Mixed metastatic lung cancer lesions in bone are inhibited by noggin overexpression and Rank:Fc administration
Brian T Feeley1, Nancy Q Liu, Augustine H Conduah
1Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA.
Unlabelled:
Lung cancer metastases to bone produce a primarily mixed osteolytic/osteoblastic lesion. The purpose of this study was to determine if blockade of both pathways would inhibit the formation these lesions in bone. Inhibition of the osteoblastic lesion with noggin and the osteolytic lesion with RANK:Fc was a successful treatment strategy to inhibit progression of mixed lung cancer lesions in bone.
Introduction:
Approximately 9-30% of patients with lung cancer develop bone metastases, leading to significant morbidity and mortality. A549 is a non-small-cell lung cancer (NSCLC) line that produces a mixed metastatic lesion in bone. We sought to determine if blockade of key components in both osteolytic and osteoblastic pathways would result in a reduction of a NSCLC tumor progression in a murine model of bony metastasis.
Materials And Methods:
The study used a retroviral vector overexpressing noggin (RN), a specific inhibitor of BMP, and RANK:Fc, a chimeric protein that inhibits the RANK-RANKL interaction. A549 cells were transduced with RN before implantation in SCID mice. Cells were implanted in a subcutaneous model and tibial injection model. RANK:Fc was administered twice weekly at 15 mg/kg. There were five treatment groups: A549; A549 + RN; A549 + RANK:Fc; A549 + empty vector; and A549 + RN + RANK:Fc (n = 10/group).
Results:
In SCID mice who underwent subcutaneous A549 tumor cell injection, animals treated with A549 + RN had significantly smaller subcutaneous tumor size at 8 weeks. In an intratibial model of bony metastasis, animals injected with A549 cells developed a mixed lytic/blastic lesion with cortical destruction at 8 weeks. Treatment with RANK:Fc inhibited the formation of osteoclasts, led to a smaller tumor volume in bone, and inhibited the lytic component of the mixed lesion. Animals treated with A549 + RN had a decreased number of osteoblasts in bone lesions, smaller tumor volume, and inhibition of the blastic component of the mixed lesions. Combination treatment inhibited both the lytic and blastic components of the lesion.
Conclusions:
The NSCLC cell line A549 forms a mixed osteolytic/osteoblastic lesion in vivo. Noggin overexpression inhibited the formation of the osteoblastic aspect of the lesion in bone and the tumor growth in vivo. Treatment with RANK:Fc limited the formation of the lytic aspect of the mixed lesion and also inhibited the rate of in vivo tumor growth. Inhibition of both pathways is necessary to effectively inhibit the progression of mixed metastatic lesions in bone.
Insights
Blocking both osteoblastic and osteolytic pathways effectively inhibits lung cancer bone metastasis progression. Combination therapy with noggin and RANK:Fc significantly reduces mixed metastatic lesions in bone.
Area of Science:
- Oncology
- Bone Metastasis Research
- Molecular Biology
Background:
- Lung cancer frequently metastasizes to bone, causing significant patient morbidity.
- The A549 non-small-cell lung cancer (NSCLC) cell line creates mixed osteolytic/osteoblastic lesions in bone.
- Investigating dual pathway blockade for NSCLC bone metastasis treatment is crucial.
Purpose of the Study:
- To determine if blocking both osteolytic and osteoblastic pathways inhibits NSCLC bone metastasis.
- To evaluate the efficacy of noggin and RANK:Fc in a murine model of bone metastasis.
Main Methods:
- Utilized a retroviral vector for noggin (RN) overexpression and RANK:Fc to inhibit BMP and RANK-RANKL pathways, respectively.
- A549 cells were transduced with RN and implanted in SCID mice (subcutaneous and intratibial models).
- Administered RANK:Fc and assessed five treatment groups, including combination therapy.
Main Results:
- Noggin overexpression (RN) reduced subcutaneous tumor size and inhibited the osteoblastic component of bone lesions.
- RANK:Fc treatment inhibited osteoclast formation, reduced tumor volume, and suppressed the osteolytic component of bone lesions.
- Combination therapy effectively inhibited both osteolytic and osteoblastic aspects of mixed lung cancer bone metastases.
Conclusions:
- The A549 NSCLC cell line forms mixed osteolytic/osteoblastic bone lesions in vivo.
- Dual blockade of osteoblastic (noggin) and osteolytic (RANK:Fc) pathways is essential for inhibiting mixed lung cancer bone metastasis progression.
- Combination therapy presents a promising strategy for managing bone metastases in NSCLC.
