CISH, or chromogenic in situ hybridization, is a process in which a labeled complementary DNA or RNA strand is used to localize a specific DNA or RNA sequence in a tissue specimen. CISH methodology may be used to evaluate gene amplification, gene deletion, chromosome translocation, and chromosome number. CISH utilizes conventional peroxidase or alkaline phosphatase reactions visualized under a standard bright-field microscope, and is applicable to formalin-fixed, paraffin-embedded (FFPE) tissues, blood or bone marrow smears, metaphase chromosome spreads, and fixed cells.

What CISH offers:

  • Evaluation of gene status simultaneously with tissue morphology
  • Use of existing bright-field microscopy and techniques similar to IHC
  • Archivable and quantitative results

About the Technology

Invitrogen's CISH probes are created with Subtraction Probe Technology (SPT™), a proprietary technology that produces highly specific probes by significantly reducing the repetitive sequences found in human DNA. Consequently, our probes do not require the repetitive sequence blocking that is common for traditional cytogenetic DNA probes.

On Day 1, major steps include tissue preparation, heat pretreatment, pepsin digestion, probe addition, and denaturation/hybridization. Following an overnight hybridization step, Day 2 begins with a stringent wash before proceeding with the immunodetection steps. After using a standard tissue mounting procedure, the specimens are ready for interpretation on a bright-field microscope.

CISH detection of non-amplified HER2 gene status (A) and amplified HER2 gene status (B) in different breast cancer tissue samples at 40X magnification.

How does CISH compare to IHC and FISH?

Signal stability Archivable Fades over time Archivable
Microscope Bright-field Fluorescence Bright-field
Magnification 40x 60–100x 20–40x
CProtocol length Overnight + 3 hr, 55 min Overnight + 3 hr, 12 min 3 hr, 2 min
Morphology Good Limited Good
Amount of training required Medium High Low
Internal control Yes Yes No
Interpretation Objective/quantitative Objective/quantitative Subjective/qualitative
Overall cost Medium High Low
CMD SchemaApp code