Transrectal colour Doppler ultrasonography for quantifying angiogenesis in prostate cancer

The adjunctive use of power Doppler imaging in the preoperative assessment of prostate cancer

OBJECTIVE

To determine if the adjunctive use of power Doppler imaging (PDI) could provide prognostic utility in the treatment of prostate cancer, as an accurate prediction of the clinical behaviour of prostate cancer is important to determine appropriate treatment.

PATIENTS AND METHODS

Most centres rely on a digital rectal examination or transrectal ultrasonography (TRUS) to assess the clinical stage of patients. In 2002, we began using a standardized form to evaluate TRUS findings and PDI findings. We compared preoperative clinical findings with those from pathological analysis of 620 radical prostatectomy specimens from 2002 to 2007.

RESULTS

The mean (sd) patient age was 58 (6.6) years with a mean prostate-specific antigen (PSA) level of 7.0 (4.5) ng/mL. Of the 620 specimens 157 (25.3%) had evidence of extracapsular extension on pathological evaluation; 443 (71.5%) men had a hypervascular lesion seen on TRUS, while 177 (28.5%) patients had none. There was no difference in preoperative PSA level, grade or stage of tumour. Furthermore, rates of biochemical recurrence or secondary treatment did not differ based on PDI findings. As a tool to help locate prostate tumours, PDI improved the specificity of TRUS but did not improve the overall accuracy or sensitivity.

CONCLUSION

PDI provides little prognostic utility to assess risk in prostate cancer. However, PDI might improve the specificity of TRUS in identifying prostate tumours and could have a role in image guidance for focal therapy of prostate cancer.

[Assessment of tumour angiogenesis using contrast-enhanced ultrasound]

Microbubbles are useful for imaging tumour angiogenesis and relatively crude forms of this approach are now routinely used for subjective diagnosis, especially in the liver. More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves and have shown great promise in revealing effective tumour response to anti-angiogenic drugs in humans before tumour shrinkage occurs. These are beginning to be accepted into clinical practice. In the long term, targeted microbubbles for molecular imaging and eventually for directed anti-tumour therapy are expected to be tested.

Rationale and clinical implication of combined chemotherapy with cisplatin and oestrogen in prostate cancer: primary evidence based on methylation analysis of oestrogen receptor-alpha

OBJECTIVE

To determine whether oestrogen enhances platinum sensitivity, and if promoter CpG methylation of the oestrogen receptor-alpha (ER-alpha) gene determines the potential of cisplatin-induced apoptosis in prostate cancer, as the high-mobility group 1 (HMG1) preferentially binds to cisplatin-modified DNA and is up-regulated after oestrogen treatment in breast cancer cell line MCF-7.

MATERIALS AND METHODS

The study comprised prostate cancer cell lines (LNCaP and PC-3), 156 pathologically confirmed 156 radical prostatectomy samples and eight hormone-refractory prostate cancer (HRPC) samples (from needle biopsy). Expression of HMG1 in cell lines was analysed by Western blotting or differential reverse-transcription-polymerase chain reaction (PCR). The methylation status of ER-alpha was analysed by methylation-specific PCR using bisulphite DNA as a template or bisulphite DNA sequencing.

RESULTS

In LNCaP cells, treatment with oestrogen increased HMG1 expression and co-treatment with cisplatin and oestrogen reduced cell viability by accelerating apoptosis, compared with cisplatin alone. However, in PC-3, oestrogen did not up-regulate HMG1 or accelerate the cisplatin-induced apoptosis. Although ER-beta was expressed in both LNCaP and PC-3, ER-alpha was expressed only in LNCaP. Bisulphite DNA sequencing of the ER-alpha promoter showed partial methylation in LNCaP but complete methylation in PC-3. ER-alpha AS transfection diminished the cisplatin-induced apoptosis in oestrogen-treated LNCaP cells. In clinical samples there was ER-alpha hypermethylation in 40% of prostate cancers this correlated with Gleason score (GS, 31% for GS < 7, 50% for GS = 7 and 56% for GS > 7). In addition, five of eight HRPC samples showed ER-alpha hypermethylation.

