Interleukin-4 induces senescence in human renal carcinoma cell lines through STAT6 and p38 MAPK.

Interleukin (IL)-4, originally identified as a lymphocyte growth factor, can directly inhibit growth of certain tumor cell types. We reported previously that IL-4 induced cell cycle arrest in G1 phase through an increase in p21(WAF1/CIP1) expression in human renal cell carcinoma (RCC) cell lines. In the present study, we investigated the underlying mechanism of IL-4-induced growth inhibition. In four of six human RCC cell lines, including Caki-1, A498, SNU482, and SNU228, IL-4 induced cellular senescence as demonstrated by enlarged and flattened morphology, increased granularity, and senescence-associated-ß-galactosidase (SA-ß-gal) staining. Signal tranducer and activator of transcription 6 (STAT6) and p38 MAPK were found to mediate IL-4-induced growth inhibition and cellular senescence. Both of these molecules were activated by 10 min after IL-4 treatment, and inhibition of their activity or expression prevented growth suppression and cellular senescence induced by IL-4. Inhibiting or silencing either STAT6 or p38 MAPK alone partially reduced the effect of IL-4, whereas inhibiting or silencing both molecules exerted an additive effect and almost completely abrogated the effect of IL-4. Thus STAT6 and p38 MAPK appeared to independently mediate IL-4-induced growth inhibition and cellular senescence. The p21(WAF1/CIP1) up-regulation that accompanied growth inhibition and cellular senescence by IL-4 was also attenuated additively when p38 MAPK and STAT6 were silenced. Taken together, these results show that IL-4 induces cellular senescence through independent signaling pathways involving STAT6 and p38 MAPK in some human RCC cell lines.

Phenylbutyric acid induces the cellular senescence through an Akt/p21(WAF1) signaling pathway.

It has been well known that three sentinel proteins - PERK, ATF6 and IRE1 - initiate the unfolded protein response (UPR) in the presence of misfolded or unfolded proteins in the ER. Recent studies have demonstrated that upregulation of UPR in cancer cells is required to survive and proliferate. Here, we showed that long exposure to 4-phenylbutyric acid (PBA), a chemical chaperone that can reduce retention of unfolded and misfolded proteins in ER, induced cellular senescence in cancer cells such as MCF7 and HT1080. In addition, we found that treatment with PBA activates Akt, which results in p21(WAF1) induction. Interestingly, the depletion of PERK but not ATF6 and IRE1 also induces cellular senescence, which was rescued by additional depletion of Akt. This suggests that Akt pathway is downstream of PERK in PBA induced cellular senescence. Taken together, these results show that PBA induces cellular senescence via activation of the Akt/p21(WAF1) pathway by PERK inhibition.

Estradiol treatment increases M2-like visceral adipose tissue macrophages in obese ovariectomized mice regardless of its anorectic action.

Estradiol (E2) treatment has been known to induce changes in food intake, energy expenditure, and weight gain. However, its direct effects on adipose tissue macrophages (ATM) in vivo are not fully understood. Thus, we aimed to explore this aspect at cellular and molecular levels in ovariectomized obese mice. We examined the changes in ATMs after eight weeks of a high-fat diet (HFD) in male, female, and ovariectomized (OVX) mice. After eight weeks, osmotic pumps were inserted into OVX mice to provide two weeks of E2 treatment. We additionally set up a vehicle Pair-Fed (PF) control group that supplied the same amount of HFD consumed by the E2-treated group. We then investigated the in vivo phenotypic changes of visceral adipose tissue (VAT) macrophages. The percentage of M1-like ATMs decreased by the anorectic effect of E2, while M2-like ATMs increased regardless of the anorexia. E2 treatment increased the expression of anti-inflammatory genes but decreased pro-inflammatory genes in VAT. Monocyte recruitment and local proliferation contributed to M2-like ATMs. Furthermore, M2-like phenotypes were induced by E2 treatment in human macrophages. E2 treatment increases M2-like macrophages and improves the tissue milieu of VAT regardless of the anorectic reaction of E2.

Effects of Autologous Platelet-Rich Plasma on Regeneration of Damaged Endometrium in Female Rats.

PURPOSE: To investigate whether autologous platelet-rich plasma (PRP) treatment can improve regeneration of the endometrium in an experimental model of ethanol-induced damage. MATERIALS AND METHODS: Sixty female Sprague-Dawley rats were randomly assigned into three groups: control group, ethanol group, and PRP-treated group (administration of 0.25 mL of PRP into both uterine cavities 72 hours after ethanol injection). After 15 days of endometrial damage, all the animals were sacrificed during the estrous cycle, and samples were taken from the mid-uterine horn. Functional and structural recovery of the endometrium was analyzed by hematoxylin-eosin (H&E) and Masson trichrome (MT) staining, real-time polymerase chain reaction (PCR) assay, and immuno-histochemical (IHC) analyses. RESULTS: H&E and MT staining confirmed significantly decreased fibrosis and increased cellular proliferation in the PRP-treated group, compared to the ethanol group. The endometrial areas in the ethanol and PRP-treated groups were 212.83±15.84 µm² and 262.34±12.33 µm² (p=0.065). Significantly stronger IHC expression of cytokeratin, homeobox A10 (HOXA10), vascular endothelial growth factor (VEGF), and Ki-67 was found in the PRP-treated group, compared to the ethanol group. In real-time PCR analyses, interleukin-1ß mRNA was down-regulated, while c-Kit mRNA was up-regulated, in the PRP-treated group, compared to the ethanol group. CONCLUSION: Intrauterine administration of autologous PRP stimulated and accelerated regeneration of the endometrium and also decreased fibrosis in a murine model of damaged endometrium.