A Rapid Filter Insert-based 3D Culture System for Primary Prostate Cell Differentiation

Summary

Here, we present a method for the establishment of a rapid in vitro system that supports the three dimensional culturing and subsequent luminal differentiation of primary prostate epithelial cells.

Abstract

Conditionally reprogrammed cells (CRCs) provide a sustainable method for primary cell culture and the ability to develop extensive "living biobanks" of patient derived cell lines. For many types of epithelial cells, various three dimensional (3D) culture approaches have been described that support an improved differentiated state. While CRCs retain their lineage commitment to the tissue from which they are isolated, they fail to express many of the differentiation markers associated with the tissue of origin when grown under normal two dimensional (2D) culture conditions. To enhance the application of patient-derived CRCs for prostate cancer research, a 3D culture format has been defined that enables a rapid (2 weeks total) luminal cell differentiation in both normal and tumor-derived prostate epithelial cells. Herein, a filter insert-based format is described for the culturing and differentiation of both normal and malignant prostate CRCs. A detailed description of the procedures required for cell collection and processing for immunohistochemical and immunofluorescent staining are provided. Collectively the 3D culture format described, combined with the primary CRC lines, provides an important medium- to high- throughput model system for biospecimen-based prostate research.

Introduction

The identification and use of cancer therapies that are personalized to individuals are a primary goal in cancer research. Recently, new approaches have been developed that allow for greater ease in the establishment of primary cell cultures, potentially providing ways of both identifying and testing personalized therapies. For example, the R-spondin-based prostate organoid approach¹ allows for three-dimensional (3D) culturing of normal and metastatic prostate cancer cells in a commercial extracellular matrix (e.g., Matrigel), while the Conditionally Reprogramming of Cells (CRC) method developed at Georgetown²

Protocol

1. Establishment of the 3D Cell Culture Insert System

1. Place 2 polycarbonate cell culture inserts in an inverted orientation (filter side up) down in a 6 well plate (Figure 1A).
2. Apply a thin layer of 0.1% gelatin in water to the bottom side of the insert and allow to dry (10-20 min) in a biological safety cabinet to maintain sterility.
3. Repeat step 1.2 two more times for a total of 3 applications of 0.1% gelatin on the inserts.
   NOTE: The gelatin coating will help limit diffusion between the chambers.
4. To collect the primary CRCs from standard culture conditions, add 5 mL of PBS to wash the culture flask. ....

Results

The cell culture insert based system is a relatively simple and rapid procedure for producing 3D cultures of prostate CRCs that supports luminal cell differentiation. A schematic of the system is shown (Figure 1A) highlighting the application of the gelatin coating to the bottom surface of the filter insert. The inserts are only overturned for the application of the gelatin. In Figure 1B the filters are in the appropriate orientation for culturing. Using .......

Discussion

Primary cell lines are an important and rapidly developing platform for cancer research. The culture insert-based 3D culture system supports the differentiation of primary prostate CRCs within a two-week timeframe. The CRC filter method represents a new, medium throughput method for prostate research. Existing mouse PDX models are time consuming and extremely expensive, and many of the PDX samples cannot be grown in culture, limiting investigator-initiated experimentation and their usefulness. In addition, while success .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Corning Costar Snapwell Culture Inserts	Corning	3801
Millicell Cell Culture Inserts	Millipore	PIHP01250
Multiwell 6 Well	Falcon	353046
Gelatin 0.1% in water	Stemcell Technologies	7903
Sterile Saftey Scapel 10 Blade	Integra Miltex	4-510
Sterile Standard Scalpel 11 Blade	Integra Miltex	4411
RIPA Lysis and Extraction Buffer	Thermofisher Scientific	89900
Sodium Fluoride	Fishcer Scientific	S299-100
Sodium Vanadate	Fishcer Scientific	13721-39-6
Dithiothreitol	Sigma-Aldrich	3483123
Protease Inhibitor Cocktail (AEBSF, Aprotinin, Bestatin, E-64, Leupeptin and Pepstatin A)	Sigma-Aldrich	P8340
0.25% Trypsin-EDTA (1x)	Thermofisher Scientific	25200-056
DMEM	Thermofisher Scientific	11965-092
FBS	Sigma-Aldrich	F2442
Glutamine	Thermofisher Scientific	25030081
Penicillin Streptomycin	Thermofisher Scientific	15140-122
F-12 Nutrient Mix Media	Thermofisher Scientific	11765054
Y-27632 dihydrochloride Rock inhibitor	Enzo	ALX-270-333-M025
Hydrocortisone	Sigma-Aldrich	H0888
EGF	Thermofisher Scientific	PHG0315
Insulin	Thermofisher Scientific	12585-014
Cholera Toxin	Sigma-Aldrich	C3012
Gentamicin	Thermofisher Scientific	15710-064
Fungizone	Fisher Scientific	BP264550
Trizol Reagent	Invitrogen	15596026
Histogel Specimen Processing Gel (hydroxyethyl agarose (HEA))	Thermo Scientific	HG-4000-012
Non-Adherent Dressing	Telfa	KDL2132Z
Cell Culture Dish	Sigma	SIAL0167
HISTOSETTE II Tissue Processing / Embedding Cassettes	Crystalgen	CG-M492