Obtaining high-quality genomic DNA from tumor tissues is an essential first step for analyzing genetic alterations using next generation sequencing. In this article, we present a simple and rapid method to enrich tumor cells and obtain intact DNA from touch imprint cytology specimens.
A subscription to JoVE is required to view this content. Sign in or start your free trial.
Method Article
Simple and Rapid Method to Obtain High-quality Tumor DNA from Clinical-pathological Specimens Using Touch Imprint Cytology
In This Article
Summary
Abstract
It is critical to determine the mutational status in cancer before administration and treatment of specific molecular targeted drugs for cancer patients. In the clinical setting, formalin-fixed paraffin-embedded (FFPE) tissues are widely used for genetic testing. However, FFPE DNA is generally damaged and fragmented during the fixation process with formalin. Therefore, FFPE DNA is sometimes not adequate for genetic testing because of low quality and quantity of DNA. Here we present a method of touch imprint cytology (TIC) to obtain genomic DNA from cancer cells, which can be observed under a microscope. Cell morphology and cancer cell numbers can be evaluated using TIC specimens. Furthermore, the extraction of genomic DNA from TIC samples can be completed within two days. The total amount and quality of TIC DNA obtained using this method was higher than that of FFPE DNA. This rapid and simple method allows researchers to obtain high-quality DNA for genetic testing (e.g., next generation sequencing analysis, digital PCR, and quantitative real time PCR) and to shorten the turnaround time for reporting results.
Introduction
Next generation sequencing technology has provided researchers significant advancements in analyzing genome information in genetic variations, Mendelian disease, hereditary predisposition, and cancer 1,2,3. The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) have pursued the identification of genetic alterations in several types of common cancers4. Hundreds of essential cancer driver genes have been successfully identified, and some of these molecules are being targeted for drug development1,
Access restricted. Please log in or start a trial to view this content.
Protocol
1. TIC Preparation for Quick Microscopic Assessment Using Normal Glass Slides
- Perform the TIC preparation as soon as possible after clinical pathological tissue materials are available. If TIC specimens cannot immediately be prepared, keep the tissue materials covered with saline moistened sterile-gauze and store in the refrigerator to prevent drying of tissues.
- Prepare 5 mm3 tissue material such as solid tumors (e.g., liver, lung, and breast tissues) clinically obtained by surgery or endoscopy.
- Gently wipe the tissue with sterile-gauze coated with physiological saline and remove blood, if the tissue surface has a ....
Access restricted. Please log in or start a trial to view this content.
Results
Figure 1 shows the entire process from preparing TIC specimens to DNA extraction. Notably, the procedure takes only two days to obtain genomic DNA from TIC samples. We evaluated any effects of tumor storage before the slide processing. We found that tumor cells were attached onto the glass slide when tissue specimens were immediately touched onto the slide, and when tissues were kept in saline moistened sterile-gauze for 1 h (Figure 2
Access restricted. Please log in or start a trial to view this content.
Discussion
In this study, we presented an alternative method for obtaining tumor DNA from clinical pathological specimens using TIC. TIC preparation is very simple and needs less time compared with FFPE methods, without the requirement for special instruments10. All procedures from the TIC preparation to DNA extraction can be completed within two days (Figure 1). This method thus shortens the turnaround time for performing genetic testing. Notably, this provides a significant ad.......
Access restricted. Please log in or start a trial to view this content.
Disclosures
The authors have nothing to disclose.
Acknowledgements
We thank all the medical and ancillary staff of the hospital and the patients for consenting to participate. We thank Gabrielle White Wolf, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this report. This study was supported by a Grant-in-Aid for Genome Research Project from the Yamanashi Prefecture (Y.H. and M.O.) and a grant from The YASUDA Medical Foundation (Y.H.).
....Access restricted. Please log in or start a trial to view this content.
Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| FINE FROST white20 micro slide glass | Matsunami Glass ind, Ltd | SFF-011 | |
| Arcturus PEN Membrane Glass Slides | Thermo Fisher Scientific | LCM0522 | |
| Cyto Quick A solution | Muto Pure Chemicals | 20571 | |
| Cyto Quick B solution | Muto Pure Chemicals | 20581 | |
| May-Grunwald Solution | Muto Pure Chemicals | 15053 | |
| Giemsa solution | Muto Pure Chemicals | 15002 | |
| QIAamp DNA FFPE tissue kit | Qiagen | 56404 | |
| TaqMan Fast Advanced Master Mix | Thermo Fisher Scientific | 4444557 | |
| TaqMan RNase P Detection Reagents Kit | Thermo Fisher Scientific | 4316831 | |
| TaqMan Assay from FFPE DNA QC Assay v2 | Thermo Fisher Scientific | 4324034 | |
| MicroAmp Fast Optical 96-Well Reaction Plate | Thermo Fisher Scientific | 4346907 | |
| MicroAmp optical Adhesive Film | Thermo Fisher Scientific | 4311971 | |
| MicroMixer E36 | TITEC | 0027765-000 | |
| ViiA 7 Real-Time PCR System | Thermo Fisher Scientific | VIIA7-03 | |
| Himac CF16RXII | Hitachi-koki | CF16RII | |
| Ion Library TaqMan Quantitation Kit | Thermo Fisher Scientific | 4468802 | |
| Ion AmpliSeq Cancer Hotspot Panel v2 | Thermo Fisher Scientific | 4475346 | |
| Ion AmpliSeq Library Kit 2.0 | Thermo Fisher Scientific | 4480442 | |
| Ion Xpress Barcode Adapters 1-16 Kit | Thermo Fisher Scientific | 4471250 | |
| Ion PGM Hi-Q View Sequencing Kit (200 base) | Thermo Fisher Scientific | A30044 | |
| Ion Chef System | Thermo Fisher Scientific | 4484177 | |
| Veriti 96-well Thermal Cycler | Thermo Fisher Scientific | Veriti200 | |
| Ion 318 Chip Kit v2 BC | Thermo Fisher Scientific | 4488150 | |
| Ion PGM System | Thermo Fisher Scientific | PGM11-001 | |
| Ion PGM Wash 2 Bottle kit | Thermo Fisher Scientific | A25591 | |
| Agencourt™ AMPure™ XP Kit | Beckman Coulter | A63881 | |
| 16-position Magnetic Stand | Thermo Fisher Scientific | 4457858 | |
| Nonstick, RNase-free Microfuge Tubes, 1.5 mL (Low binding tube) | Thermo Fisher Scientific | AM12450 | |
| Nuclease-free water | Thermo Fisher Scientific | AM9938 | |
| MicroAmp™ Optical 96-well Reaction Plates | Thermo Fisher Scientific | 4306737 | |
| MicroAmp™ Clear Adhesive Film | Thermo Fisher Scientific | 4306311 | |
| Agencourt™ AMPure™ XP Kit | Beckman Coulter | A63881 | |
| Ethanol(99.5) | Nacalai Tesque | 08948-25 | |
| Sodium hydroxide (10M) | Sigma | 72068 | |
| DTU-Neo | TAITEC | 0063286-000 | |
| E-36 | TAITEC | 0027765-000 | |
| ECLIPSE Ci-L | Nikon | 704354 | |
| Pipet-Lite LTS Pipette L-2XLS+ | METTLER TOLEDO | 17014393 | |
| Pipet-Lite LTS Pipette L-10XLS+ | METTLER TOLEDO | 17014388 | |
| Pipet-Lite LTS Pipette L-20XLS+ | METTLER TOLEDO | 17014392 | |
| Pipet-Lite LTS Pipette L-100XLS+ | METTLER TOLEDO | 17014384 | |
| Pipet-Lite LTS Pipette L-200XLS+ | METTLER TOLEDO | 17014391 | |
| Pipet-Lite LTS Pipette L-1000XLS+ | METTLER TOLEDO | 17014382 | |
| petit-change | WAKEN | MODEL8864 | Mini centrifuge |
| petit-incubator | WAKEN | WKN-2290 | Air incubator |
| SensiCare Powder-free Nitrile Exam Gloves | MEDLINE | SEM486802 | |
| Sterile gauze | Osaki | 11138 | |
| Refrigerator MediCool | SANYO | MPR-312DCN-PJ | |
| FEATHER TRIMMING BLAD | FEATHER | No.130 | |
| FEATHER TRIMMING BLAD | FEATHER | No.260 | |
| FEATHER S | FEATHER | FA-10 | |
| Vortex Genius 3 | IKA | 41-0458 | Vortex mixer |
| Pincette | NATSUME | A-5 | |
| 1.5 mL microtube | BIOBIK | RC-0150 |
References
- Vogelstein, B., Kinzler, K. W. The Path to Cancer - Three Strikes and You're Out. N Engl J Med. 373 (20), 1895-1898 (2015).
- Weinstein, J. N., et al. The cancer genome atlas pan-cancer analysis project. Nat. Genet. 45 (10), 1113-1120 (2013).
- Nagasaki, M., et al.
Access restricted. Please log in or start a trial to view this content.
Reprints and Permissions
