Markku Tammi

Hyaluronan in Peritumoral Stroma and Malignant Cells Associates with Breast Cancer Spreading and Predicts Survival

Hyaluronan (HA) is an extracellular matrix polysaccharide that promotes cell migration through its cell surface receptors and by effecting changes in the physical environment. HA expression is frequently increased in malignant tumors, whereas its association with the invasive potential and patient outcome in breast cancer has not been reported. The localization and signal intensity of HA was analyzed in 143 paraffin-embedded tumor samples of human breast carcinoma using a biotinylated HA-specific probe. In the immediate peritumoral stroma, HA signal was moderately or strongly increased in 39% and 56% of the cases, respectively. Normal ductal epithelium showed no HA, whereas in 57% of the tumors at least some of the carcinoma cells were HA positive. The intensity of the stromal HA signal and the presence of cell-associated HA were both significantly related to poor differentiation of the tumors, axillary lymph node positivity, and short overall survival of the patients. In Coxs multivariate analysis, both the intensity of stromal HA signal alone and that combined with the HA positivity in tumor cells were independent prognostic factors for overall survival. These results suggest that HA is directly involved in the spreading of breast cancer and may offer a potential target for new therapies.

Microspectrophotometric quantitation of glycosaminoglycans in articular cartilage sections stained with Safranin O

SummaryA new microspectrophotometric method was developed for quantitation of glycosaminoglycans with Safranin O dye in articular cartilage matrix. From histological sections molar extinction coefficient of Safranin O was determined and used to measure the dye content of the sections. The amount of glycosaminoglycans was determined with depth of bovine articular cartilage by both gas chromatography and thin layer chromatography to calculate the fixed negative charge content. Comparison between the results revealed that binding of Safranin O to glycosaminoglycan polyanions was stoichiometric and showed minimal nonspecific staining. The method provides an accurate technique for quantitation and localization of fixed negative charge content of glycosaminoglycans in the articular cartilage matrix. Specific enzyme digestions enable detection of separate glycosaminoglycans.

Epidermal Growth Factor Activates Hyaluronan Synthase 2 in Epidermal Keratinocytes and Increases Pericellular and Intracellular Hyaluronan

Hyaluronan is an abundant and rapidly turned over matrix molecule between the vital cell layers of the epidermis. In this study, epidermal growth factor (EGF) induced a coat of hyaluronan and a 3–5-fold increase in its rate of synthesis in a rat epidermal keratinocyte cell line that has retained its ability for differentiation. EGF also increased hyaluronan in perinuclear vesicles, suggesting concurrent enhancement in its endocytosis. Cell-associated hyaluronan was most abundant in elongated cells that were stimulated to migrate by EGF, as determined in vitroin a wound healing assay. Large fluctuations in the pool size of UDP-N-acetylglucosamine, the metabolic precursor of hyaluronan, correlated with medium glucose concentrations but not with EGF. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed no increase in hyaluronan synthases 1 and 3 (Has1 and Has3), whereas Has2 mRNA increased 2–3-fold in less than 2 h following the introduction of EGF, as estimated by quantitative RT-PCR with a truncated Has2 mRNA internal standard. The average level of Has2 mRNA increased from ∼6 copies/cell in cultures before change of fresh medium, up to ∼54 copies/cell after 6 h in EGF-containing medium. A control medium with 10% serum caused a maximum level of ∼21 copies/cell at 6 h. The change in the Has2 mRNA levels and the stimulation of hyaluronan synthesis followed a similar temporal pattern, reaching a maximum level at 6 h and declining toward 24 h, a finding in line with a predominantly Has2-dependent hyaluronan synthesis and its transcriptional regulation.

Hyaluronan in human tumors: pathobiological and prognostic messages from cell-associated and stromal hyaluronan.

Cancers are supported by a distinct type of connective tissue stroma, crucial for tumor survival and advancement. Hyaluronan is a major matrix molecule in the stroma of many common tumors, and involved in their growth and spreading. Here we focus in recent data on stromal hyaluronan in human tumors, and that on the surface of the malignant cells. Hyaluronan accumulation is most conspicuous in malignancies that develop in cells and tissues normally devoid of hyaluronan, such as single layered epithelia and their hyaluronan-poor connective tissue stroma. The magnitude of the hyaluronan accumulation in the malignant epithelium itself (e.g. colon and gastric cancers) or tumor stroma (breast, ovarian, prostate cancers) strongly correlates with an unfavorable prognosis of the patient, i.e. advancement of the malignancy. A completely different pattern arises from stratified epithelia that normally produce hyaluronan and are surrounded by a hyaluronan-rich stroma. The cell surface of the latter group of tumors (e.g. squamous cell carcinomas of skin, mouth, larynx and esophagus, and skin melanoma) show abundant hyaluronan which tends to get reduced and patchy in the most advanced stages of the tumors, suggesting enhanced turnover. While the assays of human tumors represent snapshots of currently unknown processes and kinetics of hyaluronan metabolism, it is obvious that hyaluronan accumulation at some stage is an inherent feature in most of the common epithelial malignant tumors. The possible contributions of inflammatory cells, stem cells, mutated stromal cells, or otherwise deranged growth factor exchange between stromal and cancer cells are discussed as possible explanations to hyaluronan abundance in the tumors. The importance of hyaluronan in human tumor progression will be further clarified when drugs become available to modify hyaluronan metabolism.

