A mutant TP53 gene status is associated with a poor prognosis and anthracycline-resistance in breast cancer patients

This study evaluates the prognostic and predictive relevance of a mutated p53 in a series of 254 samples from primary breast cancer patients. C-erbB-2 analysis was defined in a limited subpopulation of 79 patients. p53 and c-erbB-2 status was analysed by immunohistochemical staining of the tumour samples. Positive p53 immunostaining was present in 86 cases (34%) and correlated with a high malignant grade, negative progesterone receptor status and ductal histology of tumour. C-erbB-2 positivity was seen in 38 samples (48%). Within an average follow-up time of 74 months, 121 patients developed recurrent or metastatic disease. Patients with mutated p53 showed a statistically significant shorter overall survival and disease-free survival in both univariate and multivariate analyses. The worst clinical outcome was seen in patients who were both p53- and c-erbB-2-positive. The response rate to anthracycline-based chemotherapy in metastatic disease was low in the p53-positive cases. Our results help to clarify the independent prognostic role of a mutated p53 status in breast cancer patients, indicating that this gene might be predictive of anthracycline resistance. Patients with a mutant p53 status and overexpressing c-erbB-2 should be regarded as high-risk cases.

Radiation therapy induces tenascin expression and angiogenesis in human skin

In analysing radiation-induced connective tissue changes, we studied tenascin expression, elastic fibres, angiogenesis and physio-mechanical properties in irradiated and contralateral healthy skin of radiotherapy-treated breast cancer patients. Skin biopsies were obtained from a radiotherapy-treated skin area and a corresponding non-treated skin area. Haematoxylin-eosin and Verhoeff stainings as well as immunohistochemical stainings for tenascin and factor VIII were performed. Epidermal and total skin thickness, together with the amount of elastic tissue calculated by computerized digital image analysis, were measured. Suction blisters were induced on both skin areas. Transepidermal water loss was analysed. Skin elasticity was also measured. Tenascin expression was found to be increased in irradiated human skin. In haematoxylin-eosin and factor VIlI-stained sections, an increase in the number of blood vessels was detected. Although skin stiffness measured by an elastometer was increased in irradiated skin, no marked difference in the elastic fibres could be found between treated and non-treated skin. The increased tenascin expression could be due to activation of cytokines as a result of irradiation. An increase in angiogenesis could be caused by an activation of angiogenetic factors by irradiation or due to direct radiation damage on blood vessel walls. Our findings suggest that the effects of irradiation tend to accumulate in the dermal parts of skin. The higher skin stiffness values measured by elastometer in irradiated skin could be due to an accumulation of dermal connective tissue as a result of irradiation.

Postoperative PINP in serum reflects metastatic potential and poor survival in node-positive breast cancer

The aim of this work was to evaluate the postoperative serum markers of type I collagen synthesis (PINP,PICP) and degradation (ICTP) and their possible potential for predicting the spread of disease and survival. 373 node-positive breast cancer patients were enrolled. 120 patients (32%) developed recurrent disease in the follow-up. The mean time to recurrence was 17 months and the mean follow-up time was 45 months. The mean level of PINP was significantly elevated in the patients who developed metastatic disease in the follow-up as compared with those without metastases. PINP was statistically significantly higher in all the patients who developed bone metastases than in those without metastases. When patients with only bone metastases or patients with bone and soft tissue and/or visceral metastases and patients with only visceral or soft tissue metastases were compared with those not exhibiting metastases, PINP was significantly higher in the group with recurrence in the bone, but there were no significant differences in serum PINP, PICP or ICTP values between the patients with only bone metastases and those who developed soft or visceral metastases during the follow-up. Postoperative high PINP was also a factor for poorer survivaL Tumor size, malignancy grade and progesterone receptors were shown in multivariate analysis to be predictors of recurrence and tumor size and PINP and progesterone receptors to be predictors of survivaL

Aminoterminal propeptide of the alpha1-homotrimer variant of human type I procollagen (hotPINP) in malignant pleural effusion

