Reduced Klotho expression contributes to poor survival rates in human patients with ovarian cancer, and overexpression of Klotho inhibits the progression of ovarian cancer partly via the inhibition of systemic inflammation in nude mice

Abstract

Klotho is a recently discovered anti‑aging gene, which has been reported as a tumor suppressor in numerous human malignancies; however, the role of Klotho in human ovarian cancer remains to be elucidated. The aim of the present study was to detect the expression of Klotho and evaluate its association with the progression of human ovarian cancer. A clinical follow‑up study of 120 patients with ovarian cancer and 78 normal controls was conducted. The expression levels of Klotho were determined by western blotting and immunohistochemistry. The results demonstrated that high Klotho expression levels were detected in all normal controls, whereas the positive rate of Klotho was 61.6% in the ovarian cancer group, which was significantly decreased compared with in the control group (P<0.01). Furthermore, reduced Klotho expression was significantly correlated with decreased survival rates in patients with ovarian cancer (P=0.025). Subsequently, Klotho levels were detected in seven human ovarian cancer cell lines by western blotting. The results demonstrated that the highest levels of Klotho were detected in CaOV3 cells, medium levels of Klotho were detected in CaOV4 and SKOV‑3 cells, and almost no Klotho was detected in the other four cell lines: OVCA 432, OVCAR‑5, OVCAR‑8 and A2780 cells. The association between Klotho levels and cell proliferation was determined by MTT assay, and the results indicated that higher levels of Klotho inhibited the proliferation of A2780 and OVCAR‑5 cells, whereas reduced Klotho expression promoted cell growth of CaOV3 and SKOV‑3 cells. In addition, the plasma levels of inflammatory cytokines in tumor‑bearing mice and normal control mice were detected by enzyme‑linked immunosorbent assay, and plasma interleukin (IL)‑6 and IL‑1β levels were elevated in all tumor‑bearing mice. Notably, the mRNA expression levels of IL‑6 were significantly higher in the liver, ovaries and kidneys of Klotho‑/‑ mice compared with in wild type mice (P<0.01), thus indicating that aberrant Klotho expression may contribute to systemic inflammation in Klotho‑/‑ mice. Finally, the in vivo antitumor role of aberrant Klotho expression was determined in a nude mice model. A2780 cells were transfected with pCMV6‑Klotho and the stably transfected cells were screened; the mice were injected with the stably transfected cells. The results indicated that tumor volume and tumor weight were significantly decreased in the pCMV6‑Klotho group compared with in the pCMV6 vector group (P<0.01). These findings suggest that overexpression of Klotho may suppress tumor growth in animal models. In conclusion, Klotho was demonstrated to act as a potent tumor suppressor in human ovarian cancer cells. Reduced Klotho expression was detected in the specimens of patients with ovarian cancer, and overexpression of Klotho significantly inhibited cell proliferation of human ovarian cancer cells. Therefore, Klotho may be considered a useful key target for the molecular therapy of human ovarian cancer.

Human alternative Klotho mRNA is a nonsense-mediated mRNA decay target inefficiently spliced in renal disease

“…For example, Lu et al found that ovarian carcinoma patients positive for alternative Klotho mRNA have a higher tumor grade (17), which is interesting in light of the generally accepted view of Klotho as a tumor suppressor (44,46,60,61), including in ovarian carcinoma (62,63). However, higher alternative Klotho expression levels may not implicate effects of Klotho protein in whichever form and may even indicate dysregulated splicing or NMD dysfunction, which would lead to ER stress and may therefore reflect general cellular health.…”

Overexpression of klotho suppresses growth and pulmonary metastasis of osteosarcoma in vivo

“…It is reported that the anti-tumor effects of klotho are found to include the inhibition of proliferation. It is shown that klotho can suppress tumor growth and improve survival in several human malignancies, including lung, pancreatic, breast and colorectal carcinoma (Chen et al, 2016;Mencke et al, 2017;Yan et al, 2017). Notably, klotho-deficient mice present several bone-associated problems.…”

Klotho and the Treatment of Human Malignancies

“…Several studies have evaluated protein expression in malignant tissue compared with matched normal tissue in different tumour groups. Klotho expression has been shown to be significantly down-regulated in malignant tissue compared to adjacent non-malignant tissue using immunohistochemical (IHC) techniques, including colorectal [44,45], pancreatic [46], gastric [47], oesophageal [48], breast [49], hepatocellular [50], ovarian [51], and renal cancers [52] (Table 1). Furthermore, more than ten single nucleotide polymorphisms (SNPs) have been identified in the human KLOTHO gene, and a number of studies have been performed to evaluate the associations between allelic variations in the KLOTHO gene and the aetiology of ageing-related diseases [53][54][55][56][57][58][59][60][61], including the effect of Klotho's functional variants on cancer predisposition [62][63][64].…”