Increased LDH5 expression is associated with lymph node metastasis and outcome in oral squamous cell carcinoma

Identification of Metabolism-Associated Biomarkers for Early and Precise Diagnosis of Oral Squamous Cell Carcinoma

The 5-year survival rate for oral squamous cell carcinoma (OSCC), one of the most common head and neck cancers, has not improved in the last 20 years. Poor prognosis of OSCC is the result of failure in early and precise diagnosis. Metabolic reprogramming, including the alteration of the uptake and utilisation of glucose, amino acids and lipids, is an important feature of OSCC and can be used to identify its biomarkers for early and precise diagnosis. In this review, we summarise how recent findings of rewired metabolic networks in OSCC have facilitated early and precise diagnosis of OSCC.

Metabolic Regulation of Lysine Acetylation: Implications in Cancer

Lysine acetylation is the second most well-studied post-translational modification after phosphorylation. While phosphorylation regulates signaling cascades, one of the most significant roles of acetylation is regulation of chromatin structure. Acetyl-coenzyme A (acetyl-CoA) serves as the acetyl group donor for acetylation reactions mediated by lysine acetyltransferases (KATs). On the other hand, NAD+ serves as the cofactor for lysine deacetylases (KDACs). Both acetyl-CoA and NAD+ are metabolites integral to energy metabolism, and therefore, their metabolic flux can regulate the activity of KATs and KDACs impacting the epigenome. In this chapter, we review our current understanding of how metabolic pathways regulate lysine acetylation in normal and cancer cells.

Development of a rational strategy for integration of lactate dehydrogenase A suppression into therapeutic algorithms for head and neck cancer

BACKGROUND

Lactate dehydrogenase (LDH) is a critical metabolic enzyme. LDH A (LDHA) overexpression is a hallmark of aggressive malignancies and has been linked to tumour initiation, reprogramming and progression in multiple tumour types. However, successful LDHA inhibition strategies have not materialised in the translational and clinical space. We sought to develop a rational strategy for LDHA suppression in the context of solid tumour treatment.

METHODS

We utilised a doxycycline-inducible short hairpin RNA (shRNA) system to generate LDHA suppression. Lactate and LDH activity levels were measured biochemically and kinetically using hyperpolarised 13C-pyruvate nuclear magnetic resonance spectroscopy. We evaluated effects of LDHA suppression on cellular proliferation and clonogenic survival, as well as on tumour growth, in orthotopic models of anaplastic thyroid carcinoma (ATC) and head and neck squamous cell carcinoma (HNSCC), alone or in combination with radiation.

RESULTS

shRNA suppression of LDHA generated a time-dependent decrease in LDH activity with transient shifts in intracellular lactate levels, a decrease in carbon flux from pyruvate into lactate and compensatory shifts in metabolic flux in glycolysis and the Krebs cycle. LDHA suppression decreased cellular proliferation and temporarily stunted tumour growth in ATC and HNSCC xenografts but did not by itself result in tumour cure, owing to the maintenance of residual viable cells. Only when chronic LDHA suppression was combined with radiation was a functional cure achieved.

CONCLUSIONS

Successful targeting of LDHA requires exquisite dose and temporal control without significant concomitant off-target toxicity. Combinatorial strategies with conventional radiation are feasible as long as the suppression is targeted, prolonged and non-toxic.

Glycolytic pathway candidate markers in the prognosis of oral squamous cell carcinoma: a systematic review with meta-analysis

Molecular changes that affect mitochondrial glycolysis have been associated with the maintenance of tumor cells. Some metabolic factors have already been described as predictors of disease severity and outcomes. This systematic review was conducted to answer the question: Is the glycolytic pathway correlated with the prognosis of oral squamous cell carcinoma (OSCC)? A search strategy was developed to retrieve studies in English from PubMed, Scopus, and ISI Web of Science using keywords related to squamous cell carcinoma, survival, and glycolytic pathway, with no restriction of publication date. The search retrieved 1273 publications. After the titles and abstracts were analyzed, 27 studies met inclusion criteria. Studies were divided into groups according to two subtopics, glycolytic pathways and diagnosis, which describe the glycolytic profile of OSCC tumors. Several components of tumor energy metabolism found in this review are important predictors of survival of patients with OSCC.

