation is less common in these tumors and is mutually exclusive with the DICER1 mutation.

An extensive immunohistochemical analysis of 290 ovarian adult granulosa cell tumors with 29 markers

The current knowledge about the immunohistochemical features of adult granulosa cell tumor (AGCT) is mostly limited to the "traditional" immunohistochemical markers of sex cord differentiation, such as inhibin, calretinin, FOXL2, SF1, and CD99. Knowledge about the immunohistochemical markers possibly used for predictive purpose is limited. In our study, we focused on the immunohistochemical examination of 290 cases of AGCT classified based on strict diagnostic criteria, including molecular testing. The antibodies used included 12 of the "diagnostic" antibodies already examined in previous studies, 10 antibodies whose expression has not yet been examined in AGCT, and 7 antibodies with possible predictive significance, including the expression of HER2, PD-L1, CTLA4, and 4 mismatch repair (MMR) proteins. The results of our study showed expression of FOXL2, SF1, CD99, inhibin A, calretinin, ER, PR, AR, CKAE1/3, and CAIX in 98%, 100%, 90%, 78%, 45%, 41%, 94%, 82%, 26%, and 9% of AGCT, respectively. GATA3, SATB2, napsin A, MUC4, TTF1, and CD44 were all negative. PTEN showed a loss of expression in 71% of cases and DPC4 in 4% of cases. The aberrant staining pattern (overexpression) of p53 was found in 1% (3/268) of cases, 2 primary tumors, and 1 recurrent case. Concerning the predictive markers, the results of our study showed that AGCT is microsatellite stable, do not express PD-L1, and are HER2 negative. The CTLA4 expression was found in almost 70% of AGCT tumor cells.

Cadherin-16 (CDH16) immunohistochemistry: a useful diagnostic tool for renal cell carcinoma and papillary carcinomas of the thyroid

Cadherin-16 (CDH16) plays a role in the embryonal development in kidney and thyroid. Downregulation of CDH16 RNA was found in papillary carcinomas of the thyroid. To determine the expression of CDH16 in tumors and to assess the diagnostic utility a tissue microarray containing 15,584 samples from 152 different tumor types as well as 608 samples of 76 different normal tissue types was analyzed. A membranous CDH16 immunostaining was predominantly seen in thyroid, kidney, cauda epididymis, and mesonephric remnants. In the thyroid, CDH16 staining was seen in 100% of normal samples, 86% of follicular adenomas, 60% of follicular carcinomas, but only 7% of papillary carcinomas (p < 0.0001). CDH16 positivity was frequent in nephrogenic adenomas (100%), oncocytomas (98%), chromophobe (97%), clear cell (85%), and papillary (76%) renal cell carcinomas (RCCs), various subtypes of carcinoma of the ovary (16-56%), various subtyped of carcinomas of the uterus (18-40%), as well as in various subtypes of neuroendocrine neoplasms (4-26%). Nineteen further tumor entities showed a weak to moderate CDH16 staining in up to 8% of cases. Our data suggest CDH16 as a potential diagnostic marker-as a part of a panel-for the identification of papillary carcinomas of the thyroid, nephrogenic adenomas, and the distinction of renal cell tumors from other neoplasms.

Carbonic anhydrase IX-related tumoral hypoxia predicts worse prognosis in breast cancer: A systematic review and meta-analysis

Background

Tumoral hypoxia is associated with aggressiveness in many cancers including breast cancer. However, measuring hypoxia is complicated. Carbonic anhydrase IX (CAIX) is a reliable endogenous marker of hypoxia under the control of the master regulator hypoxia-inducible factor-1α (HIF-1α). The expression of CAIX is associated with poor prognosis in many solid malignancies; however, its role in breast cancer remains controversial.

Methods

The present study performed a meta-analysis to evaluate the correlation between CAIX expression and disease-free survival (DFS) and overall survival (OS) in breast cancer.

Results

A total of 2,120 publications from EMBASE, PubMed, Cochrane, and Scopus were screened. Of these 2,120 publications, 272 full texts were reviewed, and 27 articles were included in the meta-analysis. High CAIX was significantly associated with poor DFS (HR = 1.70, 95% CI = 1.39–2.07, p &lt; 0.00001) and OS (HR = 2.02, 95% CI 1.40–2.91, p = 0.0002) in patients with breast cancer. When stratified by subtype, the high CAIX group was clearly associated with shorter DFS (HR = 2.09, 95% CI =1.11–3.92, p = 0.02) and OS (HR = 2.50, 95% CI =1.53–4.07, p = 0.0002) in TNBC and shorter DFS in ER+ breast cancer (HR = 1.81 95% CI =1.38–2.36, p &lt; 0.0001).

Conclusion

High CAIX expression is a negative prognostic marker of breast cancer regardless of the subtypes.

Gallic acid markedly stimulates GLUT1-mediated glucose uptake by the AsPC-1 pancreatic cancer cell line

Phenolic acids are recognized as chemopreventive and chemotherapeutic agents. Altered glucose and glutamine metabolism are recognized hallmarks of cancer cells. We aimed to test the influence of phenolic acids on glucose and glutamine cellular uptake by a breast (MCF-7) and a pancreatic (AsPC-1) cancer cell line. Several phenolic acids (caffeic, ferrulic, proctocatechuic, coumaric and gallic acid) affected ³H-glutamine and/or ³H-deoxy-d-glucose (³H-DG) uptake. Gallic acid (100 µM) caused a 3-fold increase in ³H-DG uptake by AsPC-1 cells, associated with a 3.7-fold increase in lactic acid production. Gallic acid stimulated GLUT1-mediated ³H-DG uptake and increased the affinity of this transporter for ³H-DG. We further verified that gallic acid does not change GLUT1 transcription rates and cellular redox state and that its effect does not involve PI3K, mTOR and MAP kinases and is not associated with a proproliferative effect. Gallic acid also increased ³H-DG uptake by MCF-7 cells, although less potently. Further investigation is necessary to elucidate the cellular pathways involved in this effect of gallic acid.

Understanding metabolic alterations and heterogeneity in cancer progression through validated immunodetection of key molecular components: a case of carbonic anhydrase IX

Cancer metabolic heterogeneity develops in response to both intrinsic factors (mutations leading to activation of oncogenic pathways) and extrinsic factors (physiological and molecular signals from the extracellular milieu). Here we review causes and consequences of metabolic alterations in cancer cells with focus on hypoxia and acidosis, and with particular attention to carbonic anhydrase IX (CA IX). CA IX is a cancer-associated enzyme induced and activated by hypoxia in a broad range of tumor types, where it participates in pH regulation as well as in molecular mechanisms supporting cancer cells’ invasion and metastasis. CA IX catalyzes reversible conversion of carbon dioxide to bicarbonate ion plus proton and cooperates with a spectrum of molecules transporting ions or metabolites across the plasma membrane. Thereby CA IX contributes to extracellular acidosis as well as to buffering intracellular pH, which is essential for cell survival, metabolic performance, and proliferation of cancer cells. Since CA IX expression pattern reflects gradients of oxygen, pH, and other intratumoral factors, we use it as a paradigm to discuss an impact of antibody quality and research material on investigating metabolic reprogramming of tumor tissue. Based on the validation, we propose the most reliable CA IX-specific antibodies and suggest conditions for faithful immunohistochemical analysis of molecules contributing to heterogeneity in cancer progression.

Pathological Significance of GLUT-1 Expression in Breast Cancer Cells in Diabetic and Obese Patients: The French Guiana Study

Simple Summary

This study describes the clinical, histological, and molecular features of breast cancer in French Guiana, and characterizes the expression of the tumor metabolic marker GLUT-1 in breast cancers cells in diabetic and obese patients compared to a control group. This study reveals an overall overexpression of GLUT-1 in 60% of invasive breast carcinomas and in all medullary pattern and carcinoma in situ lesions. Our results highlight the potential role of GLUT-1 as a tumor metabolic prognostic marker and also as an interesting target therapy, independently of patient metabolic disorder.

Abstract

The prevalence of obesity and type 2 diabetes is higher in French Guiana compared to mainland France. These metabolic disorders are associated with an increased risk of cancer. One of the factors involved is hyperinsulinemia that promotes the action of glucose transporter 1 (GLUT-1). The objective of this study is to characterize the expression of GLUT-1 in breast cancers cells in diabetic and obese patients compared to those who are not and to describe the clinical and histological prognostic factors of breast cancer in this population. We conducted a monocentric study including patients with breast cancer diagnosed between 2014 and 2020. Patients were classified into three groups: diabetes, obesity, and control group. The GLUT-1 expression was assessed by immunohistochemistry. In total, 199 patients were included in this study. The median age was 53.5 years, and the median tumor size was 2.8 cm. Luminal A was the most frequent molecular type (58.1%), followed by the triple-negative type (19.9%). The breast cancer in our population was characterized by a younger age at diagnosis, more aggressive molecular types, and larger tumor size. Thus, we suggest the advancement of the age of breast cancer screening in this territory. A total of 144 patients (31 diabetes, 22 obese, and 91 control group) were included for the study of GLUT-1 expression. Overexpression of GLUT-1 was observed in 60.4% of cases and in all carcinoma in situ lesions. GLUT-1 overexpression was associated with more aggressive cancers. This overexpression is correlated with high histological grade, high proliferation index, and aggressive molecular types. Our study found no difference in GLUT-1 expression between the diabetic or obese patients and the control group. These results highlight the potential role of GLUT-1 as a tumor metabolic prognostic marker and also as an interesting target therapy, independently of patient metabolic disorder.

