Klotho rewires cellular metabolism of breast cancer cells through alteration of calcium shuttling and mitochondrial activity

Revealing the tumor suppressive sequence within KL1 domain of the hormone Klotho

Klotho, a 1012 amino acid transmembrane protein, is a potent tumor suppressor in different cancer types. Klotho is composed of two internal repeats KL1 and KL2, and the tumor suppressor activity is primarily attributed to the KL1 domain. Despite its significant role in regulating various cancer-related pathways, the precise mechanism underlying its tumor suppressor activity remains unresolved. In this study, we aimed to identify the sequence responsible for the tumor suppressor function of Klotho and gain insights into its mechanism of action. To accomplish this, we generated expression vectors of truncated KL1 at the C and N-terminal regions and evaluated their ability to inhibit the colony formation of several cancer cell lines. Our findings demonstrated that truncated KL1 1-340 (KL340) effectively inhibited colony formation similar to KL1, while truncated KL1 1-320 (KL320) lost this activity. Furthermore, this correlated with the inhibitory effect of KL1 and KL340 on the Wnt/β-catenin pathway, whereas KL320 had no effect. Transcriptomic analysis of MCF-7 cells expressing the constructs revealed enriched pathways associated with tumor suppressor activity in KL1 and KL340. Interestingly, the α-fold predictor tool highlighted distinct differences in the α and β sheets of the TIM barrel fold of the truncated Klotho constructs, adding to our understanding of their structural variations. In summary, this study identified the 340 N-terminal amino acids as the sequence that possesses Klotho's tumor suppressor activity and reveals a critical role in the 320-340 sequence for this function. It also provides a foundation for the development of Klotho-based therapeutic approaches for cancer treatment.

The Role of Genetic Mutations in Mitochondrial-Driven Cancer Growth in Selected Tumors: Breast and Gynecological Malignancies

There is an increasing understanding of the molecular and cytogenetic background of various tumors that helps us better conceptualize the pathogenesis of specific diseases. Additionally, in many cases, these molecular and cytogenetic alterations have diagnostic, prognostic, and/or therapeutic applications that are heavily used in clinical practice. Given that there is always room for improvement in cancer treatments and in cancer patient management, it is important to discover new therapeutic targets for affected individuals. In this review, we discuss mitochondrial changes in breast and gynecological (endometrial and ovarian) cancers. In addition, we review how the frequently altered genes in these diseases (BRCA1/2, HER2, PTEN, PIK3CA, CTNNB1, RAS, CTNNB1, FGFR, TP53, ARID1A, and TERT) affect the mitochondria, highlighting the possible associated individual therapeutic targets. With this approach, drugs targeting mitochondrial glucose or fatty acid metabolism, reactive oxygen species production, mitochondrial biogenesis, mtDNA transcription, mitophagy, or cell death pathways could provide further tailored treatment.

The Circulating Level of Klotho Is Not Dependent upon Physical Fitness and Age-Associated Methylation Increases at the Promoter Region of the Klotho Gene

(1) Background: Higher levels of physical fitness are believed to increase the physiological quality of life and impact the aging process with a wide range of adaptive mechanisms, including the regulation of the expression of the age-associated klotho (KL) gene and protein levels. (2) Methods: Here, we tested the relationship between the DNA methylation-based epigenetic biomarkers PhenoAge and GrimAge and methylation of the promoter region of the KL gene, the circulating level of KL, and the stage of physical fitness and grip force in two groups of volunteer subjects, trained (TRND) and sedentary (SED), aged between 37 and 85 years old. (3) Results: The circulating KL level is negatively associated with chronological age in the TRND group (r = -0.19; p = 0.0295) but not in the SED group (r = -0.065; p = 0.5925). The age-associated decrease in circulating KL is partly due to the increased methylation of the KL gene. In addition, higher plasma KL is significantly related to epigenetic age-deceleration in the TRND group, assessed by the biomarker of PhenoAge (r = -0.21; p = 0.0192). (4) Conclusions: The level of physical fitness, on the other hand, does not relate to circulating KL levels, nor to the rate of the methylation of the promoter region of the KL gene, only in males.

Novel Anti-Cancer Products Targeting AMPK: Natural Herbal Medicine against Breast Cancer

Breast cancer is a common cancer in women worldwide. The existing clinical treatment strategies have been able to limit the progression of breast cancer and cancer metastasis, but abnormal metabolism, immunosuppression, and multidrug resistance involving multiple regulators remain the major challenges for the treatment of breast cancer. Adenosine 5'-monophosphate (AMP)-Activated Protein Kinase (AMPK) can regulate metabolic reprogramming and reverse the "Warburg effect" via multiple metabolic signaling pathways in breast cancer. Previous studies suggest that the activation of AMPK suppresses the growth and metastasis of breast cancer cells, as well as stimulating the responses of immune cells. However, some other reports claim that the development and poor prognosis of breast cancer are related to the overexpression and aberrant activation of AMPK. Thus, the role of AMPK in the progression of breast cancer is still controversial. In this review, we summarize the current understanding of AMPK, particularly the comprehensive bidirectional functions of AMPK in cancer progression; discuss the pharmacological activators of AMPK and some specific molecules, including the natural products (including berberine, curcumin, (-)-epigallocatechin-3-gallate, ginsenosides, and paclitaxel) that influence the efficacy of these activators in cancer therapy; and elaborate the role of AMPK as a potential therapeutic target for the treatment of breast cancer.

