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Alexander Kirschenbaum

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  • American Board of Urology


  • MD, Mount Sinai School of Medicine

  • Residency, Urology
    Mount Sinai Hospital

  • Fellowship, Urology Oncology
    Mount Sinai Hospital


Kirschenbaum A, Pacheco E, Schuval BJ, Levine A. Lack of correlation between prostate-specific antigen density and prostatic shrinkage in response to finasteride therapy. World J Urol 1996; 14(6): 360-2.

We attempted to correlate prostate volume reduction in response to finasteride treatment with initial prostate-specific antigen (PSA) levels and PSA density in men with symptomatic benign prostatic hyperplasia (BPH). The average reductions in prostatic volume (transrectal ultrasonography) were 27% and 34% after 6 and 12 months of finasteride therapy, respectively. Serum PSA levels decreased by 45% (6 months) and 50% (12 months). There was a positive correlation between initial serum PSA values and initial prostate volumes (r = 0.57, P < 0.001). There was no correlation, however, between the initial serum PSA or PSA-density values and prostate volume reduction. These data indicate that initial serum PSA and PSA-density values are not predictive of the response to finasteride therapy in terms of prostate size reduction.

Robbins SE, Shu WP, Kirschenbaum A, Levine A, Miniati DN, Liu BC. Bone extracellular matrix induces homeobox proteins independent of androgens: Possible mechanism for androgen independent growth in human prostate cancer. Prostate 1996 Dec; 29(6): 362-70.

BACKGROUND: Differences in gene expression in prostate cells are believed to be secondary to epithelial-stromal interactions. We theorized that bone matrix may provide a fertile "soil" for prostate cancer by inducing androgen-dependent genes and allowing for androgen-independent growth. METHODS: Human prostate cancer cells (LNCaP) were grown under different conditions and analyzed for differential expression of mRNA. LNCaP cells were grown in the presence of 10 nM dihydrotestosterone (DHT), on extracellular matrix (ECM) derived from bone cells (without exogenous DHT), and on plastic culture dishes without exogenous DHT. A differential display of mRNA produced by LNCaP cells grown in the above conditions was then analyzed. RESULTS: Multiple unique transcripts were present in cells that were grown in the presence of DHT and on bone ECM (without exogenous DHT), but not on plastic culture dishes without exogenous DHT. Nine of these transcripts were then cloned and analyzed. Many (5/9) of these transcripts were found to contain multiple ATTA motifs in their corresponding 3'-untranslated regions. ATTA motifs have been shown to be homeobox protein-binding sites. Homeobox proteins and their target genes are thought to regulate cellular differentiation. Consistent with this, we demonstrated by reverse transcription polymerase chain reaction (PCR) that homeobox genes were differentially expressed in LNCaP cells when the cells were grown in the presence of DHT and on bone ECM (without exogenous DHT), but not on plastic culture dishes without exogenous DHT. Furthermore, we assayed LNCaP/fetal fibroblast chimeric tumors (n = 8) that were grown in male nude mice. Some of these tumors continued to grow in these mice despite treatment with surgical castration. In blinded studies, we were able to determine which tumor samples were androgen independent by their expression of homeobox genes. All samples that were androgen independent (n = 4) expressed the homeobox genes. Finally, gel retardation assay demonstrated that the homeobox proteins were able to bind to our cloned DNA sequences. Furthermore, footprinting analysis showed that the homeobox proteins bound to the ATTA motif in the 3'-region of our target DNA. CONCLUSIONS: Bone ECM, in the absence of DHT, has the ability to regulate androgen-responsive genes. Furthermore, many of these genes contain homeobox binding sites and the expression of homeobox genes may itself be regulated by bone ECM. If so, this may partially explain the clinical observation that bone provides a fertile "soil" for prostate cancer growth and metastasis.

Levine A, Wang JP, Ren M, Eliashvili E, Russell DW, Kirschenbaum A. Immunohistochemical localization of steroid 5a-reductase 2 in the human male fetal reproductive tract. J Clin Endocrinol Metab 1996 Jan; 81(1): 384-9.

The activity of the type 2 isozyme of steroid 5 alpha-reductase is crucial for normal development of the external genitalia and prostate in human males. We used immunohistochemistry to localize type 2 isozyme expression in the human male fetal reproductive tract and adult prostate. In fetal tissue, the stroma of the seminal vesicles, corpus cavernosum, corpus spongiosum, dorsal vein complex, scrotal skin, and prostate expressed the enzyme. In addition, the epithelial cells of the fetal urethra and proximal prostatic ducts stained positively. The type 2 isozyme could not be detected in epithelial cells of the fetal prostatic acini, seminal vesicles, prostatic utricle, ejaculatory ducts, epididymides, and Cowper's glands. Adult prostate specimens were derived from transurethral prostatectomies performed for benign prostatic hyperplasia. Enzyme expression in these benign prostatic hyperplasia samples localized to the stroma and epithelial cells of the urethra and proximal ducts. No staining was detected in the acinar (luminal and basal) epithelial cells. Double staining with an antismooth muscle actin antibody localized type 2 isozyme expression to the stromal fibroblast cells of the prostate. Double staining with an androgen receptor antibody localized AR expression to the acinar epithelial cells and stromal fibroblasts. These data indicate that 5 alpha-reductase type 2 is expressed throughout the developing male genitourinary tract and functions as both an autocrine and a paracrine mediator of growth and differentiation.

