If I were to say, \" Tumor cells cause changes in cell surface marker protein B

Question

If I were to say, "Tumor cells cause changes in cell surface marker protein B of associated immune cells (TAM’s or tumor-associated macrophages)," what experimental approach would you use to prove this hypothesis? Include:

a) the experimental approach.

b) a general outline of the procedure for that approach, i.e. an overview of how the protocol is conducted, including critical reagents or steps.

c) expected results, including any specific marker proteins associated with the assay that would change or vary.

Nothing too lengthy, please and thank you!

Explanation / Answer

Ans a: Body is consisting of large number of cells, which are arranged into tissues and organs. Tissue and organ growth and its repair occur in a controlled manner. There are certain chemical signals which stimulate the cells either to divide or to stop dividing. Cells divide and reproduce themselves exactly i.e., cell divides into two identical cells which then divide into four and so on. Cells normally grow and divide to produce more cells so as to replace aging and damaged cells. Many cells live for a given amount of time and then are programmed to die by a process called apoptosis. Cells of different tissues and organs divide at different rates. For example skin cells divide quickly while nerve cells divide very slowly or not at all once they mature.

Tumors arise in older animals and humans but most pose little risk to their host because they are localised and of small size called as benign. And it consists of cells that closely resemble and function like normal cells. The surface interaction molecules hold the tissues together and keep benign tumor cells localised to appropriate tissues. Benign tumors cuses health problems only if their sheer bulk interferes with normal functions or if t when they start secreting excess amounts of biologically active substances like hormones. While the malignant tumor cells divide more rapidly than normal cells. And they also do not remain in their original site and migrates to the surrounding tissues and gain the entry into the body circulatory system and thus set up areas of proliferation away from the site of their original appearance and this process is known as metastasis.

Cancer develops in three main steps. It will take a long time for cell to develop cancer as several steps and several genetic mutations are required. The chance of cancer developing increases as a person gets older because there has been more time for exposures and mutations to build up.

Initiation: This initial change may be caused by carcinogens like chemicals, smoking or exposure to radiation but often the cause is unknown and may be a random. Changes caused by carcinogens are called as initiators. The cell starts to become abnormal at this stage.
Promotion: Agents like hormones or some drugs cause damage and are called promoters. Promoters itself do not cause cancer but they allow a cell that has undergone initiation to become cancerous.
Progression: the increased rate of doubling time.

Ans b: Tumor cells often produce increased levels of cell-surface receptors specific for the proteins and polysaccharides and secrete certain enzymes which digest these proteins. Many of them secrete a protease called plasminogen activator that cleaves a peptide bond in the serum protein plasminogen and converting it to the active protease plasmin. This secretion of a small amount of plasminogen activator causes a large increase in protease concentration by catalytically activating the abundant ant plasminogen in normal serum. This increased protease activity promotes metastasis by helping tumor cells digest and penetrate the basal lamina. The normally invasive extra embryonic cells of the fetus secrete plasminogen activator when they are implanting in the uterine wall, a compelling analogy to invasion by tumor cells. As the basal lamina disintegrates some of the tumor cells enter the blood and the primary tumor survive to colonize another tissue and form a secondary metastatic tumor. These cells adhere to an endothelial cell lining a capillary and migrate through it into the underlying tissue. For metastasis a tumor cell must be able to multiply without a mass of surrounding identical cells and to adhere to new types of cells.

Ans c:A variety of biomarkers have been identified for molecular diagnosis and prognosis of cancer which includes the Mamma Print and Oncotype DX multigene tests predict breast cancer subtypes and treatment response. While other tests measure human epidermal growth factor receptor type 2 (Her2) and estrogen receptor levels in breast cancer patients. Elevated Her2 levels predict resistance to endocrine and chemotherapy treatment and susceptibility to Her2-targeted treatment elevated estrogen receptor levels correlate with increased endocrine response but chemotherapy resistance. While many cancer screens utilize DNA analysis to detect and characterize disease some applications require protein examination for greater accuracy because transcription at the gene level does not necessarily correspond to expression at the protein level. For example, in cervical cancer screening, DNA testing can detect the presence of HPV and protein methods are needed to determine whether HPV is active or latent.

Protein analysis just provides opportunities for diagnosing, stratifying and monitoring disease. And for showing clinical usefulness an assay must meet certain requirements i.e., it must be sensitive enough to detect the protein or proteins of interest. Protein concentrations in blood vary by more than twele orders of magnitude and the cancer biomarkers may be present in trace (pg/ml) levels. And also an assay must be specific to the protein that it aims to detect i.e., in case of ovarian cancer an assay needs 99% specificity for the benefiting early detection.

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