3-Bromopyruvate-mediated MCT1-dependent metabolic perturbation sensitizes triple negative breast cancer cells to ionizing radiation

BACKGROUND

Triple negative breast cancer (TNBC) poses a serious clinical challenge as it is an aggressive form of the disease that lacks estrogen receptor, progesterone receptor, and ERBB2 (formerly HER2) gene amplification, which limits the treatment options. The Warburg phenotype of upregulated glycolysis in the presence of oxygen has been shown to be prevalent in TNBC. Elevated glycolysis satisfies the energy requirements of cancer cells, contributes to resistance to treatment by maintaining redox homeostasis and generating nucleotide precursors required for cell proliferation and DNA repair. Expression of the monocarboxylate transporter 1 (MCT1), which is responsible for the bidirectional transport of lactate, correlates with an aggressive phenotype and poor outcome in several cancer types, including breast cancer. In this study, 3-bromopyruvate (3BP), a lactate/pyruvate analog, was used to selectively target TNBC cells that express MCT1.

METHODS

The cytotoxicity of 3BP was tested in MTT assays using human TNBC cell lines: BT20 (MCT1+/MCT4-), MDA-MB-23 (MCT1-/MCT4+), and BT20 in which MCT1 was knocked down (siMCT1-BT20). The metabolite profile of 3BP-treated and 3BP-untreated cells was investigated using LC-MS/MS. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of BT20 and MDA-MB-231 cells treated with 3BP were measured using a Seahorse XF96 extracellular flux analyzer. The impact of ionizing radiation on cell survival, alone or in combination with 3BP pre-treatment, was evaluated using clonogenic assays.

RESULTS

Metabolomic analyses showed that 3BP causes inhibition of glycolysis, disturbance of redox homeostasis, decreased nucleotide synthesis, and was accompanied by a reduction in medium acidification. In addition, 3BP potentiated the cytotoxic effect of ionizing radiation, a treatment that is frequently used in the management of TNBC.

CONCLUSIONS

Overall, MCT1-mediated metabolic perturbation in combination with radiotherapy is shown to be a promising strategy for the treatment of glycolytic tumors such as TNBC, overcoming the selectivity challenges of targeting glycolysis with glucose analogs.

Co-expression and prognosis analyses of GLUT1-4 and RB1 in breast cancer

BACKGROUND

Current treatment methods for patients with triple-negative breast cancer (TNBC) are very limited, and the prognosis of TNBC is relatively poor. It has been reported that glucose transporter 1 (GLUT1) is overexpressed in breast cancer cells; however, its association with the prognosis is mostly unclear. Moreover, retinoblastoma gene 1 (RB1) might be used as a biomarker for the sensitivity of breast cancer cells to GLUT1 inhibitors, which brought us to the hypothesis that there might be a close correlation between the expression of GLUT1-4 and the expression of RB1.

METHODS

In this study, we systematically analyzed the co-expression of GLUT1-4 and the influence of GLUT1-4 gene expression on the prognosis of breast cancer using data mining methods. We also explored possible relationships between GLUT1-4 and RB1 expression in breast cancer tissues. We used public databases such as ONCOMINE, GEPIA, LinkedOmics, and COEXPEDIA.

RESULTS

According to the results, the mRNA expression of SLC2A1 was significantly higher in breast cancer, while the expression levels of SLC2A2-4 were downregulated. The results also indicate that GLUT1 expression does not have significant influence on the overall survival of patients with breast cancer. The mRNA expression of SLC2A1 and RB1 is significantly correlated, which means that tissues with high RB1 mRNA expression might have relatively higher mRNA expression of SLC2A1; however, further study analyzing their roles in the expression regulation pathways with human samples is needed to verify the hypothesis.

CONCLUSIONS

The mRNA expression of SLC2A1 was significantly higher in breast cancer. The overall survival of breast cancer patients wasn't significantly correlated with GLUT1-4 expression. The mRNA expression of SLC2A1 and RB1 is significantly correlated according to the analysis conducted in LinkedOmics. It provides reference for future possible individualized treatment of TNBC using GLUT1 inhibitors, especially in patients with higher mRNA expression of RB1. Further study analyzing the roles of these two genes in the regulation pathways is needed.

Glucose Metabolism and Glucose Transporters in Breast Cancer

Breast cancer is the most common malignancy in women worldwide and is associated with high mortality rates despite the continuously advancing treatment strategies. Glucose is essential for cancer cell metabolism owing to the Warburg effect. During the process of glucose metabolism, various glycolytic metabolites, such as serine and glycine metabolites, are produced and other metabolic pathways, such as the pentose phosphate pathway (PPP), are associated with the process. Glucose is transported into the cell by glucose transporters, such as GLUT. Breast cancer shows high expressions of glucose metabolism-related enzymes and GLUT, which are also related to breast cancer prognosis. Triple negative breast cancer (TNBC), which is a high-grade breast cancer, is especially dependent on glucose metabolism. Breast cancer also harbors various stromal cells such as cancer-associated fibroblasts and immune cells as tumor microenvironment, and there exists a metabolic interaction between these stromal cells and breast cancer cells as explained by the reverse Warburg effect. Breast cancer is heterogeneous, and, consequently, its metabolic status is also diverse, which is especially affected by the molecular subtype, progression stage, and metastatic site. In this review, we will focus on glucose metabolism and glucose transporters in breast cancer, and we will additionally discuss their potential applications as cancer imaging tracers and treatment targets.

Betulin Sulfonamides as Carbonic Anhydrase Inhibitors and Anticancer Agents in Breast Cancer Cells

Hypoxia-regulated protein carbonic anhydrase IX (CA IX) is up-regulated in different tumor entities and correlated with poor prognosis in breast cancer patients. Due to the radio- and chemotherapy resistance of solid hypoxic tumors, derivatives of betulinic acid (BA), a natural compound with anticancer properties, seem to be promising to benefit these cancer patients. We synthesized new betulin sulfonamides and determined their cytotoxicity in different breast cancer cell lines. Additionally, we investigated their effects on clonogenic survival, cell death, extracellular pH, HIF-1α, CA IX and CA XII protein levels and radiosensitivity. Our study revealed that cytotoxicity increased after treatment with the betulin sulfonamides compared to BA or their precursors, especially in triple-negative breast cancer (TNBC) cells. CA IX activity as well as CA IX and CA XII protein levels were reduced by the betulin sulfonamides. We observed elevated inhibitory efficiency against protumorigenic processes such as proliferation and clonogenic survival and the promotion of cell death and radiosensitivity compared to the precursor derivatives. In particular, TNBC cells showed benefit from the addition of sulfonamides onto BA and revealed that betulin sulfonamides are promising compounds to treat more aggressive breast cancers, or are at the same level against less aggressive breast cancer cells.

Heteromeric Solute Carriers: Function, Structure, Pathology and Pharmacology

Solute carriers form one of three major superfamilies of membrane transporters in humans, and include uniporters, exchangers and symporters. Following several decades of molecular characterisation, multiple solute carriers that form obligatory heteromers with unrelated subunits are emerging as a distinctive principle of membrane transporter assembly. Here we comprehensively review experimentally established heteromeric solute carriers: SLC3-SLC7 amino acid exchangers, SLC16 monocarboxylate/H⁺ symporters and basigin/embigin, SLC4A1 (AE1) and glycophorin A exchanger, SLC51 heteromer Ost α-Ost β uniporter, and SLC6 heteromeric symporters. The review covers the history of the heteromer discovery, transporter physiology, structure, disease associations and pharmacology - all with a focus on the heteromeric assembly. The cellular locations, requirements for complex formation, and the functional role of dimerization are extensively detailed, including analysis of the first complete heteromer structures, the SLC7-SLC3 family transporters LAT1-4F2hc, b^0,+AT-rBAT and the SLC6 family heteromer B⁰AT1-ACE2. We present a systematic analysis of the structural and functional aspects of heteromeric solute carriers and conclude with common principles of their functional roles and structural architecture.

Tumor stiffness measured by shear wave elastography correlates with tumor hypoxia as well as histologic biomarkers in breast cancer

Background

Shear wave elastography (SWE) is an ultrasound technique for the noninvasive quantification of tissue stiffness. The hypoxic tumor microenvironment promotes tumor stiffness and is associated with poor prognosis in cancer. We aimed to investigate the correlation between tumor hypoxia and histologic biomarkers and tumor stiffness measured by SWE in breast cancer.

Methods

From June 2016 to January 2018, 82 women with invasive breast cancer who underwent SWE before treatment were enrolled. Average tumor elasticity (E_average) and tumor-to-fat elasticity ratio (E_ratio) were extracted from SWE. Immunohistochemical staining of glucose transporter 1 (GLUT1) was used to assess tumor hypoxia in breast cancer tissues and automated digital image analysis was performed to assess GLUT1 activities. Spearman correlation and logistic regression analyses were performed to identify associations between GLUT1 expression and SWE values, histologic biomarkers, and molecular subtypes. The Mann–Whitney U test, t test, or Kruskal–Wallis test was used to compare SWE values and histologic features according to the GLUT1 expression (≤the median vs > median).

Results

E_average (r = 0.676) and E_ratio (r = 0.411) correlated significantly with GLUT1 expression (both p <  0.001). E_average was significantly higher in cancers with estrogen receptor (ER)–, progesterone receptor (PR)–, Ki67+, and high-grade (p <  0.05). E_ratio was higher in cancers with Ki67+, lymph node metastasis, and high-grade (p <  0.05). Cancers with high GLUT1 expression (>median) had higher E_average (mean, 85.4 kPa vs 125.5 kPa) and E_ratio (mean, 11.7 vs 17.9), and more frequent ER– (21.7% vs 78.3%), PR– (26.4% vs 73.1%), Ki67+ (31.7%% vs 68.3%), human epidermal growth factor receptor 2 (HER2) + (25.0% vs 75.0%), high-grade (28.6% vs 71.4%), and HER2-overexpressing (25.0% vs 75.0%) and triple-negative (23.1% vs 76.9%) subtypes (p <  0.05). Multivariable analysis showed that E_average was independently associated with GLUT1 expression (p <  0.001).