The predictive power of CD3+ T cell infiltration of oral squamous cell tumors is limited to non-diabetic patients

Diabetes mellitus type II (DM) and immune cell infiltration determine patient outcome in many tumor entities. Here we studied a possible link between the metabolic and immune cell status of OSCC patients. Glucose transporter (GLUT) 1 mRNA expression was elevated in all tumor samples, whereas other glycolytic markers such as lactate dehydrogenase (LDH) A or monocarboxylate transporter (MCT) 1 were increased in tumor samples from patients with diabetes and these patients had a significantly worse prognosis compared to non-diabetic patients. Analyses of immune cell infiltration in tumors from diabetic and non-diabetic patients revealed an increased leukocyte (CD45⁺) infiltration compared to normal mucosa only in non-diabetic patients. In line, the amount of CD3⁺ T cells per mm² tumor tissue, was elevated in patients without diabetes and crucial for patient outcome in OSCC patients without diabetes, as compared to healthy mucosa using fluorescence immunohistochemistry in tissue microarrays of 229 patients. Our results demonstrate that diabetes is a prognostic factor for OSCC patients and associates with decreased leukocyte and CD3⁺ infiltration indicating that metabolic differences between diabetic and non-diabetic patients may alter tumor-infiltrating T cells and thereby determine patient outcome.

Salvianolic acid B inhibits glycolysis in oral squamous cell carcinoma via targeting PI3K/AKT/HIF-1α signaling pathway

Our previous study demonstrated a progressive glycolytic perturbation during the course of DMBA-induced hamster oral carcinogenesis, which was attenuated by salvianolic acid B (Sal-B) treatment along with decreased incidences of oral squamous cell carcinoma (OSCC) formation. It was proposed that metabolic modulation should be an additional mode of action attributable to Sal-B’s anti-carcinogenic activity. However, the molecular mechanisms underlying Sal-B-induced metabolic modulation function remained elusive. In the present study, we performed next-generation sequencing (NGS) profiling in the same animal model and found Sal-B treatment evoked a general downregulation of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and hypoxia inducible factor 1α subunit (HIF-1α) signaling pathways, which might contribute to Sal-B’s metabolic modulation activity. The inhibitory effects of Sal-B on aerobic glycolysis, as well as PI3K/AKT and HIF-1α signaling pathways, were validated in two well-characterized OSCC cell lines (Cal27 and HN4), and premalignant oral Leuk1 cells and Sal-B treatment led to elevation of the loss of mitochondrial membrane potential (MMP), increased cell apoptosis, and reduced abilities of colony formation. Rescue assays suggested that compared with Sal-B treatment group, Akt or hif-1a overexpression attenuated the inhibitory effect of Sal-B on glucose uptake and intracellular lactate level. Taken together, our results suggested that Sal-B modulated aberrant glucose metabolism via the PI3K/AKT/HIF-1α signaling pathways, which might contribute to the anti-carcinogenic activity of Sal-B.

miR-448 downregulates MPPED2 to promote cancer proliferation and inhibit apoptosis in oral squamous cell carcinoma

The incidence of oral squamous cell carcinoma (OSCC) is continuously increasing while its survival rate has not notably improved. There is a pressing need for improved understanding of the genetic regulation of OSCC tumorigenesis and progression. In this study, the function of miR-448 in the regulation of OSCC growth and its putative target were thoroughly analyzed in vitro. The expression of miR-448 was detected in human OSCC specimens and OSCC cell lines (Cal-27 and Scc-9) by reverse transcription-quantitative polymerase chain reaction. The function of miR-448 was investigated in Cal-27 cells transfected with miR-448 inhibitor, and its putative target determined using a luciferase reporter assay. MTT and wound healing assays and flow cytometry were used to evaluate the effects of miR-448 on OSCC proliferation, metastasis and apoptosis. The level of miR-448 was significantly elevated in human OSCC tissues and the Cal-27 cell line. Suppression of miR-448 expression attenuated cell proliferation and migration, and induced apoptosis of Cal-27 cells. Furthermore, miR-448 bound with the 3'-untranslated region of metallophosphoesterase domain containing 2 (MPPED2) mRNA, thereby reducing the MPPED2 protein level. Thus, it appears that miR-448 acts as a tumor inducer, causing OSCC growth by inhibiting the expression of its target MPPED2. These results demonstrate that miR-448 plays a critical role in OSCC tumorigenesis, and is a potential therapeutic target.

