Nanoparticle-Based Therapeutics for Targeting Oncogenic Microenvironment in Obesity-Induced Endometrial Cancer

Introduction: There has been an unprecedented rise in the incidence of endometrial cancer in women due to the obesity pandemic. This increase in endometrial cancer is in contrast to the decrease in other women’s malignancies like breast and ovarian cancers. The absence of targeted therapies engenders a public health concern given the increasing numbers of obesity-driven endometrial cancer cases. We have shown that the numbers of infiltrating adipose stem cells (ASCs) in the endometrial microenvironment directly correlate with increased adiposity, and that these cells exert paracrine effects on endometrial epithelial cells (EECs) enhancing their motility. Specifically, ASC-secreted adipokine plasminogen activator inhibitor-1 (PAI-1) is a primary signaling molecule in endometrial epithelial cells, acting via the receptor LDL receptor-like protein 1 (LRP1), and is a major biochemical effector of EEC interactions with ECM that drive endometrial oncogenesis. Therefore, the goal of our study is to develop a nanoparticle-based system that targets the microenvironment of obesity-driven endometrial tumors to deliver PAI-1 siRNA.

Materials and

Methods: We used 2D models and spheroids to study changes in integrins (ITG) expression of the ASC-ECM interaction, providing valuable information for designing new targeted therapy options. Human ASCs were exposed to conditioned media (CM) derived from an endometrial cancer cell line (KLE) and non-oncogenic endometrial epithelial cells (EME6/7). Spheroids were formed as co-cultures between ASC and EME6/7. Changes in integrin expression were evaluated using RT-PCR and cyTOF analysis. As drug delivery system we used lipid coated mesoporous silica nanoparticles (LCMSN) loaded with PAI-1 si-RNA. LCMSN were synthesized using a solution-based surfactant directed self-assembly method. Liposomes were fused to fluorescently labeled MSN (Dylight 800-NHS) through electrostatic interactions and coated with integrin alpha 7 (ITGA7) antibody as a targeting strategy. To test the effect of our nanosystem on silencing PAI-1 in the endometrium, LCMSNs were injected intraperitoneally (IP) into ob/ob female mice. The uterus was then isolated after 48h of treatment injection, to evaluate PAI-1 gene expression using RT-PCR

Results, Conclusions, and Discussions: Exposure of ASCs to CM in both 2D and 3D studies revealed a significant increase in ITGA7 expression in ASCs exposed to KLE CM compared to non-oncogenic EME6/7 CM (p < 0.05) or control media (p < 0.0001) (Fig 1A). cyTOF analysis also showed elevated ITGA7 expression when ASCs were co-cultured with EME6/7 (Fig 1B). Consequently, we decided to use an ITGA7 antibody as a targeting mechanism for infiltrating ASCs in the endometrium, utilizing ITGA7-targeted LCMSNs.

To test the in vivo biodistribution of ITGA7-LCMSN, we conducted IP injections and observed strong retention in the uterus of obese mice compared to lean mice after 24 hours (Fig 1C). Importantly, RT-PCR results demonstrated the ability of ITGA7-LCMSN to silence PAI-1 in the uterus of ob/ob mice (Fig 1D).

These studies highlight the potential for targeting ASCs using LCMSNs coated with anti-ITGA7 antibodies to deliver PAI-1 siRNA to endometrial tumors. Future studies will investigate whether silencing PAI-1 in a mouse model of obesity-associated endometrial cancer can block tumor growth

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