CONCLUSION

These findings suggest that HMG1 induction as an enhancer of platinum sensitivity is mediated through interaction between oestrogen and ER-alpha. As CpG hypermethylation of the ER-alpha promoter is a frequent event in aggressive prostate cancer, negative conversion of ER-alpha methylation is essential to achieve the most beneficial effect when combined chemotherapy of cisplatin with oestrogen is used in patients with prostate cancer.

Epigenetic modifications of RASSF1A gene through chromatin remodeling in prostate cancer

PURPOSE

The RAS-association domain family 1, isoform A (RASSF1A) gene is shown to be inactivated in prostate cancers. However, the molecular mechanism of silencing of the RASSFIA gene is not fully understood. The present study was designed to investigate the mechanisms of inactivation of the RASSF1A gene through the analysis of CpG methylation and histone acetylation and H3 methylation associated with the RASSF1A promoter region.

EXPERIMENTAL DESIGN

Methylation status of the RASSF1A gene was analyzed in 131 samples of prostate cancer, 65 samples of benign prostate hypertrophy (BPH), and human prostate cell lines using methylation-specific PCR. Histone acetylation (acetyl-H3, acetyl-H4) and H3 methylation (dimethyl-H3-K4, dimethyl-H3-K9) status associated with the promoter region in prostate cells were analyzed by chromatin immunoprecipitation (ChIP) assay.

RESULTS

Aberrant methylation was detected in 97 (74.0%) prostate cancer samples and 12 (18.5%) BPH samples. The methylation frequency of RASSF1A showed a significant increase with high Gleason sum and high stage. The ChIP assays showed enhancement of histone acetylation and dimethyl-H3-K4 methylation on the unmethylated RASSF1A promoter. TSA alone was unable to alter key components of the histone code. However, after 5-aza-2'-deoxy-cytidine treatment, there was a complete reversal of the histone components in the hypermethylated promoter. Levels of acetyl-H3, acetyl-H4, and dimethyl-H3-K4 became more enriched, whereas H3K9me2 levels were severely depleted.

CONCLUSIONS

This is the first report suggesting that reduced histone acetylation or H3K4me2 methylation and increased dimethyl-H3-K9 methylation play a critical role in the maintenance of promoter DNA methylation-associated RASSF1A gene silencing in prostate cancer.

Angiogenesis imaging in the management of prostate cancer

Angiogenesis is an integral part of benign prostatic hyperplasia, is associated with prostatic intraepithelial neoplasia and is a key factor in the growth and metastasis of prostate cancer. This review focuses on ultrasound and dynamic MRI in the evaluation of prostate cancer angiogenesis, and compares these techniques to functional CT and hydrogen magnetic resonance spectroscopic imaging. Image-based evaluation of angiogenesis in the prostate has established clinical roles in lesion detection, tumor staging and the detection of suspected tumor recurrence. One limitation of all these imaging techniques, however, is inadequate lesion characterization, particularly in differentiating prostatitis from cancer in the peripheral zone of the prostate, and in distinguishing between benign prostatic hyperplasia and central-gland tumors. Ultimately, local availability, expertise and the need to minimize patients' radiation burden will influence which technique is used in prostatic evaluations.

Cytochrome P450 1B1 is overexpressed and regulated by hypomethylation in prostate cancer

PURPOSE

Cytochrome P450 1B1 (CYP1B1), a dioxin inducible member of the CYP supergene family, is overexpressed in various human malignancies including prostate cancer. We hypothesized that promoter/enhancer CpG methylation contributes to the regulation of CYP1B1 expression in human prostate tissue.

EXPERIMENTAL DESIGN

Expression and induction of the CYP1B1 gene in clinical prostate tissues and prostate cancer cell lines were investigated. The methylation status of the CYP1B1 gene was analyzed in 175 prostate cancer and 96 benign prostatic hyperplasia samples using methylation-specific PCR (MSP) and bisulfite-modified DNA sequencing. MSP primers covered dioxin response elements (DRE) and Sp1 sites that are important for the expression of CYP1B1.

