Clinicopathologic significance of leptin and leptin receptor expressions in papillary thyroid carcinoma

The relationship between body mass index and thyroid cancer pathology features and outcomes: a clinicopathological cohort study

BACKGROUND

Obesity has been implicated as a predisposing and disease-modifying factor in cancer. Epidemiological studies suggest that obesity is associated with an increased risk of thyroid cancer; however, the relationships between obesity and thyroid cancer stage or behavior are uncertain. We hypothesized that a higher body mass index (BMI) would be associated with aggressive thyroid cancer features and a higher incidence of persistent/recurrent disease.

METHODS

Two hundred fifty-nine consecutive patients with thyroid cancer were enrolled in this retrospective cohort study. Histopathological tumor features, stage at diagnosis, and disease status during and at the end of the study were determined based on chart review. BMI was calculated at the first clinical visit to our institution. The relationships between BMI and these parameters were assessed.

RESULTS

Mean follow-up time for the group was 6.2 yr (0.11-46 yr). No positive associations were identified between BMI and T, N, or M stage at diagnosis, vascular invasion, or recurrent or persistent disease on univariate or multivariate analyses. The absence of an association was also demonstrated on analysis by BMI quartiles. An unexpected inverse association was identified between BMI and nodal metastasis and tumor invasion on both univariate and multivariate analyses, suggesting that obesity may be associated with less aggressive tumor features, a finding that requires confirmatory studies.

CONCLUSION

Although obesity has been associated with increased thyroid cancer incidence, a higher BMI was found not to be associated with more aggressive tumor features or a greater likelihood of recurrence or persistence over the analyzed time period.

Molecular cloning and gene expression analysis of the leptin receptor in the Chinese mitten crab Eriocheir sinensis

Background

Leptin is an adipocyte-derived hormone with multiple functions that regulates energy homeostasis and reproductive functions. Increased knowledge of leptin receptor function will enhance our understanding of the physiological roles of leptin in animals.

Methodology/Principal Findings

In the present study, a full-length leptin receptor (lepr) cDNA, consisting of 1,353 nucleotides, was cloned from Chinese mitten crab (Eriocheir sinensis) using rapid amplification of cDNA ends (RACE) following the identification of a single expressed sequence tag (EST) clone in a cDNA library. The lepr cDNA consisted of a 22-nucleotide 5′-untranslated region (5′ UTR), a 402-nucleotide open reading frame (ORF) and a 929-nucleotide 3′ UTR. Multiple sequence alignments revealed that Chinese mitten crab lepr shared a conserved vacuolar protein sorting 55 (Vps55) domain with other species. Chinese mitten crab lepr expression was determined in various tissues and at three different reproductive stages using quantitative real-time RT-PCR. Lepr expression was highest in the intestine, thoracic ganglia, gonad, and accessory gonad, moderate in hepatopancreas and cranial ganglia, and low in muscle, gill, heart, haemocytes, and stomach. Furthermore, lepr expression was significantly higher in the intestine, gonad and thoracic ganglia in immature crabs relative to precocious and mature crabs. In contrast, lepr expression was significantly lower in the hepatopancreas of immature crabs relative to mature crabs.

Conclusions/Significance

We are the first to identify the lepr gene and to determine its gene expression patterns in various tissues and at three different reproductive stages in Chinese mitten crab. Taken together, our results suggest that lepr may be involved in the nutritional regulation of metabolism and reproduction in Chinese mitten crabs.