Spontaneous development of Epstein-Barr Virus associated human lymphomas in a prostate cancer xenograft program.

Prostate cancer research is hampered by the lack of in vivo preclinical models that accurately reflect patient tumour biology and the clinical heterogeneity of human prostate cancer. To overcome these limitations we propagated and characterised a new collection of patient-derived prostate cancer xenografts. Tumour fragments from 147 unsupervised, surgical prostate samples were implanted subcutaneously into immunodeficient Rag2-/-γC-/- mice within 24 hours of surgery. Histologic and molecular characterisation of xenografts was compared with patient characteristics, including androgen-deprivation therapy, and exome sequencing. Xenografts were established from 47 of 147 (32%) implanted primary prostate cancers. Only 14% passaged successfully resulting in 20 stable lines; derived from 20 independent patient samples. Surprisingly, only three of the 20 lines (15%) were confirmed as prostate cancer; one line comprised of mouse stroma, and 16 were verified as human donor-derived lymphoid neoplasms. PCR for Epstein-Barr Virus (EBV) nuclear antigen, together with exome sequencing revealed that the lymphomas were exclusively EBV-associated. Genomic analysis determined that 14 of the 16 EBV+ lines had unique monoclonal or oligoclonal immunoglobulin heavy chain gene rearrangements, confirming their B-cell origin. We conclude that the generation of xenografts from tumour fragments can commonly result in B-cell lymphoma from patients carrying latent EBV. We recommend routine screening, of primary outgrowths, for latent EBV to avoid this phenomenon.

JAK-STAT blockade inhibits tumor initiation and clonogenic recovery of prostate cancer stem-like cells.

Interleukin (IL)-6 overexpression and constitutive STAT3 activation occur in many cancers, including prostate cancer. However, their contribution to prostate stem and progenitor cells has not been explored. In this study, we show that stem-like cells from patients with prostate cancer secrete higher levels of IL-6 than their counterparts in non-neoplastic prostate. Tumor grade did not influence the levels of expression or secretion. Stem-like and progenitor cells expressed the IL-6 receptor gp80 with concomitant expression of pSTAT3. Blockade of activated STAT3, by either anti-IL-6 antibody siltuximab (CNTO 328) or LLL12, a specific pSTAT3 inhibitor, suppressed the clonogenicity of the stem-like cells in patients with high-grade disease. In a murine xenograft model used to determine the in vivo effects of pSTAT3 suppression, LLL12 treatment effectively abolished outgrowth of a patient-derived castrate-resistant tumor. Our results indicate that the most primitive cells in prostate cancer require pSTAT3 for survival, rationalizing STAT3 as a therapeutic target to treat advanced prostate cancer.

Monoallelic expression of TMPRSS2/ERG in prostate cancer stem cells.

While chromosomal translocations have a fundamental role in the development of several human leukaemias, their role in solid tumour development has been somewhat more controversial. Recently, it was shown that up to 80% of prostate tumours harbour at least one such gene fusion, and that the most common fusion event, between the prostate-specific TMPRSS2 gene and the ERG oncogene, is a critical, and probably early factor in prostate cancer development. Here we demonstrate the presence and expression of this significant chromosomal rearrangement in prostate cancer stem cells. Moreover, we show that in the prostate epithelial hierarchy from both normal and tumour tissues, TMPRSS2 transcription is subjected to tight monoallelic regulation, which is retained upon asymmetric division and relaxed during epithelial cell differentiation. The presence and expression of TMPRSS2/ERG in prostate stem cells would provide ERG-driven survival advantages, allowing maintenance of this mutated genotype.

Correlation of ADC and T2 measurements with cell density in prostate cancer at 3.0 Tesla.

