Lactate Dehydrogenase A or B Knockdown Reduces Lactate Production and Inhibits Breast Cancer Cell Motility in vitro

Abstract

Background: Lactate dehydrogenase (LDH) plays an important role in cancer pathogenesis and enhanced expression/activity of this enzyme has been correlated with poor prognosis. In this study we determined the expression profile of LDH-A and B in normal as well as in endocrine-resistant and -responsive breast cancer cells and the effect of their knockdown on LDH activity, lactate production, proliferation and cell motility.Methods: Knockdown experiments were performed using siRNA and shRNA. The expression profile of LDH and signaling molecules was determined using PCR and western blotting. Intracellular LDH activity and extracellular lactate levels were measured by a biochemical assay. Cell motility was determined using wound healing, while proliferation was determined using MTT assay.Results: LDH-A was expressed in all of the tested cell lines, while LDH-B was specifically expressed only in normal and endocrine-resistant breast cancer cells. This was correlated with significantly enhanced LDH activity and lactate production in endocrine resistant breast cancer cells when compared to normal or endocrine responsive cancer cells. LDH-A or -B knockdown significantly reduced LDH activity and lactate production, which led to reduced cell motility. Exogenous lactate supplementation enhanced cell motility co-incident with enhanced phosphorylation of ERK1/2 and reduced E-cadherin expression. Also, LDH-A or -B knockdown reduced ERK 1/2 phosphorylation.Conclusion: Enhanced cell motility in endocrine resistant breast cancer cells is at least in part mediated by enhanced extracellular lactate levels, and LDH inhibition might be a promising therapeutic target to inhibit cancer cell motility.

WITHDRAWN: Mechanism of the microRNA-4677-3p/LDHB axis in the regulation of paclitaxel resistance of breast cancer cells

“…Likewise, LDHB silencing can repress maxillary sinus squamous cell carcinoma cell proliferation and invasion, and thus LDHB exerts an oncogenic function in this cancer [30]. Moreover, LDHB knockdown has been revealed to markedly reduce LDH activity and lactate generation, leading to reduced motility of BC cells [31],…”

“…Likewise, LDHB silencing can repress maxillary sinus squamous cell carcinoma cell proliferation and invasion, and thus LDHB exerts an oncogenic function in this cancer [30]. Moreover, LDHB knockdown has been revealed to markedly reduce LDH activity and lactate generation, leading to reduced motility of BC cells [31], which has also indicated the oncogenic function of LDHB in BC. These data suggested that targeting LDHB potentiated sensitivity of BC cells to PTX treatment.…”

Energy metabolism pathways in breast cancer progression: The reprogramming, crosstalk, and potential therapeutic targets

“…The expression of LDHA in BC tissues was significantly higher than that in adjacent tissues [ 48 , 49 ], and a 10-fold lactate was generated in 4T1 murine BC cell lines [50] . However, the LDHB was specifically expressed only in normal and endocrine-resistant BC cells [51] . The high expression of LDHA and serum LDH status were closely related to brain metastasis free survival and may be a predictor for TNBC brain metastasis [49] .…”

“…In the glucose metabolism, high glucose content induced the expression of microrchidia family CW-type zinc finger 2 (MORC2) by activating c-MYC, which subsequently promoted MORC2 to form a complex with c-MYC to increase LDHA transcription [53] , leading to the BC cell migration. Study showed that both LDHA or LDHB knockdown inhibited the cell motility in MCF7 and MDA-MB-231 BC cell lines by reducing the phosphorylation level of ERK1/2 [51] , and exogenous lactate supplementation also increased the phosphorylation level of ERK1/2, reduced E-cadherin expression [48] , and finally enhanced the cell motility. More interestingly is that stable LDHA silencing alone in human MDA-MB-231 BC cell line with high concentrations of LDHB using lentivirus V-165 cannot change the lactic acid production, glycolytic activity, and the survival [54] , indicating that multiple isoforms such as LDHA/B are likely compensatory elements to maintain the production of lactic acid through glycolysis in tumor cells.…”

NAD/NAMPT and mTOR Pathways in Melanoma: Drivers of Drug Resistance and Prospective Therapeutic Targets

“…Specifically, pyruvate is catabolized into lactate by LDHA. LDHA is associated with cancer progression and poor prognosis, since its overexpression promotes angiogenesis and tumor dissemination [ 109 , 110 ]. In neoplastic diseases, the high activity of LDHA produces large amounts of lactate, which is secreted by cancer cells.…”