Tumor cells are released from the primary tumor and/or metastatic sites into blood.
Circulating tumor cells (CTC), as a part of liquid biopsy, is acted as a new method to
diagnose cancer. Many studies indicated that CTC counts had a correlation with breast, colon,
lung, or prostate cancer development. When individual cells or clusters of cancer cells
acquire ability to separate and move away from the primary tumor, migrate through the
surrounding tissue, and enter the lymphatic system and/or blood circulation, the metastatic
trait of the given tumor become obvious [1-3]. Tumor cells that escape from their primary
microenvironment need to avoid anoikis and might be challenged by the host's immunologic
defense. Finally, CTC is like a seed that transfer to other organs, contributing to
metastasis and recurrence. These CTC could be enriched and detected via different
technologies that take advantage of their physical and biologic properties. This study
collected CTC by iset platform which checks CTC
(pre-operative\postoperative\pre-treatment\during treatment) and observed the association
between CTC counts and PC development [4].
Patient-derived xenograft (PDX) was demonstrated to consistently retained tumor morphology
and genetic phenotype. Different from traditional cell line xenotransplantation model and
genetically engineered mouse model, pancreatic adenocarcinoma specimens were engrafted to
immuno-deficient mice. Above all, PDX could keep special functional gene structure and
biomarkers in personal case, closer to the individual clinical biological characteristics and
providing better prediction effect for drug screening and observation for treatment
efficiency.
As some researches discovered, the effective of contrasting drug sensitivity test with
clinical drug response is >90% [5]. Now, we build the PDX of PC, checking the genetic
information by the second genetic sequence or RNA-sequence. If PDX has similar genetic
information to the primary tumor, we will do drug sensitivity test. PC PDX model, whereby we
have demonstrated that the early PDX was morphologically similar to the original cancer and
retained both inter-patient and intra-patient heterogeneity of the tumor, could provide
reference model for personalized treatment of PC.
Above all, the most obvious advantage of PDX is the similarity to primary tumor, so we could
check the sensitivity of the same drug. But building PDX will take about 3-4months (including
building the model and drug sensitivity test). As a result, we need clinical precision
therapeutic plan applying to the developed pancreatic cancer patients. Miniature Patient
Derived Xenograft (Mini-PDX), from Shanghai LIDE(lide) Biotech CO(company), was carried out
with the OncoVeeTM-Mini PDX product of LIDE Biotech, and followed the instruction from the
manufacturer. Tumor samples were harvested, and washed with HBSS(Hank's balanced salt
solution) to remove non-tumor tissue and necrotic tumor tissue in biosafety cabinet. After
the tumor samples were cut into small fragments, they were incubated with collagenase
solution at 37℃ for 1-2 hours. Then we collected the cells followed by removing the blood
cells and fibroblast cells and the cell suspension was transferred to the HBSS washed
capsules. For subcutaneous (s.c.) implantation, a small skin incision was made and the
capsule was inserted through the subcutaneous tissue. Generally, each mouse received 4
capsules and drug administration was carried out for 7 days. The anti-tumor activity was
evaluated through the CTG (cell viability) assay.
The combination of irradiated fibroblast feeder cells and Rho kinase inhibitor, Y-27632,
conditionally induced an indefinite proliferative state in primary mammalian epithelial
cells. These conditionally reprogrammed cells (CRCs) were karyotype-stable and
nontumorigenic. Because self-renewal was a recognized property of stem cells, we investigated
whether Y-27632 and feeder cells induced a stem-like phenotype. We found that CRCs shared
characteristics of adult stem cells and exhibited up-regulated expression of α6 and β1
integrins, ΔNp63α, CD44, and telomerase reverse transcriptase, as well as decreased Notch
signaling and an increased level of nuclear β-catenin. The induction of CRCs was rapid
(occurs within 2 d) and resulted from reprogramming of the entire cell population rather than
the selection of a minor subpopulation. CRCs did not overexpress the transcription factor
sets characteristic of embryonic or induced pluripotent stem cells (e.g., Sox2, Oct4, Nanog,
or Klf4). The induction of CRCs was also reversible, and removal of Y-27632 and feeders
allowed the cells to differentiate normally. CRCs was called on the news human precision
protocol. In the pancreatic cancer precision study, patients with inoperable or developed who
acquired a little tissue could not build PDX and lost the chance of PDX treatment. Hence, we
used the CRCs platform to grew tumor stem cell in vitro, when having adequate cells, we could
do Mini-PDX or PDX drug assay[6].
In summary, as different stages of PC patients could not acquire precision personalized in
clinical treatment at present, this study by CTC\PDX\Mini-PDX\CRs\RNA-SEQ\NGS (Next
generation sequencing)platforms were predicted to provide precision diagnosis and treatment
for different stages of PC patients. Meanwhile, we could build tumor information biobank,
which provided ideal research materials and platforms for oncology basic research and
translational medicine research.