Constitutively tyrosine phosphorylated p52 Shc in breast cancer cells: correlation with ErbB2 and p66 Shc expression

Breast cancer cell lines display a wide variety of growth factor receptors, and considerable evidence implicates signaling from these receptors, especially ErbB2, in the important early stages of this disease, contributing to malignant progression. If this is true, then we would hypothesize that a useful prognostic indicator would be the level of activity of a second messenger protein used in common by these receptors. One such second messenger is the Shc adapter protein, which is activated when tyrosine phosphorylated by receptors. Therefore, one prediction from the hypothesis is that the level of tyrosine-phosphorylated Shc (PY-Shc) in breast cancer cell lines would correlate with total receptor tyrosine kinase activity. To begin to test this prediction, we examined Shc tyrosine phosphorylation in a diverse group of breast cancer cell lines that display varied levels of ErbB2. Using Shc immunoprecipitation and anti-phosphotyrosine immunoblotting analysis, we found a strong correlation between the level of ErbB2 overexpression (r=0.91, p < 0.0002) and PY-ErbB2 levels (r=0.89, p=0.0005) compared with the level of tyrosine phosphorylation of the p52 and p46 Shc isoforms. Consistent with Shc tyrosine phosphorylation being driven by ErbB2, an ErbB2-specific tyrosine kinase inhibitor markedly reduced Shc tyrosine phosphorylation. Unexpectedly, although all cell lines had comparable total amounts of p52 and p46 Shc, the amount of an inhibitory Shc isoform, p66, was inversely related to the level of ErbB2 expression (r=– 0.86, p=0.0013). This suggests that reduced p66 Shc expression may play a role in ErbB2-positive breast cancer. In summary, these data are consistent with our prediction that the cellular level of PY-Shc would correlate with the levels of activated ErbB2 displayed by cell lines derived from breast cancers.     

p53 expression is decreased in primary breast carcinomas with microsatellite instability

p53 and p185 expression in primary breast cancer with microsatellite instability (MSI) is still largely unexplored. To investigate the relationship between these oncoproteins and the pathways of genomic instability, we examined 52 primary invasive breast cancers stratified by the presence and absence of MSI. We determined the status of eight microsatellite loci using radioactive and silver staining methods, and evaluated the immunohistochemical expression of p53 and p185 in a consecutive series of Italian cancer patients characterized by clinical-pathological and biological parameters. Nineteen cases (36.5%) were MSI-positive in at least two loci. p53 was expressed in 15 cases (28.8%) and p185 in eight (15.4%). MSI-positive tumors were inversely correlated with p53 expression (p=0.0007); in addition, the percent of p53-expressing cells decreased as the number of MSI-positive loci increased. MSI-positive tumors were correlated with a larger tumor size (p=0.04), lymph-node metastasis (p=0.001), and advanced clinical stage (p=0.0006). These data demonstrate the existence of two subsets of primary breast cancers: one characterized by MSI, the other by p53 expression. MSI-positive patients had a more advanced and/or aggressive disease.     

Altered response to thyroid hormones by prostate and breast cancer cells

Transferrin, an abundant bone marrow constituent, has been shown to be a potent mitogen in vitro in the prostate cancer cell line PC3. T4 (L-thyroxine) and T3 (3′,3,5-tri-iodo-L-thyronine) are regulators of cell metabolism. In this study, the effects of nonphysiological concentrations (about two orders of magnitude higher) of T4, T3, T2 (3,5-di-iodo-L-thyronine), RT3 (reverse T3, 3′,5′,3-tri-iodo-L-thyronine) and transferrin (about three orders of magnitude lower) were tested on the prostate cancer cell lines PC3, DU145 and LNCaP, and the breast cancer cell line MCF-7. In PC3 cells, increased proliferation by transferrin could be reversed by the addition of T3 or T4. T4 decreased proliferation in all cell lines tested, while transferrin increased proliferation in PC3 cells only. T3 decreased proliferation in PC3, LNCaP and MCF-7 cells but had no effect on DU145 cells. T4 and T3 gave two-state behavior in LNCaP cells. These results were combined to determine the essential iodines which produced the observed proliferative effects. Cell lines responded differently to T4, T3, T2, RT3 and transferrin suggesting a specific interaction among the compounds tested and the different cell lines. Finally, regulation of gene expression was demonstrated using DU145 cells. Upregulation of c-fos mRNA was observed in cultures at early time-points in the presence of T4, transferrin or both. Decreased expression was observed at later time-points with no expression at 4 h. An explanation for these results may be a change in thyroid hormone receptor/ligand affinity. Thus, the interactions between thyroid hormones and cancer cells may be different from those between thyroid hormones and normal cells. Received: 28 January 1999 / Accepted: 26 August 1999     

