Effect of vitamin C on prostate cancer cells in vitro: effect on cell number, viability, and DNA synthesis

BACKGROUND

Many studies describe the protective role of vitamin C (ascorbic acid) against cancer development and in treatment of established cancer. The present study investigated whether ascorbic acid demonstrates a therapeutic benefit for prostate cancer.

METHODS

Androgen-independent (DU145) and androgen-dependent (LNCaP) human prostate cancer cell lines were both treated in vitro with vitamin C (0-10 mM). Cell counts, cell viability, and thymidine incorporation into DNA were determined.

RESULTS

Treatment of DU145 and LNCaP cells with vitamin C resulted in a dose- and time-dependent decrease in cell viability and thymidine incorporation into DNA. Vitamin C induced these changes through the production of hydrogen peroxide; addition of catalase (100-300 units/ml), an enzyme that degrades hydrogen peroxide, inhibited the effects of ascorbic acid. Superoxide dismutase, an enzyme that dismutates superoxide and generates hydrogen peroxide, did not prevent decreases in cell number and DNA synthesis, suggesting further the involvement of hydrogen peroxide in vitamin C-induced changes. These results clearly indicate that reactive oxygen species (ROS) are involved in vitamin C-induced cell damage. However, that singlet oxygen scavengers such as sodium azide and hydroquinone and hydroxyl radical scavengers such as D-mannitol and DL-alpha-tocopherol did not counteract the effects of ascorbic acid on thymidine incorporation suggests that vitamin C-induced changes do not occur through the generation of these ROS.

CONCLUSIONS

Vitamin C inhibits cell division and growth through production of hydrogen peroxide, which damages the cells probably through an as yet unidentified free radical(s) generation/mechanism. Our results also suggest that ascorbic acid is a potent anticancer agent for prostate cancer cells.

Neurotensin receptor expression in prostate cancer cell line and growth effect of NT at physiological concentrations

BACKGROUND

Neurotensin (NT), a neuroendocrine peptide, exerts trophic effects in vivo and stimulates growth of some tumor cells in vitro. Androgen-sensitive prostate cells derived from lymph node carcinoma of the prostate (LNCaP) secrete NT and exhibit growth responses to NT. This study examines NT secretion, NT receptor and NT-growth responses in androgen-independent prostatic carcinoma (PC3) cells derived from prostate adenocarcinoma metastatic to bone.

METHODS

Binding of 125I-NT to PC3 membranes was studied by filtration. NT was measured by RIA. Reverse transcriptase polymerase chain reaction (RT-PCR) was used for NT and NT receptor mRNA. Growth was measured as 3H-thymidine incorporation into DNA.

RESULTS

Scatchard analyses gave two binding components (Kd1 = 40 pM and Kd2 = 300 pM) in equal amounts (15-30 x 10(3) sites/cell). The bioactive region of NT was essential and the specific, non-peptide NT antagonist, SR48692, inhibited (IC50 = 3 nM). GTP analogs, sodium ion and SH-directed alkylating agents also inhibited. Glutaraldehyde crosslinking labeled two substances (M(r) of 23 and 46 kDa). RT-PCR indicated robust expression of authentic NT receptor but little for NT precursor. NT was stable in PC3 cultures but it was not found in cells or conditioned media. Incubated with PC3 cells, NT exhibited a mitogenic effect with bell-shaped dose-response and maximum at 100 pM NT.

CONCLUSIONS

PC3 cells expressed genuine NT receptors and generated growth responses to physiologic levels of NT which were blocked by SR48692. If NT contributes to the survival of prostate tumor cells upon androgen deprivation therapy, NT antagonists might be useful agents in further treatment.

Mechanism of stone formation

This article reviews the physical principles involved in urolithiasis. For urinary stones to form, crystals must form first and they then should be retained in the urinary tract. These phenomena require the interaction between the forces of saturation, crystal inhibition, crystal nucleation, growth aggregation, and retention, which all occur in a complex solution. In the latter part of the article the authors review the relevance of these physical principles in the lithogenesis of the most common urinary stones.

Diameter-Selective Raman Scattering from Vibrational Modes in Carbon Nanotubes

Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant, bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.

