Surgical wounding enhances pro‐tumor macrophage responses and accelerates tumor growth and lung metastasis in a triple negative breast cancer mouse model

Abstract

Approximately one‐third of all breast cancer mortality results from metastatic recurrence after initial success of surgery and/or therapy. Although primary tumor removal is widely accepted as beneficial, it has long been suspected that surgery itself contributes to accelerated metastatic recurrence. We investigated surgical wounding's impact on tumor progression and lung metastasis in a murine model of triple negative breast cancer (TNBC). Ten‐week‐old female mice were inoculated with 4 T1 cells (week 0) and were either subjected to a 2 cm long cutaneous contralateral incision (wounded) or control (non‐wounded) on week 2 and monitored for 3 weeks (week 5). Mice with surgical wounding displayed significantly accelerated tumor growth observable as early as 1‐week post wounding. This was confirmed by increased tumor volume and tumor weight, post‐mortem. Further, surgical wounding increased metastasis to the lungs, as detected by IVIS imaging, in vivo and ex vivo (week 5). As expected then, wounded mice displayed decreased apoptosis and increased proliferation in both the primary tumor and in the lungs. Flow cytometry revealed that primary tumors from wounded mice exhibited increased tumor associated macrophages and specifically M2‐like macrophages, which are important in promoting tumor development, maintenance, and metastasis. Immunofluorescence staining and gene expression data further confirms an increase in macrophages in both the primary tumor and the lungs of wounded mice. Our data suggests that surgical wounding accelerates tumor progression and lung metastasis in a mouse model of TNBC, which is likely mediated, at least in part by an increase in macrophages.

Emodin reduces surgical wounding‐accelerated tumor growth and metastasis via macrophage suppression in a murine triple‐negative breast cancer model

“…It has previously been documented that monocytes, predecessors of macrophages, are summoned into circulation succeeding surgical wounding, intensifying their accessibility for enrollment into tumors and signifying a means whereby surgical wounding may enhance metastasis to the lungs (Krall et al, 2018). Our previous work lends credence to this as we demonstrated that surgical wounding does indeed enhance macrophages in the primary tumor and in the lungs, and specifically M2-like protumor macrophages or tumor-associated macrophages (TAMs) (McDonald, VanderVeen, Bullard, et al, 2022). TAMs have been widely reported to promote tumor development and metastasis and in multiple cancer models through driving tumor cell proliferation and invasiveness, enhancing angiogenesis, promoting immunosuppression, and enabling cancer stem cell formation and maintenance (Medrek et al, 2012;Qian & Pollard, 2010;Rudnick & Kuperwasser, 2012).…”

“…It is becoming more evident that tumor resection surgery and the succeeding wound healing response contribute to early metastatic relapse (Dillekas et al, 2014(Dillekas et al, , 2016Tohme et al, 2017). Indeed, we recently reported that the surgical wounding procedure itself, at a remote site and in the absence of tumor resection, is adequate to hasten primary tumor progression and promote lung metastasis in a murine model of TNBC (McDonald, VanderVeen, Bullard, et al, 2022). This is of great concern given that surgical resection is a mainstay of BC therapy.…”

“…Indeed, clinical evidence strongly favors the hypothesis that clinically untraceable cancer cells termed micrometastases are existent in distant organs preceding surgery but remain quiescent and under immune regulation, until this metastatic latency is disturbed by the surgical procedure itself to result in enhanced enlargement of micrometastases into clinically measurable macrometastases (Demicheli et al, 2007 ; Dillekas et al, 2014 , 2016 ; Klein, 2020 ). Given that it is impractical and unethical to perform pseudo‐surgery to directly test this hypothesis in patients, our group and others have devised mouse models to link surgical wounding to the hastening of local as well as distant tumor development (i.e., lung metastasis) (Krall et al, 2018 ; McDonald, VanderVeen, Bullard, et al, 2022 ). We recently reported that the surgical wounding procedure, at a remote site and in the absence of tumor resection, is adequate to enhance primary tumor succession and promotion of lung metastasis in a murine model of triple‐negative breast cancer (TNBC) (McDonald, VanderVeen, Bullard, et al, 2022 ).…”

Good CARMA: Turning bad tumor‐resident myeloid cells good with chimeric antigen receptor macrophages

“…The prominent role of macrophages in wound healing suggests that they can promote recurrence or metastasis after an initial insult, such as surgical excision or chemotherapy. Indeed, resection of the primary tumor with curative intent has been shown in several murine cancer models to contribute to metastatic spread 55–57 . TAMs play a role in chemoresistance, for example, by expressing cathepsins that help protect cancer cells from cytotoxic chemotherapy and by upregulating VEGF to stimulate tumor relapse from chemotherapy 58–60 .…”

“…Indeed, resection of the primary tumor with curative intent has been shown in several murine cancer models to contribute to metastatic spread. [55][56][57] TAMs play a role in chemoresistance, for example, by expressing cathepsins that help protect cancer cells from cytotoxic chemotherapy and by upregulating VEGF to stimulate tumor relapse from chemotherapy. [58][59][60] In glioblastoma, an aggressive primary brain cancer characterized by an abundant TAM infiltration, most TAMs at diagnosis are derived from the brainresident macrophage lineage cells (microglia), whereas upon recurrence the dominant TAM populations are derived from peripherally-derived monocytes.…”