RESULTS

Expressions of CYP1B1 mRNA and protein were increased in prostate cancer. The aryl hydrocarbon receptor (AhR)/AhR nuclear translocator (ARNT) heterodimer complex activates gene transcription by binding to the DREs of CYP1B1. In prostate cancer cells, CYP1B1 mRNA was induced by 2,3,7,8-tetrachlorodigenzo-p-dioxin (TCDD) and/or demethylation agent (5-aza-2-deoxycytidine). There was no change in the expressions of AhR and ARNT. Methylation of promoter/enhancer regions was significantly higher in benign prostatic hyperplasia compared with prostate cancer. MSP-positive patients had significantly lower risk for prostate cancer as compared with MSP-negative patients. There was no correlation between CYP1B1 methylation status and clinicopathologic features.

CONCLUSIONS

CYP1B1 is overexpressed in prostate cancer and regulated by hypomethylation of its promoter/enhancer region. This is the first report about CYP1B1 regulation in human clinical prostate samples showing that hypomethylation of the CYP1B1 gene may play an important role in prostate cancer.

Transitional cell carcinoma involving the distal ureter: assessment with transrectal and color Doppler ultrasonography

OBJECTIVE

The purpose of this study was to compare the feasibility of transrectal ultrasonography (TRUS) and color Doppler ultrasonography (CDUS) with transabdominal ultrasonography (TAUS) for the diagnosis of transitional cell carcinoma (TCC) involving the distal ureter.

METHODS

Our study group consisted of 12 patients having TCC involving the distal ureter who had undergone TAUS and TRUS. Verification of the TCC involving the distal ureter was made by surgery (n = 9) or urine cytologic examination combined with the imaging findings (n = 3). The gray scale images of TAUS and TRUS were retrospectively evaluated to determine whether the ureteral mass was visualized. The CDUS findings were compared with the T stage, the histopathologic grade, and the mean microvessel density of histopathologically proved distal ureteral TCCs (n = 8).

RESULTS

Transabdominal ultrasonography showed hypoechoic ureteral dilatation in 6 patients, a ureteral mass in 5, and anechoic ureteral dilatation in 1. Transrectal ultrasonography showed a ureteral mass in all 12 patients. Color Doppler ultrasonography could show blood flow in the ureteral mass in all patients. The tumor vascularity on CDUS showed no statistically significant relationship with the T stage, the histopathologic grade, and the mean microvessel density.

CONCLUSIONS

Compared with TAUS, TRUS seems to improve the ability to detect TCC involving the distal ureter. In conjunction with TRUS, CDUS shows blood flow in the ureteral mass, and this may be helpful for the diagnosis of TCC involving the distal ureter.

PSA testing: an evolving relationship with prostate cancer screening

PSA testing has made prostate cancer screening a reality for men in many parts of the world, but its benefit for men's health continues to be debated. In men exposed to PSA testing, there has been a well-documented change in the presentation of prostate cancer with a shift towards earlier pathological stage, not without justifiable concern about over-diagnosis by prostate biopsy. Increasingly, men now diagnosed with early stage cancer have previous PSA exposure and are selected for biopsy based on PSA change in relation to cutoff values. Some recent observations suggest that PSA may no longer be an effective marker for early stage tumours, with PSA elevation failing to discriminate tumour-specific characteristics from benign gland enlargement. Traditionally, variation in pathological stage of clinically localised prostate cancer at diagnosis has related to clinical stage, PSA and biopsy Gleason grade, but with distinctions based upon these three assessments declining and an increasing proportion of organ-confined tumours at presentation, new methods of cancer detection and prognostic assessment are now required. Molecular technologies hold great promise in this respect, and in the future biomarker signatures are likely to overshadow total PSA for guiding early diagnosis and prognostic assessment. While arguments about prostate screening will continue, owing not least to its feasibility, future debate is likely to focus increasingly on technological advances and molecular profiling of these notoriously heterogeneous tumours.

Echo contrast-enhanced power Doppler ultrasonography for assessment of angiogenesis in renal cell carcinoma

OBJECTIVE

Tumoral growth is an angiogenesis-dependent event. Although there are studies about the importance of histopathologic angiogenesis in various malignancies, the assessment of the angiogenesis by radiologic techniques is not well established. The aim of this study was to investigate the efficacy of echo contrast-enhanced power Doppler ultrasonography (PDUS) in determining the angiogenic status of renal cell carcinoma (RCC).