‘Charting a new course for prostate cancer’ – currying favor for docetaxel in hormone-sensitive metastatic prostate cancer

Docetaxel has an established role in the treatment of metastatic castrate-resistant prostate cancer. A number of recent treatments have been shown to improve the survival outcomes for this group of patients and many with improved toxicity profiles, bringing the role of docetaxel into question. We discuss the results and implications of the CHAARTED study that demonstrated a significant improvement in overall survival with docetaxel in metastatic hormone-sensitive prostate cancer.     

Circulating tumor cells as a predictive biomarker in patients with hormone-sensitive prostate cancer

Introduction

Circulating tumor cell (CTC) enumeration by using the Cellsearch platform has established prognostic and predictive value in patients with metastatic castration-resistant prostate cancer (mCRPC). Limited information exists regarding the clinical utility of CTC enumeration in metastatic hormone-sensitive prostate cancer (mHSPC). The goal of this study was to prospectively determine the relative clinical utility of CTCs in mHSPC.

Patients and Methods

We analyzed serial CTC in conjunction with other classic biomarkers in 33 consecutive patients treated at the Nevada Cancer Institute with HSPC initiating androgen deprivation therapy and correlated these patients with prognostic prostate-specific antigen (PSA) endpoints and onset of CRPC.

Results

Initial CTC correlated positively with lactate dehydrogenase and alkaline phosphatase, and were unrelated to PSA and testosterone. In univariate analysis, baseline CTC, alkaline phosphatase, lactate dehydrogenase, testosterone, and follow-up CTC were individual predictors of progression to CRPC. In a multivariate Cox regression, only baseline CTC retained independent predictive value. Threshold analysis revealed the cutpoint that optimized specificity and sensitivity of the test to be 3 cells per 7.5 mL whole blood. Baseline CTC also correlated well with PSA nadir benchmarks.

Conclusions

Initial CTC values predict the duration and magnitude of response to hormonal therapy. CTC enumeration may identify patients at risk of progression to CRPC before initiation of androgen deprivation therapy.     

p66Shc—a longevity redox protein in human prostate cancer progression and metastasis

p66Shc, a 66 kDa proto-oncogene Src homologous-collagen homologue (Shc) adaptor protein, is classically known in mediating receptor tyrosine kinase signaling and recently identified as a sensor to oxidative stress-induced apoptosis and as a longevity protein in mammals. The expression of p66Shc is decreased in mice and increased in human fibroblasts upon aging and in aging-related diseases, including prostate cancer. p66Shc protein level correlates with the proliferation of several carcinoma cells and can be regulated by steroid hormones. Recent advances point that p66Shc protein plays a role in mediating cross-talk between steroid hormones and redox signals by serving as a common convergence point in signaling pathways on cell proliferation and apoptosis. This article first reviews the unique function of p66Shc protein in regulating oxidative stress-induced apoptosis. Subsequently, we discuss its novel role in androgen-regulated prostate cancer cell proliferation and metastasis and the mechanism by which it mediates androgen action via the redox signaling pathway. The data together indicate that p66Shc might be a useful biomarker for the prognosis of prostate cancer and serve as an effective target for its cancer treatment.     