Conclusions

Tumor stiffness on SWE is significantly correlated with tumor hypoxia as well as histologic biomarkers. In particular, E_average on SWE has independent prognostic significance for tumor hypoxia in the multivariable analysis and can potentially be used as a noninvasive imaging biomarker to predict prognosis and pretreatment risk stratification in breast cancer patients.

Towards an Integral Therapeutic Protocol for Breast Cancer Based upon the New H+-Centered Anticancer Paradigm of the Late Post-Warburg Era

A brand new approach to the understanding of breast cancer (BC) is urgently needed. In this contribution, the etiology, pathogenesis, and treatment of this disease is approached from the new pH-centric anticancer paradigm. Only this unitarian perspective, based upon the hydrogen ion (H+) dynamics of cancer, allows for the understanding and integration of the many dualisms, confusions, and paradoxes of the disease. The new H+-related, wide-ranging model can embrace, from a unique perspective, the many aspects of the disease and, at the same time, therapeutically interfere with most, if not all, of the hallmarks of cancer known to date. The pH-related armamentarium available for the treatment of BC reviewed here may be beneficial for all types and stages of the disease. In this vein, we have attempted a megasynthesis of traditional and new knowledge in the different areas of breast cancer research and treatment based upon the wide-ranging approach afforded by the hydrogen ion dynamics of cancer. The concerted utilization of the pH-related drugs that are available nowadays for the treatment of breast cancer is advanced.

Tissue expression of lactate transporters (MCT1 and MCT4) and prognosis of malignant pleural mesothelioma (brief report)

BACKGROUND

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm of the pleura, mainly related to asbestos exposure. As in other solid tumors, malignant cells exhibit high glucose uptake and glycolytic rates with increased lactic acid efflux into the interstitial space. Lactate transport into and out of cells, crucial to maintaining intracellular pH homeostasis and glycolysis, is carried out by monocarboxylate transporters (MCTs) and the chaperone basigin (CD147). We set out to examine the clinical significance of basigin, MCT1 and MCT4 in the context of MPM and to evaluate their expression in relation to the evolution of the disease.

METHODS

We used immunohistochemistry to measure the expression of basigin, MCT1 and MCT4 in a cohort of 135 individuals with MPM compared to a series of 15 non-MPM pleura specimens. Moreover, by Kaplan-Meier and Cox analyses we evaluated whether an expression over the average of these markers could be associated with the patients' overall survival (OS).

RESULTS

We detected positive staining of basigin, MCT1, and MCT4 in most MPM specimens. In particular, MCT4 was always positive in malignant tissues but undetectable in the 4 normal pleural specimens incorporated within the tissue microarray. This was confirmed in the additional series of 15 normal pleural samples. Moreover, MCT4 expression was significantly associated with reduced OS.

CONCLUSION

In this study, the tissue expression of basigin did not prove to be exploitable as a diagnostic or prognostic marker for MPM patients. The expression of MCT1 was not informative either, being tightly correlated with that of basigin. However, the expression of MCT4 showed promise as a diagnostic/therapeutic and prognostic biomarker.

Prognostic and predictive value of monocarboxylate transporter 4 in patients with breast cancer

The Warburg effect explains the large amount of lactic acid that tumour cells produce to establish and maintain the acidic characteristics of the tumour microenvironment, which contributes to the migration, invasion and angiogenesis of tumour cells. Monocarboxylate transporter 4 (MCT-4) is a key marker of tumour glycolysis and lactic acid production; however, the role of MCT-4 in breast cancer remains unclear. In the present study, immunohistochemistry (IHC) was used to detect the expression levels of MCT-4 in tissue microarrays of 145 patients diagnosed with invasive ductal breast cancer. The IHC score was used to assess the intensity of staining and the proportion of positive cells. Western blotting and reverse transcription-quantitative PCR were also performed to detect the expression levels of MCT-4 in 30 pairs of breast cancer tissues and adjacent normal tissues. In vitro experiments (EdU incoporation and Cell Counting Kit-8) were performed to examine the role of MCT-4 in the breast cancer MCF-7 cell line. The results of the present study indicated that high MCT-4 expression was associated with pT status (P=0.018), oestrogen receptor (ER) status (P=0.001), progesterone receptor (PR) status (P=0.024), Ki67 index (P=0.043) and androgen receptor (AR) status (P=0.033). In addition, an association between MCT-4 expression and pathological grade was observed (P=0.030). Furthermore, univariate (P=0.027) and multivariate (P=0.001) survival analysis revealed that MCT-4 expression and lymph node involvement were significant independent predictors of breast cancer prognosis. In addition, silencing MCT-4 expression attenuated breast cancer cell viability. Therefore, MCT-4 may be used as a potential predictor of invasive breast cancer.

In Vitro and In Vivo Efficacy of AZD3965 and Alpha-Cyano-4-Hydroxycinnamic Acid in the Murine 4T1 Breast Tumor Model

Monocarboxylate transporter 1 (MCT1) represents a potential therapeutic target in cancer. The objective of this study was to determine the efficacy of AZD3965 (a specific inhibitor of MCT1) and α-cyano-4-hydroxycinnamic acid (CHC, a nonspecific inhibitor of MCTs) in the murine 4T1 tumor model of triple-negative breast cancer (TNBC). Expression of MCT1 and MCT4 in 4T1 and mouse mammary epithelial cells were determined by Western blot. Inhibition of MCT1-mediated L-lactate uptake and cellular proliferation by AZD3965 and CHC was determined. Mice bearing 4T1 breast tumors were treated with AZD3965 100 mg/kg i.p. twice-daily or CHC 200 mg/kg i.p. once-daily. Tumor growth, metastasis, intra-tumor lactate concentration, immune function, tumor MCT expression, and concentration-effect relationships were determined. AZD3965 and CHC inhibited cell growth and L-lactate uptake in 4T1 cells. AZD3965 treatment resulted in trough plasma and tumor concentrations of 29.1 ± 13.9 and 1670 ± 946 nM, respectively. AZD3965 decreased the tumor proliferation biomarker Ki67 expression, increased intra-tumor lactate concentration, and decreased tumor volume, although tumor weight was not different from untreated controls. CHC had no effect on tumor volume and weight, or intra-tumor lactate concentration. AZD3965 treatment reduced the blood leukocyte count and spleen weight and increased lung metastasis, while CHC did not. These findings indicate AZD3965 is a potent MCT1 inhibitor that accumulates to high concentrations in 4T1 xenograft tumors, where it increases tumor lactate concentrations and produces beneficial effects on markers of TNBC; however, overall effects on tumor growth were minimal and lung metastases increased.

The Hypoxic Response Expression as a Survival Biomarkers in Treatment-Naive Advanced Breast Cancer

OBJECTIVE

Hypoxia-associated biomarkers profiling may provide information for prognosis, staging, and subsequent therapy. We aim to evaluate whether the quantitative gene and protein expression of hypoxic response tumor markers - carbonic anhydrase IX (CAIX) and hypoxia- inducible factor 1 alpha (HIF1A) - may have a role in predicting survival in advanced breast cancer of Indonesian population.

METHODS

Tumor tissues and peripheral blood samples were collected from treatment - naïve locally advanced (LABC) or metastatic breast cancer patients (MBC) at Wahidin Sudirohusodo General Hospital (Makassar, South Sulawesi) and its referral network hospitals from July 2017 to March 2019. The level of mRNA (of blood and tumor tissue samples) and soluble protein (of blood samples) of CAIX and HIF1A were measured by RT-qPCR and ELISA methods, respectively, besides the standard histopathological grading and molecular subtype assessment. The CAIX and HIF1A expression, patients' age, tumor characteristics, surgery status, and neoadjuvant chemotherapy drug classes were further involved in survival analyses for overall survival (OS) and progression-free survival (PFS).

RESULTS

Forty (30 LABC, 10 MBC) eligible patients examined were 21 hormone-receptors positives (15 Luminal A, 6 Luminal B) and 19 hormone-receptors negatives (10 HER2-enriched, 9 triple-negative). The CAIX blood mRNA and CAIX soluble protein levels in hormone-receptors negative patients were higher than in hormone-receptor-positive patients (p < 0.05). In univariate analysis, both CAIX and HIF1A levels predict OS (except HIF1A protein) with CAIX tissue mRNA has the highest hazard ratio (HR 8.04, 95%CI:2.45-26.39), but not PFS. Cox proportional hazard model confirmed that CAIX tissue mRNA is the independent predictor of OS (HR 6.10, 95%CI: 1.16-32.13) along with surgical status and tumor advancement type (LABC or MBC).