METHODS

Power Doppler ultrasonography was performed before and after intravenous administration of an echo contrast agent in 42 patients with renal masses. Twenty-one of these renal masses were diagnosed as RCC histopathologically, and these 21 patients were reevaluated retrospectively. The color pixel ratios of selected images were calculated as the ratio of the number of pixels showing power Doppler signals to the total number of pixels within the lesion. The results were compared with the histopathologic microvessel density (MVD).

RESULTS

A significant correlation was found between color pixel ratio and MVD values in both PDUS techniques. The use of the echo contrast agent improved this correlation and P values (Spearman rho from 0.436 to 0.551; P from .048 to .01).

CONCLUSIONS

Color pixel ratio values reflect the MVD in RCC. Therefore, these results suggest that preoperative quantification of angiogenesis can be possible with the help of PDUS in RCC.

Power Doppler Ultrasonografy (Pdu) as an Additional Tool to Increase Reliability of Systematic Biopsy of the Prostate

Diagnosis of prostate cancer has until recently relied primarily on eight core TR biopsy.

Tests are being carried out to verify whether PDU can effectively aid such diagnosis thereby reducing the number of biopsies and tissue samplings.

This has also been our attempt.

Two groups of patients were examined for increased PSA with or without a palpable prostatic nodule. The first group was composed by 52 patients between 55 and 83 years of age (av. 69.57) with PSA values between 0.87 and 94.91 ng/mL (r.8.085) of which 29 (55.75%) showed a palpable nodule. All patients underwent prostatic eight core TR ecobiopsy.

The second group was composed by 56 patients between 49 and 84 years of age (av.69.19) with PSA values between 1.14 and 59.7ng/mL (r.8.74) of which 33 (58.97%) showed a palpable nodule. This group of patients underwent a PDU just before TR biopsy in order to assess prostatic blood supply and locate possible alterations. Prostatic volume in both groups was never higher than 50 cc. Of the first group 25 patients (48.08%) were prostate cancer positive. Of the second group 31 patients (55.36%) were positive to a biopsy for prostate cancer. In addition 22 out of the 31 showed a vascular irregularity.

From the evidence above (tests carried out by the same operator with two homogeneous groups of patients-Wilcoxon test-) it is clear that PDU usefully worked in diagnosing a higher number of prostate cancers.

Diagnostic sensitivity and specificity was markedly increased by the association of PDU and TR biopsy.

Power Doppler ultrasound imaging for quantification of urinary bladder neck blood flow changes

This study was designed to evaluate power Doppler imaging for assessment of urinary bladder neck blood flow in comparison with laser Doppler flowmetry (LDF) in an animal model. Transrectal power Doppler ultrasound (US) and LDF of the urinary bladder neck were performed in three anesthetized pigs during comparative cystometry. Normal saline (NaCl) was used for the first run, followed by a second run with 0.2 mol/L potassium chloride (KCl). Standardized sonographic equipment settings (Acuson Sequoia 512); MountainView, CA) were used for power Doppler imaging. Computer-assisted calculation of color pixel density (CPD) of power Doppler images was performed using Scion Image) software image analysis. Tissue perfusion units (TPU) were measured using a BLF21 laser Doppler flowmeter (Transonic Systems Inc., Ithaca, NY, USA). The power Doppler results were compared with the findings obtained by LDF. NaCl filling resulted in a mean CPD increase at the bladder neck from 18.65 (+/- 1.78) at empty bladder to 37.8 (+/- 1.84) at 100 mL and to 88.32 (+/- 1.35) at full bladder capacity (C(max)) of 270 mL, respectively. With KCl filling, a mean CPD increase from 18.65 (+/- 1.78) to 59.63 (+/- 0.5) at 100 mL and 110.82 (+/- 2.98) at full bladder capacity (270 mL) was observed. The CPD increase was significantly higher for KCl than with NaCl (p < 0.001). With NaCl filling, bladder neck blood flow increased from 22 TPU (empty) to 46 TPU (100 mL) and 62.5 TPU at C(max), compared to 22 TPU, 50 TPU and 102.5 TPU with KCl. CPD and TPU measurements showed a strong correlation at p = 0.01. In conclusion, transrectal power Doppler US image quantification is a feasible and accurate method for assessing blood flow changes in the urinary bladder neck.