Elevated Physiologic Tumor Pressure Promotes Proliferation and Chemosensitivity in Human Osteosarcoma

Saminathan S Nathan,Jorge E Casas-Ganem,Bang H Hoang,John H Healey,Rebecca Sowers,Gene R Diresta,Andrew G Huvos,Richard Gorlick,Rui Yang

doi:10.1158/1078-0432.ccr-04-2048

Saminathan S Nathan, Jorge E Casas-Ganem + Show 7 more

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https://doi.org/10.1158/1078-0432.ccr-04-2048

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Abstract

This study investigates the effect of constitutively raised interstitial fluid pressure on osteosarcoma physiology and chemosensitivity. We did pressure and blood flow assessments at the time of open biopsy in patients with the diagnosis of high-grade osteosarcoma and correlated this to survival and chemotherapy-associated tumor necrosis. Osteosarcoma cell lines were then evaluated for proliferative and therapeutic indices in a replicated high-pressure environment. Sixteen osteosarcomas in vivo were assessed and exhibited elevated interstitial fluid pressures (mean 35.2 +/- SD, 18.6 mmHg). This was not associated with significantly impeded blood flow as measured by a Doppler probe at a single site (P < 0.12). Nonetheless, greater chemotherapy-associated necrosis and associated longer survival were seen in tumors with higher interstitial fluid pressures (P < 0.05). In vitro, cells undergo significant physiologic changes under pressure. Osteosarcoma cell lines grown in a novel hydrostatically pressurized system had variable cell line-specific growth proportional to the level of pressure. They were more proliferative as indicated by cell cycle analysis with more cells in S phase after 48 hours of pressurization (P < 0.01). There was a significant elevation in the cell cycle-related transcription factors E2F-1 (P < 0.03) and E2F-4 (P < 0.002). These changes were associated with increased chemosensitivity. Cells tested under pressure showed an increased sensitivity to cisplatin (P < 0.00006) and doxorubicin (P < 0.03) reminiscent of the increased chemotherapy-associated necrosis seen in tumors with higher interstitial fluid pressure in the clinical study. The results of this study suggest that cells in the in vivo pressurized environment are at a higher state of regenerative activity than is demonstrable in conventional cell culture systems. Variations in tumor interstitial fluid pressure have the potential to alter chemotherapeutic effects.

Highlights

Tumors in vivo have high interstitial fluid pressures (1 – 5).Interstitial fluid pressure results in a rapid transmembrane stress equilibration in cells
The present study investigated the biological effect that this elevated interstitial fluid pressure has on osteosarcoma cells
It has been suggested that because tumor interstitial fluid pressures and microvascular pressures are similar and the resultant pressure gradient negligible, the movement of molecules across the vascular membranes would be reduced—an explanation for reduced drug delivery and efficacy (3, 13 – 15). We investigated this proposition through a clinical analysis of tumor chemotherapy – associated necrosis in relation to tumor interstitial fluid pressures

Summary

Introduction

Tumors in vivo have high interstitial fluid pressures (1 – 5).Interstitial fluid pressure results in a rapid transmembrane stress equilibration in cells. Controversy exists as to the relationship between interstitial fluid pressure and blood flow in tumors. This pressure could reduce perfusion of the tumor resulting in necrosis [1]. It has been shown that solid stress or tension derived from appositional tumor cell growth is sufficient to occlude vessels and may affect the spatial heterogeneity seen in tumor microvasculature (6 – 8). This solid stress may be the mechanism of reduced tumor perfusion rather than the raised interstitial fluid pressure per se

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