The Actual Role of LDH as Tumor Marker, Biochemical and Clinical Aspects

Lactate dehydrogenase (LDH) among many biochemical parameters represents a very valuable enzyme in patients with cancer with possibility for easy routine measurement in many clinical laboratories. Previous studies where mostly based on investigated LDH in serum of patients with cancer with aims to estimate their clinical significance. The new directions in investigation of LDH where based on the principle that tumor cells release intracellular enzymes trough damaged cell membrane, that is mostly consequence in intracellular mitochondrial machinery alteration, and apoptosis deregulation. This consideration can be used not only in-vitro assays, but also in respect to clinical characteristics of tumor patients. Based on new techniques of molecular biology it is shown that intracellular characteristics of LDH enzyme are very sensitive indicators of the cellular metabolic state, aerobic or anaerobic direction of glycolysis, activation status and malignant transformation. Using different molecular analyses it is very useful to analyzed intracellular LDH activity in different cell line and tumor tissues obtained from patients, not only to understanding complexity in cancer biochemistry but also in early clinical diagnosis. Based on understandings of the LDH altered metabolism, new therapy option is created with aims to blocking certain metabolic pathways and stop tumors growth.

Lactate as a predictive marker for tumor recurrence in patients with head and neck squamous cell carcinoma (HNSCC) post radiation: a prospective study over 15 years

OBJECTIVES

Lactate as a key regulator of the glycolytic phenotype has been recently described in fueling tumor growth and metastatic spread in head and neck squamous cell carcinoma (HNSCC). However, in context of tumor recurrence following adjuvant radiation, the underlying mechanisms remain uncertain. We therefore investigate the role of lactate towards radioresistance in HNSCC in this prospective study for the first time in vivo.

MATERIALS AND METHODS

Herein, we analyzed biopsies of primary squamous cell carcinoma after surgery and adjuvant irradiation in 17 patients. Tumor tissue levels of ATP, glucose, and lactate were detected using induced metabolic bioluminescence imaging (imBI) and correlated with clinical data within an observation period of up to 15 years.

RESULTS

High amounts of lactate levels in tumors of HNSCC are significantly negatively correlated with overall patient survival. Moreover, high expression of lactate in a primary tumor site is significantly correlated with tumor recurrence post radiation, whereas ATP and/or glucose showed no such correlation.

CONCLUSION

Lactate can be seen not only as a waste product of altered glycolytic metabolism but also as a key master of malignancy as well as resistance mechanism towards irradiation.

CLINICAL RELEVANCE

High expression of lactate levels in tumor tissue, obtained by metabolic bioluminescence imaging, may therefore serve as a predictor for overall and recurrence-free survival and could represent a future biomarker in the validation of adjuvant irradiation.

Equating salivary lactate dehydrogenase (LDH) with LDH-5 expression in patients with oral squamous cell carcinoma: An insight into metabolic reprogramming of cancer cell as a predictor of aggressive phenotype

Oral squamous cell carcinoma (OSCC) is the sixth most common human malignancy. According to World Health Organization, oral cancer has been reported to have the highest morbidity and mortality and a survival rate of approximately 50 % at 5 years from diagnosis. This is attributed to the subjectivity in TNM staging and histological grading which may result in less than optimum treatment outcomes including tumour recurrence. One of the hallmarks of cancer is aerobic glycolysis also known as the Warburg effect. This glycolytic phenotype (hypoxic state) not only confers immortality to cancer cells, but also correlates with the belligerent behaviour of various malignancies and is reflected as an increase in the expression of lactate dehydrogenase 5 (LDH-5), the main isoform of LDH catalysing the conversion of pyruvate to lactate during glycolysis. The diagnostic role of salivary LDH in assessing the metabolic phenotype of oral cancer has not been studied. Since salivary LDH is mainly sourced from oral epithelial cells, any pathological changes in the epithelium should reflect diagnostically in saliva. Thus in our current research, we made an attempt to ascertain the biological behaviour and aggressiveness of OSCC by appraising its metabolic phenotype as indirectly reflected in salivary LDH activity. We found that salivary LDH can be used to assess the aggressiveness of different histological grades of OSCC. For the first time, an evidence of differing metabolic behaviour in similar histologic tumour grade is presented. Taken together, our study examines the inclusion of salivary LDH as potential diagnostic parameter and therapeutic index in OSCC.