The role of α-klotho in human cancer: molecular and clinical aspects

Klotho is a well-established longevity hormone. Its most prominent function is the regulation of phosphate homeostasis. However, klotho possesses multiple pleiotropic activities, including inhibition of major signaling pathways, reducing oxidative stress and suppressing inflammation. These activities are tightly associated with cancer, and klotho was discovered as a universal tumor suppressor. We review here novel molecular aspects of klotho activity in cancer, focusing on its structure-function relationships and clinical aspects regarding its expression, blood levels, clinical risk, and prognostic value in the clinical setting. In addition, the potential benefit of klotho treatment combined with chemotherapy, biological therapy, or immunotherapy, are discussed. Finally, as klotho was shown in preclinical models to inhibit cancer development and growth, we discuss various approaches to developing klotho-based therapies.

Renal hyperparathyroidism

The number of the patients with chronic kidney disease is now increasing in the world. The pathophysiology of renal hyperparathyroidism is closely associated with Klotho-FGF-endocrine axes, which must be solved definitively as early as possible. It was revealed that the expression of fgf23 is activated by calciprotein particles, which induces vascular ossification. And it is well known that phosphorus overload directly increases parathyroid hormone and hyperparathyroid bone disease develops in those subjects. On the other hand, low turnover bone disease is often recently. Both the patients with chronic kidney disease suffering from hyperparathyroid bone disease or low turnover bone disease are associated with increased fracture risk. Micropetrosis may be one of the causes of increased fracture risk in the subjects with low turnover bone disease. In this chapter, we now describe the diagnosis, pathophysiology and treatments of renal hyperparathyroidism.

Association of serum Klotho levels with cancer and cancer mortality: Evidence from National Health and Nutrition Examination Survey

BACKGROUND

Klotho has both anticancer and hormone-like functions. But the research on Klotho and cancer is mainly based on animal experiments and small-scale clinical research, thus we explored the association between serum Klotho and cancer and cancer mortality based on the National Health and Nutrition Survey (NHANES).

METHODS

Participants were employed from the NHANES 2007-2016, excluding pregnant, chronic renal insufficiency, and incomplete data of cancer questionnaire and serum Klotho level. The association of serum Klotho with cancer and mortality was analyzed by weighted Logistic regression, weighted Cox regression and competitive risk model, respectively. Correlations between serum Klotho and testosterone and estradiol levels were analyzed by Spearman correlation and restricted cubic spline respectively.

RESULTS

We found Klotho had an inverse effect with risk of pan-cancer (all p < 0.02), with each unit increase in Klotho (1ug/g creatinine) associated with a 0.9%-2.2% reduction in the risk of cancer, and higher levels showing a stronger negative association (all p-trend <= 0.0005). Whereas, we did not observe any association between serum Klotho level with all-cause mortality and cancer-specific mortality (all p > 0.05). Then, stratified analysis found that people aged 60-79, female, overweight and non-Hispanic whites or Mexican Americans were less likely to develop cancer. In addition, there was a strong nonlinear and linear positive correlation of Klotho with estradiol (p-nonlinear = 0.0178) and testosterone only among male participants (β = -0.513, p = 0.0137), respectively.

CONCLUSIONS

We found an inverse association between serum Klotho and cancer, but without cancer mortality. And this effect may be partially mediated by estradiol and testosterone. Further prospective studies are needed to prove these findings.

Klotho an Autophagy Stimulator as a Potential Therapeutic Target for Alzheimer’s Disease: A Review

Alzheimer’s disease (AD) is an age-associated neurodegenerative disease; it is the most common cause of senile dementia. Klotho, a single-pass transmembrane protein primarily generated in the brain and kidney, is active in a variety of metabolic pathways involved in controlling neurodegeneration and ageing. Recently, many studies have found that the upregulation of Klotho can improve pathological cognitive deficits in an AD mice model and have demonstrated that Klotho plays a role in the induction of autophagy, a major contributing factor for AD. Despite the close association between Klotho and neurodegenerative diseases, such as AD, the underlying mechanism by which Klotho contributes to AD remains poorly understood. In this paper, we will introduce the expression, location and structure of Klotho and its biological functions. Specifically, this review is devoted to the correlation of Klotho protein and the AD phenotype, such as the effect of Klotho in upregulating the amyloid-beta clearance and in inducing autophagy for the clearance of toxic proteins, by regulating the autophagy lysosomal pathway (ALP). In summary, the results of multiple studies point out that targeting Klotho would be a potential therapeutic strategy in AD treatment.