Hyaluronan in human malignancies

Hyaluronan, a major macropolysaccharide in the extracellular matrix of connective tissues, is intimately involved in the biology of cancer. Hyaluronan accumulates into the stroma of various human tumors and modulates intracellular signaling pathways, cell proliferation, motility and invasive properties of malignant cells. Experimental and clinicopathological evidence highlights the importance of hyaluronan in tumor growth and metastasis. A high stromal hyaluronan content is associated with poorly differentiated tumors and aggressive clinical behavior in human adenocarcinomas. Instead, the squamous cell carcinomas and malignant melanomas tend to have a reduced hyaluronan content. In addition to the stroma-cancer cell interaction, hyaluronan can influence stromal cell recruitment, tumor angiogenesis and epithelial-mesenchymal transition. Hyaluronan receptors, hyaluronan synthases and hyaluronan degrading enzymes, hyaluronidases, are involved in the modulation of cancer progression, depending on the tumor type. Furthermore, intracellular signaling and angiogenesis are affected by the degradation products of hyaluronan. Hyaluronan has also therapeutic implications since it is involved in multidrug resistance.

4-Methylumbelliferone inhibits hyaluronan synthesis by depletion of cellular UDP-glucuronic acid and downregulation of hyaluronan synthase 2 and 3.

Hyaluronan accumulation on cancer cells and their surrounding stroma predicts an unfavourable disease outcome, suggesting that hyaluronan enhances tumor growth and spreading. 4-Methylumbelliferone (4-MU) inhibits hyaluronan synthesis and retards cancer spreading in experimental animals through mechanisms not fully understood. These mechanisms were studied in A2058 melanoma cells, MCF-7 and MDA-MB-361 breast, SKOV-3 ovarian and UT-SCC118 squamous carcinoma cells by analysing hyaluronan synthesis, UDP-glucuronic acid (UDP-GlcUA) content, and hyaluronan synthase (HAS) mRNA levels. The maximal inhibition in hyaluronan synthesis ranged 22-80% in the cell lines tested. Active glucuronidation of 4-MU produced large quantities of 4-MU-glucuronide, depleting the cellular UDP-GlcUA pool. The maximal reduction varied between 38 and 95%. 4-MU also downregulated HAS mRNA levels: HAS3 was 84-60% lower in MDA-MB-361, A2058 and SKOV-3 cells. HAS2 was the major isoenzyme in MCF-7 cells and lowered by 81%, similar to 88% in A2058 cells. These data indicate that both HAS substrate and HAS2 and/or HAS3 mRNA are targeted by 4-MU. Despite different target point sensitivities, the reduction of hyaluronan caused by 4-MU was associated with a significant inhibition of cell migration, proliferation and invasion, supporting the importance of hyaluronan synthesis in cancer, and the therapeutic potential of hyaluronan synthesis inhibition.

Softening of canine articular cartilage after immobilization of the knee joint

Using the indentation method, effects of immobilization with a splint for 11 weeks on the stiffness of the articular cartilage in the canine knee were investigated. Stiffness was determined for femoral, tibial, and patellar articular cartilages with nine, eight, and three test points, respectively, in the form of elastic moduli. Immobilization, without causing any macroscopic changes on cartilage surface, influenced the quality and quantity of articular cartilage. Immobilization caused significant softening of the femoral and tibial cartilages. The rate of deformation under the test load increased (42%) and the average thickness of the cartilage decreased (9%) as compared with the controls. Normal cartilage stiffness remained in the contact area between the patella and patellar surface of the femur, probably as a consequence of the sustained, but not forceful, loading between the femur and the patella produced by the flexion of the knee joint.