Fascin, an actin-bundling protein associated with cell motility, is upregulated in hormone receptor negative breast cancer

Loss of hormone receptor (HR) status in breast carcinomas is associated with increased tumour cell motility and invasiveness. In an immunohistological study of 58 primary breast cancers, oestrogen (ER) and progesterone (PR) receptor levels were inversely correlated with the expression of fascin, an actin-bundling protein associated with cell motility (P< 0.0001 and P = 0.0019, respectively). In addition, fascin was preferentially expressed in non-diploid tumours (P = 0.03). In summary, the upregulation of fascin in HR-negative breast cancers may contribute to their more aggressive behaviour.     

Neuroserpin (PI-12) is upregulated in high-grade prostate cancer and is associated with survival

We carried out Genechip analysis using prostate cancer and non-malignant tissue to identify specific genes related to prostate cancer. We focused on neuroserpin (PI-12), which has been identified as one of the genes with high expression in prostate cancer. We analyzed the relationship between its expression pattern and clinical characteristics. Prostate cancer and normal prostate tissue were analyzed by Affymetrix GeneChip technology. We carried out real-time quantitative PCR on a total of 102 specimens: 45 of normal prostate, 45 of previously untreated prostate cancer (constituting 45 pairs of samples obtained at radical prostatectomy, with each pair dissected from the same prostate specimen) and 12 of recurrent hormone refractory prostate cancer (HRPC). Results showed that the neuroserpin gene was more highly expressed in prostate cancer than in normal prostate tissue. Neuroserpin expression in untreated prostate cancer was significantly higher than that in normal prostate. In HRPC it was significantly higher than that in untreated prostate cancer and normal prostate. In untreated prostate cancer, neuroserpin expression was significantly higher in high grade tumors such as poorly differentiated adenocarcinoma than in lower grade tumors such as well or moderately differentiated adenocarcinoma. Higher neuroserpin expression was associated with shorter recurrence-free survival after radical prostatectomy, shorter recurrence-free survival in HRPC patients and shorter overall survival in HRPC patients. The neuroserpin gene may be associated with the development, progression and aggressiveness of prostate cancer. Our present data suggests that higher neuroserpin expression may predict an unfavorable outcome after radical prostatectomy or hormone therapy.     

Postmenopausal breast cancer risk in relation to sex steroid hormones, prolactin and SHBG (Sweden)

Objective: High levels of sex steroid hormones and prolactin have been suggested to enhance breast cancer development. Low levels of SHBG may indicate high levels of (bio-available) steroid hormones. The present study investigates whether high levels of sex steroid hormones and prolactin, and/or low levels of SHBG, are associated with high breast cancer risk. Methods: Blood samples were collected in about 65,000 women participating in two population-based prospective cohort studies in Sweden. Follow-up yielded 173 postmenopausal breast cancer cases who had not been exposed to HRT. Levels of estrone, estradiol, SHBG, FSH, prolactin, testosterone, androstenedione and DHEAs were analysed in cases and 438 controls. Logistic regression analysis yielded odds ratios (ORs), with 95% confidence intervals, adjusted for potential confounders. Results: The risk of breast cancer was associated with the highest versus lowest quartiles of estrone, OR: 2.58 (1.50–4.44), estradiol (dichotomised: high versus low) (1.73: 1.04–2.88), and testosterone (1.87: 1.08–3.25). High risks, although not statistically significant, were seen for androstenedione (1.58: 0.92–2.72) and DHEAs (1.62: 0.89–2.72). No strong associations were seen between SHBG or prolactin and risk of breast cancer. Conclusions: High levels of estrone, estradiol, testosterone, and possibly androstenedione and DHEAs, in postmenopausal women are associated with a high risk of subsequent breast cancer.     

Induction of prostate specific antigen production by steroids and tamoxifen in breast cancer cell lines

Summary We demonstrate that the steroid hormone receptor-positive breast carcinoma cell lines T-47D and MCF-7 can be induced by androgens, progestins, mineralocorticosteroids, glucocorticosteroids, and antiestrogens, to produce prostate specific antigen (PSA). Estrogens failed to induce such stimulation in both cell lines and, in addition, were able to block the induction by androgens in the cell line T-47D. These data support and extend our previous report on PSA production by breast tumors and describe anin vitro system which can be used to study the phenomenon for possible application in prognosis and design of new therapy.     

