Interleukin‐6 drives melanoma cell motility through p38α‐MAPK‐dependent up‐regulation of WNT5A expression

Abstract

Extensive research has demonstrated a tumor‐promoting role of increased WNT5A expression in malignant melanoma. However, very little light has been shed upon how WNT5A expression is up‐regulated in melanoma. A potential regulator of WNT5A expression is the pro‐inflammatory cytokine Interleukin (IL)‐6, which shares the ability of WNT5A to increase melanoma cell invasion. Here, we investigate whether IL‐6 can promote melanoma cell motility through an increased expression of WNT5A. We clearly demonstrate that the WNT5A‐antagonistic peptide Box5 could inhibit IL‐6‐induced melanoma cell migration and invasion. Furthermore, IL‐6 stimulation of the human melanoma cell lines HTB63 and A375 increased the expression of WNT5A in a dose‐dependent manner. To identify the signaling mechanism responsible for this up‐regulation, we explored the involvement of the three main signals induced by IL‐6; STAT3, Akt and ERK 1/2. Of these, only STAT3 was activated by IL‐6 in the melanoma cell lines tested. However, the STAT3 inhibitor S3I‐201 failed to inhibit IL‐6‐induced WNT5A up‐regulation in HTB63 and A375 cells. Nor did STAT3 siRNA silencing affect the expression of WNT5A. In search of an alternative signaling mechanism, we detected IL‐6‐induced activation of p38‐MAPK in HTB63 and A375 cells. The p38‐MAPK inhibitor SB203580 abolished the IL‐6‐induced WNT5A up‐regulation and blocked IL‐6‐induced melanoma cell invasion. The latter effect could be rescued by the addition of recombinant WNT5A. Notably, immunoprecipitation analysis revealed that only the p38α‐MAPK isoform was activated by IL‐6, and subsequent siRNA silencing of p38α‐MAPK abolished the IL‐6‐induced up‐regulation of WNT5A. Taken together, we demonstrate a novel link between the two melanoma pro‐metastatic agents IL‐6 and WNT5A explaining how IL‐6 can increase melanoma cell invasion and thus promote the metastatic process. This finding provides a basis for future therapeutic intervention of melanoma progression.

Demonstration of a WNT5A-IL-6 positive feedback loop in melanoma cells: Dual interference of this loop more effectively impairs melanoma cell invasion

“…The algorithm phenotypically stratifies publicly available microarray data sets to classify individual melanoma cell lines as either proliferative or invasive [22]. As previously demonstrated [12], extracted data revealed that significantly increased mRNA expression of WNT5A (Figure 1A) is associated with an invasive phenotype signature of melanoma cells. Interestingly, the same association was discovered for the mRNA expression of IL-6 (Figure 1B).…”

“…Similar to WNT5A, the pro-inflammatory cytokine IL-6 promotes melanoma cell invasion, and its increased expression is correlated with reduced overall patient survival [7–10]. Two recent studies have demonstrated a link between IL-6 secretion and WNT5A expression in melanoma cells [11, 12], suggesting that the combined therapeutic interference with this link might be beneficial for preventing disease progression and metastatic spread.…”

“…In agreement to these classical pathways, we have recently shown that IL-6 can induce p38α-MAPK activation in melanoma cells. More importantly, we demonstrated that the IL-6-induced p38α-MAPK activation promoted melanoma cell migration and invasion through increased WNT5A expression [12]. …”

Identification and quantification of ineffective chlorine by NaAsO 2 selective quenching method during drinking water disinfection

“…A regularly calibrated pH meter (FE20-FiveEasy, Mettler Toledo, Switzerland) was used to measure the solution pH. The living E. coli cells were counted using a Countess TM automatic cell counter (Invitrogen, USA) [34,35].…”

WNT5A and Its Receptors in the Bone-Cancer Dialogue

“…(69) Different studies indicate that WNT5A is regulated by the pro-inflammatory cytokine interleukin-6 (IL-6) in a p38a-MAPK-dependent manner. (70) Melanoma cell migration can be inhibited by targeting the RNA-binding protein human antigen R (HuR), which interacts with WNT5A mRNA, whereby HuR regulates its protein expression. (71) Moreover, WNT5A expression and secretion in melanoma is induced by the inhibition of the RNA helicase Mov10.…”