Prostate cancer stem cells

The role of FOSL1 in stem-like cell reprogramming processes

Cancer stem-like cells (CSCs) have self-renewal abilities responsible for cancer progression, therapy resistance, and metastatic growth. The glioblastoma stem-like cells are the most studied among CSC populations. A recent study identified four transcription factors (SOX2, SALL2, OLIG2, and POU3F2) as the minimal core sufficient to reprogram differentiated glioblastoma (GBM) cells into stem-like cells. Transcriptomic data of GBM tissues and cell lines from two different datasets were then analyzed by the SWItch Miner (SWIM), a network-based software, and FOSL1 was identified as a putative regulator of the previously identified minimal core. Herein, we selected NTERA-2 and HEK293T cells to perform an in vitro study to investigate the role of FOSL1 in the reprogramming mechanisms. We transfected the two cell lines with a constitutive FOSL1 cDNA plasmid. We demonstrated that FOSL1 directly regulates the four transcription factors binding their promoter regions, is involved in the deregulation of several stemness markers, and reduces the cells' ability to generate aggregates increasing the extracellular matrix component FN1. Although further experiments are necessary, our data suggest that FOSL1 reprograms the stemness by regulating the core of the four transcription factors.

Reprogramming Prostate Cancer Cells into Induced Pluripotent Stem Cells: a Promising Model of Prostate Cancer Stem Cell Research

Prostate cancer stem cells (PrCSCs) are responsible for the development of castration-resistant disease and are associated with poor outcomes; however, the origin of PrCSCs is still not known due to the lack of a suitable model. In the current study, the human prostate cancer cell line 22RV1 was used to generate induced pluripotent stem cells (iPSCs) via the exogenous expression of four classic transcription factors (OCT-4, SOX2, KLF4, and C-MYC). The iPSCs were analyzed by phase contrast microscopy, real-time polymerase chain reaction, immunofluorescence, alkaline phosphatase (AP) activity, and examined for karyotype and embryoid body and teratoma formation. The analyses demonstrated that the prostate cancer cells were successfully reprogrammed into iPSCs by characteristic human embryonic stem cell morphology, cell marker expression, AP activity, embryoid body, and pluripotency capability in generating all three embryonic germ layers. These results may provide a convenient and accessible model for studying the origin of PrCSCs and the process by which progenitor cells are transformed into PrCSCs.

Cancer-stromal cell fusion as revealed by fluorescence protein tracking

PURPOSE

We previously determined that cancer-stromal interaction was a direct route to tumor cell heterogeneity progression, since cancer-stromal cell fusion in coculture resulted in the creation of heterogeneous clones of fusion hybrid progeny. In this report, we modified the cancer-stromal coculture system to establish optimal experimental conditions for investigating cell fusion machinery and the mechanism of heterogeneity progression.

EXPERIMENTAL DESIGN

Red fluorescence protein-tagged LNCaP cells were cocultured with green fluorescence protein-labeled prostate stromal cells for cancer-stromal cell fusion, which was tracked as dual fluorescent cells by fluorescence microscopy.

RESULTS

We identified the most efficient strategy to isolate clones of fusion hybrid progenies. From the coculture, mixed cells including fusion hybrids were subjected to low-density replating for colony formation by fusion hybrid progeny. These colonies could propagate into derivative cell populations. Compared to the parental LNCaP cells, clones of the fusion hybrid progeny displayed divergent behaviors and exhibited permanent genomic hybridization.

CONCLUSIONS

Cancer-stromal cell fusion leads to cancer cell heterogeneity. The cancer-stromal coculture system characterized in this study can be used as a model for molecular characterization of cancer cell fusion as the mechanism behind the progression of heterogeneity observed in clinical prostate cancers.

Integrated Therapeutic Targeting of the Prostate Tumor Microenvironment

Prostate cancer is a common and deadly cancer among men. The heterogeneity that characterizes prostate tumors contributes to clinical challenges in the diagnosis, prognosis, and treatment of this malignancy. While localized prostate cancer can be treated with surgery or radiotherapy, metastatic disease to the lymph nodes and the bone requires aggressive treatment with androgen deprivation treatment (ADT). Unfortunately, this often eventually progresses to metastatic castration-resistant prostate cancer (mCRPC). Advanced prostate cancer treatment today involves 1st- and 2nd-line taxane chemotherapy and 2nd-generation antiandrogens. The process of epithelial mesenchymal transition (EMT), during which epithelial cells lose their adhesions and their polarity, is a critical contributor to prostate cancer metastasis. In this article, we aim to integrate the current understanding of mechanisms dictating the dynamics of phenotypic EMT, with apoptosis outcomes in prostate tumors in response to antiandrogen and taxane chemotherapy for the treatment of advanced disease. Novel insights into the signaling mechanisms that target the functional interface between apoptosis and EMT will be considered in the context of potential clinical markers of tumor prognosis, as well as for effective therapeutic targeting of α- and β- adrenergic signaling (by novel and existing chemotherapeutic agents and antiandrogens). Interfering with EMT and apoptosis simultaneously toward eradicating the tumor mass is of major significance in combating the lethal disease and increasing patient survival.