CONCLUSIONS

CAIX mRNA expression of tumor tissue in treatment-naïve advanced breast cancer has a predictive value for OS.
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A New and Integral Approach to the Etiopathogenesis and Treatment of Breast Cancer Based upon Its Hydrogen Ion Dynamics

Despite all efforts, the treatment of breast cancer (BC) cannot be considered to be a success story. The advances in surgery, chemotherapy and radiotherapy have not been sufficient at all. Indeed, the accumulated experience clearly indicates that new perspectives and non-main stream approaches are needed to better characterize the etiopathogenesis and treatment of this disease. This contribution deals with how the new pH-centric anticancer paradigm plays a fundamental role in reaching a more integral understanding of the etiology, pathogenesis, and treatment of this multifactorial disease. For the first time, the armamentarium available for the treatment of the different types and phases of BC is approached here from a Unitarian perspective-based upon the hydrogen ion dynamics of cancer. The wide-ranged pH-related molecular, biochemical and metabolic model is able to embrace most of the fields and subfields of breast cancer etiopathogenesis and treatment. This single and integrated approach allows advancing towards a unidirectional, concerted and synergistic program of treatment. Further efforts in this line are likely to first improve the therapeutics of each subtype of this tumor and every individual patient in every phase of the disease.

Targeting Glucose Transporters for Breast Cancer Therapy: The Effect of Natural and Synthetic Compounds

Reprogramming of cellular energy metabolism is widely accepted to be a cancer hallmark. The deviant energetic metabolism of cancer cells-known as the Warburg effect-consists in much higher rates of glucose uptake and glycolytic oxidation coupled with the production of lactic acid, even in the presence of oxygen. Consequently, cancer cells have higher glucose needs and thus display a higher sensitivity to glucose deprivation-induced death than normal cells. So, inhibitors of glucose uptake are potential therapeutic targets in cancer. Breast cancer is the most commonly diagnosed cancer and a leading cause of cancer death in women worldwide. Overexpression of facilitative glucose transporters (GLUT), mainly GLUT1, in breast cancer cells is firmly established, and the consequences of GLUT inhibition and/or knockout are under investigation. Herein we review the compounds, both of natural and synthetic origin, found to interfere with uptake of glucose by breast cancer cells, and the consequences of interference with that mechanism on breast cancer cell biology. We will also present data where the interaction with GLUT is exploited in order to increase the efficiency or selectivity of anticancer agents, in breast cancer cells.

CAIX is a predictor of pathological complete response and is associated with higher survival in locally advanced breast cancer submitted to neoadjuvant chemotherapy

BACKGROUND

Locally advanced breast cancer often undergoes neoadjuvant chemotherapy (NAC), which allows in vivo evaluation of the therapeutic response. The determination of the pathological complete response (pCR) is one way to evaluate the response to neoadjuvant chemotherapy. However, the rate of pCR differs significantly between molecular subtypes and the cause is not yet determined. Recently, the metabolic reprogramming of cancer cells and its implications for tumor growth and dissemination has gained increasing prominence and could contribute to a better understanding of NAC. Thus, this study proposed to evaluate the expression of metabolism-related proteins and its association with pCR and survival rates.

METHODS

The expression of monocarboxylate transporters 1 and 4 (MCT1 and MCT4, respectively), cluster of differentiation 147 (CD147), glucose transporter-1 (GLUT1) and carbonic anhydrase IX (CAIX) was analyzed in 196 locally advanced breast cancer samples prior to NAC. The results were associated with clinical-pathological characteristics, occurrence of pCR, disease-free survival (DFS), disease-specific survival (DSS) and overall survival (OS).

RESULTS

The occurrence of pCR was higher in the group of patients whith tumors expressing GLUT1 and CAIX than in the group without expression (27.8% versus 13.1%, p = 0.030 and 46.2% versus 13.5%, p = 0.007, respectively). Together with regional lymph nodes staging and mitotic staging, CAIX expression was considered an independent predictor of pCR. In addition, CAIX expression was associated with DFS and DSS (p = 0.005 and p = 0.012, respectively).

CONCLUSIONS

CAIX expression was a predictor of pCR and was associated with higher DFS and DSS in locally advanced breast cancer patients subjected to NAC.

CAIX forms a transport metabolon with monocarboxylate transporters in human breast cancer cells

Tumor cells rely on glycolysis to meet their elevated demand for energy. Thereby they produce significant amounts of lactate and protons, which are exported via monocarboxylate transporters (MCTs), supporting the formation of an acidic microenvironment. The present study demonstrates that carbonic anhydrase IX (CAIX), one of the major acid/base regulators in cancer cells, forms a protein complex with MCT1 and MCT4 in tissue samples from human breast cancer patients, but not healthy breast tissue. Formation of this transport metabolon requires binding of CAIX to the Ig1 domain of the MCT1/4 chaperon CD147 and is required for CAIX-mediated facilitation of MCT1/4 activity. Application of an antibody, directed against the CD147-Ig1 domain, displaces CAIX from the transporter and suppresses CAIX-mediated facilitation of proton-coupled lactate transport. In cancer cells, this "metabolon disruption" results in a decrease in lactate transport, reduced glycolysis, and ultimately reduced cell proliferation. Taken together, the study shows that carbonic anhydrases form transport metabolons with acid/base transporters in human tumor tissue and that these interactions can be exploited to interfere with tumor metabolism and proliferation.

The Role of Sodium Hydrogen Exchanger 1 in Dysregulation of Proton Dynamics and Reprogramming of Cancer Metabolism as a Sequela

Cancer cells have an unusual regulation of hydrogen ion dynamics that are driven by poor vascularity perfusion, regional hypoxia, and increased glycolysis. All these forces synergize/orchestrate together to create extracellular acidity and intracellular alkalinity. Precisely, they lead to extracellular pH (pH_e) values as low as 6.2 and intracellular pH values as high as 8. This unique pH gradient (∆pH_i to ∆pH_e) across the cell membrane increases as the tumor progresses, and is markedly displaced from the electrochemical equilibrium of protons. These unusual pH dynamics influence cancer cell biology, including proliferation, metastasis, and metabolic adaptation. Warburg metabolism with increased glycolysis, even in the presence of Oxygen with the subsequent reduction in Krebs’ cycle, is a common feature of most cancers. This metabolic reprogramming confers evolutionary advantages to cancer cells by enhancing their resistance to hypoxia, to chemotherapy or radiotherapy, allowing rapid production of biological building blocks that support cellular proliferation, and shielding against damaging mitochondrial free radicals. In this article, we highlight the interconnected roles of dysregulated pH dynamics in cancer initiation, progression, adaptation, and in determining the programming and re-programming of tumor cell metabolism.

MCT4 has a potential to be used as a prognostic biomarker - a systematic review and meta-analysis

The role of several metabolic changes, such as hypoxia and acidosis, in the tumour environment has caught the attention of researchers in cancer progression and invasion. Lactate transport is one of the acidosis-enhancing processes that are mediated via monocarboxylate transporters (MCTs). We conducted a systematic review and meta-analysis to investigate the expression of two cancer-relevant MCTs (MCT1 and MCT4) and their potential prognostic significance in patients with metastasis of different types of cancer. Studies were included if they reported the number of metastatic tissue samples expressing either low or high levels of MCT1 and/or MCT4 or those revealing the hazard ratios (HRs) of the overall survival (OS) or disease-free survival (DFS) as prognostic indicators. During the period between 2010 and 2018, a total of 20 articles including 3831 patients (56.3% males) were identified. There was a significant association between MCT4 expression (high versus low) and lymph node metastasis [odds ratio (OR)=1.87, 95% confidence interval (CI)=1.10-3.17, P=0.02] and distant metastasis (OR=2.18, 95%CI=1.65-2.86, P<0.001) and the correlation remained significant for colorectal and hepatic cancer in subgroup analysis. For survival analysis, patients with shorter OS periods exhibited a higher MCT4 expression [hazard ratio (HR)=1.78, 95%CI=1.49-2.13, P<0.001], while DFS was shorter in patients with high MCT1 (HR=1.48, 95%CI=1.04-2.10, P=0.03) and MCT4 expression (HR=1.70, 95%CI=1.19-2.42, P=0.003) when compared to their counterparts with low expression levels. Future research studies should consider the pharmacologic inhibition of MCT4 to effectively inhibit cancer progression to metastasis.

Downregulation of lncRNA AWPPH inhibits colon cancer cell proliferation by downregulating GLUT-1

Long non-coding RNA (lncRNA) associated with poor prognosis of hepatocellular carcinoma (AWPPH) serves pivotal roles in bladder cancer and liver cancer; however, to the best of our knowledge, its functionality in colon cancer has not been characterized. The present study aimed to investigate the involvement of lncRNA AWPPH in colon cancer. Serum levels of lncRNA AWPPH and glucose transporter 1 (GLUT-1) in patients with early stage colon cancer and healthy controls were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and ELISA. Correlation between lncRNA AWPPH and GLUT-1 expression was analyzed by Pearson's correlation coefficient. χ² test was performed to investigate the associations between serum levels of lncRNA AWPPH and clinical data of patients with colon cancer. lncRNA AWPPH short hairpin RNA and GLUT-1 expression vectors were transfected into colon cancer cells, and the effects on lncRNA AWPPH, GLUT-1 and cell proliferation were detected by RT-qPCR, western blotting and Cell Counting Kit-8 assay. It was observed that serum levels of lncRNA AWPPH and GLUT-1 were significantly higher in patients with colon cancer patients compared with healthy controls. Serum levels of AWPPH and GLUT-1 were significantly positively correlated in patients with colon cancer. Serum levels of lncRNA AWPPH were associated with the tumor size. Furthermore, AWPPH-silencing significantly inhibited GLUT-1 expression and inhibited cancer cell proliferation. GLUT-1 overexpression promoted cancer cell proliferation and attenuated the inhibitory effects of AWPPH-silencing on cancer cell proliferation. However, GLUT-1 overexpression failed to significantly affect the expression of AWPPH. Therefore, it can be concluded that a downregulation of lncRNA AWPPH may inhibit colon cancer cell proliferation by downregulating GLUT-1.

