Page 29 - Read Online

Udukala et al. J Cancer Metastasis Treat 2020;6:25 I http://dx.doi.org/10.20517/2394-4722.2020.45 Page 3 of 13

Figure 1. Patient 5-year survival (in percent) as a function of cancer stage at the time of cancer diagnosis. Data from references [1-3]

Optical nanobiosensors for protease detection
It is established that virtually all solid tumors are characterized by dysfunctional protease expression
patterns [20-22] . These deviations from the proteasome of healthy cells have been successfully used by the
[5]
authors for the early detection of breast and pancreatic cancer. In cancer, numerous proteases, such as
[7]
[23]
matrix metalloproteinases (MMPs) , cathepsins [24-26] , and urokinase plasminogen activator (uPA) [20,22,25] are
either over- or underexpressed, when compared to healthy cells. This enables the detection of solid tumors
[5,7]
in liquid biopsies through the simultaneous detection of several proteases in serum .
The Bossmann group has continuously developed their patented technology for ultra-sensitive protease
detection since 2007 [27-29] . These fluorescence-based optical nanobiosensors are composed of water-
dispersible dopamine-coated Fe/Fe O core/shell nanoparticles and an attached Fluorescence resonance
3
4
[30]
energy transfer pair [tetrakis (4-carboxyphenyl) porphyrin (TCPP) and cyanine 5.5]. Both the central
nanoparticle and cyanine 5.5 are able to quench photoexcited TCPP, which is attached via a protease-
[4]
cleavable consensus sequence . The consensus sequences have been optimized to show only minimal
[5]
cross-sensitivity between the proteases used [Figure 2].
Selection of protease biomarkers
[31]
About two percent of the human genome encodes proteases, 553 in total . For detecting NSCLC, we
selected the following proteases: MMPs 1, 2, 3, 7, 9 and 13, uPA and cathepsins B and L. This selection
is identical to that in a previous study, in which breast cancer at stage 1 could be detected . Evidently,
[5]
we have ascertained that this selected group of proteases is indeed implicated in NSCLC [20,22,23,25,26] . The
advantage of using the same panel of proteases for detecting breast cancer and non-small cell lung cancer
is that we can compare the resulting “significance tables” and begin to find answers to the question whether
protease expression pattern of different types of solid tumors are similar or significantly different. In Table 1,
the consensus sequences for the nine proteases used are summarized. Note that the cross-reactivity of these