Tumour-Associated Macrophages Case Study

We studied the correlation between the micro-vascular density and type of cells “benign and malignant”: We noticed the higher vascularity of cases of cystitis, compared to the vascularity of malignant tumors, this could be explained by the higher vascularity of the active cells, edema, inflammatory infiltrate and vascular congestion during the inflammatory process.

Cancer, medically called ‘tumorigenesis’ (Thaker, Lutgendorf, & Sood, 2007, p.430) occurs when cells in the body orient themselves for malignant growth. Such cells show ‘self-sufficiency in growth signals’, are ‘insensitive to anti-growth signals’ and have ‘limitless replicative potential’ (Thaker, Lutgendorf, & Sood, 2007, p.430). Once a particular set of cells become malignant, the malignancy can spread to other set of cells in different organs due to ‘crosstalk’ between the affected cells and their surrounding ‘tissues’ and ‘micro-environments’(Thaker, Lutgendorf, & Sood, 2007, p.430).

N-cadherin is a protein encoded by the CDH2 gene. It interacts with the cellular cytoskeleton, and is often involved in cardiac muscle, as well as certain cancers. Being calcium dependent, it helps to maintain cellular structure and integrity. For example, it plays a role in trans-endothelial migration, which involves cell-cell adhesion [3]. The endothelial layer contains many different fibers, as well as pathways that allow attachment for the cadherin protein. Some cancer cells can eventually pass through the endothelium, causing the cancer to become malignant and spread. Cadherins in this case can be used to identify and track the spread of the cells, and further identify common routes of travel through the human vasculature.

Distant metastases are mostly identified in patients of osteosarcoma with the estimation of about 85% after surgery. Mostly they occur in lungs however it may also metastasizes to soft tissues and other different bone. Osteosarcoma is lethal because of pulmonary metastasis with widespread progression that leads to respiratory failure. Tumor metastasis and invasion are multistep complex process in which tumor cells alter cell–extracellular matrix (ECM) associations at the primary tumor site to invade adjacent tissues and thus translocated through the vascular vessels to other systems to form secondary tumors there. MMPs are family of proteolytic enzyme that plays an essential role in tumor metastasis and invasion by breaking the ECM and basement

Cancer is defined as unregulated growth of cells that deviate from usual cellular activities (NIH, 2015). This includes the development of tumors and eventually the invasion of other tissues. Metastasis of tumor cell undergoes multiple steps: invasion, intravasation, extravasation, survival and proliferation (Sethi & Kang, 2011; Van Zijl, Krupitza, & Mikulits, 2011). As GJPs have been described to provide a conduit for intracellular communication, it has been shown in many reports where connexin channels provided the means of initial metastatic lesion formation to the vasculature. Once the metastatic tumor cells invade into the blood circulation (intravasation), these cells will then be able to spread to other locations (i.e. from the breast to the brain).

Injury to the endothelial cells will then decrease production of NO and this will enable the accumulation of lipids. As the build-up progress and permeability decreases, macrophages infiltration and release of pro-inflammatory cytokines occur. The damage caused by oxidation causes a compensatory response which increases the endothelial adhesiveness to leukocytes and platelets via cell adhesion molecule upregulation. Circulating monocytes and leukocytes initially bind cell adhesion molecules on the endothelial surface, but chemokines are required for recruitment into the subendothelial space. Once monocytes enter the subendothelial space, they may mature into macrophages leading to formation of foam cells and then eventually to the appearance of “fatty streaks” in the arteries. As lesion severity progresses into a fibroatheroma, macrophages, T-cells and mast cells penetrate the cap edges and stimulate the production and movement of vascular smooth muscle cells. Vascular smooth muscle cells contribute to plaque growth through producing pro-inflammatory cytokines that attract and activate leukocytes, generate VSMC proliferation, express adhesion molecules that

This ability of malign cancer to make their way across basement membrane and into blood vessels is what makes cancer so fatal and impossible to be cure by surgery alone. The result of metastasis and invasion in normal tissue by cancer cells are often seen as one of the distinctive features of malignancy (Ruoslahti 1996). Even though the ability of invasion and metastasis are one of the hallmarks for cancer, these abilities are not unique to cancer cells as it can also occur during the early development stage of the embryo, in healthy organisms and in many noncancerous diseases (Mareel & Leroy 2003). It does not matter whenever the organism has developed benign or malign cancer, all cancer cells have the ability to disturb the normal cell cycle and threaten the survival of the organism.