The aminoterminal propeptide (hotPINP) of type I homotrimer, a putative malignancy-associated type I collagen variant, was purified for the first time and a method was established for its detection in pleural fluid. Samples of 58 patients, with malignant or benign disease, were studied with specific immunoassays for the two propeptides of type-I procollagen (PICP and PINP) and with HPLC-DEAE chromatography to separate the two PINP variants. HotPINP was present in 64% of both benign and malignant pleural effusion fluids, with the exception of malignant mesotheliomas, none of which showed the presence of hotPINP. Also the PICP to PINP ratios were lower than normal in both benign and malignant samples (altogether in 69% of samples), although this deviation was greater in malignancy. These two phenomena were independent of each other. As synthesis of the alpha1-homotrimer-variant of type-I collagen seems to be relatively common during the formation of pleural effusion, it may be generally related to a fibroproliferative reaction in the pleural wall.

Elevated serum levels of type I collagen degradation marker ICTP and tissue inhibitor of metalloproteinase (TIMP) 1 are associated with poor prognosis in lung cancer

PURPOSE

The aim of this study was to evaluate the correlation between type I collagen degradation marker ICTP, MMP (matrix metalloproteinase)-9, and tissue inhibitor of metalloproteinase (TIMP)-1 and to compare their value as prognostic factors in lung cancer.

EXPERIMENTAL DESIGN

From the sera of 141 lung cancer patients, we assessed markers of type I collagen synthesis (PINP and PICP) and degradation (ICTP) by radioimmunoassays, and we assessed MMP-9 and its tissue inhibitor TIMP-1 by ELISA. There were 62 squamous cell carcinomas, 42 adenocarcinomas, 14 small cell carcinomas, and 23 cases with other histology. Seventeen of these patients had advanced disease. Sixty-seven patients had been operated on, 33 had received radiation therapy, 7 had received chemotherapy, and the rest had received other treatment combinations.

RESULTS

We examined the relationship between these markers and found a correlation between ICTP and MMP-9 (r = 0.201; P = 0.01) or TIMP-1 (r = 0.415; P = 0.00). Elevated serum concentrations of ICTP (>5 microg/liter) and/or TIMP-1 (>300 ng/ml) correlated with poor prognosis. In univariate regression analysis, ICTP had prognostic value (odds ratio, 1.6462; P < 0.03): the patients with elevated serum concentrations of ICTP (>5 microg/liter) had a 64% higher risk of dying from lung cancer than did patients with opposite values.

CONCLUSIONS

Our results indicated that ICTP and TIMP-1 are good prognostic markers in lung cancer. The association between serum MMP-9 and ICTP suggests that MMP-9 could play a role in the degradation of the extracellular matrix producing ICTP in this pathological situation.

Type I collagen turnover and cross-linking are increased in irradiated skin of breast cancer patients

BACKGROUND AND PURPOSE

The effects of radiation therapy on the turnover and structure of type I collagen were studied in irradiated and contralateral skin of 18 breast cancer patients without clinically evident fibrosis.

MATERIALS AND METHODS

The rates of on-going type I collagen synthesis and degradation were assessed by the aminoterminal propeptide of type I procollagen (PINP) and by two different assays (ICTP and SP4) for the carboxyterminal telopeptide of type I collagen in the soluble tissue extracts, respectively. Also, TIMP-1, TIMP-2 and the MMP-2/TIMP-2 complex were measured in the tissue extracts. Insoluble skin matrices, containing the cross-linked type I collagen fibres, were heat-denatured and digested with trypsin. Then, the variants of the carboxyterminal telopeptide of type I collagen were separated by high performance liquid chromatography (HPLC). The major histidinohydroxylysinonorleucine (HHL)-cross-linked variant was quantified by the SP4 assay, and the minor pyridinoline analogue (PA)-cross-linked telopeptide was quantified by the ICTP assay.

RESULTS

Both the synthesis and degradation of type I collagen were increased (r=0.906; P<0.001) on the irradiated side, whereas the concentration of the MMP-2/TIMP-2 complex was decreased. In the insoluble tissue digests, the HHL-cross-linked telopeptides of type I collagen, also, when expressed/tissue hydroxyproline, were increased in the irradiated skin. TIMP-1, TIMP-2 or PA-cross-linked telopeptides of type I collagen showed no differences between the two sides.