Carbonic anhydrase 9 expression is associated with poor prognosis, tumor proliferation, and radiosensitivity of thymic carcinomas

Introduction

Thymic epithelial tumors (TETs) comprise several histologies of thymoma and thymic carcinomas (TCs), and TC frequently metastasizes and causes death. We therefore aimed here to identify key molecules closely related to prognosis and their biological roles in high-risk TETs, particularly TCs.

Results

RNA sequence analysis demonstrated that hypoxia-related genes were highly expressed in TETs. The expression of the hypoxia-related gene CA9 was noteworthy, particularly in TCs. Immunohistochemical analysis revealed that CA9 was expressed in 81.0% of TCs and 20.7% of all TET samples. CA9 expression was significantly associated with Masaoka stage, WHO classification, and recurrence-free survival after tumor resection (P = 0.005). The down-regulation of CA9 transcription in TC cell lines by small interfering RNAs significantly inhibited CA9 expression, which inhibited proliferation and increased sensitivity to irradiation.

Conclusions

CA9 expression may serve as a significant prognostic marker of TETs and therefore represents a potential target for the development of novel drugs and radiation-sensitizing therapy designed to improve the outcomes of patients with TCs.

Materials and Methods

We performed comprehensive transcriptome sequencing of 23 TETs and physiologic thymic specimens to identify genes highly and specifically expressed in high-risk TETs, particulary TCs. We performed immunohistochemical analysis of 179 consecutive surgically resected TETs to evaluate the significance of the association of protein expression with clinicopathological features and prognosis. The biological significance of the most promising prognostic marker was further studied using the TC cell lines, Ty-82 and MP57.

Cellular Uptake of MCT1 Inhibitors AR-C155858 and AZD3965 and Their Effects on MCT-Mediated Transport of L-Lactate in Murine 4T1 Breast Tumor Cancer Cells

AR-C155858 and AZD3965, pyrrole pyrimidine derivatives, represent potent monocarboxylate transporter 1 (MCT1) inhibitors, with potential immunomodulatory and chemotherapeutic properties. Currently, there is limited information on the inhibitory properties of this new class of MCT1 inhibitors. The purpose of this study was to characterize the concentration- and time-dependent inhibition of L-lactate transport and the membrane permeability properties of AR-C155858 and AZD3965 in the murine 4T1 breast tumor cells that express MCT1. Our results demonstrated time-dependent inhibition of L-lactate uptake by AR-C155858 and AZD3965 with maximal inhibition occurring after a 5-min pre-incubation period and prolonged inhibition. Following removal of AR-C155858 or AZD3965 from the incubation buffer, inhibition of L-lactate uptake was only fully reversed after 3 and 12 h, respectively, indicating that these inhibitors are slowly reversible. The uptake of AR-C155858 was concentration-dependent in 4T1 cells, whereas the uptake of AZD3965 exhibited no concentration dependence over the range of concentrations examined. The uptake kinetics of AR-C155858 was best fitted to a Michaelis-Menten equation with a diffusional clearance component, P (K_m = 0.399 ± 0.067 μM, V_max = 4.79 ± 0.58 pmol/mg/min, and P = 0.330 ± 0.088 μL/mg/min). AR-C155858 uptake, but not AZD3965 uptake, was significantly inhibited by alpha-cyano-4-hydroxycinnamic acid, a known nonspecific inhibitor of MCTs 1, 2, and 4. AR-C155858 demonstrated a trend toward higher uptake at lower pH, a characteristic of proton-dependent MCT1. These findings provide evidence that AR-C155858 and AZD3965 exert slowly reversible inhibition of MCT1-mediated L-lactate uptake in 4T1 cells, with AR-C155858 representing a potential substrate of MCT1.

The Warburg Effect Is Associated With Tumor Aggressiveness in Testicular Germ Cell Tumors

Testicular Germ Cell Tumors (TGCTs) are a rare group of neoplasms and the most common solid malignancy arising in young male adults. Despite the good response of these tumors to platinum-based chemotherapy, some patients are refractory to treatment and present poor clinical outcomes. During carcinogenesis and tumor development, cancer cells reprogram energy metabolism toward a hyper-glycolytic phenotype, an emerging hallmark of cancer. This phenomenon, known as the Warburg effect or aerobic glycolysis, involves overexpression of metabolism-related proteins, like glucose and monocarboxylate transporters, pH regulators and intracellular glycolytic enzymes. The metabolic profile of TGCTs is very little explored and, recently, this metabolic rewiring of cancer cells has been associated with aggressive clinicopathological characteristics of these tumors. The overexpression of monocarboxylate transporter 4 (MCT4) in TGCTs has been pointed out as a poor prognostic factor, as well as a promising therapeutic target. As a result, the main aim of the present study was to evaluate the prognostic value of key metabolism-related proteins in TGCTs. The immunohistochemical expressions of CD44 (as a monocarboxylate transporter chaperone), glucose transporter 1 (GLUT1), carbonic anhydrase IX (CAIX), hexokinase II (HKII) and lactate dehydrogenase V (LDHV) were evaluated in a series of 148 adult male patients with TGCTs and associated with clinicopathological parameters. In addition, paired normal tissues were also evaluated. The sample included 75 seminoma and 73 non-seminoma tumors. GLUT1 and CD44 expression was significantly increased in malignant samples when compared to paired normal samples. Conversely, HKII and LDHV expressions were significantly decreased in malignant samples. Concerning the clinicopathological values, CAIX expression was significantly associated with disease recurrence, while HKII expression was significantly associated with aggressive characteristics of TGCTs, including higher staging and non-seminoma histology. In conclusion, this study brings new insights on the metabolic characteristics of TGCTs, showing alterations in the expression of proteins related with the Warburg effect, as well as associations of the hyper-glycolytic and acid-resistant phenotype with aggressive clinicopathological parameters.

In Vitro and In Vivo Efficacy of the Monocarboxylate Transporter 1 Inhibitor AR-C155858 in the Murine 4T1 Breast Cancer Tumor Model

Monocarboxylate transporter 1 (MCT1), also known as a L-lactate transporter, is a potential therapeutic target in cancer. The objectives of this study were to evaluate efficacy and assess concentration-effect relationships of AR-C155858 (a selective and potent MCT1 inhibitor) in murine 4T1 breast cancer cells and in the 4T1 tumor xenograft model. Western blotting of 4T1 cells demonstrated triple negative breast cancer (TNBC) characteristics and overexpression of MCT1 and CD147 (a MCT1 accessory protein), but absence of MCT4 expression. AR-C155858 inhibited the cellular L-lactate uptake and cellular proliferation at low nanomolar potencies (IC₅₀ values of 25.0 ± 4.2 and 20.2 ± 0.2 nM, respectively). In the xenograft 4T1 mouse model of immunocompetent animals, AR-C155858 (10 mg/kg i.p. once daily) had no effect on tumor volume and weight. Treatment with AR-C155858 resulted in slightly increased tumor lactate concentrations; however, the changes were not statistically significant. AR-C155858 was well tolerated, as demonstrated by the unchanged body weight and blood lactate concentrations. Average blood and tumor AR-C155858 concentrations (110 ± 22 and 574 ± 245 nM, respectively), 24 h after the last dose, were well above the IC₅₀ values. These data indicate that AR-C155858 penetrated 4T1 xenograft tumors and was present at high concentrations but was ineffective in decreasing tumor growth. Evaluations of AR-C155858 in other preclinical models of breast cancer are needed to further assess its efficacy.

Loss of function of miR-342-3p results in MCT1 over-expression and contributes to oncogenic metabolic reprogramming in triple negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous and aggressive neoplasia lacking the expression of hormonal receptors and human epidermal growth factor receptor-2. Accumulating evidence has highlighted the importance of miRNAs dysregulation in the establishment of cancer programs, but the functional role of many miRNAs remains unclear. The description of miRNAs roles might provide novel strategies for treatment. In the present work, an integrated analysis of miRNA transcriptional landscape was performed (N = 132), identifying the significant down-modulation of miR-342-3p in TNBC, probably because of the aberrant activity of estrogen receptor, which serves as a transcription factor of the miRNA, as demonstrated by a siRNA-knockdown approach. The enhanced expression of miR-342-3p significantly decreased cell proliferation, viability and migration rates of diverse TN cells in vitro. Bioinformatic and functional analyses revealed that miR-342-3p directly targets the monocarboxylate transporter 1 (MCT1), which promotes lactate and glucose fluxes alteration, thus disrupting the metabolic homeostasis of tumor cells. Optical metabolic imaging assay defined a higher optical redox ratio in glycolytic cells overexpressing miR-342-3p. Furthermore, we found that hypoxic conditions and glucose starvation attenuate miR-342-3p expression, suggesting a crosstalk program between these metabolic factors. Consistently, miR-342-3p down-modulation is associated with an increased MCT1 expression level and glycolytic score in human triple negative tumors. Overall, we described for the first time the regulatory activity of miR-342-3p on relevant metabolic carcinogenic pathways in TN breast cancers.

Antimetabolic Effects of Polyphenols in Breast Cancer Cells: Focus on Glucose Uptake and Metabolism

In the last years, metabolic reprogramming became a new key hallmark of tumor cells. One of its components is a deviant energetic metabolism, known as Warburg effect—an aerobic lactatogenesis—characterized by elevated rates of glucose uptake and consumption with high-lactate production even in the presence of oxygen. Because many cancer cells display a greater sensitivity to glucose deprivation-induced cytotoxicity than normal cells, inhibitors of glucose cellular uptake (facilitative glucose transporter 1 inhibitors) and oxidative metabolism (glycolysis inhibitors) are potential therapeutic targets in cancer treatment. Polyphenols, abundantly contained in fruits and vegetables, are dietary components with an established protective role against cancer. Several molecular mechanisms are involved in the anticancer effect of polyphenols, including effects on apoptosis, cell cycle regulation, plasma membrane receptors, signaling pathways, and epigenetic mechanisms. Additionally, inhibition of glucose cellular uptake and metabolism in cancer cell lines has been described for several polyphenols, and this effect was shown to be associated with their anticarcinogenic effect. This work will review data showing an antimetabolic effect of polyphenols and its involvement in the chemopreventive/chemotherapeutic potential of these dietary compounds, in relation to breast cancer.

