Coevolution of the tumor microenvironment revealed by quantum dot-based multiplexed imaging of hepatocellular carcinoma

Multimodal Imaging-Based Potential Visualization of the Tumor Microenvironment in Bone Metastasis

Bone metastasis (BM) is the most common malignant bone tumor and a significant cause of morbidity and mortality for patients with cancer. Compared to other metastatic organs, bone has unique characteristics in terms of the tumor microenvironment (TME). Precise assessments of the TME in BM could be an important step for developing an optimized management plan for patient care. Imaging approaches for BM have several advantages, such as biopsy not being required, multiple site evaluation, and serial assessment in the same sites. Owing to the developments of new imaging tracers or imaging modalities, bone TME could be visualized using multimodal imaging techniques. In this review, we describe the BM pathophysiology, diagnostic principles of major imaging modalities, and clinically available imaging modalities to visualize the TME in BM. We also discuss how the interactions between various factors affecting the TME could be visualized using multimodal imaging techniques.

Lysyl Oxidase Mechanisms to Mediate Gastrointestinal Cancer Progression

Background

Malignancy is a complex process resulting from different changes such as extracellular matrix (ECM) remodeling and stiffness. One of the important enzymes that contribute to ECM remodeling is lysyl oxidase (Lox) that is overexpressed in different types of human cancers. Because of the high prevalence and poor survival of gastrointestinal (GI) malignancies in this review, we discuss the association between Lox activity and the progression of GI cancers. Lox proteins are a group of extracellular enzymes that catalyzed the cross-linking of collagen and elastin, so they have important roles in the control of structure and homeostasis of ECM. Abnormal activation and expression of the Lox family of proteins lead to changes in the ECM toward increased rigidity and fibrosis. Stiffness of ECM can contribute to the pathogenesis of cancers.

Summary

Dysregulation of Lox expression is a factor in both fibrotic diseases and cancer. ECM stiffness by Lox overactivity creates a physical barrier against intratumoral concentration of chemotherapeutic drugs and facilitates cancer inflammation, angiogenesis, and metastasis.

Key Message

Because of the roles of Lox in GI cancers, development targeting Lox protein isotypes may be an appropriate strategy for treatment of GI cancers and improvement in survival of patients.

Characterization of the Tumor Microenvironment and Tumor-Stroma Interaction by Non-invasive Preclinical Imaging

Tumors are often characterized by hypoxia, vascular abnormalities, low extracellular pH, increased interstitial fluid pressure, altered choline-phospholipid metabolism, and aerobic glycolysis (Warburg effect). The impact of these tumor characteristics has been investigated extensively in the context of tumor development, progression, and treatment response, resulting in a number of non-invasive imaging biomarkers. More recent evidence suggests that cancer cells undergo metabolic reprograming, beyond aerobic glycolysis, in the course of tumor development and progression. The resulting altered metabolic content in tumors has the ability to affect cell signaling and block cellular differentiation. Additional emerging evidence reveals that the interaction between tumor and stroma cells can alter tumor metabolism (leading to metabolic reprograming) as well as tumor growth and vascular features. This review will summarize previous and current preclinical, non-invasive, multimodal imaging efforts to characterize the tumor microenvironment, including its stromal components and understand tumor-stroma interaction in cancer development, progression, and treatment response.

Co-evolution of tumor-associated macrophages and tumor neo-vessels during cervical cancer invasion

Considering the crucial significance of the tumor microenvironment in cancer development and progression, the present study aimed to investigate the changes in macrophages and angiogenesis during the cervical cancer (CC) progression process from chronic cervicitis to cervical intraepithelial neoplasia grades I-III (CIN I-III) to CC. This investigation included quantitative analysis and assessment of the spatial associations between tumor-associated macrophages (TAMs) and tumor neo-vessels. The conventional immunohistochemistry staining technique was used to detect cluster of differentiation (CD)68 and CD105 biomarker expression for TAMs and tumor neo-vessels, respectively. In addition, with the assistance of quantum dot (QD)-based two-component in situ imaging technology, the expression of the TAMs and tumor neo-vessels could be observed simultaneously. The quantitative analysis and co-evolution of the TAMs and tumor neo-vessels could then be processed. During the progression process from chronic cervicitis to cervical CIN I-III, and ultimately to invasive CC, the expression of the macrophages and neo-vessels in the tumor microenvironment increased synchronously. According to the quantitative analysis results, the median value of the TAM density was higher in the CC group (5,540.14) than in the CIN I-III group (2,502.17) and the chronic cervicitis group (1,403.31), with statistical significance in all three groups (P<0.001, for between-group comparisons). The number of neo-vessels was also much higher in the CC group (n=27) than in the CIN I-III group (n=17) or the chronic cervicitis group (n=6.5), with statistical significance in all three groups (P<0.001, for between-group comparisons). These findings demonstrated the great significance and close association of TAMs and tumor angiogenesis during CC development and progression. Thus, QDs-based in situ and simultaneous imaging of key cancer molecules may provide insights with regard to the biology of cancer invasion.