The phosphatonins and the regulation of phosphate homeostasis

sFRP-4, a potential novel serum marker for chronic hepatitis B-related hepatocellular carcinoma

BACKGROUND

The current methods used for diagnosing hepatocellular carcinoma (HCC) are unsatisfactory. Here, we assessed the serum levels of secreted frizzled related protein 4 (sFRP-4) for diagnosing HCC in patients infected with chronic hepatitis B (CHB).

METHODS

In 272 patients with CHB enrolled, 142 were patients with HCC. Thirty-three healthy subjects were recruited as healthy controls. The CHB patients were assigned to a test group or a validation group based on the time of enrollment. Human antibody arrays were used to screen 15 patients (8 CHB-related HCC patients, 7 CHB patients) for serum markers. Four markers and one candidate marker were assessed in the test group and validation group, respectively.

RESULTS

Human antibody assays indicated that the serum levels of sFRP-4 in HCC patients were significantly higher than those in CHB patients (P<0.05). Additionally, serum sFRP-4 levels were significantly higher in the HCC patients than those in the non-HCC patients in both test group (79.7 vs 41.3 ng/mL; P<0.001) and validation group (89.0 vs 39.0 ng/mL; P<0.001). Areas under the Receiver Operating Characteristic curves (AUCs) for alpha-fetoprotein (AFP) and sFRP-4 were similar in both test group and validation group. In the test group, the combination of sFRP-4 (a sensitivity of 94.4%, a specificity of 60.5% at 46.4 ng/mL) and AFP (a sensitivity of 75.0%, a specificity of 87.2% at 11.3 ng/mL) showed better performance for diagnosing HCC (a sensitivity of 79.2% and a specificity of 95.3%). The AUC for combined sFRP-4 and AFP increased to 0.941 (95% CI: 0.908-0.975), and similar results were seen in the validation group.

CONCLUSION

sFRP-4 is a candidate serum marker for diagnosing HCC in CHB patients, and the combination of sFRP-4 with AFP may improve the diagnostic accuracy of HCC.

Novel mechanisms in the regulation of phosphorus homeostasis

Phosphorus plays a critical role in diverse biological processes, and, therefore, the regulation of phosphorus balance and homeostasis are critical to the well being of the organism. Changes in environmental, dietary, and serum concentrations of inorganic phosphorus are detected by sensors that elicit changes in cellular function and alter the efficiency by which phosphorus is conserved. Short-term, post-cibal responses that occur independently of hormones previously thought to be important in phosphorus homeostasis may play a larger role than previously appreciated in the regulation of phosphorus homeostasis. Several hormones and regulatory factors such as the vitamin D endocrine system, parathyroid hormone, and the phosphatonins (FGF-23, sFRP-4, MEPE) among others, may play a role only in the long-term regulation of phosphorus homeostasis. In this review, we discuss how organisms sense changes in phosphate concentrations and how changes in hormonal factors result in the conservation or excretion of phosphorus.