Development and validation of a liquid chromatography tandem mass spectrometry assay for AZD3965 in mouse plasma and tumor tissue: Application to pharmacokinetic and breast tumor xenograft studies

AZD3965, a pyrole pyrimidine derivative, is a potent and orally bioavailable inhibitor of monocarboxylate transporter 1 (MCT1), currently in a Phase I clinical trial in UK for lymphomas and solid tumors. There is currently no published assay for AZD3965. The objectives of this study were to develop and validate a LC/MS/MS assay for quantifying AZD3965 in mouse plasma and tumor tissue. Protein precipitation with 0.1% formic acid in acetonitrile was used for sample preparation. Chromatographic separation was achieved on a C18 column followed by tandem mass spectrometry detection in multiple reaction monitoring mode with utilizing Atmospheric Pressure Chemical Ionization. AR-C155858 was used as the internal standard. The inter-day and intra-day precision and accuracy of quality control samples evaluated in plasma and tumor tissue were less than ±7% of the nominal concentrations. The extraction recovery, matrix effect and stability values were all within acceptable levels. Sample dilution integrity, accessed by diluting plasma spiked with AZD3965 10-fold with blank plasma, was 101%. The lower limit of quantification (LLOQ) and upper limit of quantification (ULOQ) were 0.15 ng/mL and 12 μg/mL, respectively, in plasma. The assay of AZD3965 in tumor tissue was also validated with good precision and accuracy. The LLOQ was 0.15 ng/mL in tumor tissue. This assay was successfully applied to pharmacokinetic and murine 4T1 breast tumor xenograft studies of AZD3965 in mice.

Expression of Pentose Phosphate Pathway-Related Proteins in Breast Cancer

Purpose

The purpose of this study was to assess the expression of pentose phosphate pathway- (PPP-) related proteins and their significance in clinicopathologic factors of breast cancer.

Methods

Immunohistochemical staining for PPP-related proteins (glucose-6-phosphate dehydrogenase [G6PDH], 6-phosphogluconolactonase [6PGL], 6-phosphogluconate dehydrogenase [6PGDH], and nuclear factor-erythroid 2-related factor 2 [NRF2]) was performed using tissue microarray (TMA) of 348 breast cancers. mRNA levels of these markers in publicly available data from the Cancer Genome Atlas project and Kaplan-Meier plotters were analyzed.

Results

Expression of G6PDH and 6PGL was higher in HER-2 type (p < 0.001 and p = 0.009, resp.) and lower in luminal A type. 6PGDH expression was detected only in TNBC subtype (p < 0.001). G6PDH positivity was associated with ER negativity (p = 0.001), PR negativity (p = 0.001), and HER-2 positivity (p < 0.001), whereas 6PGL positivity was associated with higher T stage (p = 0.004). The 562 expression profile from the TCGA database revealed increased expression of G6PDH and 6PG in the tumor compared with normal adjacent breast tissue. The expression of G6PDH was highest in HER-2 type. HER-2 and basal-like subtypes showed higher expression of 6PGDH than luminal types.

Conclusion

PPP-related proteins are differentially expressed in breast cancer according to molecular subtype, and higher expression of G6PDH and 6PGL was noted in HER-2 subtype.

Hypoxia-mediated upregulation of MCT1 expression supports the glycolytic phenotype of glioblastomas

Background

Glioblastomas (GBM) present a high cellular heterogeneity with conspicuous necrotic regions associated with hypoxia, which is related to tumor aggressiveness. GBM tumors exhibit high glycolytic metabolism with increased lactate production that is extruded to the tumor microenvironment through monocarboxylate transporters (MCTs). While hypoxia-mediated regulation of MCT4 has been characterized, the role of MCT1 is still controversial. Thus, we aimed to understand the role of hypoxia in the regulation of MCT expression and function in GBM, MCT1 in particular.

Methods

Expression of hypoxia- and glycolytic-related markers, as well as MCT1 and MCT4 isoforms was assessed in in vitro and in vivo orthotopic glioma models, and also in human GBM tissues by immunofluorescence/immunohistochemistry and Western blot. Following MCT1 inhibition, either pharmacologically with CHC (α-cyano-4-hydroxynnamic acid) or genetically with siRNAs, we assessed GBM cell viability, proliferation, metabolism, migration and invasion, under normoxia and hypoxia conditions.

Results

Hypoxia induced an increase in MCT1 plasma membrane expression in glioma cells, both in in vitro and in vivo models. Additionally, treatment with CHC and downregulation of MCT1 in glioma cells decreased lactate production, cell proliferation and invasion under hypoxia. Moreover, in the in vivo orthotopic model and in human GBM tissues, there was extensive co-expression of MCT1, but not MCT4, with the GBM hypoxia marker CAIX.

Conclusion

Hypoxia-induced MCT1 supports GBM glycolytic phenotype, being responsible for lactate efflux and an important mediator of cell survival and aggressiveness. Therefore, MCT1 constitutes a promising therapeutic target in GBM.

HIF-1-alpha links mitochondrial perturbation to the dynamic acquisition of breast cancer tumorigenicity

Up-regulation of hypoxia-inducible factor-1α (HIF-1α), even in normoxia, is a common feature of solid malignancies. However, the mechanisms of increased HIF-1α abundance, and its role in regulating breast cancer plasticity are not fully understood. We have previously demonstrated that dimethyl-2-ketoglutarate (DKG), a widely used cell membrane-permeable α-ketoglutarate (α-KG) analogue, transiently stabilizes HIF-1α by inhibiting prolyl hydroxylase 2. Here, we report that breast cancer tumorigenicity can be acquired through prolonged treatment with DKG. Our results indicate that, in response to prolonged DKG treatment, mitochondrial respiration becomes uncoupled, leading to the accumulation of succinate and fumarate in breast cancer cells. Further, we found that an early increase in the oxygen flux rate was accompanied by a delayed enhancement of glycolysis. Together, our results indicate that these events trigger a dynamic enrichment for cells with pluripotent/stem-like cell markers and tumorsphere-forming capacity. Moreover, DKG-mediated metabolic reprogramming results in HIF-1α induction and reductive carboxylation pathway activation. Both HIF-1α accumulation and the tumor-promoting metabolic state are required for DKG-promoted tumor repopulation capacity in vivo. Our data suggest that mitochondrial adaptation to DKG elevates the ratio of succinate or fumarate to α-KG, which in turn stabilizes HIF-1α and reprograms breast cancer cells into a stem-like state. Therefore, our results demonstrate that metabolic regulation, with succinate and/or fumarate accumulation, governs the dynamic transition of breast cancer tumorigenic states and we suggest that HIF-1α is indispensable for breast cancer tumorigenicity.

Metabolic Footprints and Molecular Subtypes in Breast Cancer

Cancer treatment options are increasing. However, even among the same tumor histotype, interpatient tumor heterogeneity should be considered for best therapeutic result. Metabolomics represents the last addition to promising “omic” sciences such as genomics, transcriptomics, and proteomics. Biochemical transformation processes underlying energy production and biosynthetic processes have been recognized as a hallmark of the cancer cell and hold a promise to build a bridge between genotype and phenotype. Since breast tumors represent a collection of different diseases, understanding metabolic differences between molecular subtypes offers a way to identify new subtype-specific treatment strategies, especially if metabolite changes are evaluated in the broader context of the network of enzymatic reactions and pathways. Here, after a brief overview of the literature, original metabolomics data in a series of 92 primary breast cancer patients undergoing surgery at the Istituto Nazionale dei Tumori of Milano are reported highlighting a series of metabolic differences across various molecular subtypes. In particular, the difficult-to-treat luminal B subgroup represents a tumor type which preferentially relies on fatty acids for energy, whereas HER2 and basal-like ones show prevalently alterations in glucose/glutamine metabolism.

Evaluation of the Expression of Amine Oxidase Proteins in Breast Cancer

We aimed to evaluate the expression of amine oxidase proteins in breast cancer and their clinical implications. We performed immunohistochemical staining of amine oxidase proteins (LOX, lysyl oxidase, AOC3, amine oxidase, MAOA, monoamine oxidase A, MAOB, monoamine oxidase B). Based on their hormone receptors, such as estrogen receptor (ER) and progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), and Ki-67 immunohistochemical staining, breast cancer was divided into four molecular subtypes: luminal A, luminal B, HER-2 type, and triple-negative breast cancer (TNBC). Luminal A was observed in 380 cases (49.4%), luminal B in 224 (29.1%), HER-2 type in 68 (8.8%), and TNBC in 98 (12.7%). Stromal AOC3, MAO-A, and MAO-B expression varied according to molecular subtypes. Stromal AOC3 expression was high in luminal B and HER-2 type and MAO-A expression was high in luminal A and luminal B (p < 0.001). MAO-B expression was higher in TNBC than in other subtypes (p = 0.020). LOX positivity was associated with high histological grade (p < 0.001) and high Ki-67 labeling index (LI) (p = 0.009), and stromal AOC3 positivity was associated with high histological grade (p = 0.001), high Ki-67 LI (p < 0.001), and HER-2 positivity (p = 0.002). MAO-A positivity was related to low histological grade (p < 0.001), ER positivity, PR positivity (p < 0.001), and low Ki-67 LI (p < 0.001). In univariate analysis, MAO-A positivity was related to short disease-free survival in HER-2 type (p = 0.013), AOC3 negativity was related to short disease-free survival and overall survival in ER-positive breast cancer, PR-positive breast cancer, HER-2-negative breast cancer, and lymph node metastasis. In conclusion, the expression of amine oxidase proteins varies depending on the molecular subtype of breast cancer. Stromal AOC3 expression was high in luminal B and HER-2 type, and MAO-A expression was high in luminal A and luminal B.

