Question

Consider a hypothetical Intracellular protein Z.

This protein has been shown to be 1) overexpressed in cancer samples compared to normal tissues (western blot), (2) it is not secreted by cells, and (3) it is expressed by endothelial cells in a tumor-associated vasculature. as shown by immunohistochemistry

Propose 5 experiments that you could use to test that your protein Z plays a role in angiogenesis. Experiments should be done within 6 months.

Answer 1

Protein Z: A putative novel biomarker for early detection of ovarian cancer

          Ovarian cancer (OC) has the highest mortality of all gynaecological cancers. Early diagnosis offers an approach to achieving better outcomes. Protein Z is a potential early detection biomarker for OC.

Protein Z was significantly down?regulated up to 2 years of pre?diagnosis (p?=?0.000000411) in 8 of 19 Type I patients whilst in 5 Type II individuals, it was significantly up?regulated up to 4 years of before diagnosis (p?=?0.01).

Protein Z is a novel independent early detection biomarker for Type I and Type II ovarian cancer; which can discriminate between both types.

Protein Z also adds to CA?125 and potentially the risk of Ovarian Cancer algorithm in the detection of both subtypes.

Protein Z Exerts Pro-Angiogenic Effects and Upregulates CXCR4

Protein Z (PZ) is a vitamin K-dependent coagulation factor without catalytic activity. Evidence points towards PZ as an independent risk factor for the occurrence of human peripheral arterial disease.

However, the role of PZ in ischemia-driven angiogenesis and vascular healing processes has not been determined so far.

Angiogenic potency of PZ was assessed in established in vitro assays using endothelial cells.

Quantification of protein Z expression in lung adenocarcinoma tissues and cells

As a regulator of coagulation, abnormal Protein Z (PZ) expression may lead to the formation of blood clots in humans. While previous studies have shown that PZ protein is altered in several types of cancer, however, additional observations are needed to understand the complex biology involved.

In addition, A549 adenocarcinoma cells were compared to a normal epithelial cell line, 16-HBE, for in vitro PZ expression. In tissues and cells, PZ protein and gene expression were determined using western blot, immunohistochemistry and PCR.

Lung adenocarcinoma tissues shows elevated expression of both PZ mRNA and protein compared with healthy tissue. Only protein expression was increased in cultured cell lines, which holds implications for the dominant source of PZ in tissues, as well as protein modifications necessary for PZ function.

Protein Z appears to be associated with the presence of lung adenocarcinoma and may be a viable prognostic biomarker for lung cancer.

Regulation of tumor angiogenesis by the microtubule-binding protein CLIP-170

Angiogenesis, the expansion of pre-existing blood vessels, is a complex process required for tumor growth and metastasis. Although current antiangiogenic strategies have shown promising results in several cancer types, identification of additional antiangiogenic targets is required to improve the therapeutic response.

Herein, we show that the microtubule-binding protein CLIP-170 (cytoplasmic linker protein of 170 kDa) is highly expressed in breast tumor samples and correlates positively with blood vessel density.

Depletion of CLIP-170 significantly impaired vascular endothelial tube formation and sprouting in vitro and inhibited breast tumor growth in mice by decreasing tumor vascularization.

In addition, CLIP-170 promotes the polarization of endothelial cells in response to the angiogenic stimulus. These findings thus demonstrate a critical role for CLIP-170 in tumor angiogenesis and suggest its potential as a novel antiangiogenic target.

Protein Z/protein Z-dependent protease inhibitor system in loco in human gastric cancer

In gastric cancer, hemostatic system components contribute to cancer progression, as activation of factor X (FX) was observed. The protein Z (PZ)/protein Z-dependent protease inhibitor (ZPI) complex inhibits factor Xa proteolytic activity.

The purpose of this study was to determine the distribution of ZPI and PZ in relation to FX, and prothrombin fragment (F1?+?2), a standard marker for blood coagulation activation, in human gastric cancer tissue.

ABC procedures and a double staining method employed polyclonal antibodies against PZ, FX, and F1?+?2 and a monoclonal antibody against ZPI.

In situ hybridization (ISH) methods employed biotin-labeled 25-nucleotide single-stranded DNA probes directed to either PZ or ZPI mRNAs. FX and components of PZ/ZPI coagulation inhibitory system were observed in cancer cells. F1?+?2 was observed in gastric cancer cells as well.

The co-localization of PZ/ZPI and FX in gastric cancer cells indicates in loco that these proteins may play a role in anticoagulant events at the tumor tissue.