OBJECTIVES: To assess the relationship between MRI derived parameters (apparent diffusion coefficient (ADC) and T2 relaxation time) and tumor cellularity as determined from whole mounted radical prostatectomy specimens, for both prostatic carcinoma and normal peripheral zone tissue. MATERIALS AND METHODS: Over a 16-month period, 20 patients (mean age: 61 years, range: 42-70 years) were prospectively recruited. Diffusion and T2 imaging were performed on a 3.0 Tesla scanner to enable subsequent ADC and T2 calculation. After radical retropubic prostatectomy specimens were whole-mounted and regions of interest (ROIs) drawn in areas of prostatic carcinoma and normal peripheral zone. Cell density was then determined using an adaptive histogram thresholding technique. Differences in tissue type were explored using the unpaired t test while the relationship between parameters was assessed using scatter-plots and the Pearson correlation coefficient. RESULTS: Significant differences (P < 0.0001 in all cases) were noted between peripheral zone tissue and prostatic carcinoma in terms of ADC (1.88 +/- 0.22 vs. 1.43 +/- 0.19 x 10(-3) mm2/s), T2 (142 +/- 24 vs. 109 +/- 20 milliseconds), and cell density (9.4% +/- 3.0% vs. 19.8% +/- 5.3%). A significant negative correlation with cell density was noted for both ADC (R = -0.695, P < 0.0001) and T2 (R = -0.505, P = 0.001). Trends for increased cell density, decreased ADC, and decreased T2 with increasing Gleason score were also noted. CONCLUSIONS: ADC and to a lesser extent T2 are good indicators of cell density. Because of the potential link with Gleason score, MRI derived parameters may have a prognostic role with regard to potential metastatic activity and tumor aggressiveness.

Description of magnetic resonance imaging-derived enhancement variables in pathologically confirmed prostate cancer and normal peripheral zone regions.

OBJECTIVE: To assess the use of a semiquantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) to produce indices for enhancement curves that might enable differentiation between malignant prostatic lesions and normal peripheral zone (PZ). PATIENTS AND METHODS: Fifty-two patients scheduled for radical prostatectomy underwent DCE-MRI before surgery using a 3 T scanner. The DCE images were used to generate variables from changes in signal intensity for pathologically confirmed malignant areas and the normal PZ, using whole-mounted pathology specimens as a reference to delineate regions of interest (ROI). These variables included maximum enhancement index (MaxEI), time to MaxEI at 30 s, the initial and final slopes of signal intensity change, and the area under curve. A threshold value for each DCE variable was identified, and the sensitivity and specificity were obtained. RESULTS: Malignant lesions had a 56% higher MaxEI than normal PZ and took half the time to reach MaxEI (P<0.001). Hence, at 30 s, cancer lesions have double the mean (sd) EI than normal PZ, of 2.22 (1.04) vs 1.04 (0.51), respectively. Tumours showed significant washout of contrast medium, which was reflected in the final slope of the curve being negative, as opposed to positive for normal PZ. The combined data of DCE variables, using a logistic regression test, gave a mean (95% confidence interval) sensitivity and specificity of 89 (81-96)% and 90 (83-97)%, respectively. CONCLUSION: This technique provides good discrimination of malignant lesions that might enable accurate localisation of the lesion. It is a simple, semiquantitive, noninvasive method that reflects the unusual vascular characteristics of newly formed microvessels and the changes in the interstitium that occur in prostate cancer.

Correlation of diffusion-weighted magnetic resonance data with cellularity in prostate cancer.

OBJECTIVE: To assess the relationship between the apparent diffusion coefficient (ADC) on magnetic resonance imaging (MRI) and cell density (CD) obtained from radical prostatectomy (RP) specimens. PATIENTS AND METHODS: In all, 36 patients with prostate cancer were recruited; T2-weighted and diffusion-weighted MRI was obtained axially using a 3.0 T scanner. Patients then proceeded to RP; the prostate was whole-mounted and sectioned axially. Slices (3 microm) were cut from the surface of each section and stained with haematoxylin and eosin (H&E). Five randomly positioned areas from the tumour and normal peripheral zone (PZ) were examined by light microscopy at x 200, then digitally photographed and analysed to obtain automatic CD. ADC values were determined from the MRI data using the H&E slides as a reference. ADC and CD values were measured in both malignant lesions and the PZ, and the correlation between ADC and CD assessed. RESULTS: ADC values were lower (P