Levine A, Kirschenbaum A, Gabrilove J. The role of sex steroids in the pathogenesis and maintenance of benign prostatic hyperplasia. Mt Sinai J Med 1997 Jan; 64(1): 20-5.

BACKGROUND: It has long been suspected that sex steroids play a key role in the pathogenesis of benign prostatic hyperplasia (BPH). Prostatic diseases do not occur in males castrated before puberty or in males with heritable disorders of androgen production or action. Both estrogens and androgens have been shown to induce BPH in experimental animals. METHODS: Clinical studies utilizing hormonal therapies to treat BPH were reviewed. Studies that used total medical castration therapy via the use of a long-acting gonadotropin-releasing hormone (GnRH agonist), partial androgen blockade via the use of the 5 alpha-reductase inhibitor finasteride, and estrogen blockade (via the use of aromatase inhibitors) were analyzed. RESULTS AND CONCLUSIONS: Both the GnRH agonists and finasteride result in prostatic size reduction and alleviate symptoms in some patients. Both therapies are more effective in men with larger prostates (> 40 cc). Finasteride is less efficacious in terms of size reduction than the GnRH agonists but also has fewer side effects. To date, clinical trials with aromatase inhibitors have not yielded dramatic positive results in the treatment of BPH.

Liu X, Yao S, Kirschenbaum A, Levine A. NS398, a selective cyclooxygenase-2 inhibitor, induces apoptosis and down-regulates Bcl-2 expression in LNCaP cells. Cancer Res 1998 Oct 1; 58(19): 4245-9.

Cyclooxygenase (COX)-2, an inducible enzyme that catalyzes the formation of prostaglandins and other eicosanoids from arachidonic acid, is constitutively expressed in LNCaP human prostate cancer cell line. To evaluate the potential role of COX-2 in prostate cancer, LNCaP cells were treated with NS398, a selective COX-2 inhibitor, and the effects on cell viability and apoptosis were determined. NS398 treatment induced apoptosis in LNCaP cells in a time- and dose-dependent fashion. Treatment with 100 microM NS398 caused a down-regulation in bcl-2 protein expression, followed by chromatin condensation, chromosomal DNA fragmentation, and changes in nuclear morphology detected by 4,6-diamidino-2-phenylindole staining, DNA fragmentation assay, and terminal deoxynucleotidyl transferase-mediated UTP-biotin nick end-labeling assay. In contrast, NS398 treatment had no effect on either cell viability or nuclear function and morphology in human fetal prostate fibroblasts. These results demonstrate that NS398 induces apoptosis in LNCaP cells but not in human fetal prostate fibroblasts, and that this induction is associated with a decreased level of bcl-2 protein.

Liu X, Kirschenbaum A, Yao S, Stearns ME, Holland J, Claffey K, Levine A. Upregulation of vascular endothelial growth factor by cobalt-induced hypoxia is mediated by persistent induction of cyclooxygenase-2 in a metastatic human prostate cancer cell line. Clin Exp Metastasis 1999 17(8):687-94.

Upregulation of vascular endothelial growth factor (VEGF) expression induced by hypoxia is crucial event leading to neovascularization. Cyclooxygenase-2, an inducible enzyme that catalyzes the formation of prostaglandins (PGs) from arachidonic acid, has been demonstrated to be induced by hypoxia and play role in angiogenesis and metastasis. To investigate the potential effect of COX-2 on hypoxia-induced VEGF expression in prostate cancer. We examined the relationship between COX-2 expression and VEGF induction in response to cobalt chloride (CoCl2)-simulated hypoxia in three human prostate cancer cell lines with differing biological phenotypes. Northern blotting and ELISA revealed that all three tested cell lines constitutively expressed VEGF mRNA, and secreted VEGF protein to different degrees (LNCaP > PC-3 > PC3ML). However, these cell lines differed in the ability to produce VEGF in the presence of CoCl2-simulated hypoxia. CoCl2 treatment resulted in 40% and 75% increases in VEGF mRNA, and 50% and 95% in protein secretion by LNCaP and PC-3 cell lines, respectively. In contrast, PC-3ML cell line, a PC-3 subline with highly invasive, metastatic phenotype, exhibits a dramatic upregulation of VEGF, 5.6-fold in mRNA and 6.3-fold in protein secretion after treatment with CoCl2. The upregulation of VEGF in PC-3ML cells is accompanied by a persistent induction of COX-2 mRNA (6.5-fold) and protein (5-fold). Whereas COX-2 expression is only transiently induced in PC-3 cells and not affected by CoCl2 in LNCaP cells. Moreover, the increases in VEGF mRNA and protein secretion induced by CoCl2 in PC-3ML cells were significantly suppressed following exposure to NS398, a selective COX-2 inhibitor. Finally, the effect of COX-2 inhibition on CoCl2-induced VEGF production was reversed by the treatment with exogenous PGE2. Our data demonstrate that VEGF induction by cobalt chloride-simulated hypoxia is maintained by a concomitant, persistent induction of COX-2 expression and sustained elevation of PGE2 synthesis in a human metastatic prostate cancer cell line, and suggest that COX-2 activity, reflected by PGE2 production, is involved in hypoxia-induced VEGF expression, and thus, modulates prostatic tumor angiogenesis.

