James H. Pringle

There is more than one kind of myofibroblast: analysis of CD34 expression in benign, in situ, and invasive breast lesions.

Aims: Smooth muscle actin (SMA) positive myofibroblasts have been implicated in tumour invasion; however, acquisition of SMA is not limited to peritumorous fibroblasts and other changes in fibroblasts may be more specifically related to the malignant environment. CD34 is a sialomucin expressed by normal breast fibroblasts but lost in invasive carcinomas. The aim of this study was to establish the relation between CD34 and SMA expression in breast fibroblasts and to analyse whether loss of CD34 is specific for invasive disease. Methods: Immunohistochemistry for CD34 and SMA was performed on 135 cases including 10 normal, 10 fibroadenomas, 40 infiltrating ductal carcinomas, 55 cases of ductal carcinoma in situ (DCIS), and 20 radial scar/complex sclerosing lesions. The relation between staining pattern and histopathological features was recorded as positive, negative, or reduced. Results: Fibroblasts around all normal duct–lobule units and those showing epithelial hyperplasia were CD34 positive and mainly SMA negative. In fibroadenomas, fibroblasts retained CD34 but acquired SMA expression. In contrast, fibroblasts around invasive carcinoma were CD34 positive and SMA negative. In DCIS, loss of CD34 was significantly more frequent in high grade tumours than in low or intermediate grade ones (p < 0.001). The acquisition of SMA was seen more frequently than the loss of CD34, particularly in non-high grade DCIS. In all radial scars, fibroblasts were SMA positive but CD34 negative, and a similar pattern was seen in stromal cells in areas of fibrosis following core biopsy. Conclusions: These results show that SMA positive myofibroblasts exhibit variable expression of CD34, indicating that these markers are not coordinately controlled. Loss of CD34 is strongly related to the malignant phenotype, in both invasive and preinvasive disease, but is not entirely specific because radial scar fibroblasts and fibroblasts in reactive fibrosis exhibit a similar phenotype. The functional relevance of altered CD34 expression is unclear but the very focal changes implicate local signalling mechanisms probably of epithelial origin.

Vascular endothelial growth factor mRNA expression in minimal change, membranous, and diabetic nephropathy demonstrated by non-isotopic in situ hybridisation.

AIM: To investigate vascular endothelial growth factor (VEGF) mRNA expression in glomerular disease in the context of heavy proteinuria. METHODS: Non-radioisotopic in situ hybridisation was performed using a cocktail of 12 deoxyoligonucleotides complementary to VEGF mRNA labelled during solid phase synthesis with 2,4-dinitrophenyl. Archival renal biopsies were studied from cases of minimal change nephropathy, membranous nephropathy, diabetic nephropathy, and controls, matched for age, sex, race, and storage time. Hybrid detection used NBT/BCIP colorimetric development. RESULTS: More VEGF mRNA positive glomerular cells per unit cross sectional diameter were seen in minimal change nephropathy (mean (SEM), 19.35 (1.5)) compared with controls (12.6 (1.73)), p < 0.01. In contrast, fewer were seen in diabetic nephropathy (5.93 (0.97)) compared with controls (9.97 (1.25)), p < 0.03. Analysis of membranous nephropathy (10 (1.62)) showed no difference from controls (10.98 (1.51)), NS. In addition, in minimal change nephropathy there was a significant correlation between 24 hour protein excretion at the time of biopsy and the number of VEGF mRNA cells per glomerulus (r = 0.08, p = 0.01). CONCLUSIONS: Using non-radioisotopic in situ hybridisation, VEGF mRNA is almost exclusively expressed by visceral glomerular epithelial cells. Abnormal numbers of cells are seen in both minimal change and diabetic nephropathy. As VEGF exists in a number of functionally distinct isoforms, further study of qualitative VEGF isoform expression in diagnostic groups is indicated.