CONCLUSIONS

Radiotherapy induces a long-term increase in the turnover of type I collagen and leads to the accumulation of cross-linked type I collagen in skin.

c-erbB-2 positivity is a factor for poor prognosis in breast cancer and poor response to hormonal or chemotherapy treatment in advanced disease

The aim of this work was to evaluate the prognostic and predictive values of c-erbB-2 in breast cancer. 650 patients were enrolled. The amplification/overexpression of c-erbB-2 from fresh frozen or paraffin-embedded breast tumour tissue samples was analysed by polymerase chain reaction (PCR) technique (75%), immunohistochemically (17%) or by Southern blot analysis (8%). 126 patients (19%) were positive for c-erbB-2. 148 patients developed metastatic disease, but only 35 were positive for c-erbB-2. Positivity for c-erbB-2 was significantly associated with node positivity, large tumour size, high grade of malignancy, low receptor status, postmenopausal status, and with a shorter overall survival. In multivariate regression analysis, only tumour size and nodal involvement were risk factors for poor survival when analysed separately together with c-erbB-2 and receptor status. Metastatic patients with c-erbB-2 positivity had a significantly shorter survival and disease-free survival (DFS) than the c-erbB-2-negative patients. 29 advanced patients with c-erbB-2 positivity showed a poor response rate to hormonal, non-anthracycline-based and anthracycline-based therapies. Positivity for the c-erbB-2 is a poor prognostic factor in breast cancer, but it also emerges as predictive of the response to hormonal or chemotherapy treatment once the disease has recurred.

Modulation of skin collagen metabolism by irradiation: collagen synthesis is increased in irradiated human skin

Radiation-induced fibrosis is a common side-effect of cancer treatment. The pathophysiological events leading to fibrosis are not known in detail. We analysed the effect of therapeutic irradiation on human skin collagen synthesis, skin thickness, gelatinases and their inhibitors. Twenty randomly chosen women who had been treated for breast cancer with surgery and radiation therapy participated in the study. In each patient, the irradiated skin area was compared with a corresponding non-treated skin area. Suction blister fluid (SBF) and serum samples were analysed for the aminoterminal propeptides of type I and type III procollagens (PINP and PIIINP), tissue inhibitors of matrix metalloproteinases (MMPs) 1 and 2 (TIMP-1 and TIMP-2) and MMP-9 and MMP-2/TIMP-2 complex. Skin biopsies were analysed for PINP and immunohistochemical staining was used for PIIINP. In irradiated skin, PINP, PIIINP, TIMP-1 and MMP-2/TIMP-2 complex levels in SBF and the number of PINP-positive fibroblasts in tissue sections were significantly higher in comparison with non-treated skin. The levels of TIMP-2 in irradiated and non-irradiated skin were similar. MMP-9 could not be detected in SBF with the assay used. The serum levels of MMP-9 were higher in the treated subjects than the reference values. The serum values of PINP, PIIINP, TIMP-1, TIMP-2 and MMP-2/TIMP-2 complex were not significantly affected. These results indicate increased local collagen synthesis and accumulation of connective tissue in irradiated skin. The marked upregulation of collagen synthesis as a result of irradiation offers a possibility to treat this complication with compounds such as topical steroids which downregulate collagen synthesis.

Serum type I collagen degradation markers, ICTP and CrossLaps, are factors for poor survival in lung cancer

We investigated the prognostic value of the serum markers of type I collagen synthesis (PINP and PICP) and degradation (ICTP and CrossLaps) in 143 lung cancer patients with a local or locally advanced disease or a metastatic disease. The mean values of ICTP, CrossLaps, PINP and PICP were significantly higher in patients with bone metastases than in those without metastases or with only soft tissue metastases. The patients with ICTP < or = 5.0 micrograms/l or CrossLaps < or = 5000 pmol/l had a better prognosis. The histopathological type, the site of metastases or the stage of the disease had no influence on these results. In multivariate regression analysis, both ICTP and CrossLaps in contrast to PINP or PICP, were prognostic factors for poor survival in lung cancer patients. ICTP, CrossLaps, sedimentation rate, hemoglobin and AFOS reached separately weaker, but statistically significant values as predictors of survival with stage and operation.