Kirschenbaum A, Itzkowitz S, Wang JP, Yao S, Eliashvili M, Levine A. MUC1 Expression in Prostate Carcinoma: Correlation with Grade and Stage. Mol Urol 1999; 3(3): 163-8.

Mucins have been implicated in the biologic behavior and progression of several types of cancer. The aims of this study were to define the expression pattern of one particular mucin, MUC1, in benign and malignant human prostate tissue and to determine if MUC1 expression correlates with tumor grade and stage. Immunohistochemical staining utilizing an anti-MUC1 monoclonal antibody was performed on 4 fetal prostates, 4 specimens of benign prostatic hyperplasia (BPH), and 34 radical prostatectomy specimens. In human fetal and BPH specimens, there was an apical pattern of MUC1 expression, similar to that reported in other normal and benign tissues. Ninety-four percent of the prostate cancers were MUC1 positive. A high percentage of prostate cancer specimens (62%) demonstrated a diffuse, cytoplasmic staining pattern. There was a statistically significant correlation between diffuse MUC1 staining and Gleason pattern, with a diffuse/total staining percentage of 9% in Gleason 2, 64% in Gleason 3, 80% in Gleason 4, and 100% in Gleason 5. More diffuse staining was also seen in samples from patients with high pathologic stage: 21% in T(2), 75% in T(3), and 67% in N(1) disease. These data indicate that MUC1 expression is prevalent in prostate cancer and that diffuse cytoplasmic staining correlates with advanced Gleason pattern and advanced pathologic stage.

Liu X, Kirschenbaum A, Yao S, Lee R, Holland J, Levine A. Inhibition of cyclooxygenase-2 suppresses angiogenesis and growth of prostate cancer in vivo. J Urol 2000 Sep; 164: 820-825.

Purpose: Cyclooxygenase (COX)-2, an inducible enzyme which catalyzes the formation of prostaglandins from arachidonic acid, is expressed in prostate cancer specimens and cell lines. To evaluate the in vivo efficacy of a COX-2 inhibitor in prostate cancer, NS398 was administered to mice inoculated with the PC-3 human prostate cancer cell line. Materials and Methods: A total of 28 male nude mice were inoculated subcutaneously with 1 million PC-3 cells. Tumors were palpable in all 28 animals 1 week after inoculation and mice were randomized to receive either vehicle (control) or NS398, 3 mg./kg. body weight, intraperitoneally three times weekly for 9 weeks. Tumors were measured at weekly intervals. After a 10-week experimental period, mice were euthanized and tumors were immuno- histochemically assayed for proliferation (PCNA), apoptosis (TUNEL) and microvessel density (MVD) (Factor-VIII-related antigen). Tumor VEGF content was assayed by Western blotting. Results: NS398 induced a sustained inhibition of PC-3 tumor cell growth and a regression of existing tumors. Average tumor surface area from control mice was 285 mm.2 as compared with 22 mm.2 from treated mice (93% inhibition, p <0.001). Immunohistochemical analysis revealed that NS398 had no effect on proliferation (PCNA), but induced apoptosis (TUNEL) and decreased MVD (angiogenesis). VEGF expression was also significantly down regulated in the NS398-treated tumors. Conclusions: These results demonstrate that a selective COX-2 inhibitor suppresses PC-3 cell tumor growth in vivo. Tumor growth suppression is achieved by a combination of direct induction of tumor cell apoptosis and down regulation of tumor VEGF with decreased angiogenesis

Industry Relationships

Physicians and scientists on the faculty of the Icahn School of Medicine at Mount Sinai often interact with pharmaceutical, device and biotechnology companies to improve patient care, develop new therapies and achieve scientific breakthroughs. In order to promote an ethical and transparent environment for conducting research, providing clinical care and teaching, Mount Sinai requires that salaried faculty inform the School of their relationships with such companies.

Dr. Kirschenbaum did not report having any of the following types of financial relationships with industry during 2015 and/or 2016: consulting, scientific advisory board, industry-sponsored lectures, service on Board of Directors, participation on industry-sponsored committees, equity ownership valued at greater than 5% of a publicly traded company or any value in a privately held company. Please note that this information may differ from information posted on corporate sites due to timing or classification differences.

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Alexander Kirschenbaum, MD

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