Experimental autoimmune cystitis in the Lewis rat: a potential animal model for interstitial cystitis

To develop an autoimmune animal model for interstitial cystitis (IC), we injected rats with Freund's adjuvant (CFA) containing bladder homogenate (experimentals) or CFA alone (shams). We observed a doubling of urinary frequency in the experimental animals over the shams (P = 0.004) and histopathologic changes (venular congestion) consistent with IC. Statistically significant bladder capacity changes were not found. Mast cell (MC) number was not statistically different between experimentals and controls but the number of MCs from section to adjacent section within the same animal's bladder did vary markedly, indicating the MC counts are not a reliable measure of disease in the rat bladder. Splenocytes cultured from the experimental animals and transferred to naive syngeneic recipients were capable of transferring the urinary frequency changes and vascular congestion while splenocytes from animals which did not develop the condition were without effect. In summary, we have developed and autoimmune model for IC consistent with the clinical features of IC. The features of this model can be transferred to naive syngeneic recipients via adoptive splenocyte transfer. The model will permit us to ask and answer important questions about the pathogenesis and treatment of the human disease.

17 beta-estradiol induced prostatitis in the rat is an autoimmune disease

PURPOSE

Studies suggest that alteration in steroid hormone levels may be one of the factors causing nonbacterial prostatitis (NBP) in rats. We hypothesized that hormonally induced prostatitis in the rat may be an autoimmune disease. Studies were carried out to prove this hypothesis.

MATERIALS AND METHODS

We injected 17 beta-estradiol (E2; 250 micrograms/kg. subcutaneously) or vehicle into 1-year-old male rats for 30 days, and isolated and cultured the splenocytes in the presence of con-A (Experiment 1). Approximately 10(7) splenocytes were adoptively transferred into young naive syngeneic rats. To find out whether or not the inflammation is mediated by T-lymphocytes, a pure population of T-lymphocytes from E2-treated 3-month-old rats was injected into young naive syngeneic rats (Experiment 2). To rule out the possibility that the inflammation was due to con-A itself, we cross-linked some T-cells with anti-CD3 antibody before adoptive transfer (Experiment 2).

RESULTS

The recipients of splenocytes from E2-treated animals presented evidence of inflammation in terms of lymphocytic infiltration and presence of degranulated mast cells. Furthermore, we observed in these animals an increase in histamine-releasing peptide (HRP) levels, an indication of plasma extravasation. The T-cells stimulated by anti-CD3 antibody produced a similar degree of inflammation, thereby ruling out the possibility that the inflammation was due to con-A. The results also indicated that the immune response to antigen(s) is not dependent on the age of the animal but is dependent on a population of CD3+ T-cells.

CONCLUSION

Our results demonstrate that hormonal imbalance and autoimmunity in male rats produce the symptoms of nonbacterial prostatitis.

Activation of c-myc gene mediates the mitogenic effects of oxalate in LLC-PK1 cells, a line of renal epithelial cells

Recent studies on LLC-PK1 cells demonstrated that oxalate, a simple dicarboxylic acid, acts as a mitogen for these renal epithelial cells. Exposure to oxalate initiates DNA synthesis, induces the expression of one of the early growth response genes c-myc and stimulates proliferation of quiescent cultures of LLC-PK1 cells. The present studies examined the possibility that expression of the c-myc protooncogene is obligatory for this mitogenic response. Specifically we determined whether pretreatment with c-myc antisense oligonucleotides would block the proliferative effects of oxalate in LLC-PK1 cells. Quiescent cultures of LLC-PK1 cells were exposed to oxalate in the presence and absence of c-myc antisense and the effects of oxalate on c-myc protein expression (Myc), DNA synthesis and cell growth were assessed. Exposure of cells to oxalate alone increased the expression of Myc within two hours. Pretreatment with c-myc antisense abolished this response. Further, pretreatment of cells with c-myc antisense but not nonsense oligonucleotides blocked the oxalate-induced initiation of DNA synthesis. Increases in cell number in response to oxalate (measured after 72 hr exposure) were also blocked by exposure to c-myc antisense. These findings suggest that c-myc gene expression is critical for the mitogenic effects of oxalate in LLC-PK1 cells.

Cryptococcal meningitis in patients with the acquired immunodeficiency syndrome

The optimum therapy for cryptococcal meningitis in patients with the acquired immunodeficiency syndrome (AIDS) remains unresolved. Traditional therapy consists of amphotericin B with or without flucytosine. Obstacles exist in administering these agents to patients with AIDS. Mortality rates during initial therapy are relatively high. Given the lack of proved benefit, we do not recommend adding flucytosine to amphotericin B routinely. The search for more efficacious and less toxic agents continues. The oral triazoles, especially fluconazole, have increased the options for treatment of this disease. New strategies and novel approaches in managing cryptococcal meningitis in patients with AIDS continue to be developed.

