Steven R. Tahan

Increased expression of stem cell markers in malignant melanoma.

The potential role of stem cells in neoplasia is a subject of recent interest. Three markers of melanocytic stem cells have been described recently. CD166 is expressed on the surface of mesenchymal stem cells and has been found on human melanoma cell lines. CD133 is expressed on the surface of dermal-derived stem cells that are capable of differentiating into neural cells. Nestin is an intermediate filament expressed in the cytoplasm of neuroepithelial stem cells. In this study, we evaluate the expression of these markers and possible differences among banal nevi, primary melanoma, and metastastic melanoma. Tissue microarrays containing normal tissue and 226 melanocytic lesions (71 banal nevi, 71 in situ and invasive melanomas, and 84 metastatic melanomas) were studied by immunohistochemistry using monoclonal antibodies CD166, CD133, and nestin. A significantly greater percentage of melanomas (combined primary and metastatic) contained cells that expressed CD166 (P=0.005), CD133 (P=0.003), and nestin (P=0.03) than banal nevi. Only nestin showed a statistical difference when comparing primary and metastatic melanoma (P=0.05). A stepwise increase in the proportion of lesions expressing all three markers was observed from banal nevi (2/19) to primary melanomas (8/17) to metastatic melanoma (19/28), P=0.0005. All cases of metastatic melanoma expressed at least one stem cell marker. The increased expression of CD166, CD133, and nestin in melanoma suggests that progression to malignant melanoma likely involves genetic pathways instrumental to stem cell biology and normal tissue development. Further studies and characterization of these pathways may also reveal new prognostic markers for a disease whose prognosis in advanced stages is dismal.

Nitric oxide production in experimental alcoholic liver disease in the rat : role in protection from injury

BACKGROUND & AIMS Regulation of blood flow and oxygen supply are important pathogenetic factors in alcoholic liver disease. Because nitric oxide may have an important role, its effects on alcoholic liver injury were investigated. METHODS Rats were fed ethanol intragastrically with either saturated fat or corn oil. Spontaneous production of NO by liver nonparenchymal cells was compared in the two dietary groups. Two additional groups of rats fed corn oil and ethanol were treated with either an NO inhibitor (L-NAME) or supplemented with L-arginine. Liver pathology and plasma NO production were evaluated. RESULTS In the corn oil and ethanol group, a progressive decrease in liver nonparenchymal cell NO production and increased plasma NO levels were associated with liver injury. Reduced nicotinamide adenine dinucleotide phosphate diaphorase staining showed increased centrilobular staining of hepatocytes in the corn oil and ethanol group and L-NAME-treated group. Moreover, L-NAME increased the severity, whereas L-arginine supplementation completely prevented liver injury. In the saturated fat and ethanol group, in which there was no liver injury, the levels of NO2- in nonparenchymal supernatant were 5-10-fold higher than in the corn oil and ethanol group. CONCLUSIONS Decreased NO production by nonparenchymal cells may contribute to liver injury in ethanol-fed rats, and the compensatory increase in hepatocyte NO production may contribute to centrilobular liver injury.

Prediction of early relapse and shortened survival in patients with breast cancer by proliferating cell nuclear antigen score.

Background. Cell cycle kinetic measures have been shown to have prognostic significance in breast cancer. Methods that have been used to assess the proliferating fraction of tumors include measurements of DNA content with S‐phase calculation by flow cytometric analysis, radioisotope‐labeled nucleotide incorporation, and cell cycle–associated protein expression. The recent discovery of the S‐phase‐specific nuclear protein proliferating cell nuclear antigen (PCNA) opens the door for a novel approach to cell kinetic measurement with an immunocytochemical assay.

Systematic underreporting of cutaneous malignant melanoma in Massachusetts: Possible implications for national incidence figures

An independent tabulation of incidence of cutaneous malignant melanoma in Massachusetts indicates that 12% and perhaps as many as 19% of new cases of cutaneous malignant melanoma in Massachusetts are not recorded in the Massachusetts Cancer Registry, significantly more than the expected 5% (p = 0.0001). The increasing number of nonhospital medical settings in which melanomas can be diagnosed and/or treated appears to account for this discrepancy. We suspect that these findings in Massachusetts also apply to cancer reporting systems in other regions of the United States. We suggest that the true incidence of cutaneous malignant melanoma in Massachusetts, and perhaps in the United States, may be significantly higher than reported.

Dissociation of Hemopoietic Chimerism and Allograft Tolerance After Allogeneic Bone Marrow Transplantation

Creation of stable hemopoietic chimerism has been considered to be a prerequisite for allograft tolerance after bone marrow transplantation (BMT). In this study, we demonstrated that allogeneic BMT with bone marrow cells (BMC) prepared from either knockout mice deficient in both CD4 and CD8 T cells or CD3E-transgenic mice lacking both T cells and NK cells maintained a high degree of chimerism, but failed to induce tolerance to donor-specific wild-type skin grafts. Lymphocytes from mice reconstituted with T cell-deficient BMC proliferated when they were injected into irradiated donor strain mice, whereas lymphocytes from mice reconstituted with wild-type BMC were unresponsive to donor alloantigens. Donor-specific allograft tolerance was restored when donor-type T cells were adoptively transferred to recipient mice given T cell-deficient BMC. These results show that donor T cell engraftment is required for induction of allograft tolerance, but not for creation of continuous hemopoietic chimerism after allogeneic BMT, and that a high degree of chimerism is not necessarily associated with specific allograft tolerance.