Genomic deletion of chromosome 12p is an independent prognostic marker in prostate cancer

Deletion of 12p is a recurrent alteration in prostate cancer, but the prevalence and clinical consequences of this alteration have not been studied in detail. Dual labeling fluorescence in situ hybridization using probes for 12p13 (CDKN1B; p27) and centromere 12 as a reference was used to successfully analyze more than 3700 prostate cancers with clinical follow-up data assembled in a tissue microarray format. CDKN1B was selected as a probe because it is located in the center of the deletion, which spans > 10 Mb and includes > 50 genes in 80% of cancers with 12p deletion. Deletion of 12p was found in 13.7% of cancers and included 13.5% heterozygous and 0.2% homozygous deletions. 12p deletion were linked to advanced tumor stage (p < 0.0001), high Gleason grade (p < 0.0001), rapid tumor cell proliferation (p < 0.0001), lymph node metastasis (p = 0.0004), and biochemical recurrence (p = 0.0027). Multivariate analysis including pT stage (p < 0.0001), Gleason grade (p < 0.0001), pN status (p = 0.0001), preoperative PSA levels (p = 0.0001), and resection margin status (p = 0.0001) revealed an independent prognostic value of 12p deletion (p = 0.0014). Deletion of 12p was unrelated to the ERG fusion status. Deletion of 12p was only marginally linked to reduced p27 expression, which by itself was unrelated to clinical outcome. This argues against p27 as the key target gene of 12p deletions. In summary, the results of our study demonstrate that 12p deletion is frequent in prostate cancer and provides independent prognostic information. 12p deletion analysis alone, or in combination with other prognostic parameters may thus have clinical utility.     

Effects of platelet-activating factor and its differential regulation by androgens and steroid hormones in prostate cancers

Background:

Platelet-activating factor (PAF) is an arachidonic acid metabolite that plays an important role in cell proliferation, migration and neoangiogenesis, but whether it is involved in the progression of prostate cancer remains undiscovered.

Methods:

Clinical prostate specimens were investigated with immunohistochemistry method and in vitro cell experiments referred to MTS cell proliferation assay, invasion and migration experiment, quantitative real-time RT–PCR assay, western blotting analysis and ELISA assay.

Results:

Platelet-activating factor synthetase, lyso-PAF acetyl transferase (LPCAT1), increased significantly in castration-resistant prostate cancer (CRPC) specimens and CRPC PC-3 cells than that in controls. Intriguingly, PAF induced invasion and migration of PC-3 cells but not LNCaP cells. The PAF receptor antagonist inhibited proliferation of LNCaP and PC-3 cells. Dihydrotestosterone (DHT) treatment caused a decrease in LPCAT1 expression and PAF release in LNCaP cells, which could be blocked by androgen receptor antagonists. Finally, DHT increased LPCAT1 expression and PAF release in PC-3 cells in a Wnt/β-catenin-dependent manner.

Conclusion:

For the first time, our data supported that PAF might play pivotal roles in the progression of prostate cancer, which might throw a new light on the treatment of prostate cancer and the prevention of the emergence of CRPC.     

Differential prognostic factors in low- and high-burden de novo metastatic hormone-sensitive prostate cancer patients

Metastatic burden is a critical factor for therapy decision-making in metastatic hormone-sensitive prostate cancer. The present study aimed to identify prognostic factors in men with high- or low-metastatic burden treated with primary androgen-deprivation therapy. The study included 2450 men with de novo metastatic prostate cancer who were treated with primary androgen-deprivation therapy at 30 institutions across Japan between 2008 and 2017. We investigated the prognostic value of various clinicopathological parameters for progression-free survival (PFS) and overall survival (OS) in patients stratified by low- or high-metastatic burden. Among the 2450 men, 841 (34.3%) and 1609 (65.7%) were classified as having low- and high-metastatic burden, respectively. Median PFS of the low- and high-burden groups were 44.5 and 16.1 months, respectively, and the median OS was 103.2 and 62.7 months, respectively. Percentage of biopsy-positive core, biopsy Gleason grade group, T-stage, and N-stage were identified to be differentially prognostic. M1a was associated with worse PFS than was M1b in the low-burden group, whereas lung metastasis was associated with better PFS and OS than was M1b in the high-burden group. Differential prognostic factors were identified for patients with low- and high-burden metastatic prostate cancer. These results may assist in decision-making to select the optimal therapeutic strategies for patients with different metastatic burdens.     

