Biomedical subjects

C J Vallorosi

Publications and source records attributed to C J Vallorosi.

5 recordsLinked to original sources

PubMed2001

Posttranslational truncation and inactivation of human E-cadherin distinguishes prostate cancer from matched normal prostate.

An essential event in the progression of adenocarcinoma is the loss of organized epithelial attachment (both to the basement membrane and to adjoining epithelial cells). The E-cadherin cell adhesion molecule has an established function in maintaining normal phenotype and tissue homeostasis, and loss of E-cadherin function has been implicated in tumorigenesis. Aberrations in E-cadherin are associated with prostate cancer progression; however, these aberrations are not simply a result of prodigious allelic loss. We have previously demonstrated a novel posttranslational truncation within the cytosolic domain of native Mr 120,000 E-cadherin to a membrane-bound Mr 97,000 species. We hypothesize that truncation of E-cadherin is an inactivating event that is significantly increased in localized prostate tumors and that it represents a novel molecular event that may distinguish prostate cancer from adjacent normal tissue. E-cadherin was characterized by Western blot analysis in matched normal and cancer tissue from 18 prostate cancer patients. Imaging and densitometry software were used to quantify the truncation of E-cadherin by measuring the ratio of Mr 97,000 E-cadherin to Mr 120,000 E-cadherin, which was significantly increased in the tumor aspect of the prostate gland. Herein, we report the first experiment comparing case-matched human normal and cancerous prostate tissue in the context of E-cadherin truncation.

Blotting, Western↗

PubMed2000

Truncation of the beta-catenin binding domain of E-cadherin precedes epithelial apoptosis during prostate and mammary involution.

A potential target of hormone action during prostate and mammary involution is the intercellular junction of adjacent secretory epithelium. This is supported by the long-standing observation that one of the first visible stages of prostate and mammary involution is the disruption of interepithelial adhesion prior to the onset of apoptosis. In a previous study addressing this aspect of involution, we acquired compelling evidence indicating that the disruption of E-cadherin-dependent adhesion initiates apoptotic programs during prostate and mammary involution. In cultured prostate and mammary epithelial cells, inhibition of E-cadherin-dependent aggregation resulted in cell death following apoptotic stimuli. Loss of cell-cell adhesion in the nonaggregated population appeared to result from the rapid truncation within the cytosolic domain of the mature, 120-kDa species of E-cadherin (E-cad(120)). Immunoprecipitations from cell culture and involuting mammary gland demonstrated that this truncation removed the beta-catenin binding domain from the cytoplasmic tail of E-cadherin, resulting in a non-beta-catenin binding, membrane-bound 97-kDa species (E-cad(97)) and a free cytoplasmic 35-kDa form (E-cad(35)) that is bound to beta-catenin. Examination of E-cadherin expression and cellular distribution during prostate and mammary involution revealed a dramatic reduction in junctional membrane staining that correlated with a similar reduction in E-cad(120) and accumulation of E-cad(97) and E-cad(35). The observation that E-cadherin was truncated during involution suggested that hormone depletion activated the same apoptotic pathway in vivo as observed in vitro. Based on these findings, we hypothesize that truncation of E-cadherin results in the loss of beta-catenin binding and cellular dissociation that may signal epithelial apoptosis during prostate and mammary involution. Thus, E-cadherin may be central to homeostatic regulation in these tissues by coordinating adhesion-dependent survival and dissociation-induced apoptosis.

Apoptosis↗

PubMed2000

Coordinate expression of cytokeratins 7 and 20 in prostate adenocarcinoma and bladder urothelial carcinoma.

We studied the expression of cytokeratin (CK)-7 and CK-20 in prostate adenocarcinoma and urothelial carcinoma and evaluated their usefulness for distinguishing high-grade forms of these tumors. We examined prostate adenocarcinoma in 59 radical prostatectomy specimens and in 10 autopsy specimens showing metastatic disease, and urothelial carcinoma of the bladder in 28 cystectomy specimens. Immunohistochemical staining for CK-7, CK-20, and prostate-specific antigen (PSA) was performed on paraffin sections. For prostate adenocarcinoma, 5 cases had only CK-7 positivity, 5 had only CK-20 focal positivity, 1 stained for both markers, and 48 were negative for both. PSA was positive in all but 1 poorly differentiated prostatic carcinoma. In the autopsy cases, PSA was expressed in the prostate and the metastatic tumors in most cases; few cases were focally positive for CK-7 or CK-20, but none was positive for both markers. For the urothelial tumors, CK-7 was the sole positive marker in 6 cases, and CK-20 in 1 case; 17 cases were positive for both, and 4 were negative for both. All urothelial carcinomas were PSA negative. Although PSA is useful for differentiating prostatic from urothelial carcinoma, CK-7 and CK-20 are helpful when both are positive, supporting the diagnosis of urothelial carcinoma. However, if only 1 marker is positive or both are negative, these markers have limited usefulness for distinguishing these carcinomas.

Adenocarcinoma↗

PubMed1999

E-cadherin mediates aggregation-dependent survival of prostate and mammary epithelial cells through the retinoblastoma cell cycle control pathway.

E-cadherin and the retinoblastoma tumor suppressor (Rb) are traditionally associated with diverse regulatory aspects of cell growth and differentiation. However, we have discovered new evidence, which suggests that these proteins are functionally linked in a physiologic pathway required for cell survival and programmed cell death. Pharmacological activation of protein kinase C (PKC) or inducible overexpression and activation of the alpha isozyme of PKC (PKCalpha) resulted in approximately 60% apoptosis of mammary and prostate epithelial cells. Interestingly, the surviving cells had undergone dramatic aggregation concurrent with increased E-cadherin expression. When aggregation was inhibited by the addition of an E-cadherin-blocking antibody, apoptosis increased synergistically. We hypothesized that survival of the aggregated population was associated with contact-inhibited growth and that apoptosis might result from aberrant growth regulatory signals in non-aggregated, cycling cells. This hypothesis was confirmed by experiments that demonstrated that E-cadherin-dependent aggregation resulted in Rb-mediated G1 arrest and survival. Immunoblot analysis and flow cytometry revealed that hypophosphorylated Rb was present in non-aggregated, S phase cultures concurrent with synergistic cell death. We have also determined that the loss of membrane E-cadherin and subsequent hypophosphorylation of Rb in luminal epithelial cells preceded apoptosis induced by castration. These findings provide compelling evidence that suggests that E-cadherin-mediated aggregation results in Rb activation and G1 arrest that is critical for survival of prostate and mammary epithelial cells. These data also indicate that Rb can initiate a fatal growth signal conflict in non-aggregated, cycling cells when the protein is hypophosphorylated as these epithelial cells enter S phase.

Apoptosis↗

PubMed1999

Renal malacoplakia.

We present a well-documented case of biopsy-proven renal malacoplakia with an excellent response to oral fluoroquinolone therapy.

Adolescent↗