Apoptosis in prostate cancer after hormonal treatment

Autophagy regulates lipolysis and cell survival through lipid droplet degradation in androgen-sensitive prostate cancer cells

BACKGROUND

Androgen deprivation therapy, one of the standard treatments for prostate cancer (PCa) induces apoptosis, as well as autophagy in androgen-responsive PCa cells. As autophagy can promote either cell survival or death, it is important to understand its role in PCa treatment. The objective of this study was to elucidate the function of autophagy in lipid droplet (LD) homeostasis and survival in androgen-sensitive PCa cells.

METHODS

To produce androgen deprivation, charcoal filtered serum or the androgen inhibitor casodex were used in LNCaP and LAPC4 cells. Autophagy was monitored by immunofluorescence/confocal microscopy and immunoblot analysis. Levels of intracellular LDs and triacyglycerols after the inhibition of autophagy by 3-methyladenine, bafilomycin A(1) , or si-ATG5 were quantified by three independent methods, Oil Red O staining, triacyglycerols lipase assay, and nuclear magnetic resonance.

RESULTS

Androgen deprivation induced autophagy and the depletion of LDs in both of the androgen-sensitive PCa cell lines examined, whereas the blockage of autophagy by pharmacological or genetic means inhibited LD degradation and therefore lipolysis and cell growth. In addition, under androgen deprivation, increased colocalization of LDs and autophagic vesicles was observed in LNCaP cells, which can be further enhanced by blocking the autophagic flux.

CONCLUSION

Autophagy mediates LD degradation and lipolysis in androgen-sensitive PCa cells during androgen deprivation which aids the survival of PCa cells during hormone therapy.

Synergistic killing effect of chloroquine and androgen deprivation in LNCaP cells

Modulation of autophagy is a new paradigm in cancer therapeutics. Recently a novel function of chloroquine (CLQ) in inhibiting degradation of autophagic vesicles has been revealed, which raises the question whether CLQ can be used as an adjuvant in targeting autophagic pro-survival mechanism in prostate cancer (PCa). We previously showed that autophagy played a protective role during hormone ablation therapy, in part, by consuming lipid droplets in PCa cells. In addition, blocking autophagy by genetic and pharmacological means in the presence of androgen deprivation caused cell death in PCa cells. To further investigate the importance of autophagy in PCa survival and dissect the role of CLQ in PCa death, we treated hormone responsive LNCaP cells with CLQ in combination with androgen deprivation. We observed that CLQ synergistically killed LNCaP cells during androgen deprivation in a dose- and time-dependent manner. We further confirmed that CLQ inhibited the maturation of autophagic vesicles and decreased the cytosolic ATP. Moreover, CLQ induced nuclear condensation and DNA fragmentation, a hallmark of apoptosis, in androgen deprived LNCaP cells. Taken together, our finding suggests that CLQ may be an useful adjuvant in hormone ablation therapy to improve the therapeutic efficacy.

Immunotherapeutic targets in estrogen deficiency-dependent Sjögren's syndrome-related manifestations

Although a number of autoimmune diseases are known to develop in postmenopausal women, the mechanisms by which estrogen deficiency influences autoimmunity remain unclear. Previously, we found that tissue-specific apoptosis in the exocrine glands in estrogen-deficient mice may contribute to the development of autoimmune exocrinopathy. We found that RbAp48 overexpression induces p53-mediated apoptosis in the exocrine glands depending on estrogen deficiency. RbAp48-inducible transfectants result in rapid apoptosis with p53 phosphorylation (Ser9), and alpha-fodrin cleavage. Indeed, transgenic expression of the RbAp48 gene induced apoptosis in the exocrine glands, resulting in the development of autoimmune exocrinopathy resembling Sjögren's syndrome (SS). CD4(+) T-cell-mediated autoimmune lesions were aggravated with age, in association with production of autoantibodies against SS-A, SS-B and alpha-fodrin. These findings demonstrated that estrogen deficiency initiates tissue-specific apoptosis in the exocrine gland cells through RbAp48 overexpression and exerts a possible gender-based risk of autoimmune exocrinopathy in postmenopausal women. Thus, these data indicate RbAp48 to be a novel immunotherapeutic target for preventing epithelial cell apoptosis and the development of gender-based autoimmune exocrinopathy.