Preoperative high type I collagen degradation marker ICTP reflects advanced breast cancer

Type I collagen synthesis (PINP, PICP) and degradation (ICTP) markers were analysed from preoperative serum samples of 138 women with breast cancer (BC), 94 women with benign breast disease (BBD) and 100 healthy controls to evaluate the levels of these markers and the stage of BC at the time of diagnosis. We also compared the clinical utility of these markers in detecting BC with CA15-3 and CEA. The mean value of ICTP was statistically significantly elevated in the BC group (p < 0.001), as compared with the control group, but the elevated values in BC group were due to stage IV disease. The sensitivity of ICTP in detecting BC was 0.23, which was equal with CA15-3(0.24) or CEA(0.23). The sensitivity of both PICP and PINP for diagnosing BC was poor, but a tendency to higher serum levels of PINP and low PICP/PINP ratio was detected in patients with advanced stage IV disease. These results indicate that high preoperative serum levels of ICTP are associated with advanced BC, but like CA15-3 and CEA, its clinical value in diagnosing purpose is poor.

Aberrant type I and type III collagen gene expression in human breast cancer in vivo

Increased synthesis and degradation of extracellular matrix components are associated with breast cancer development. This study evaluated type I and type III procollagen mRNA expression and the corresponding protein synthesis and maturation, as well as the tissue distribution of these collagens, in benign breast lesions, infiltrating ductal carcinomas, and their metastases by in situ hybridization and immunohistochemistry. In the benign lesions, the type I and type III collagen bundles were regularly organized and the expression of the corresponding mRNA was weak, indicating a relatively slow collagen turnover. In the malignant tumours, increased expression of type I and type III procollagen mRNAs was observed in the fibroblastic cells of the stroma; the malignant epithelial cells did not participate. The staining of corresponding newly-synthesized pN-collagens showed aberrant bundles in the invasive front of the malignant tumours. Newly-synthesized type I and type III procollagens were occasionally observed in fibroblastic cells, particularly in grade 2 and grade 3 tumours. Metastases of breast carcinoma resembled poorly differentiated primary tumours with respect to their collagen synthesis and deposition. The increased synthesis of fibrillar type I and type III procollagens may serve as a pathway for tumour invasion. The enhanced synthesis is associated with the formation of aberrant collagen bundles, which may be more readily degradable and may thus facilitate breast tumour invasion.

New lethal disease involving type I and III collagen defect resembling geroderma osteodysplastica, De Barsy syndrome, and Ehlers-Danlos syndrome IV

We describe the clinical findings and biochemical features of a male child suffering from a so far undescribed lethal connective tissue disorder characterised by extreme hypermobility of the joints, lax skin, cataracts, severe growth retardation, and insufficient production of type I and type III procollagens. His features are compared with Ehlers-Danlos type IV, De Barsy syndrome, and geroderma osteodysplastica, as these disorders show some symptoms and signs shared with our patient. The child died because of failure of the connective tissue structures joining the skull and the spine, leading to progressive spinal stenosis. The aortic valve was translucent and insufficient. The clinical symptoms and signs, together with histological findings, suggested a collagen defect. Studies on both skin fibroblast cultures and the patient's serum showed reduced synthesis of collagen types I and III at the protein and RNA levels. The sizes of the mRNAs and newly synthesised proteins were normal, excluding gross structural abnormalities. These findings are not in accordance with any other collagen defect characterised so far.

Type I procollagen synthesis is regulated by steroids and related hormones in human osteosarcoma cells