Prognostic value of argyrophylic nucleolar organiser regions (AgNORs) in breast lesions

A total of 200 breast tissues which included 5 normals, 55 benign and 140 malignant lesions were stained for Argyrophilic Nucleolar Organiser Regions (AGNORs). A comparison of the AGNOR values with histologic variables, viz., tumor type, size nuclear grade, desmoplasia, elastosis, lymph node metastasis and Oestrogen and Progesterone Receptor (ER/PR) status was carried out in malignant lesions. AGNOR values could sharply distinguish benign from malignant lesions. Among the malignant lesions, an attempt to determine the value of AGNOR count in prognostication was made. AGNOR counts correlated with tumor size, mitoses and desmoplasia. ER/PgR negative tumors showed a tendency for high NOR counts, but lymph node metastasis, which is considered one of the most reliable prognostic indicators, did not concur with AGNOR counts in our study. These results indicate that AGNOR counts can not be used as a sole independent marker in breast cancer prognostication.

Oxalate toxicity in LLC-PK1 cells, a line of renal epithelial cells

PURPOSE

The present studies assessed the possibility that high concentrations of oxalate may be toxic to renal epithelial cells.

MATERIALS AND METHODS

Subconfluent cultures of LLC-PK1 cells were exposed to oxalate, and the effects on cell morphology, membrane permeability to vital dyes, DNA integrity and cell density were assessed.

RESULTS

Oxalate exposure produced time- and concentration-dependent changes in the light microscopic appearance of LLC-PK1 cells with higher concentrations ( > 140 microM.) inducing marked cytosolic vacuolization and nuclear pyknosis. Exposure to oxalate also increased membrane permeability to vital dyes, promoted DNA fragmentation and, at high concentrations (350 microM. free oxalate), induced a net loss of LLC-PK1 cells.

CONCLUSIONS

Since high concentrations of oxalate can be toxic to renal epithelial cells, hyperoxaluria may contribute to several forms of renal disease including both calcium stone disease and end-stage renal disease.

Oxalate toxicity in LLC-PK1 cells: role of free radicals

Oxalate, the most common constituent of kidney stones, is an end product of metabolism that is excreted by the kidney. During excretion, oxalate is transported by a variety of transport systems and accumulates in renal tubular cells. This process has been considered benign; however, recent studies on LLC-PK1 cells suggested that high concentrations of oxalate are toxic, inducing morphological alterations, increases in membrane permeability to vital dyes and loss of cells from the monolayer cultures. The present studies examined the basis for oxalate toxicity, focusing on the possibility that oxalate exposure might increase the production/availability of free radicals in LLC-PK1 cells. Free radical production was monitored in two ways, by monitoring the reduction of nitroblue tetrazolium to a blue reaction product and by following the conversion of dihydrorhodamine 123 (DHR) to its fluorescent derivative, rhodamine 123. Such studies demonstrated that oxalate induces a concentration-dependent increase in dye conversion by a process that is sensitive to free radical scavengers. Specifically, addition of catalase or superoxide dismutase blocked the oxalate-induced changes in dye fluorescence/absorbance. Addition of these free radical scavengers also prevented the oxalate-induced loss of membrane integrity in LLC-PK1 cells. Thus it seems likely that free radicals are responsible for oxalate toxicity. The levels of oxalate that induced toxicity in LLC-PK1 cells (350 microM) was only slightly higher than would be expected to occur in the renal cortex. These considerations suggest that hyperoxaluria may contribute to the progression of renal injury in several forms of renal disease.

Successful management of intracardiac extension of tumor thrombus in a patient with advanced nonseminomatous germ cell testicular cancer

A young patient with testicular germ cell tumor presenting with inferior vena cava thrombus extending into the right heart with free-floating thrombus in the right ventricle and a simultaneous epidural spinal cord compression is presented. Due to the perceived high risk of embolization and the urgent need to begin systemic chemotherapy, he was managed with tumor thrombectomy utilizing cardiopulmonary bypass and hypothermic circulatory arrest followed shortly thereafter by systemic chemotherapy. There were no perioperative complications, and he is alive and without recurrence 24 months following four cycles of systemic chemotherapy.

