Quick histochemical staining method for measuring lactate dehydrogenase C4 activity in human spermatozoa

Cancer-testis antigen lactate dehydrogenase C4 as a novel biomarker of male infertility and cancer

A unique lactate dehydrogenase (LDH) isoenzyme designated as lactate dehydrogenase C4 (LDH-C4) is found in mammalian mature testis and spermatozoa. Thus far, LDH-C4 has been well studied with regard to its gene and amino acid sequences, structure, biological properties, and peptide synthesis. Accumulating evidence has shown that LDH-C4 is closely related to spermatic energy metabolism and plays a critical role in sperm motility, capacitation, and fertilization. Defects in the catalytic activity of LDH-C4 are key to pathophysiological abnormalities underlying infertility. LDH-C4 was originally thought to be present only in mature testis and spermatozoa; however, recent studies have implicated LDH-C4 as a cancer-testis antigen (CTA), owing to its aberrant transcription in a broad spectrum of human neoplasms. This review highlights the recent findings on LDH-C4 with particular emphasis on its role in male infertility and tumors.

Diagnostic and prognostic value of the cancer-testis antigen lactate dehydrogenase C4 in breast cancer

BACKGROUND

Lactate dehydrogenase C4 (LDH-C4) as a cancer/testis antigen (CTA) is abnormally expressed in some malignant tumors. However, the expression and clinical significance of LDH-C4 in breast cancer (BC) has not been characterized.

METHODS

We determined LDHC mRNA expression in serum and serum-derived exosomes of BC patients by quantitative RT-PCR. We also evaluated the protein expression of LDH-C4 in BC tissues using high-throughput tissue microarray analysis and immunohistochemistry.

RESULTS

Our results showed high mRNA expression level of LDHC in serum and serum-derived exosomes of BC patients. The LDHC level in serum and exosomes could distinguish BC cases from healthy individuals based on their AUCs of 0.9587 and 0.9464, respectively. Besides, the LDHC level in exosomes of BC patients associated with tumor size, and positively correlated with HER2 and Ki-67 expressions (all with P < 0.05). Serum and exosomal level of LDHC negatively correlated with medical treatment and positively with the recurrence of BC. Survival analysis showed that LDH-C4 expression negatively correlated with BC prognosis.

CONCLUSION

Serum and exosomal LDHC may be an effective indicator for the diagnosis, efficacy evaluation, and monitoring the recurrence of BC. LDH-C4 may act as a biomarker that predicts BC prognosis.

Expression of lactate dehydrogenase C in MDA‑MB‑231 cells and its role in tumor invasion and migration

The cancer/testis antigen (CTA) lactate dehydrogenase C (LDHC) is a unique LDH isoenzyme associated with glucose and adenosine triphosphate production in mammalian germ cells. However, the role of LDHC in cancer has thus far largely remained elusive. The present study described the expression status of LDHC in human MDA‑MB‑231 breast cancer cells as well as its role in tumor invasion and migration. Immunohistochemical analysis revealed endogenous LDHC expression in the cytoplasm and nuclei of MDA‑MB‑231 cells yielded. In addition, in vitro cell invasion and migration assays revealed that when LDHC expression was blocked by its specific inhibitor, cell invasion and migration were compromised in MDA‑MB‑231 cells. Of note, inhibition of LDHC was unable to induce apoptosis in MDA‑MB‑231 cells. The present study provided evidence that the LDHC enzyme acts as a CTA in breast carcinoma and exerts an essential role in tumor invasion and migration.