The emergence of solid stress as a potent biomechanical marker of tumour progression

Insights into the mechanobiology of cancer metastasis via microfluidic technologies

During cancer metastasis, cancer cells will encounter various microenvironments with diverse physical characteristics. Changes in these physical characteristics such as tension, stiffness, viscosity, compression, and fluid shear can generate biomechanical cues that affect cancer cells, dynamically influencing numerous pathophysiological mechanisms. For example, a dense extracellular matrix drives cancer cells to reorganize their cytoskeleton structures, facilitating confined migration, while this dense and restricted space also acts as a physical barrier that potentially results in nuclear rupture. Identifying these pathophysiological processes and understanding their underlying mechanobiological mechanisms can aid in the development of more effective therapeutics targeted to cancer metastasis. In this review, we outline the advances of engineering microfluidic devices in vitro and their role in replicating tumor microenvironment to mimic in vivo settings. We highlight the potential cellular mechanisms that mediate their ability to adapt to different microenvironments. Meanwhile, we also discuss some important mechanical cues that still remain challenging to replicate in current microfluidic devices in future direction. While much remains to be explored about cancer mechanobiology, we believe the developments of microfluidic devices will reveal how these physical cues impact the behaviors of cancer cells. It will be crucial in the understanding of cancer metastasis, and potentially contributing to better drug development and cancer therapy.

Ultrasound stiffness and perfusion markers correlate with tumor volume responses to immunotherapy

Immunotherapy has revolutionized the treatment of dozens of cancers and became a standard of care for some tumor types. However, the majority of patients do not benefit from current immunotherapeutics and many develop severe toxicities. Therefore, the identification of biomarkers to classify patients as likely responders or non-responders to immunotherapy is a timely task. Here, we test ultrasound imaging markers of tumor stiffness and perfusion. Ultrasound imaging is non-invasive and clinically available and can be used both for stiffness and perfusion evaluation. In this study, we employed syngeneic orthotopic models of two breast cancers, a fibrosarcoma and melanoma, to demonstrate that ultrasound-derived measures of tumor stiffness and perfusion (i.e., blood volume) correlate with the efficacy of immune checkpoint inhibition (ICI) in terms of changes in primary tumor volume. To modulate tumor stiffness and perfusion and thus, get a range of therapeutic outcomes, we employed the mechanotherapeutic tranilast. Mechanotherapeutics combined with ICI are advancing through clinical trials, but biomarkers of response have not been tested until now. We found the existence of linear correlations between tumor stiffness and perfusion imaging biomarkers as well as strong linear correlations between the stiffness and perfusion markers with ICI efficacy on primary tumor growth rates. Our findings set the basis for ultrasound imaging biomarkers predictive of ICI therapy in combination with mechanotherapeutics. STATEMENT OF SIGNIFICANCE: Hypothesis: Monitoring Tumor Microenvironment (TME) mechanical abnormalities can predict the efficacy of immune checkpoint inhibition (ICI) and provide biomarkers predictive of response. Tumor stiffening and solid stress elevation are hallmarks of tumor patho-physiology in desmoplastic tumors. They induce hypo-perfusion and hypoxia by compressing tumor vessels, posing major barriers to immunotherapy. Mechanotherapeutics is a new class of drugs that target the TME to reduce stiffness and improve perfusion and oxygenation. In this study, we show that measures of stiffness and perfusion derived from ultrasound shear wave elastography and contrast enhanced ultrasound can provide biomarkers of tumor response.

Radiotherapy-induced tumor physical microenvironment remodeling to overcome immunotherapy resistance

The clinical benefits of immunotherapy are proven in many cancers, but a significant number of patients do not respond well to immunotherapy. The tumor physical microenvironment (TpME) has recently been shown to affect the growth, metastasis and treatment of solid tumors. The tumor microenvironment (TME) has unique physical hallmarks: 1) unique tissue microarchitecture, 2) increased stiffness, 3) elevated solid stress, and 4) elevated interstitial fluid pressure (IFP), which contribute to tumor progression and immunotherapy resistance in a variety of ways. Radiotherapy, a traditional and powerful treatment, can remodel the matrix and blood flow associated with the tumor to improve the response rate of immune checkpoint inhibitors (ICIs) to a certain extent. Herein, we first review the recent research advances on the physical properties of the TME and then explain how TpME is involved in immunotherapy resistance. Finally, we discuss how radiotherapy can remodel TpME to overcome immunotherapy resistance.

The effect of mechanical force in genitourinary malignancies

INTRODUCTION

Mechanical force is attributed to the formation of tumor blood vessels, influences cancer cell invasion and metastasis, and promotes reprogramming of the energy metabolism. Currently, therapy strategies for the tumor microenvironment are being developed progressively. The purpose of this article is to discuss the molecular mechanism, diagnosis, and treatment of mechanical force in urinary tract cancers and outline the medications used in the mechanical microenvironment.

AREAS COVERED

This review covers the complex mechanical elements in the microenvironment of urinary system malignancies, focusing on mechanical molecular mechanisms for diagnosis and treatment.

EXPERT OPINION

The classification of various mechanical forces, such as matrix stiffness, shear force, and other forces, is relatively straightforward. However, little is known about the molecular process of mechanical forces in urinary tract malignancies. Because mechanical therapy is still controversial, it is critical to understand the molecular basis of mechanical force before adding mechanical therapy solutions.