Expression of the retinoblastoma protein RbAp48 in exocrine glands leads to Sjögren's syndrome-like autoimmune exocrinopathy

Although several autoimmune diseases are known to develop in postmenopausal women, the mechanisms by which estrogen deficiency influences autoimmunity remain unclear. Recently, we found that retinoblastoma-associated protein 48 (RbAp48) induces tissue-specific apoptosis in the exocrine glands depending on the level of estrogen deficiency. In this study, we report that transgenic (Tg) expression of RbAp48 resulted in the development of autoimmune exocrinopathy resembling Sjögren's syndrome. CD4(+) T cell-mediated autoimmune lesions were aggravated with age, in association with autoantibody productions. Surprisingly, we obtained evidence that salivary and lacrimal epithelial cells can produce interferon-gamma (IFN-gamma) in addition to interleukin-18, which activates IFN regulatory factor-1 and class II transactivator. Indeed, autoimmune lesions in Rag2(-/-) mice were induced by the adoptive transfer of lymph node T cells from RbAp48-Tg mice. These results indicate a novel immunocompetent role of epithelial cells that can produce IFN-gamma, resulting in loss of local tolerance before developing gender-based autoimmunity.

Novel role for RbAp48 in tissue-specific, estrogen deficiency-dependent apoptosis in the exocrine glands

Although tissue-specific apoptosis in the exocrine glands in estrogen-deficient mice may contribute to the development of autoimmune exocrinopathy, the molecular mechanism responsible for tissue-specific apoptosis remains obscure. Here we show that RbAp48 overexpression induces p53-mediated apoptosis in the exocrine glands caused by estrogen deficiency. RbAp48-inducible transfectant results in rapid apoptosis with p53 phosphorylation (Ser9) and alpha-fodrin cleavage. Reducing the expression of RbAp48 through small interfering RNA inhibits the apoptosis. Prominent RbAp48 expression with apoptosis was observed in the exocrine glands of C57BL/6 ovariectomized (OVX) mice but not in OVX estrogen receptor alpha(-/-), p53(-/-), and E2F-1(-/-) mice. Indeed, transgenic expression of the RbAp48 gene induced apoptosis in the exocrine glands but not in other organs. These findings indicate that estrogen deficiency initiates p53-mediated apoptosis in the exocrine gland cells through RbAp48 overexpression and exerts a possible gender-based risk of autoimmune exocrinopathy in postmenopausal women.

Expression of insulin-like growth factor binding protein-3 before and after neoadjuvant hormonal therapy in human prostate cancer tissues: correlation with histopathologic effects and biochemical recurrence

OBJECTIVES

To determine the effects of neoadjuvant hormonal therapy (NHT) on insulin-like growth factor binding protein (IGFBP)-3 expression and whether IGFBP-3 expression influences the pathologic effect of NHT and biochemical recurrence after radical prostatectomy in patients with prostate cancer. IGFBP-3 has pro-apoptotic activity, and its expression correlates negatively with prostate cancer cell growth. Castration induces IGFBP-3 expression and apoptosis in the rat prostate.

METHODS

We used tissue specimens from 42 patients who underwent NHT and radical prostatectomy. The pre-NHT and post-NHT specimens were examined for expression of IGFBP-3 using an immunohistochemical technique and for apoptosis using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method. The histopathologic effect was evaluated by the standardized rules for estimating the response of prostate cancer to NHT, determined by the percentage of remaining viable cancer cells, as advocated by the General Rule for Clinical and Pathological Study on Prostate Cancer published by the Japanese Urological Association.