Primary breast myoepithelial cells exert an invasion-suppressor effect on breast cancer cells via paracrine down-regulation of MMP expression in fibroblasts and tumour cells

In normal breast and ductal carcinoma in situ, myoepithelial cells form an incomplete layer separating the epithelial compartment from the stromal environment. Transition to invasive disease is marked by penetration of the myoepithelial–basement membrane (BM) interface. One mechanism involved in tumour invasion is breakdown of extracellular matrices by matrix metalloproteinases (MMPs). It was hypothesized that myoepithelial cells may modulate tumour invasion by controlling MMP gene expression, both in tumour cells and in peri‐ductal fibroblasts. To investigate this, myoepithelial cells from normal breast were purified and characterized and their effect on tumour cell invasive potential was assessed. The effect on MMP gene expression of breast cancer cells cultured alone or in combination with primary normal breast fibroblasts was also analysed using RT‐PCR with ELISA quantitation, with zymographic analysis to measure enzyme activity. Normal breast myoepithelial cells significantly reduced invasion by the breast cancer cell lines MCF‐7, T47D, MDA‐MB 231, and MDA‐MB 468 when they were cultured alone or in the presence of a fibroblast population. Reduced invasion was associated with changes in MMP gene expression. In those tumour cells expressing MMP, there was a significant down‐regulation of MMP‐2 (MDA‐MB 468, p < 0.001), MMP‐9 (MDA‐MB 231, p = 0.05; MDA‐MB 468, p < 0.001), and MT1‐MMP (p < 0.001 for both MDA‐MB 231 and MDA‐MB 468). Myoepithelial cells also caused a significant decrease in MMP gene expression in co‐cultured fibroblasts. Furthermore, this was associated with reduced gelatinolytic activity as identified by zymography. This study demonstrates for the first time that primary myoepithelial cells from normal breast reduce breast cancer cell invasion and that this is mediated via modulation of both tumour cell and fibroblast function. This emphasizes the importance of the myoepithelial cell in controlling the breast microenvironment and focuses on the potential significance of the loss of this population with disease progression. Copyright

In situ hybridization: alkaline phosphatase visualization of biotinylated probes in cryostat and paraffin sections

SummaryAlkaline phosphatase immunochemical systems were evaluated for use in the demonstration ofin situ hybridized biotin-labelled probes in frozen and fixed sections of tonsil. Three probes were used: total genomic DNA, pHY2.1, a human repetitive sequence which hybridizes to a 2.12 KB sequence on the Y chromosome (2000 repeats) and a 2.0 KB sequence on the autosomes (100–200 repeats), and human papilloma virus type II. Indirect, three- and five-stage detection methods were compared on cryostat sections. The indirect method involved the application of a streptavidin, biotinylated alkaline phosphatase sequence. The three-stage procedure comprised a mouse monoclonal anti-biotin, rabbit anti-(mouse immunoglobulin), mouse APAAP system. In the five-stage method the indirect and three-stage reagents were sequentially applied. Alkaline phosphatase was demonstrated using a Fast Red naphthol-capture method.The total genomic DNA probe was used initially to investigate hybridization conditions including the optimum temperature of denaturation, which was found to be higher than previously reported. The five-stage detection method gave the most sensitive results for the Y sequence probe, with intense demonstration of the Y body in male nuclei and autosomal sequences in female nuclei. This method was then applied to fixed tissue sections and gave Y body signals on Bouins and Carnoys fixed tissue. On the other hand tissue fixed using formalin-based solutions required proteolytic digestion as a pretreatment to hybridization for a Y body signal. The application of this methodology to viral diagnosis in routine fixed anogenital tissue and cytological preparations was also demonstrated.

Increased dimeric IgA-producing B cells in tonsils in IgA nephropathy determined by in situ hybridization for J chain mRNA

The origin of mesangial IgA deposits in IgA nephropathy (IgAN) remains obscure. A significant proportion of deposited immunoglobulin is dimeric (J chain‐positive). Previous studies of J chain expression within lymphoid tissue in IgAN have utilized antibodies which other investigators have found to be non‐specific. To address this problem, we have developed an in situ hybridization (ISH) method for the detection of J chain mRNA within IgA plasma cells. Tonsils from 12 patients with IgAN and 12 controls were studied using (i) non‐isotopic ISH for J chain mRNA, and (ii) combined immunofluorescence (IF) and fluorescent ISH. J chain mRNA‐positive cells were identified in germinal centres, and within the subepithelial and interfollicular zones. A greater number of J chain mRNA‐positive cells were found in the germinal centres of patients (mean 57.7±4.6 cells/105μm2) compared with controls (mean 36.9±3.5 cells/105μm2) (P < 0.001). Combined IF and fluorescent ISH showed a greater proportion of J chain mRNA‐positive interfollicular IgA cells in patient tonsils (3.2±3.4%) compared with controls (21±2.3%; P < 0.02). These results indicate a shift towards dimeric IgA production in the tonsils in IgAN. In addition, the finding of excess numbers of J chain‐positive IgA‐negative cells within germinal centres suggests that an abnormality may be present at the B cell differentiation stage before IgA switching. These results further highlight immune abnormalities within the tonsil as a central feature of abnormal polymeric IgA biology in this common form of glomerulonephritis.