The Regulation and Function of Lactate Dehydrogenase A: Therapeutic Potential in Brain Tumor

There are over 120 types of brain tumor and approximately 45% of primary brain tumors are gliomas, of which glioblastoma multiforme (GBM) is the most common and aggressive with a median survival rate of 14 months. Despite progress in our knowledge, current therapies are unable to effectively combat primary brain tumors and patient survival remains poor. Tumor metabolism is important to consider in therapeutic approaches and is the focus of numerous research investigations. Lactate dehydrogenase A (LDHA) is a cytosolic enzyme, predominantly involved in anaerobic and aerobic glycolysis (the Warburg effect); however, it has multiple additional functions in non‐neoplastic and neoplastic tissues, which are not commonly known or discussed. This review summarizes what is currently known about the function of LDHA and identifies areas that would benefit from further exploration. The current knowledge of the role of LDHA in the brain and its potential as a therapeutic target for brain tumors will also be highlighted. The Warburg effect appears to be universal in tumors, including primary brain tumors, and LDHA (because of its involvement with this process) has been identified as a potential therapeutic target. Currently, there are, however, no suitable LDHA inhibitors available for tumor therapies in the clinic.

INMAP overexpression inhibits cell proliferation, induces genomic instability and functions through p53/p21 pathways

INMAP is a spindle protein that plays essential role for mitosis, by ensuring spindle and centromere integrality. The aim of this study was to investigate the relevant functions of INMAP for genomic stability and its functional pathway. We overexpressed INMAP in HeLa cells, resulting in growth inhibition in monolayer cell cultures, anchorage-independent growth in soft agar and xenograft growth in nude mice. In this system caused micronuclei (MNi) formation, chromosome distortion and γH2AX expression upregulation, suggesting DNA damage induction and genomic stability impairment. As a tumour biochemical marker, lactate dehydrogenase (LDH) isoenzymes were detected to evaluate cell metabolic activity, the results confirming that total activity of LDH, as well as that of its LDH5 isoform, is significantly decreased in INMAP-overexpressing HeLa cells. The levels of p53 and p21 were upregulated, and however, that of PCNA and Bcl-2, downregulated. Indirect immunofluorescence (IIF) and coimmunoprecipitation (CoIP) analyses revealed the interaction between INMAP and p21. These results suggest that INMAP might function through p53/p21 pathways.

Lactate dehydrogenase 5: an old friend and a new hope in the war on cancer

A hallmark of most cancer cells is an altered metabolism involving a shift to aerobic glycolysis with lactate production coupled with a higher uptake of glucose as the main source of energy. Lactate dehydrogenase 5 (LDH-5) catalyzes the reduction of pyruvate by NADH to form lactate, thus determining the availability of NAD(+) to maintain the continuity of glycolysis. It is therefore an important control point in the system of cellular energy release. Its upregulation is common in many malignant tumors. Inhibiting LDH-5 activity has an anti-proliferative effect on cancer cells. It may reverse their resistance to conventional chemo- and radiotherapy. Recent research has renewed interest in LDH-5 as an anticancer drug target. This review summarizes recent studies exploring the role of LDH-5 in cancer growth, its utility as a tumor marker, and developments made in identifying and designing anti-LDH-5 therapeutic agents.

Overexpression of metabolic markers PKM2 and LDH5 correlates with aggressive clinicopathological features and adverse patient prognosis in tongue cancer

AIMS

Pyruvate kinase M2 (PKM2) and lactate dehydrogenase 5 (LDH5) are two metabolic and oncogenic markers of cancer. In this study, we sought to investigate their expression patterns and prognostic value in tongue squamous cell carcinoma (TSCC).

METHODS AND RESULTS

The expression and subcellular localization of PKM2 and LDH5 in TSCC cell lines were determined by Western blot and immunofluorescence. PKM2 and LDH5 abundance was examined by immunohistochemistry in 63 TSCC tumour specimens; their association with multiple clinicopathological parameters and overall patient survival was assessed. The protein levels of PKM2 and LDH5 were both significantly higher in TSCC cells than in an immortalized oral epithelial cell line. Overexpression of PKM2 associated significantly with cervical node metastasis (P = 0.0373), while elevated LDH5 levels correlated significantly with tumour size (P = 0.0094), pathological grade (P = 0.0052), cervical node metastasis (P = 0.0023) and clinical stage (P = 0.0024). Patients with tumours showing an increase in either PKM2 or LDH5 expression displayed significantly reduced overall survival, while patients with tumours overexpressing both proteins showed the worst prognosis with lowest overall survival. Furthermore, PKM2 and LDH5 were identified as independent prognostic predictors for overall patient survival in TSCC.