RESULTS

NHT resulted in a statistically significant increase in IGFBP-3 expression compared with baseline (P = 0.01). Such an increase in expression correlated significantly with the induction of apoptotic cells (r = 0.40 and P = 0.01). The post-NHT/pre-NHT IGFBP-3 ratio was significantly greater in the NHT-effective group than in the NHT-noneffective group (P = 0.02). Patients with high IGFBP-3 expression in the post-NHT specimens had a good prognosis (P = 0.03, log-rank test).

CONCLUSIONS

Induction of IGFBP-3 by NHT was associated with apoptosis and a histopathologic effect. IGFBP-3 expression in post-NHT specimens is a potentially useful predictor of biochemical recurrence in patients with prostate cancer.

Development of autoimmune exocrinopathy resembling Sjögren's syndrome in estrogen-deficient mice of healthy background

Although a number of autoimmune diseases are known to develop in postmenopausal women, the mechanisms by which estrogen deficiency influences autoimmune lesions remain unclear. We speculate that antiestrogenic actions might be a potent factor in the formation of pathogenic autoantigens. Previously, we have identified 120-kd alpha-fodrin as an important autoantigen in Sjögren's syndrome (SS). When healthy C57BL/6 (B6) mice were treated with an ovariectomy (Ovx), we found a significant increase in TUNEL(+)-apoptotic epithelial cells in the salivary gland cells associated with alpha-fodrin cleavage during 2 and 3 weeks after Ovx. By contrast, no apoptotic cells were found in estrogen receptor-alpha knockout mice. In in vitro studies using primary cultured mouse salivary gland cells and human salivary gland cells, we found a cleavage product of 120-kd alpha-fodrin in cells that had undergone tamoxifen (Tam)-induced apoptosis through caspase activation, especially caspase-1. Adoptive transfer of alpha-fodrin-reactive T cells into Ovx-B6 and -SCID mice resulted in the development of autoimmune exocrinopathy quite similar to SS. These results suggest that estrogen deficiency exerts a crucial influence on autoantigen cleavage, and may cause, in part, autoimmune exocrinopathy in postmenopausal women.

Repeated biopsies in evaluation of therapeutic effects in prostate carcinoma

BACKGROUND

Apoptosis is one of the major events following total androgen blockade (TAB). The aim of this study was to determine the predictive value of some histological parameters including apoptosis and gene products which influence apoptosis, based on repeated biopsies taken from the same patients.

METHODS

At the time of diagnosis by needle biopsy TNM stage, serum PSA, Gleason's grade, apoptotic and mitotic index, Ki67, p53, and bcl(2) expression were investigated in 60 prostate carcinoma patients. Antiandrogen therapy supplemented with surgical or chemical castration was administered. Serum PSA-test and needle biopsy were repeated 13-14 weeks after starting the therapy, simultaneously with determination of the apoptotic and mitotic index, Ki67, p53, and bcl(2) expression.

RESULTS

Forty-seven patients were alive at the end of the study, 13 patients died. Decrease in mitotic, increase in apoptotic index predicted favourable long-term response to antiandrogen therapy. Lower Ki67 and (mutant) p53 expression in the first and also in the second biopsy pointed to favourable effect of antiandrogen treatment. Since the ratio between Ki67 and apoptotic index strongly decreased in the survivors upon therapy, changes in Ki67/apoptosis ratio is recommended as a histologically detectable predictive factor. bcl(2) expression did not show significant correlation with the outcome of the disease.

CONCLUSIONS

Histological evaluation of mitotic and apoptotic index, Ki67, and p53 expression in repeated biopsies contributes to predicting the value of the actual treatment and may be useful to institute alterations in therapy.