Identification of a human ribosomal protein mRNA with increased expression in colorectal tumours

A human ribosomal protein cDNA was selected from a normal colon cDNA library on the basis of overexpression in familial adenomatous polyposis. Nucleotide sequence analysis was used to identify this cDNA as corresponding to the human equivalent of the rat ribosomal protein L31 (HL31). We have quantified the expression of HL31 mRNA in colorectal tumours and found overexpression in 23 out of 23 cases. Our results indicate that HL31 is associated with a malfunction of normal growth regulatory mechanisms in these tumours, and suggest a role for HL31 in proliferation and neoplasia.

Apoptosis in chronic viral hepatitis parallels histological activity: An immunohistochemical investigation using anti‐activated caspase‐3 and M30 Cytodeath antibody

Apoptosis is implicated as a major pathogenic mechanism in chronic hepatitis B and C. Previous studies of the relationship between apoptotic rates and histological necroinflammatory activity have produced conflicting results. Hepatocyte apoptosis was assessed in liver tissue from 32 cases of chronic viral hepatitis, seven cases of hepatocellular carcinoma (HCC) and six cases of steatohepatitis as non‐viral disease controls and eight cases of control liver. Apoptotic rates were measured using H&E morphological assessment and immunohistochemical staining with antibodies to activated caspase‐3 and M30. Histological necroinflammatory activity of viral hepatitis cases was scored using the Knodell scoring system, and the cases were divided according to their score into group 1 (mean 2.43 ± 0.48) and group 2 (mean 7.80 ± 0.49). Apoptotic indices were significantly higher in group 2 than group 1 using H&E (11.53 ± 2.70 vs. 0 ± 0, P = 0.015) and activated caspase‐3 (22.01 ± 5.27 vs. 1.79 ± 1.79, P = 0.03) methods but were not significantly higher with M30 (3.80 ± 1.74 vs. 0 ± 0, P = 0.207). Apoptotic scores using an antibody to activated caspase‐3 are significantly higher in cases of chronic viral hepatitis with greater histological necroinflammatory scores, supporting a central role for apoptosis in disease pathogenesis. This method offers an alternative to routine histological assessment for measuring disease activity.

Angiotropic lymphoma: report of a case with histiocytic features.

Angiotropic lymphoma, also known as intravascular lymphomatosis, is characterised by widespread intravascular proliferation of malignant lymphoid cells, usually without evidence of focal disease. A case of a 52 year old man referred for investigation of a two year history of pyrexia of unknown origin, skin rash and multiple organ failure is described. Angiotropic lymphoma was seen in gastric, colonic and skin biopsy specimens, and review of an earlier skin biopsy specimen showed similar morphological features. In contrast to previous cases which showed B or T cell differentiation, immunohistochemical examination was positive for histiocyte markers. Molecular studies showed no evidence of immunoglobulin heavy chain gene or T cell receptor gene rearrangement. The patient responded to combination chemotherapy, comprising cyclophosphamide, doxorubicin, etoposide, and prednisolone. This case highlights the fact that advanced lymphoma may be present without evidence of focal disease and that the diagnosis may be missed easily both clinically and histologically.

Detection of immunoglobulin heavy chain gene rearrangements in Hodgkin's disease using PCR.

AIM--To detect clonal rearrangements of the immunoglobulin (Ig) heavy chain gene in Hodgkins disease tissue using the polymerase chain reaction (PCR). METHODS--DNA extracted from 36 samples of Hodgkins disease was analysed using PCR and primers from conserved sequences in the variable (VH) and joining (JH) regions. RESULTS--Clonal rearrangement was detected only in one case. Evidence of clonal immunoglobulin gene rearrangement had been detected previously in this case using conventional Southern blot analysis. CONCLUSIONS--The sensitivity of the two techniques is equivalent and clonal Ig heavy chain gene rearrangements are rare in Hodgkins disease.

Absence of epstein—barr virus in carcinoma of the cervix

Background. Cervical epithelium is known to contain receptors for Epstein‐Barr virus (EBV) and is a recognized site of viral shedding. Recent cases of nasopharyngeal carcinoma have been associated with cervical carcinoma, leading to speculation of a possible etiologic link between EBV and cervical carcinoma.