Expression of Extracellular Matrix Components Versican, Chondroitin Sulfate, Tenascin, and Hyaluronan, and Their Association with Disease Outcome in Node-Negative Breast Cancer

Purpose: The purpose is to determine whether the levels of expression of extracellular matrix components in peritumoral stroma are predictive of disease outcome for women with node-negative breast cancer. Experimental Design: Tumor tissue from 86 patients with node-negative breast cancer was examined by immunohistochemical staining for the expression of versican, chondroitin sulfate (CS), tenascin, and hyaluronan (HA). With the exception of HA, the expression of the extracellular matrix components was measured by video image analysis. Statistical correlation of the immunohistochemical data with clinicopathological characteristics and disease outcome was performed. Results: All of the extracellular matrix components were present in the peritumoral stroma of the entire study cohort. In contrast, immunoreactivity within the cancer cell was observed in 82% of tumors for HA, 12% for CS, and 4% for tenascin; no immunostaining of cancer cells for versican was observed for any of the tumors. Cox regression and Kaplan-Meier analyses indicated that elevated expression of stromal versican predicted increased risk and rate of relapse in this cohort. Elevated expression of tenascin was predictive of increased risk and rate of death only. Although neither CS nor HA were predictive of disease outcome in this cohort, tumor size was predictive of increased risk and rate of both relapse and survival. Conclusions: Elevated expression within peritumoral stromal matrix of versican and tenascin was predictive of relapse-free and overall survival, respectively, in women with node-negative breast cancer.

Distribution of hyaluronan and its CD44 receptor in the epithelia of human skin appendages

SummaryBiotinylated hyaluronan (HA) binding complex (HABC) from bovine articular cartilage proteoglycan was used as a histological probe to study the localization of HA in human skin. The distribution of HA was compared with its presumptive cell surface receptor, CD44, using monoclonal antibodies. In epidermis both HA and CD44 were found in the basal and spinous cell layers, but neither was present in the stratum granulosum and stratum corneum. In the keratinizing parts of hair follicles, i.e. in the outer and inner epidermal root sheath, pilosebaceous duct and the actual hair, HA and CD44 were found between the vital but not the terminally differentiated cells. In the sebaceous glands a small amount of HA was found around all cells, whereas CD44 was restricted to the basal cell layer. The secretory acini of the sweat glands stained intensively with anti-CD44 antibodies but only weakly with HABC. In the sweat gland, CD44 was localized on the basal and lateral surfaces of the clear cells, whereas the dark cells and the myoepithelial cells were negative. Both the lower and upper layers of the sweat gland ducts showed a faint but constant staining for CD44 and only minor amounts of HA. While in the keratinizing skin epithelia both HA and its CD44 receptor showed an intense staining with a close co-distribution, in the sweat and sebaceous glands their distribution patterns were not similar. It is suggested that in epithelia with divergent differentiation programs the functions of CD44 and HA may be different.

High stromal hyaluronan level is associated with poor differentiation and metastasis in prostate cancer.

Several epithelial tumours accumulate hyaluronan (HA) which promotes cancer cell invasion and metastasis. We analysed the expression of HA and its receptor CD44 and their prognostic value in 166 prostate cancer patients followed up for a mean of 13 years; standard deviation (S.D.) 2.7; range 8.7-21.4 years. HA was detected with a specific biotinylated probe prepared from cartilage aggrecan and link protein, and CD44 with an antibody recognising all forms of CD44. The peri- and intratumoral stroma from half of the patients strongly expressed immunohistochemically detectable HA in < or = 15% of the stromal area; the tumours in the remaining half expressed HA in > 15% of the area. The staining of cancer cells for HA was scored positive or negative, and for CD44 the median value of 80% of positive tumour cells was used as a cut-off point. The expression of HA in cancer cells was weakly associated with perineural infiltration of the tumour (P = 0.03) and high Gleason score (P = 0.002). There was also a significant inverse relationship between the expression of HA and CD44 in cancer cells (P < 0.001). The high level of HA in the peri-and intratumoral stroma was related to metastasis, high T-category, high Gleason score, perineural infiltration and high mitotic activity of the tumour (for all P < 0.001). There was a significant inverse relationship between the expression of CD44 in cancer cells and high level of strong expression of HA in the tumour stroma (P < 0.001). A low fraction of CD44-positive cells was related to a high TM-category, high Gleason score and rapid cell proliferation (for all P < 0.0001; M/V P value = 0.0013). In the univariate survival analysis, the high level of strong expression of HA in tumour stroma predicted an unfavourable outcome in the entire series (P = 0.003) and also in the M0 tumours (P = 0.07), while in T1-2 M0 tumours the prognostic value did not reach the level of statistical significance (P = 0.1). A low fraction of CD44-positive cells predicted a poor outcome in the entire series (P < 0.001) and also in M0 tumours (P = 0.003). Cancer cell-associated HA expression had no prognostic value in any tumour categories. In the multivariate analysis of prognostic factors, HA expression in the cancer cells or in the tumour stroma had no additional value to the standard prognostic factors TM-classification, Gleason score and CD44 expression. Our results show that stromal HA accumulation is related to several malignant features and adverse clinical outcome in prostate cancer. However, further studies based on uniformly treated patient cohorts are needed to establish the clinical significance of these findings in current clinical practice.