Common Pathogenetic Mechanisms Underlying Aging and Tumor and Means of Interventions

Recently, there has been an increase in the incidence of malignant tumors among the older population. Moreover, there is an association between aging and cancer. During the process of senescence, the human body suffers from a series of imbalances, which have been shown to further accelerate aging, trigger tumorigenesis, and facilitate cancer progression. Therefore, exploring the junctions of aging and cancer and searching for novel methods to restore the junctions is of great importance to intervene against aging-related cancers. In this review, we have identified the underlying pathogenetic mechanisms of aging-related cancers by comparing alterations in the human body caused by aging and the factors that trigger cancers. We found that the common mechanisms of aging and cancer include cellular senescence, alterations in proteostasis, microbiota disorders (decreased probiotics and increased pernicious bacteria), persistent chronic inflammation, extensive immunosenescence, inordinate energy metabolism, altered material metabolism, endocrine disorders, altered genetic expression, and epigenetic modification. Furthermore, we have proposed that aging and cancer have common means of intervention, including novel uses of common medicine (metformin, resveratrol, and rapamycin), dietary restriction, and artificial microbiota intervention or selectively replenishing scarce metabolites. In addition, we have summarized the research progress of each intervention and revealed their bidirectional effects on cancer progression to compare their reliability and feasibility. Therefore, the study findings provide vital information for advanced research studies on age-related cancers. However, there is a need for further optimization of the described methods and more suitable methods for complicated clinical practices. In conclusion, targeting aging may have potential therapeutic effects on aging-related cancers.

Role of Fibroblast Growth Factor 23 (FGF23) and αKlotho in Cancer

Together with fibroblast growth factors (FGFs) 19 and 21, FGF23 is an endocrine member of the family of FGFs. Mainly secreted by bone cells, FGF23 acts as a hormone on the kidney, stimulating phosphate excretion and suppressing formation of 1,25(OH)₂D₃, active vitamin D. These effects are dependent on transmembrane protein αKlotho, which enhances the binding affinity of FGF23 for FGF receptors (FGFR). Locally produced FGF23 in other tissues including liver or heart exerts further paracrine effects without involvement of αKlotho. Soluble Klotho (sKL) is an endocrine factor that is cleaved off of transmembrane Klotho or generated by alternative splicing and regulates membrane channels, transporters, and intracellular signaling including insulin growth factor 1 (IGF-1) and Wnt pathways, signaling cascades highly relevant for tumor progression. In mice, lack of FGF23 or αKlotho results in derangement of phosphate metabolism and a syndrome of rapid aging with abnormalities affecting most organs and a very short life span. Conversely, overexpression of anti-aging factor αKlotho results in a profound elongation of life span. Accumulating evidence suggests a major role of αKlotho as a tumor suppressor, at least in part by inhibiting IGF-1 and Wnt/β-catenin signaling. Hence, in many malignancies, higher αKlotho expression or activity is associated with a more favorable outcome. Moreover, also FGF23 and phosphate have been revealed to be factors relevant in cancer. FGF23 is particularly significant for those forms of cancer primarily affecting bone (e.g., multiple myeloma) or characterized by bone metastasis. This review summarizes the current knowledge of the significance of FGF23 and αKlotho for tumor cell signaling, biology, and clinically relevant parameters in different forms of cancer.

Alginate Oligosaccharide Ameliorates D-Galactose-Induced Kidney Aging in Mice through Activation of the Nrf2 Signaling Pathway

Aging is an independent risk factor for the development of age-related progressive kidney injury. As a part of the aging process, kidney aging has been indicated to be associated with oxidative stress-induced damage. Ameliorating oxidative damage is therefore considered a promising strategy for delaying kidney aging. Alginate oligosaccharide (AOS) has been reported to have a wide range of biological and pharmacological activities. However, no studies have focused on the role of AOS in delaying the kidney aging process. In this study, we aimed to evaluate the potential effects of AOS on kidney aging and its possible mechanisms. Subcutaneous injection of D-galactose (D-gal) (200 mg·kg⁻¹·d⁻¹) in C57BL/6J mice for 8 weeks was used to establish the aging model. AOS (200 mg·kg⁻¹·d⁻¹) was administered via oral gavage for the last four weeks. As a result, AOS inhibited the D-gal-induced upregulation of aging markers and significantly improved the kidney index and kidney function of D-gal-induced mice. In addition, AOS ameliorated the degree of tissue damage and fibrosis in the aging kidney. To further explore the potential mechanisms by which AOS attenuates the kidney aging process, the associated oxidative stress-induced damage was analyzed in depth. The data showed that AOS upregulated the expression of Klotho and decreased malondialdehyde levels by increasing the expression of antioxidant enzymes. Furthermore, our results suggested that AOS activated the nuclear factor erythrogen-2 associated factor 2 (Nrf2) pathway by promoting Nrf2 nuclear translocation in aging mice and upregulated the downstream expression of heme oxygenase-1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1). In conclusion, the present study demonstrated that AOS is a promising agent for attenuating kidney aging, and the underlying molecular mechanisms are related to the activation of the Nrf2 signaling pathway.