microRNA (miR)-199a-3p serves critical roles in cancer development and progression. In order to improve knowledge of the functional mechanism of miR‑199a‑3p in testicular tumors, the present study characterized the regulation of aerobic glycolysis by miR‑199a‑3p and its impact on metabolism. Using 3‑4,5‑dimethylthiazol‑2‑yl‑2,5 diphenyl tetrazolium bromide, wound healing and flow cytometry assays, it was determined that overexpression of miR‑199a‑3p in Ntera‑2 cells caused suppression of cell growth and migration. Further biochemical methods and high‑throughput quantitative polymerase chain reaction array of metabolic genes showed that inhibition of miR‑199a‑3p markedly elevated lactate production and 12 differentially expressed genes, including 2 upregulated and 10 downregulated genes, were identified following treatment with miR‑199a‑3p in Ntera‑2 cells. In clinical samples, four selected genes, lactate dehydrogenase A, monocarboxylate transporter 1, phosphoglycerate kinase 1 and TP53‑inducible glycolysis and apoptosis regulator, were significantly overexpressed in malignant testicular germ cell tumor, and their expression inversely correlated with the expression of miR‑199a‑3p, suggesting that these four genes may be affected by miR‑199a‑3p. Using bioinformatics analysis, the transcription factor Sp1 binding site was identified in the promoter region of the four selected genes. In addition, miR‑199a‑3p was predicted to bind to conservative target sequences in the 3'‑untranslated region of Sp1 mRNA, suggesting that miR-199a-3p may downregulate these four metabolic genes through Sp1. It was demonstrated the dysregulated expression and activation of miR‑199a‑3p may serve important roles in aerobic glycolysis and tumorigenesis in patients with testicular cancer. Therefore, miR-199a-3p may be a potential biomarker in the prognosis and treatment of testicular tumors.

Aerobic glycolysis is one of the characteristics of tumor metabolism and contributes to the development of tumors. Studies have identified that microRNA (miRNA/miR) serves an important role in glucose metabolism of tumors. miR‑199a‑3p is a member of the miR‑199a family that controls the outcomes of cell survival and death processes, and previous studies have indicated that the expression of miR‑199a‑3p is low and may be an inhibitor in several cancer types, including testicular tumors. The present study discussed the role and underlying mechanism of miR‑199a‑3p in aerobic glycolysis of Ntera‑2 cells and identified its downstream factors. Firstly, miR‑199a‑3p exhibited an inhibitory effect on lactic acid production, glucose intake, and reactive oxygen species (ROS) and adenosine 5'‑triphosphate (ATP) levels in Ntera‑2 cells. Then, using bioinformatics, recombinant construction and a dual luciferase reporter gene system, transcription factor Specificity protein 1 (Sp1) was determined as the direct target of miR‑199a‑3p. Also, downregulation of Sp1 by RNA interference decreased lactic acid production, glucose intake, and ROS and ATP levels in Ntera‑2 cells. Subsequently, through a functional rescue experiment, it was identified that the overexpression of Sp1 may abate the inhibition of miR‑199a‑3p on glucose metabolism, with the exception of ATP level, suggesting a reciprocal association between Sp1 and miR‑199a‑3p. Finally, it was determined that miR‑199a‑3p overexpression and Sp1 knockdown decreased lactate dehydrogenase A (LDHA) protein expression, which indicated that LDHA is a downstream target of the miR‑199a‑3p/Sp1 signaling pathway. To additionally verify the regulation of LDHA expression by 199a‑3p/Sp1, a LDHA promoter reporter plasmid was generated and the high activity of the promoter, which contained 3 potential Sp1 binding elements, was confirmed. In addition, the overexpression of Sp1 led to the increased activity of the LDHA promoter, whereas knockdown of Sp1 exhibited the opposite effect. Therefore, the results of the present study demonstrated that miR‑199a‑3p can inhibit LDHA expression by downregulating Sp1, and provided mechanistic evidence supporting the existence of a novel miR‑199a‑3p/Sp1/LDHA axis and its critical contribution to aerobic glycolysis in testicular cancer cells.

Cervical cancer is a common malignancy in females. Diagnosis and treatment of cervical cancer remains a challenge due to difficulties in the presence of tumor metastasis. Increased expression level of Erb-b2 receptor tyrosine kinase 3 (ERBB3) has previously been demonstrated to be associated with the occurrence of cervical cancer; however, the functionality of ERBB3 in the development of cervical cancer remains incompletely understood. In the present study, the expression level of ERBB3 in patients with cervical squamous cell carcinoma and cervical adenocarcinoma was detected by reverse transcription quantitative polymerase chain reaction. The effects of ERBB3 small interfering RNA silencing on cell proliferation, migration and invasion were explored, and the interaction between ERBB3 and mitogen-activated protein kinase kinase kinase 4 (MTK-1) was also investigated. It was identified that the downregulation of ERBB3 significantly decreased the proliferative, migratory and invasive abilities of cervical cancer cells. In addition, the expression level of MTK-1 was also significantly decreased following MTK-1 siRNA silencing. Therefore, we hypothesize that the downregulation of ERBB3 may decrease the proliferative, migratory and invasive abilities of cervical cancer cells by inhibiting the expression of MTK-1.

Spermatogenesis-associated gene 12 (SPATA12) functions as an inhibitor in spermatogenesis and tumorigenesis. Our previous study demonstrated that SPATA12 may be induced in tumor cells by ultraviolet (UV) C-mediated DNA damage, suggesting its importance in maintaining genomic integrity. In order to understand whether and how SPATA12 responds to oxidative damage, the present study established a cellular model of oxidative stress by detecting the effect of H2O2 on cell viability and intracellular superoxide dismutase activity, and the levels of glutathione and malondialdehyde (MDA). Quantitative polymerase chain reaction results demonstrated that H2O2 upregulated the expression of SPATA12, and a dual luciferase reporter gene assay indicated that transcription factor activator protein-1 (AP-1) was involved in the response of SPATA12 to oxidative stress. Through the exogenous expression of SPATA12, it was identified that SPATA12 decreased the level of reactive oxygen species and MDA, and also may reduce the degree of cellular oxidative damage and apoptosis induced by H2O2. In addition, resveratrol was demonstrated to increase the expression of SPATA12 by activating AP-1, and it may be used as a nontoxic activator of the SPATA12 gene. In conclusion, these results suggest that SPATA12 is upregulated by oxidative stress via AP-1, and that the exogenous expression of SPATA12 protects against H2O2-induced oxidative damage and apoptosis.