Amplification of the Y chromosome in three murine tumor cell lines transformed in vivo by different human prostate cancers

Challenges and Prospects of Patient-Derived Xenografts for Cancer Research

We discuss the importance of the in vivo models in elucidating cancer biology, focusing on the patient-derived xenograft (PDX) models, which are classic and standard functional in vivo platforms for preclinical evaluation. We provide an overview of the most representative models, including cell-derived xenografts (CDX), tumor and metastatic cell-derived xenografts, and PDX models utilizing humanized mice (HM). The orthotopic models, which could reproduce the cancer environment and its progression, similar to human tumors, are particularly common. The standard procedures and rationales of gastric adenocarcinoma (GAC) orthotopic models are addressed. Despite the significant advantages of the PDX models, such as recapitulating key features of human tumors and enabling drug testing in the in vivo context, some challenges must be acknowledged, including loss of heterogeneity, selection bias, clonal evolution, stroma replacement, tumor micro-environment (TME) changes, host cell carryover and contaminations, human-to-host cell oncogenic transformation, human and host viral infections, as well as limitations for immunologic research. To compensate for these limitations, other mouse models, such as syngeneic and humanized mouse models, are currently utilized. Overall, the PDX models represent a powerful tool in cancer research, providing critical insights into tumor biology and potential therapeutic targets, but their limitations and challenges must be carefully considered for their effective use. Lastly, we present an intronic quantitative PCR (qPCR) method to authenticate, detect, and quantify human/murine cells in cell lines and PDX samples.

A new intronic quantitative PCR method led to the discovery of transformation from human ascites to murine malignancy in a mouse model

Purpose

To establish a fast and accurate detection method for interspecies contaminations in the patient-derived xenograft (PDX) models and cell lines, and to elucidate possible mechanisms if interspecies oncogenic transformation is detected.

Methods

A fast and highly sensitive intronic qPCR method detecting Gapdh intronic genomic copies was developed to quantify if cells were human or murine or a mixture. By this method, we documented that murine stromal cells were abundant in the PDXs; we also authenticated our cell lines to be human or murine.

Results

In one mouse model, GA0825-PDX transformed murine stromal cells into a malignant tumorigenic murine P0825 cell line. We traced the timeline of this transformation and discovered three subpopulations descended from the same GA0825-PDX model: epithelium-like human H0825, fibroblast-like murine M0825, and main passaged murine P0825 displayed differences in tumorigenic capability in vivo. P0825 was the most aggressive and H0825 was weakly tumorigenic. Immunofluorescence (IF) staining revealed that P0825 cells highly expressed several oncogenic and cancer stem cell markers. Whole exosome sequencing (WES) analysis revealed that TP53 mutation in the human ascites IP116-generated GA0825-PDX may have played a role in the human-to-murine oncogenic transformation.

Conclusion

This intronic qPCR is able to quantify human/mouse genomic copies with high sensitivity and within a time frame of a few hours. We are the first to use intronic genomic qPCR for authentication and quantification of biosamples. Human ascites transformed murine stroma into malignancy in a PDX model.

Expression analysis of thirty one Y chromosome genes in human prostate cancer

Rapid advances in positional cloning studies have identified most of the genes on the human Y chromosome, thereby providing resources for studying the expression of its genes in prostate cancer. Using a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) procedure, we had examined the expression of the Y chromosome genes in a panel of prostate samples diagnosed with benign prostatic hyperplasia (BPH), low and/or high grade carcinoma, and the prostatic cell line, LNCaP, stimulated by androgen treatment. Results from this expression analysis of 31 of the 33 genes, isolated so far from the Y chromosome, revealed three types of expression patterns: i) specific expression in other tissues (e.g., AMELY, BPY1, BPY2, CDY, and RBM); ii) ubiquitous expression among prostate and control testis samples, similar to those of house-keeping genes (e.g., ANT3, XE7,ASMTL, IL3RA, SYBL1, TRAMP, MIC2, DBY, RPS4Y, and SMCY); iii) differential expression in prostate and testis samples. The last group includes X-Y homologous (e.g., ZFY, PRKY, DFFRY, TB4Y, EIF1AY, and UTY) and Y-specific genes (e.g., SRY, TSPY, PRY, and XKRY). Androgen stimulation of the LNCaP cells resulted in up-regulation of PGPL, CSFR2A, IL3RA, TSPY, and IL9R and down regulation of SRY, ZFY, and DFFRY. The heterogeneous and differential expression patterns of the Y chromosome genes raise the possibility that some of these genes are either involved in or are affected by the oncogenic processes of the prostate. The up- and down-regulation of several Y chromosome genes by androgen suggest that they may play a role(s) in the hormonally stimulated proliferation of the responsive LNCaP cells.

A review of fluorescence in situ hybridization (FISH): current status and future prospects

Fluorescence in situ hybridization (FISH) is a powerful technique for detecting DNA or RNA sequences in cells, tissues and tumors. This molecular cytogenetic technique enables the localization of specific DNA sequences within interphase chromatin and metaphase chromosomes and the identification of both structural and numerical chromosome changes. FISH is quickly becoming one of the most extensively used cytochemical staining techniques owing to its sensitivity and versatility, and with the improvement of current technology and cost effectiveness, its use will surely continue to expand. Here we review the wide variety of current applications and future prospects of FISH technology.