V-ATPase-dependent repression of androgen receptor in prostate cancer cells.

Prostate Cancer (PCa) is the most commonly diagnosed cancer and the third leading cause of death for men in the United States. Suppression of androgen receptor (AR) expression is a desirable mechanism to manage PCa. Our studies showed that AR expression was reduced in LAPC4 and LNCaP PCa cell lines treated with nanomolar concentrations of the V-ATPase inhibitor concanamycin A (CCA).

F-actin reorganization by V-ATPase inhibition in prostate cancer.

The vacuolar ATPase (V-ATPase) proton pump sustains cellular pH homeostasis, and its inhibition triggers numerous stress responses. However, the cellular mechanisms involved remain largely elusive in cancer cells. We studied V-ATPase in the prostate cancer (PCa) cell line PC-3, which has characteristics of highly metastatic PCa.

Cell-extrinsic consequences of epithelial stress: activation of protumorigenic tissue phenotypes.

Introduction: Tumors are characterized by alterations in the epithelial and stromal compartments, which both contribute to tumor promotion. However, where, when, and how the tumor stroma develops is still poorly understood. We previously demonstrated that DNA damage or telomere malfunction induces an activin A-dependent epithelial stress response that activates cell-intrinsic and cell-extrinsic consequences in mortal, nontumorigenic human mammary epithelial cells (HMECs and vHMECs).

Human mammary cancer progression model recapitulates methylation events associated with breast premalignancy.

Introduction: We have previously identified a rare subpopulation of variant human mammary epithelial cells (vHMEC) with repressed p16INK4A that exist in disease-free women yet display premalignant properties, suggesting that they have engaged the process of malignant transformation. In order to gain insight into the molecular alterations required for vHMEC to progress to malignancy, and to characterize the epigenetic events associated with early progression, we examined the effect of oncogenic stress on the behavior of these cells.

Methods: HMEC that express p16INK4A and vHMEC that do not, were transduced with constitutively active Ha-rasV12 and subsequently exposed to serum to determine whether signals from the cellular microenvironment could cooperate with ras to promote the malignant transformation of vHMEC.

Telomere content correlates with stage and prognosis in breast cancer.

Purpose: To evaluate the hypothesis that telomere DNA content (TC) in breast tumor tissue correlates with TNM staging and prognosis.

Experimental Design: Slot blot assay was used to quantitate TC in 70 disease-free normal tissues from multiple organ sites, and two independent sets of breast tumors containing a total of 140 samples. Non-parametric Rank-Sums tests, logistic regression and Cox proportional hazards models were used to evaluate the relationships between TC and tumor size, nodal involvement, TNM stage, 5-year survival and disease-free interval.

Telomere DNA content and allelic imbalance demonstrate field cancerization in histologically normal tissue adjacent to breast tumors.

Cancer arises from an accumulation of mutations that promote the selection of cells with progressively malignant phenotypes. Previous studies have shown that genomic instability, a hallmark of cancer cells, is a driving force in this process. In the present study, two markers of genomic instability, telomere DNA content and allelic imbalance, were examined in two independent cohorts of mammary carcinomas.

p38 regulates cyclooxygenase-2 in human mammary epithelial cells and is activated in premalignant tissue.

The immediate-early gene, cyclooxygenase-2 (COX-2), is induced in a variety of inflammatory and neoplastic processes and is believed to play an important role in tumorigenesis. In this study, we identify an important upstream regulatory pathway of COX-2 expression in variant human mammary epithelial cells (vHMEC), which has been shown to exhibit phenotypes important for malignancy. We find that the stress-activated kinase, p38, is phosphorylated and activated in vHMEC compared with HMEC and is responsible for the expression of COX-2 in vHMEC as cells grow in culture.

Association between cancer-free survival and telomere DNA content in prostate tumors.

Purpose: We evaluated the hypothesis that telomere DNA content (TC) in prostate tumor tissue is associated with time to prostate cancer recurrence.

Materials And Methods: The cohort was comprised of 77 men who underwent prostatectomy between 1982 and 1995. Slot blot assay was used to measure TC in DNA extracted from paraffin embedded tumor and nearby, histologically normal prostate (NHN) tissues.

Genetic and epigenetic changes in mammary epithelial cells may mimic early events in carcinogenesis.

Studies of human mammary epithelial cells from healthy individuals are providing novel insights into how early epigenetic and genetic events affect genomic integrity and fuel carcinogenesis. Key epigenetic changes, such as the hypermethylation of the p16 (INK4a) promoter sequences, create a previously unappreciated preclonal phase of tumorigenesis in which a subpopulation of mammary epithelial cells are positioned for progression to malignancy (Romanov et al. , 2001, Nature , 409:633-637; Tlsty et al.

Chemiluminescent measurement of telomere DNA content in biopsies.

Telomeres are nucleoprotein complexes that protect the ends of chromosomes from fusion and degradation. They are typically shorter in tumor cells than in paired normal cells, and shorter telomeres are associated with poor outcome in cancer. We previously described a slot blot-based methodfor measuring telomere DNA content, a proxy for telomere length.