CONCLUSION

Our data indicate that overexpression of PKM2 and LDH5 associates with key clinicopathological features and unfavourable prognosis in TSCC.

Expression of Glucose Transporters 1 and 3 in Metastatic and Non-Metastatic Lower Lip Squamous Cell Carcinoma

This study aimed to evaluate the immunoexpression of glucose transporters 1 (GLUT-1) and 3 (GLUT-3) in metastatic and non-metastatic lower lip squamous cell carcinoma (LLSCC). Twenty LLSCCs with regional nodal metastasis and 20 LLSCCs without metastasis were selected. The distribution of staining and the percentage of GLUT-1 and GLUT-3 staining in each tumor core and at the deep invasive front were assessed. Most tumors (70%) exhibited peripheral staining for GLUT-1 in nests, sheets and islands of neoplastic cells, whereas predominantly central staining was observed for GLUT-3 (72.5%). A high percentage of GLUT-1-positive cells was observed at the deep invasive front and in the tumor core of metastatic and non-metastatic tumors (p>0.05). The percentage of GLUT-1-positive cells was much higher than that of GLUT-3-positive cells both in the deep invasive front (p<0.001) and in the tumor core (p<0.001) of LLSCCs. No significant differences in the percentage of GLUT-1- and GLUT-3-positive cells were observed according to nodal metastasis, clinical stage or histological grade of malignancy (p>0.05). In conclusion, the results of the present study suggest an important role of GLUT-1 in glucose uptake in LLSCCs, although this protein does not seem to be involved in the progression of these tumors. On the other hand, GLUT-3 expression may represent a secondary glucose uptake mechanism in LLSCCs.

Association of cancer metabolism-related proteins with oral carcinogenesis - indications for chemoprevention and metabolic sensitizing of oral squamous cell carcinoma?

Background

Tumor metabolism is a crucial factor for the carcinogenesis of oral squamous cell carcinoma (OSCC).

Methods

Expression of IGF-R1, glycolysis-related proteins (GLUT-1, HK 2, PFK-1, LDHA, TKTL1), mitochondrial enzymes (SDHA, SDHB, ATP synthase) were analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I-III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry and real-time polymerase chain reaction (qPCR) analysis in OSCC cell lines. Metabolism-related proteins were correlated with proliferation activity (Ki-67) and apoptotic properties (TUNEL assay) in OSCC. Specificity of antibodies was confirmed by western blotting in cancer cell lines.

Results

Expression of IGF-R1, glycolysis-related proteins (GLUT-1, HK 2, LDHA, TKTL1), and mitochondrial enzymes (SDHA, SDHB, ATP synthase) were significantly increased in the carcinogenesis of OSCC. Metabolic active regions of OSCC were strongly correlated with proliferating cancer (Ki-67+) cells without detection of apoptosis (TUNEL assay).

Conclusions

This study provides the first evidence of the expression of IGF-R1, glycolysis-related proteins GLUT-1, HK 2, PFK-1, LDHA, and TKTL1, as well as mitochondrial enzymes SDHA, SDHB, and ATP synthase in the multi-step carcinogenesis of OSCC. Both, hypoxia-related glucose metabolism and mitochondrial oxidative phosphorylation characteristics are associated with the carcinogenesis of OSCC. Acidosis and OXPHOS may drive a metabolic shift towards the pentose phosphate pathway (PPP). Therefore, inhibition of the PPP, glycolysis, and targeted anti-mitochondrial therapies (ROS generation) by natural compounds or synthetic vitamin derivatives may act as sensitizer for apoptosis in cancer cells mediated by adjuvant therapies in OSCC.