Should we treat localized prostate cancer? An opinion

Localized prostate cancer is a progressive disease if left untreated. However, cancer-specific mortality is low in patients with moderately and well-differentiated prostate cancer treated with observation and delayed hormonal therapy, being 13% at 10 years and 20% to 30% at 15 years. By and large, radiation therapy does not appear to improve survival in these patients. With modern surgical techniques, mortality from prostate cancer is lowered by 23% to 65% in patients with moderately or well-differentiated tumors. However, the impact on relative cancer-specific survival is modest, since the mortality rate in untreated patients is low. The survival of conservatively managed patients with poorly differentiated prostate cancer is dismal: here radiation therapy or surgery significantly improves outcome. The QOL of patients with localized prostate cancer is significantly affected by the occurrence of distant metastasis. Metastatic rates are high in patients who are followed with observation and delayed endocrine treatment (19% to 85%). We were unable to deduce the effects of radiation therapy on grade-specific metastatic rates at 10 and 15 years. The only surgical series that addresses the issue shows a 50% to 80% reduction in metastatic rates. This results in an improvement in metastasis-free survival of 19% to 300%. The reduction in metastatic rates with surgery holds true for patients with poorly, moderately, or well-differentiated tumors. However, a significant proportion of the surgical patients were treated with adjuvant endocrine therapy, and it is impossible to identify the benefit from surgery and the benefit from adjuvant therapy. Radical prostatectomy improves survival in men who are 65 years or younger with moderately or well-differentiated adenocarcinoma of the prostate, and in men 75 years or younger who have poorly differentiated adenocarcinoma of the prostate. Its efficacy in reducing cancer-specific mortality in patients who have a survival expectancy of less than 15 years (older than 65 years) and moderately or well-differentiated adenocarcinoma of the prostate is less clear. Radical prostatectomy, with or without adjuvant hormonal therapy, decreases metastatic rates in men with a life expectancy of 10 years or more (age 75 years or younger) irrespective of tumor grade and, thus, should improve the QOL expectancy in these men. Nevertheless, between 20% and 60% of patients undergoing radical prostatectomy have biochemical recurrence, as defined by a detectable PSA, at 10 years of follow-up. This is worrisome and may portend clinical failure with longer follow-up.(ABSTRACT TRUNCATED AT 400 WORDS)

The University of Massachusetts technique of radical retropubic prostatectomy

A modified technique of radical retropubic prostatectomy is described which takes advantage of combining the antegrade dissection of prostate described by Skinner and the early control of prostatic vasculature as publicized by Walsh. Integration of both techniques of radical retropublic prostatectomy has resulted in improved exposure and minimal blood loss. The average blood loss with this technique was 500 ml in contrast to the average blood loss of 1100 ml while performing over 300 radical retropubic prostatectomies by the standard technique. The average operating times have been 150 minutes. Because of improved exposure and reduced blood loss, it is easy to teach this technique of radical prostatectomy to the surgeon in training (resident or the registrar) without any compromise to the primary goal of surgery which is to remove all tumour. No intra-operative complications were encountered during the performance of this modified technique of radical retropubic prostatectomy.

Oxalate-induced damage to renal tubular cells

Our own studies and those of others have shown that the incidence of calcium oxalate stones and plaques is markedly increased by nephrotoxins. The possible role of oxalate as a nephrotoxin has not been fully appreciated. However, recent studies in experimental animals and in cultured cells support this possibility. The results of these studies led us to hypothesize that hyperoxaluria promotes stone formation in several ways: by providing a substrate for the formation of the most common form of renal stones, calcium oxalate stones, and by inducing damage to renal epithelial cells. Damaged cells in turn would produce an environment favorable for crystal retention and provide membranous debris that promotes crystal nucleation, aggregation and adherence. The present report summarizes evidence for oxalate nephrotoxicity and discusses the potential importance of oxalate toxicity in the pathogenesis of stone disease.

Oxalate-induced initiation of DNA synthesis in LLC-PK1 cells, a line of renal epithelial cells

These studies examined the effects of oxalate, a constituent of renal stones, on the growth of LLC-PK1 cells. Exposure to oxalate resulted in an initiation of DNA synthesis in serum-starved, growth-arrested cells as measured by 3H-thymidine incorporation. The effects of oxalate were comparable to those observed in response to 10% serum. Moreover, exposure to oxalate plus 10% serum stimulated DNA synthesis to a greater extent than oxalate or serum alone. These studies indicate that oxalate promotes the progression of cells from the G0/G1 to the S phase of the cell cycle. However, the increase in DNA synthesis was not always followed by an increase in cell number since high concentrations of oxalate led to a reduction in cell number.