Histological characterization of regression in acquired immunodeficiency syndrome-related Kaposi's sarcoma.

Background:  Kaposis sarcoma (KS) is an angioproliferative lesion that may regress or progress. Progression is related to spindle cell proliferation and the expression of human herpes virus‐8 latency genes, including latent nuclear antigen‐1 (LNA‐1), cyclin‐D1, and bcl‐2. KS regression has not been well characterized histologically. Therefore, this study was undertaken to characterize the histopathology of pharmacologically induced regressed cutaneous KS.

Clinical validation of a gene expression signature that differentiates benign nevi from malignant melanoma

Histopathologic examination is sometimes inadequate for accurate and reproducible diagnosis of certain melanocytic neoplasms. As a result, more sophisticated and objective methods have been sought. The goal of this study was to identify a gene expression signature that reliably differentiated benign and malignant melanocytic lesions and evaluate its potential clinical applicability. Herein, we describe the development of a gene expression signature and its clinical validation using multiple independent cohorts of melanocytic lesions representing a broad spectrum of histopathologic subtypes.

Accuracy of biopsy sampling for subtyping basal cell carcinoma.

BACKGROUND Basal cell carcinoma (BCC) is a common skin cancer for which the treatment and recurrence risk correlate with the histologic subtype. Limited information is available regarding the accuracy of biopsy in diagnosing BCC subtypes. OBJECTIVE We sought to determine the correlation between BCC subtypes present in a biopsy specimen and the actual subtypes present in a tumor. METHODS In this retrospective study, skin biopsy specimens and corresponding excisions were reviewed. All histologic subtypes present in the biopsy specimen were reported and compared with the composite BCC subtype present in the biopsy specimen and excision. RESULTS A total of 232 biopsy specimens and corresponding wide excisions were examined. The biopsy specimen accuracy rate was 82% for punch and shave biopsy specimens. Mixed histologic subtypes were seen in 54% of the cases, half of which contained an aggressive subtype (infiltrative, morpheaform, or micronodular). There was an 18% discordance rate between the biopsy specimen subtype and the composite subtype. Importantly, 40% of these discordant cases (7% of all cases examined) had an aggressive subtype that was not sampled in the initial biopsy specimen. Furthermore, some cases were misidentified as infiltrative subtype in the biopsy specimen as a result of misinterpretation of surface ulceration and reactive stromal changes. LIMITATIONS The limited number of punch biopsy specimens and the fact that Mohs excisions were not included are limitations. CONCLUSIONS Punch and shave biopsy specimens provided adequate sampling for correct BCC subtyping in 82% of the cases examined. However, 18% of the biopsy specimens were misidentified, some of which missed an aggressive component. Thus, there are potential pitfalls in the identification of BCC subtypes in biopsy specimens, which may have important implications in treatment outcome.

DNA flow cytometric analysis and prognosis of axillary lymph node-negative breast carcinoma

Methods. The prognostic significance of flow cytometric analysis in patients with node‐negative invasive breast carcinoma was evaluated in a retrospective series of 158 patients with a minimum follow‐up study of 9 years.

Nucleolar organizer regions (AgNOR) and Ki-67 immunoreactivity in cutaneous melanocytic lesions.

A stepwise schema for the developmental biology of malignant melanomas has been proposed. In this study, two properties associated with malignant transformation— AgNOR production and Ki-67 immunoreactivity—were tested on a series of lesions representative of this model. Fourteen ordinary nevi (N). seven dysplastic nevi (DN), 12 radial growth phase melanomas (RGPM). and eight vertical growth phase melanomas (VGPM) were stained for AgNORs; Ki-67 immunoreactivity was determined in paraffin sections after antigen retrieval. AgNORs averaged 2.1 in N. 3.8 in DN. 5.4 in RGPM. and 7.3 in VGPM (p < 0.001 between all groups). Ki-67 immunoreactivity averaged <1 in nevi. 1.6 in dysplastic nevi, 23.3 in RGPM. and 20.1 in VGPM. No difference was observed between N and DN. and RGPM/VGPM had higher Ki-67 indices than N/DN (p < 0.01). Stepwise increases in cellular AgNORs parallel the melanocytic progression model and thereby corroborate the intermediate nature of the dysplastic nevus. The order of magnitude increase in Ki-67 immunoreactivity observed in RGP and VGP melanomas compared with N and DN likely reflects the onset of loss of cell cycle control in these lesions.