The potential role of GLP-1 receptor agonist targeting in fertility-sparing treatment in obese patients with endometrial malignant pathology: a call for research.

INTRODUCTION: Most patients diagnosed with endometrial hyperplasia or cancer are obese. Obesity, along with polycystic ovarian syndrome (PCOS) and type-2 diabetes mellitus (T2DM), may act synergistically to increase risk of malignant endometrial pathology. Incidence of malignant endometrial pathology is increasing, particularly in reproductive aged women. In patients who desire future fertility, the levonorgestrel intrauterine device (LNG-IUD) is often utilized. If the first-line progestin therapy fails, there is not an effective second-line adjunct option. Moreover, pregnancy rates following fertility-sparing treatment are lower-than-expected in these patients. AREAS COVERED: This clinical opinion provides a summary of recent studies exploring risk factors for the development of malignant endometrial pathology including obesity, PCOS, and T2DM. Studies assessing efficacy of fertility-sparing treatment of malignant endometrial pathology are reviewed, and a potential new adjunct treatment approach to LNG-IUD is explored. EXPERT OPINION: There is an unmet-need for a personalized treatment approach in cases of first-line progestin treatment failure. Glucagon-like peptide 1 receptor agonists are a class of anti-diabetic agents, but may have a role in fertility-sparing treatment of obese patients with malignant endometrial pathology by reducing weight, decreasing inflammation, and decreasing insulin resistance; these changes may also improve chances of subsequent pregnancy. This hypothesis warrants further exploration.

Differentiation of human circulating fibrocytes as mediated by transforming growth factor-beta and peroxisome proliferator-activated receptor gamma.

Fibrocytes are a distinct population of fibroblast-like progenitor cells in peripheral blood that have recently been shown to possess plasticity to differentiate along mesenchymal lineages, including commitment to myofibroblast and adipocyte cells. Here, we demonstrated that transforming growth factor (TGF) beta1 drives fibrocyte-to-myofibroblast differentiation through activating Smad2/3 and SAPK/JNK MAPK pathways, which in turn stimulates alpha-smooth muscle actin expression. We determined that SAPK/JNK signaling acts in a positive feedback loop to modulate Smad2/3 nuclear availability and Smad2/3-dependent transcription. Conversely, fibrocyte-to-adipocyte differentiation is driven by the peroxisome proliferator-activated receptor (PPAR) gamma agonist troglitazone, which is associated with cytoplasmic lipid accumulation and induction of aP2. Treatment with troglitazone also disrupted TGF beta 1-activated SAPK/JNK signaling, leading to decreased Smad2/3 transactivation activity and alpha-smooth muscle actin expression. Interestingly, TGF beta 1 was demonstrated to have reciprocal inhibition on fibrocyte differentiation to adipocytes. By activating SAPK/JNK signaling, which is normally suppressed during adipogenesis, PPARgamma-dependent transactivation activity and induction of aP2 expression were disrupted. Taken together, within the context of the local microenvironmental niche, the delicate balance of PPARgamma and TGF beta 1 activation drives the selection of an adipocyte or myofibroblast differentiation pathway through SAPK/JNK signaling.

Characterization of human fibrocytes as circulating adipocyte progenitors and the formation of human adipose tissue in SCID mice.

An increase in fat mass associated with obesity results from recruitment and differentiation of adipocyte progenitor cells. The precise origin of these cells is unknown, although accumulating evidence suggests that circulating stem cells can differentiate into cells of mesenchymal lineage. It is currently unclear whether a progenitor adipocyte population exists in circulation. One potential candidate is the fibrocyte, which may represent a common progenitor cell for several mesenchymal lineages. We demonstrate that these circulating progenitors become adipocytes when cultured under adipogenic conditions, with intracellular lipids accumulation and up-regulation of proteins specific for adipocyte differentiation, including leptin, PPARgamma, and FABP4. cDNA microarray analysis revealed gene clusters that were differentially regulated during adipogenesis of fibrocytes, which were similar to visceral and subcutaneous adipose tissue preadipocyte-to-adipocyte differentiation. Moreover, these progenitors engrafted and formed human adipose tissue following injection into SCID mice. Although fibrocytes express an array of chemokine receptors, we observed an up-regulation of CCR2 expression following fibrocytes differentiation into adipocytes, which was associated with increased chemotactic response to CCL2. This paradigm supports the notion that elevated CCL2 levels in visceral adipose tissue associated with Metabolic Syndrome is a chemotactic niche, whereby fibrocytes can home to and differentiate into adipocytes to perpetuate its tissue formation.