Lactate stimulates CA IX expression in normoxic cancer cells

Besides hypoxia, other factors and molecules such as lactate, succinate, and reactive oxygen species activate transcription factor hypoxia-inducible factor-1 (HIF-1) even in normoxia. One of the main target gene products of HIF-1 is carbonic anhydrase IX (CA IX). CA IX is overexpressed in many tumors and serves as prognostic factor for hypoxic, aggressive and malignant cancers. CA IX is also induced in normoxia in high cell density. In this study, we observed that lactate induces CA IX expression in normoxic cancer cells in vitro and in vivo. We further evidenced that participation of both HIF-1 and specificity protein 1 (SP1) transcription factors is crucial for lactate-driven normoxic induction of the CA9 gene. By inducing CA IX, lactate can facilitate the maintenance of cancer cell aggressive behavior in normoxia.

Tumor LDH-A expression and serum LDH status are two metabolic predictors for triple negative breast cancer brain metastasis

There are limited therapeutic methods for triple negative breast cancer in the clinic, which is easy to progress into the brain to form metastatic lesions and evolve into the terminal stage. Because both the primary cancer and the brain metastasis have high glycolysis, we hypothesize that lactate dehydrogenase (LDH), which catalyzes the final step of glycolysis, may be a predictor, as well as a treatment target, for breast cancer brain metastasis. Therefore, the expression of LDH-A was detected on 119 triple negative breast cancer tissues with immunohistochemistry, and the serum LDH levels were also measured. Our results showed that the LDH-A expression inside the tumor was significantly higher than the matched normal tissues. Tumor LDH-A expression, serum LDH status, and the slope of serum LDH status were closely associated with triple negative breast cancer brain metastasis and brain metastasis free survival. This study indicates that tumor LDH and serum LDH status are two predictors for triple negative breast cancer brain metastasis.

GLUT1 expression in pediatric adrenocortical tumors: a promising candidate to predict clinical behavior

Background

Discrimination between benign and malignant tumors is a challenging process in pediatric adrenocortical tumors. New insights in the metabolic profile of pediatric adrenocortical tumors may contribute to this distinction, predict prognosis, as well as identify new molecular targets for therapy. The aim of this work is to characterize the expression of the metabolism-related proteins MCT1, MCT2, MCT4, CD147, CD44, GLUT1 and CAIX in a series of pediatric adrenocortical tumors.

Methods

A total of 50 pediatric patients presenting adrenocortical tumors, including 41 clinically benign and 9 clinically malignant tumors, were included. Protein expression was evaluated using immunohistochemistry in samples arranged in tissue microarrays.

Results

The immunohistochemical analysis showed a significant increase in plasma membrane expression of GLUT1 in malignant lesions, when compared to benign lesions (p=0.004), being the expression of this protein associated with shorter overall and disease-free survival (p=0.004 and p=0.001, respectively). Although significant differences were not observed for proteins other than GLUT1, MCT1, MCT4 and CD147 were highly expressed in pediatric adrenocortical neoplasias (around 90%).

Conclusion

GLUT1 expression was differentially expressed in pediatric adrenocortical tumors, with higher expression in clinically malignant tumors, and associated with shorter survival, suggesting a metabolic remodeling towards a hyperglycolytic phenotype in this malignancy.

GLUT1 as a Prognostic Factor for Classical Hodgkin's Lymphoma: Correlation with PD-L1 and PD-L2 Expression

Background

Glucose transporter type 1 (GLUT1) expression is linked to glucose metabolism and tissue hypoxia. A recent study reported that GLUT1 was significantly associated with programmed death ligand 1 (PD-L1) as a therapeutic target in relapsed or refractory classical Hodgkin’s lymphoma (cHL). The purpose of this study was to measure the expression of GLUT1 and assess its prognostic significance and potential relationships with PD-L1, programmed death ligand 2 (PD-L2), and programmed death-1 (PD-1) expressions in cHL.

Methods

Diagnostic tissues from 125 patients with cHL treated with doxorubicin, bleomycin, vinblastine, and dacarbazine were evaluated retrospectively via immunohistochemical analysis of GLUT1, PD-L1, PD-L2, and PD-1 expression.

Results

The median follow-up time was 4.83 years (range, 0.08 to 17.33 years). GLUT1, PD-L1, PD-L2, and PD-1 were expressed in 44.8%, 63.2%, 9.6%, and 13.6% of the specimens, respectively. Positive correlations were found between GLUT1 and PD-L1 expression (p = .004) and between GLUT1 and PD-L2 expression (p = .031). GLUT1 expression in Hodgkin/Reed-Sternberg (HRS) cells was not associated with overall survival or event-free survival (EFS) in the entire cohort (p = .299 and p = .143, respectively). A subgroup analysis according to the Ann Arbor stage illustrated that GLUT1 expression in HRS cells was associated with better EFS in advanced-stage disease (p = .029). A multivariate analysis identified GLUT1 as a marginally significant prognostic factor for EFS (p = .068).

Conclusions

This study suggests that GLUT1 expression is associated with better clinical outcomes in advanced-stage cHL and is significantly associated with PD-L1 and PD-L2 expressions.

Glucose transporters 1, 3, 6, and 10 are expressed in gastric cancer and glucose transporter 3 is associated with UICC stage and survival

BACKGROUND

Due to proliferation and increased metabolism, cancer cells have high glucose requirements. The glucose uptake of cells is influenced by a group of membrane proteins denoted the glucose transporter family (Glut-1 to -12). Whereas increased expression and a negative correlation with survival have been described for Glut-1 in several types of cancer, the impact of other glucose transporters on tumor biology is widely unknown.

METHODS

In this retrospective study, gastric cancer specimens of 150 patients who underwent total gastrectomy between 2005 and 2010 were stained for Glut-1, -3, -6, and -10 by immunohistochemistry. Expression of Glut-1, -3, -6, and 10 was correlated to prognosis as well as clinical and pathological parameters.

RESULTS

Glut-1, Glut-3, Glut-6, and Glut-10 were expressed in 22.0, 66.0, 38.0, and 43.3 % of the analyzed samples. Whereas Glut-1, -6, and -10 did not show a correlation with prognosis, positive staining for Glut-3 was associated with higher UICC stage and inferior prognosis. The mean overall survival was 38.6 months for Glut-3 positive patients, as compared to 51.2 months for Glut-3 negative patients (p < 0.05). Coexpression of two or more of the analyzed glucose transporters was correlated to inferior prognosis. Glut-3 and UICC stage were significant prognostic factors in multivariate analysis.

CONCLUSIONS

All of the analyzed glucose transporters were expressed in a significant proportion of the gastric cancer samples. Glut-3 was associated with higher UICC stage and inferior prognosis. These findings are relevant to therapeutic approaches that target glucose metabolism as well as to imaging using radioactively labeled glucose.

GLUT1 and ASCT2 as Predictors for Prognosis of Hepatocellular Carcinoma

An emerging hallmark of cancer is reprogrammed cellular metabolism, and several cancers involve increased glucose intake and glutamine addiction. Hepatocellular carcinoma (HCC) is one of the most fatal cancers, and its molecular basis needs to be delineated to identify biomarkers for its potential treatment without resection. Therefore, this study aimed to determine the metabolism status of HCC by evaluating the expression of the glucose transporter GLUT1 and glutamine transporter ASCT2. We enrolled 192 patients with surgically resected HCC in this study. Their tissue samples were subjected to immunohistochemistry to detect GLUT1 and ASCT2 expression. The prognostic value of GLUT1 and ASCT2 expression and their combined metabolic index was determined by Kaplan–Meier analysis and the Cox proportional hazards model. We found that GLUT1 and ASCT2 expression was significantly upregulated in tumor tissues as compared to adjacent non-tumor tissues and was positively associated with tumor size. Survival analysis revealed that patients with high GLUT1 or ASCT2 expression had poor overall survival (OS) and recurrence-free survival (RFS). In HCC patients, ASCT2 expression was an independent negative prognostic factor for OS (hazard ratio [HR], 1.760; 95% confidence interval [CI] = 1.124−2.755; p = 0.013) and the metabolic index was an independent negative prognostic factor for OS (HR = 1.672, 95% CI = 1.275−2.193, p < 0.001) and RFS (HR = 1.362, 95% CI = 1.066−1.740, p = 0.013). In conclusion, the tumor metabolism status determined by expression of GLUT1 and ASCT2 and their metabolic index is a promising prognostic predictor for HCC patients.

The glucose transporter GLUT1 is required for ErbB2-induced mammary tumorigenesis

BACKGROUND

Altered tumor cell metabolism is an emerging hallmark of cancer; however, the precise role for glucose in tumor initiation is not known. GLUT1 (SLC2A1) is expressed in breast cancer cells and is likely responsible for avid glucose uptake observed in established tumors. We have shown that GLUT1 was necessary for xenograft tumor formation from primary mammary cells transformed with the polyomavirus middle-T antigen but that it was not necessary for growth after tumors had formed in vivo, suggesting a differential requirement for glucose depending on the stage of tumorigenesis.