Immunocytochemical detection of leukocyte-associated and apoptosis-related antigen expression in childhood brain tumors

During systematic cell-surface antigen expression profile analyses of 76 primary childhood brain tumors [34 medulloblastomas (MED)/primitive neuroectodermal tumors (PNETs) and 42 astrocytomas (ASTR)], a library of monoclonal antibodies (MoABs) directed against various leukocyte-associated, lymphocyte cell-line differentiation antigens in childhood brain tumors was utilized. The antigens were detected employing an indirect, biotin-streptavidin conjugated alkaline phosphatase (AP) immunocytochemical technique. Major histocompatibility complex (MHC) class I restricted, tumor-associated antigen (TAA) specific, CD8(+) cytotoxic T lymphocytes (CTL) were identified in 58/76 (76.32%) brain tumors, and usually represented 1-10% of all cells, but in some cases 30-44% of the cells were CD8(+). CD4(+), MHC class II restricted helper lymphocytes were present in 65/76 (85.53%) brain tumors, and accounted for 1-10% of the observed cells. Macrophages were present in 74/76 (97.37%) brain tumors, and their number also represented 1-10% of all observed cells in the brain tumor frozen sections. Leukocyte common antigen (LCA) expression was detected in all 76 (100%) brain tumors studied. MoAB UJ 308 detected the presence of premyelocytes and mature granulocytes in 60/76 (78.95%) brain tumors. Natural killer (NK) cells were not defined in the observed brain tumors. The great majority of childhood glial tumors, particularly ASTRs express Fas (APO-1/CD95) receptor whereas normal cells in the central nervous system (CNS) do not. FasR is a transmembrane glycoprotein which belongs to the nerve growth factor/tumor necrosis factor (NGF/TNF) receptor superfamily. As part of our screening, the 42 childhood ASTRs were also investigated for expression of CD95. We detected strong expression (strong intensity of staining, number of stained cells 50-100%) of FasR, employing formalin fixed, paraffin-wax embedded tissue slides. Brain tumors and melanomas have been shown to produce their autocrine FasL, and are even capable of switching CD95-related signal transduction from the PCD pathway to a proliferative pathway. In view of our results, we conclude that: (1) the tumor infiltrating leukocytes in MEDs/PNETs and ASTRs represent a very diverse population and are present in a great majority of the cases studied; (2) the strong expression of FasR in ASTRs provides a manner in which T lymphocytes may exert their anti-tumor effects, but may also represent yet another way that tumors may evade the immune response; and (3) further observations of the expression of various antigens involved in juxtacrine, in situ growth control are necessary for the refinement of cellular immunotherapeutical approaches in the treatment of human malignancies.

Apoptosis in Untreated and Hormone-Treated Prostate Cancer of Various Histological Types

A total of 102 (66 untreated and 36 hormone-treated) prostate cancers were examined histologically in order to determine their histological grade and the percentage of apoptotic tumor cells. The less differentiated the tumors were, the higher the spontaneous apoptotic activity was. Hormone therapy increased the apoptotic index in the prostate cancers. The increase was of greater significance in grade I than in grade II and grade III tumors. The therapeutic consequences of these findings and the possibility of different oncogene-expressions in various histological types of prostate cancer are discussed.

Apoptosis in rat prostatic adenocarcinoma is associated with rapid infiltration of cytotoxic T-cells and activated macrophages

Rats transplanted with the androgen-sensitive, syngeneic Dunning R3327 PAP prostatic tumor were castrated and treated with estrogen or vehicle for 4, 12 and 24 hr and for 6 weeks. Tumor growth was retarded by castration and further inhibited by estrogen. Immediately after castration, an increased number of activated macrophages and T-cells were found in parallel with increasing apoptotic tumor cells. Administration of an immunosuppressive drug, FK 506, abolished the growth-inhibitory effects of castration and estrogen. The tumor growth rate correlated negatively with the number of R73- and OX8-positive T-cells and NK cells and with the percentage of ED3-positive macrophages. There was a positive correlation between the percentage of TdT-mediated-dUTP nick end labeling (TUNEL)-positive apoptotic cells and that of ED3-positive cells. Our results suggest that apoptosis of prostatic carcinoma cells induced by endocrine treatment in vivo is partly due to a rapid infiltration by immunocompetent cells.