Neurotrophin receptor p75(NTR) suppresses growth and nerve growth factor-mediated metastasis of human prostate cancer cells

The loss of tumor- and/or metastasis-suppressor gene function contributes to the transformation of human prostate epithelial cells to a malignant pathology. Such a putative tumor-suppressor and metastasis-suppressor gene(s) has been mapped to the region of 17q21, which coincidentally is in the vicinity of the human gene locus for the neurotrophin receptor p75(NTR). The p75(NTR) is expressed in normal human prostate epithelial cells and exhibits an inverse association of p75(NTR) expression with the malignant progression of the prostate, consistent with a pathologic role of the p75(NTR) as a putative tumor and metastasis suppressor. Utilizing stable transfectants of the TSU-pr1 and PC-3 human prostate tumor cell lines that exhibit a rank order (dose-dependent) increase in p75(NTR) protein expression, we investigated the effects of the p75(NTR) in combination with its predominant ligand, nerve growth factor (NGF), on tumor cell growth. A rank order (dose-dependent) increase in p75(NTR) expression was found to suppress the growth of prostate tumors in severe combined immunodeficient (SCID) mice. Treatment of these tumors with NGF stimulated both proliferation as indicated by PCNA expression and apoptosis as indicated by TUNEL assay, the net result of which was no change in the overall growth of the tumors. However, NGF was found to increase the formation of satellite tumors, both contiguous and noncontiguous with respect to the primary tumor mass, indicating dose-dependent induction of metastasis. Significantly, the formation of satellite tumors was suppressed by the expression of p75(NTR). This suggests that p75(NTR) is a tumor suppressor of growth and a metastasis suppressor of NGF-stimulated migration of human prostate tumor cells.     

P73 functionally replaces p53 in Adriamycin-treated, p53-deficient breast cancer cells

p53-Related genes, p73 and p63, encode 2 classes of proteins, TA-p73/p63 and DeltaN-p73/p63. TA-p73/p63 demonstrate p53-like properties including gene transactivation and cell death promotion, whereas DeltaN-p73/p63 lack these p53-like functions. Although p53-deficient cancer cells are often less responsive to chemotherapy, they are not completely drug resistant, suggesting that other apoptotic pathways are at work. Here, we compared for the first time to our knowledge p73 and p63 activation in various breast cancer (BC) cell lines after Adriamycin (ADR) treatment, an agent considered as mandatory in breast cancer chemotherapy. Our study was carried out using 1 p53-proficient BC cell line (MCF7 cells) and 3 BC cell lines deficient in p53 response (MCF7/ADR(IGR), MDA-MB157 and T47D) after ADR-induced genotoxic stress. We report that in cells with no p53 response after ADR treatment, TAp73, but not TAp63 or DeltaN-p73/p63, may replace p53 in triggering not only apoptosis but also cell cycle arrest or DNA repair effectors such as p21, GADD45, 14-3-3sigma and p53R2. We also demonstrate that TAp73 siRNA inhibits the accumulation of TAp73 in response to ADR treatment in MDA-MB157 cells and confers protection against ADR. ADR-induced downregulation of the DeltaNp73 isoform in the T47D cell line with nonfunctional mutant p53 further supports anti-apoptotic function of the isoform antagonistic to both p53 and TA-p73/p63. Exogenous TAp73 and DeltaNp73 overexpression in p53-response-deficient cell lines further confirms these results. cDNA microarray techniques demonstrated that the cellular response induced by p73 during ADR treatment could involve specific genes.