METHODS

To determine whether GLUT1 is required early during mammary tumorigenesis, we crossed MMTV-NIC mice, which express activated HER2/NEU/ERBB2 and Cre recombinase, to Slc2a1 ^Flox/Flox (GLUT1^Flox/Flox) mice to generate NIC-GLUT1^+/+, NIC-GLUT1^Flox/+, and NIC-GLUT1^Flox/Flox mice. In addition, we evaluated effects of glucose restriction or GLUT1 inhibition on transformation in MCF10A-ERBB2 breast epithelial cells in three-dimensional culture. Finally, we utilized global gene expression profiling data of primary human breast tumors to determine the relationship between SLC2A1 and stage of tumorigenesis.

RESULTS

All of the NIC-GLUT1^+/+ mice developed tumors in less than 200 days. In contrast, only 1 NIC-GLUT1^Flox/Flox mouse and 1 NIC-GLUT1^Flox/+ mouse developed mammary tumors, even after 18 months. Mammary gland development was not disrupted in NIC mice lacking GLUT1; however, epithelial content of mature glands was reduced compared to NIC-GLUT1^Flox/+ mice. In MCF10A-ERBB2 cells, glucose restriction or GLUT1 inhibition blocked transformation induced by activated ERBB2 through reduced cell proliferation. In human breast cancers, SLC2A1 was higher in ductal carcinoma in situ compared to the normal breast, but lower in invasive versus in situ lesions, suggesting the requirement for GLUT1 decreases as tumors progress.

CONCLUSIONS

This study demonstrates a strict requirement for GLUT1 in the early stages of mammary tumorigenesis in vitro and in vivo. While metabolic adaptation has emerged as a hallmark of cancer, our data indicate that early tumor cells rely heavily on glucose and highlight the potential for glucose restriction as a breast cancer preventive strategy.

Metabolic reprogramming: a new relevant pathway in adult adrenocortical tumors

Adrenocortical carcinomas (ACCs) are complex neoplasias that may present unexpected clinical behavior, being imperative to identify new biological markers that can predict patient prognosis and provide new therapeutic options. The main aim of the present study was to evaluate the prognostic value of metabolism-related key proteins in adrenocortical carcinoma. The immunohistochemical expression of MCT1, MCT2, MCT4, CD147, CD44, GLUT1 and CAIX was evaluated in a series of 154 adult patients with adrenocortical neoplasia and associated with patients' clinicopathological parameters. A significant increase in was found for membranous expression of MCT4, GLUT1 and CAIX in carcinomas, when compared to adenomas. Importantly MCT1, GLUT1 and CAIX expressions were significantly associated with poor prognostic variables, including high nuclear grade, high mitotic index, advanced tumor staging, presence of metastasis, as well as shorter overall and disease free survival. In opposition, MCT2 membranous expression was associated with favorable prognostic parameters. Importantly, cytoplasmic expression of CD147 was identified as an independent predictor of longer overall survival and cytoplasmic expression of CAIX as an independent predictor of longer disease-free survival. We provide evidence for a metabolic reprogramming in adrenocortical malignant tumors towards the hyperglycolytic and acid-resistant phenotype, which was associated with poor prognosis.

Key Players in Choline Metabolic Reprograming in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), defined as lack of estrogen and progesterone receptors in the absence of protein overexpression/gene amplification of human epidermal growth factor receptor 2, is still a clinical challenge despite progress in breast cancer care. ¹H magnetic resonance spectroscopy allows identification and non-invasive monitoring of TNBC metabolic aberrations and elucidation of some key mechanisms underlying tumor progression. Thus, it has the potential to improve in vivo diagnosis and follow-up and also to identify new targets for treatment. Several studies have shown an altered phosphatidylcholine (PtdCho) metabolism in TNBCs, both in patients and in experimental models. Upregulation of choline kinase-alpha, an enzyme of the Kennedy pathway that phosphorylates free choline (Cho) to phosphocholine (PCho), is a major contributor to the increased PCho content detected in TNBCs. Phospholipase-mediated PtdCho headgroup hydrolysis also contributes to the build-up of a PCho pool in TNBC cells. The oncogene-driven PtdCho cycle appears to be fine tuned in TNBC cells in at least three ways: by modulating the choline import, by regulating the activity or expression of specific metabolic enzymes, and by contributing to the rewiring of the entire metabolic network. Thus, only by thoroughly dissecting these mechanisms, it will be possible to effectively translate this basic knowledge into further development and implementation of Cho-based imaging techniques and novel classes of therapeutics.

Glucose Uptake and Intracellular pH in a Mouse Model of Ductal Carcinoma In situ (DCIS) Suggests Metabolic Heterogeneity

Mechanisms for the progression of ductal carcinoma in situ (DCIS) to invasive breast carcinoma remain unclear. Previously we showed that the transition to invasiveness in the mammary intraepithelial neoplastic outgrowth (MINO) model of DCIS does not correlate with its serial acquisition of genetic mutations. We hypothesized instead that progression to invasiveness depends on a change in the microenvironment and that precancer cells might create a more tumor-permissive microenvironment secondary to changes in glucose uptake and metabolism. Immunostaining for glucose transporter 1 (GLUT1) and the hypoxia marker carbonic anhydrase 9 (CAIX) in tumor, normal mammary gland and MINO (precancer) tissue showed differences in expression. The uptake of the fluorescent glucose analog dye, 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose (2-NBDG), reflected differences in the cellular distributions of glucose uptake in normal mammary epithelial cells (nMEC), MINO, and Met1 cancer cells, with a broad distribution in the MINO population. The intracellular pH (pHi) measured using the fluorescent ratio dye 2',7'-bis(2-carboxyethyl)-5(6)-155 carboxyfluorescein (BCECF) revealed expected differences between normal and cancer cells (low and high, respectively), and a mixed distribution in the MINO cells, with a subset of cells in the MINO having an increased rate of acidification when proton efflux was inhibited. Invasive tumor cells had a more alkaline baseline pHi with high rates of proton production coupled with higher rates of proton export, compared with nMEC. MINO cells displayed considerable variation in baseline pHi that separated into two distinct populations: MINO high and MINO low. MINO high had a noticeably higher mean acidification rate compared with nMEC, but relatively high baseline pHi similar to tumor cells. MINO low cells also had an increased acidification rate compared with nMEC, but with a more acidic pHi similar to nMEC. These findings demonstrate that MINO is heterogeneous with respect to intracellular pH regulation which may be associated with an acidified regional microenvironment. A change in the pH of the microenvironment might contribute to a tumor-permissive or tumor-promoting progression. We are not aware of any previous work showing that a sub-population of cells in in situ precancer exhibits a higher than normal proton production and export rate.

HIF isoforms have divergent effects on invasion, metastasis, metabolism and formation of lipid droplets

Cancer cells adapt to hypoxia by the stabilization of hypoxia inducible factor (HIF)-α isoforms that increase the transcription of several genes. Among the genes regulated by HIF are enzymes that play a role in invasion, metastasis and metabolism. We engineered triple (estrogen receptor/progesterone receptor/HER2/neu) negative, invasive MDA-MB-231 and SUM149 human breast cancer cells to silence the expression of HIF-1α, HIF-2α or both isoforms of HIF-α. We determined the metabolic consequences of HIF silencing and the ability of HIF-α silenced cells to invade and degrade the extracellular matrix (ECM) under carefully controlled normoxic and hypoxic conditions. We found that silencing HIF-1α alone was not sufficient to attenuate invasiveness in both MDA-MB-231 and SUM149 cell lines. Significantly reduced metastatic burden was observed in single (HIF-1α or HIF-2α) and double α-isoform silenced cells, with the reduction most evident when both HIF-1α and HIF-2α were silenced in MDA-MB-231 cells. HIF-2α played a major role in altering cell metabolism. Lipids and lipid droplets were significantly reduced in HIF-2α and double silenced MDA-MB-231 and SUM149 cells, implicating HIF in their regulation. In addition, lactate production and glucose consumption were reduced. These results suggest that in vivo, cells in or near hypoxic regions are likely to be more invasive. The data indicate that targeting HIF-1α alone is not sufficient to attenuate invasiveness, and that both HIF-1α and HIF-2α play a role in the metastatic cascade in these two cell lines.

Targeting lactate transport suppresses in vivo breast tumour growth

BACKGROUND

Most cancers, including breast cancer, have high rates of glucose consumption, associated with lactate production, a process referred as "Warburg effect". Acidification of the tumour microenvironment by lactate extrusion, performed by lactate transporters (MCTs), is associated with higher cell proliferation, migration, invasion, angiogenesis and increased cell survival. Previously, we have described MCT1 up-regulation in breast carcinoma samples and demonstrated the importance of in vitro MCT inhibition. In this study, we performed siRNA knockdown of MCT1 and MCT4 in basal-like breast cancer cells in both normoxia and hypoxia conditions to validate the potential of lactate transport inhibition in breast cancer treatment.

RESULTS

The effect of MCT knockdown was evaluated on lactate efflux, proliferation, cell biomass, migration and invasion and induction of tumour xenografts in nude mice. MCT knockdown led to a decrease in in vitro tumour cell aggressiveness, with decreased lactate transport, cell proliferation, migration and invasion and, importantly, to an inhibition of in vivo tumour formation and growth.

CONCLUSIONS

This work supports MCTs as promising targets in cancer therapy, demonstrates the contribution of MCTs to cancer cell aggressiveness and, more importantly, shows, for the first time, the disruption of in vivo breast tumour growth by targeting lactate transport.

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.