# Pro-Inflammatory Cytokines Differentially Induce Intercellular Tunneling Nanotube Conduits and Cellular Migration in Pancreatic, Breast, and Colorectal Cancer Cells

## TL;DR

This study shows that certain cytokines after cancer surgery can boost tunneling nanotubes in pancreatic and breast cancer cells, aiding their spread, and a drug called oseltamivir phosphate can block this.

## Contribution

The study reveals that specific pro-inflammatory cytokines post-surgery trigger tunneling nanotubes in some cancer cells, promoting migration, and identifies oseltamivir phosphate as a potential inhibitor.

## Key findings

- TGF-β1, IL-6, and HGF cytokines significantly increased tunneling nanotubes in PANC-1 and MCF-7 cancer cells.
- Oseltamivir phosphate reduced nanotube formation in pancreatic and breast cancer cells but not in colorectal cancer cells.
- Cytokine treatment enhanced wound closure in PANC-1 cells but not in SW620 or MCF-7 cells.

## Abstract

Background: When tumors are surgically removed, an immediate rise in circulating tumor cells is often observed, accompanied by several postoperative changes that can enable these cells to evade immune detection and metastasize. The perioperative period following tumor resection can often promote the formation of new distant micrometastatic foci triggered by upregulation of distinct molecules. Our lab previously reported an increase in distinct inflammatory cytokine molecules following surgical resection in prostate, breast, and colorectal cancer patients, and the secretion of these signals begins as early as 2–24 h after surgery. Here, we investigated whether these distinct cytokines could orchestrate the formation of tunneling nanotube (TNT) conduits to enhance cancer cell migration. Methods and Results: Here, we provide supporting evidence that specific pro-inflammatory cytokines upregulated following cancer surgery may be potential triggers of disease recurrence and migration through TNT formation. In the tumor microenvironment, TNTs act as conduits between cancer and normal cells, facilitating the transfer of organelles that contribute to cancer cell survival and metastasis. Here, The effects of TGF-β1, IL-6, and HGF cytokines on the development of TNT conduits between adjacent cancer cells, as well as the effects of oseltamivir phosphate (OP) treatment, were measured using fluorescent microscopy and image analysis software. In PANC-1 pancreatic cancer cells, the addition of these cytokines significantly increased (p < 0.009) the quantity and extent of TNTs compared with untreated control cells. MCF-7 breast cancer cells yielded comparable results, with a significant increase in TNT observed in cells treated with TGFβ-1, IL-6, and HGF. In contrast, SW620 colorectal cancer cells did not express TNTs in response to any of the three cytokines tested. OP treatment with cytokines significantly reduced TNT formation in pancreatic and breast cancer cells, with no effect on the colorectal SW620 cancer cell line. Cell migration in response to cytokines was assessed using the scratch wound assay. Out of the three cell lines analyzed, the PANC-1 cells fully closed after 12 h of the wound gap. In contrast, the SW620 and MCF-7 cells had no significant change in wound closure rate following cytokine treatment. The SW620 cells exhibited a slight but insignificant increase in the wound closure rate with TGFβ-1 and HGF treatment, while IL-6 in the SW620 cells and all three cytokines in the MCF-7 cells were comparable to the control. OP significantly reduced the scratch wound closure rate on PANC-1, SW620, and MCF-7 cells treated with these cytokines. Conclusions: These findings further support the link between perioperative cytokine activity and increased metastatic potential by promoting the formation of intercellular tunneling nanotube conduits. OP, a specific inhibitor of the mammalian neuraminidase-1 (NEU-1) enzyme, disrupts this process.