More evidence demonstrates that tumor microenvironment has played a role in tumor outgrowth and progression. Multiple host defense systems, including host immune system, constantly fight against the invader, and their efficacy is directly associated with the disease outcomes. To understand the molecular mechanism of viral-host interaction

George Mackaness coined the concept of macrophage resistance and activation in the beginning of the 20th century. He showed that the “inactivation” of macrophages had a lot to do with the pathogen-host interaction. In other words, substances in their respective microenvironments could influence macrophages to attain a particular phenotype (7). This eventually becomes significant when studying cancer and the microenvironment associated with it. One of the most important milestones in the study of macrophages was the their identification as sources of cytokines.

Therefore, patients can receive treatment before cancer metastasizes to other areas of the body, which is resulting in better health outcomes. The main challenge in circulating tumor cell (CTC) research is their detection, which requires the ability to detect one CTC out of almost 1 billion normal blood cells [2, 3]. Based on the known properties of tumor cells, several platforms for CTC detection have been developed. Such platforms can be classified into two major categories: (I) Immunochemistry-based methods, and (II) physical property-based methods. CELLSEARCHTM from Janssen Diagnostics is considered the most successful and the only FDA-approved platform for CTC detection in clinical practice in patients with breast, prostate, and colorectal cancers. Limitation of this method is the low yield of CTC capture from larger blood volume. Metastasis often involves epithelial-to-mesenchymal transition (EMT) of cells; thus, epithelial marker-dependent approaches may miss numerous CTCs that have low or absent epithelial marker expression. Isolation by size of epithelial tumor cells (ISET) [4] is another widely accepted size-based approach. This platform applies a specific membrane filter for tumor cell selection, because tumor cells are often larger and stiffer than blood cells. Main advantage of using membrane filter is that cells can be retained for further investigation. Nonetheless, the sizes of tumor cells may vary

Hypoxia is a characteristic feature of most solid tumors. Hypoxia induces tumor chemoresistance in proportion to distance from the vasculature. Hypoxic cells are exposed to less chemo

Tumor recruitment and reprogramming (R&R) of bystander cells in cancer progression. We reported that cancer cells could transform normal host cells in xenograft tumor formation (REF). Using 3-dimensional (3-D) cancer-stromal co-culture and chimeric xenograft tumor formation, we identified that, inside a cancer cell population, there existed a subgroup of metastasis-initiating cells (MICs). Importantly, we found that MICs function as “drivers” to recruit and reprogram dormant cells to become an integral part of the tumor (REF). Bystander cell R&R may be one of the strategies for cancer progression and metastasis. CTCs represent the spreading and metastasizing cancer phenotype and thus represent MICs at metastatic sites. Thus, our proposed work will have important implications in cancer biology (REF). The biomarker and biological behaviors we are able to associate to CTCs will provide confident predictors for cancer progression and clinical response.

The first difference in malignant and benign tumors is how they invade cell tissue. Malignant tumors in general, have a tendency to penetrate tissues, whereas benign tumors don’t though they can add pressure to organs resulting in organ damage1. A simplified

According to the stochastic model, tumor cells are biologically equivalent but their behavior is influenced by intrinsic and extrinsic factors and is therefore both variable and unpredictable. Thus, tumor-initiating activity cannot be enriched by sorting cells based on intrinsic characteristics.

Cancer is one of the most dangerous and fatal diseases, which is caused by uncontrolled growth and proliferation of cells. Cancer cells’ survival, progression and metastasis are tightly associated with the cellular components. For example, when cells metastasizing, they use cell protrusion which provided by actin cytoskeleton to penetrate the extracellular matrix, they also secrete plasminogen activator to increase protease plasmin’s activity in order to penetrate the membrane. Then some of the tumor cells transfer to another tissue and form metastatic tumor. The specific functions of several cell structures and transporters in tumor cells are discussed as follows.