Small-molecule inhibitors of human LDH5

The latest findings on the role played by human LDH5 (hLDH5) in the promotion of glycolysis in invasive tumor cells indicates that this enzyme subtype is a promising therapeutic target for invasive cancer. Compounds able to selectively inhibit hLDH5 hold promise for the cure of neoplastic diseases. hLDH5 has so far been a rather unexplored target, since its importance in the promotion of cancer progression has been neglected for decades. This enzyme should also be considered as a challenging target due the high polar character (mostly cationic) of its ligand cavity. Recently, significant progresses have been reached with small-molecule inhibitors of hLDH5 displaying remarkable potencies and selectivities. This review provides an overview of the newly developed hLDH5 inhibitors. The roles of hLDH isoforms will be briefly discussed, and then the inhibitors will be grouped into chemical classes. Furthermore, general pharmacophore features will be emphasized throughout the structural subgroups analyzed.

MicroRNA-29a upregulates MMP2 in oral squamous cell carcinoma to promote cancer invasion and anti-apoptosis

Abnormal microRNA expression is a common and important feature of human malignancies. Matrix metalloproteinase 2 (MMP2), which has been reported in several cancers, plays important roles in cancer progression. However, the microRNA regulatory mechanism on MMP2 expression remains unclear. In this study, we first detected MMP2 and microRNA-29a (miR-29a) expression in oral squamous carcinoma (OSCC) specimens, which showed that MMP2 was higher in OSCC cancer tissues than adjacent tissues but that miR-29a was lower in OSCC cancer tissues than adjacent tissues. Then, we confirmed that miR-29a, which directly targeted 3'-UTR of MMP2 gene, negatively regulated MMP2 expression by miR-29a transfection and luciferase reporter assay. Exogenous overexpression of miR-29a inhibited OSCC cell invasion and anti-apoptosis significantly in vitro. Whereas, knockdown of miR-29a promoted OSCC cell invasion and induced drug-resistance in vitro. This study suggests that miR-29a plays an inhibiting role in the progression of OSCC, which may be a potentially therapeutic approach in the future.

Can immunohistochemistry serve as an alternative to subjective histopathological diagnosis of oral epithelial dysplasia?

Many attempts have been made to identify objective molecular biomarkers to diagnose and prognosticate oral epithelial dysplasia (OED) because histopathological interpretation is subjective and lacks sensitivity. The majority of these efforts describe changes in gene expression at protein level in OED as determined by immunohistochemistry (IHC). However, the literature on these putative markers of oral cancer progression is vast and varied. The main purpose of this article is to review current knowledge on biomarkers of protein expression for OED by IHC approaches. We further discuss these findings in terms of the proposed essential hallmarks of cancer cells to better understand their role in oral oncogenesis.

Lactate dehydrogenase 5 expression in Non-Hodgkin lymphoma is associated with the induced hypoxia regulated protein and poor prognosis

Lactate dehydrogenase 5 (LDH-5) is one of the major isoenzymes catalyzing the biochemical process of pyruvate to lactate. The purpose of this study was to investigate the expression of serum LDH-5 and test whether this enzyme is regulated by tumor hypoxia and represents a prognostic marker in patients with Non-Hodgkin’s lymphoma (NHL). In this study, LDH-5 levels were detected using agarose gel electrophoresis in NHL patients (n = 266) and non-NHL controls including benign lymphadenectasis (n = 30) and healthy cohorts (n = 233). We also explored the expression of LDH-5 and hypoxia-inducible factor (HIF) 1α in NHL and benign controls by immunohistochemistry and immunofluorescence staining, respectively. Moreover, the role of LDH-5 in the progression of NHL was assessed by multivariate Cox analyses and Kaplan-Meier survival estimates. Serum concentrations of LDH-5 were significantly higher in NHL patients (9.3%) than in benign patients and healthy controls (7.5% and 7.2%, respectively, P<0.01). Application of LDH-5 detection increased the sensitivity of NHL detection, identifying 53.4% of NHL patients as positive, compared with the measurement of total LDH levels (36.5% sensitivity). LDH-5 concentrations increased with clinical stage, extra-nodal site involvement, and WHO performance status of patients with NHL. Exposure to a hypoxic environment induced the expression of LDH-5 and its overexpression correlated with HIF1α cytoplasmic accumulation in NHL cells. In multivariate analyses, LDH-5 was an independent marker for progression-free survival in patients with NHL (P<0.001). Overall, the expression of LDH-5 was elevated in NHL, showing an association with tumor hypoxia and unfavorable prognosis. Thus, LDH-5 emerges as a promising prognostic predictor for NHL patients.