Aim: To examine the role of the chemokine pathway in cervix cancer in the regulation of hypoxia-induced metastases and bone marrow derived myeloid cells (BMDCs) in the tumor microenvironment.
Methods: Cervix cancer biopsies from patients in clinical studies at PMH were used for implantation into the cervix of NRG mice. Relative CXCR4 expression by qRT-PCR in biopsies from 117 patients with cervical cancer and 17 primary, orthotopic, cervical cancer xenografts was conducted. Mice bearing orthotopic xenografts were exposed to cyclic hypoxia (12x 10min cycles of breathing 7%O2 or air; 4hr/day for 2 wks) during their growth in combination with AMD3100 (Plerixafor), administered by osmotic pumps (5mg/kg/day) implanted subcutaneously for 3 weeks. Primary tumor size and para-aortic lymph node metastases were assessedfor metastases (H&E staining). Mice received 15x30Gy (2Gy daily 5x/wk) targeted radiotherapy with cisplatin (4mg/kg/wk)(RTCTx) with or without AMD3100. The mice were monitored weekly for tumor growth by CT scanning. Immunohistochemistry was used to analyse levels of hypoxia (EF5/CA-9), blood (CD31) and lymphatic (LYVE-1) vessels, and CXCR4/CXCL12 in the orthotopic tumors and involved lymphnodes. Cd11b staining was used to assess neutrophil infiltration into the tumors. The GI toxicity of AMD3100 with RTCTx was assessed by gut crypt assay.
Results: The (early passage) primary orthotopic cervical xenografts used in this study invade and metastasize to lymph nodes in a manner similar to cervical cancer in patients. The microenvironmental features (vascularity, stroma content, hypoxia, IFP) of the xenografts match the original biopsy. The variability in baseline CXCR4 gene expression (by qRT-PCR) in our xenograft models is also similar to that seen in the patient biopsies. Preliminary data also shows comparable CXCL12 and CD11b+ BMDC infiltration in a patient biopsy and in primary xenografts. Induction of tumor hypoxia by exposing the animals to a low oxygen environment increased CXCL12 and CXCR4 gene and protein expression and resulted in a significant increase in the number of lymph node metastases. Treatment with the CXCR4 antagonist AMD3100 reversed these effects. Tumor-bearing animals treated with targeted RTCTx combined with AMD3100 demonstrated significantly enhanced growth delay compared to RTCTx alone and demonstrated reduced metastases at the end of the study. There was no evidence that AMD3100 enhanced the gut toxicity of the RTCTx treatment.
Conclusions: Our results suggest that CXCR4 plays an important role in metastasis and tumor growth, under hypoxic conditions, in human cervical cancer. Targeting the CXCR4-CXCL12 axis, with chemokine specific inhibitors,may serve as a novel and attractive therapeutic approach in cervix cancer.These studies provide a strong focus on developing and optimizing new targeted therapeutic approaches aimed at mitigating the adverse consequences of altered chemokine/BMDC signaling and translating these to high-impact phase I/II clinical trials.
Citation Format: Naz Chaudary, Salomeh Jelveh, Patricia Lindsay, Melania Pintilie, Michael Milosevic, Richard P. Hill. Hypoxia-induced chemokine activation and lymphnode metastases in primary cervix xenografts. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr B13. doi:10.1158/1538-7445.CHTME14-B13