Change in the synthesis of type I collagen, the major extracellular matrix component of skin and bone, are associated with normal growth, tissue repair processes, and several pathological conditions. Expression of the COL 1A1 gene is regulated by transcriptional and post-transcriptional mechanisms. However, the hormonal regulation of type I collagen synthesis in human bone has not been well characterized. We have studied the influence of calcitriol, dexamethasone, retinoic acid, and estradiol on the COL 1A1 gene expression by determining the secretion of the C-terminal propeptide (PICP) and the levels of alpha 1(I) procollagen mRNA in cultured human MG-63 and SaOs-2 osteoblast-like osteosarcoma cells. Similar experiments were also performed with respect to expression of the nuclear proto-oncogenes, c-fos and c-jun, in MG-63 cells. In MG-63 cells, calcitriol stimulated the synthesis and secretion of PICP. The alpha 1(I) procollagen mRNA level was elevated with no effect on message stability, indicating a transcriptional mechanism of regulation. In contrast, dexamethasone treatment was accompanied by an accelerated rate of alpha 1(I) procollagen mRNA turnover, observed as decreased amounts of the message and the secreted PICP, implying a posttranscriptional regulation. Retinoic acid, in turn, decreased the levels of alpha 1(I) procollagen mRNA and secreted PICP by slowing down transcription of the COL1A1 gene without any effect on message stability. The ability of these hormones to regulate the alpha 1(I) transcripts was sensitive to puromycin treatment, suggesting an involvement of an induced mediator protein in the action of the hormones on the COL1A1 gene. Both dexamethasone and calcitriol rapidly but transiently increased the expression of the c-fos and c-jun proto-oncogenes. Neither proto-oncogene responded to retinoic acid treatment with significant changes in mRNA levels. Estradiol treatment was found to have no influence on type I procollagen synthesis. In SaOs-2 cells, which are not as well differentiated as the MG-63 cells, calcitriol and dexamethasone did not influence type I procollagen synthesis. Retinoic acid as well as estradiol reduced collagen gene expression in these cells. These findings suggest that hormonal effects on type I procollagen synthesis may depend on the maturational state of the osteoblastic cells that express different regulatory factors and receptors, resulting in, in each case, a finely adjusted rate of gene expression.

Aggressive breast cancer leads to discrepant serum levels of the type I procollagen propeptides PINP and PICP

The propeptides PICP and PINP are derived from the synthesis of type I collagen, a major matrix protein of bone and soft tissues. The aim of this cross-sectional study was to investigate their value as indicators of the aggressivity of breast cancer. Serum PINP, PICP, and total alkaline phosphatase were determined from 89 breast cancer patients. Forty had major bone and/or soft tissue metastases with an aggressive disease course: the progressive disease (PD) group. Forty-nine had either none or minor bone and/or soft tissue metastases with a stable clinical course: the stable disease group (SD). The mean value of PINP in the PD group was 7.2 times higher than that in the SD group (276 +/- 79 microg/l versus 38 +/- 3 microg/l, respectively; P = 0.005), whereas PICP mean value was only 1.7 times higher in the PD group (174 +/- 20 microg/l versus 100 +/- 5 microg/l; P = 0.001). The ratio of PICP to PINP was 1.02 +/- 0.07 in the PD group and 3.07 +/- 0.18 in the SD group (P < 0.001). The correlation between PICP and PINP was linear in the SD group and nonlinear in the PD group. The results indicate that high serum PICP and PINP concentrations and a low PICP:PINP ratio are associated with a highly aggressive nature of breast cancer. Determination of PINP, in particular, may be valuable when evaluating the clinical status of a breast cancer patient.

Immunoassay for intact amino-terminal propeptide of human type I procollagen

We have developed quantitative immunoassays for the intact, trimeric amino-terminal propeptide of human type I procollagen (PINP) and its Col1 domain. Intact PINP was isolated from the pleural fluids of cancer patients by a combination of ion-exchange, gel-filtration, and reversed-phase chromatographies. The amino-terminal Col1 domain of PINP was isolated after bacterial collagenase treatment of the heat-denatured trimeric propeptide. For the intact PINP assay we used a polyclonal antibody with only 1.2% cross-reaction with the monomeric Col1 domain. In human serum, this assay detects only one peak of PINP antigenicity that has the size of known intact PINP. Under similar conditions, an assay for the Coll domain of PINP recognized two circulating antigens. The biological relevance was further verified in wound fluid. Interassay and intraassay CVs were 3.1-9.3% for values within the reference intervals (mean +/- 2SD) for intact PINP in serum, which were 19-84 microg/L for women and 20-76 microg/L for men.

Immunoassay for intact amino-terminal propeptide of human type I procollagen

We have developed quantitative immunoassays for the intact, trimeric amino-terminal propeptide of human type I procollagen (PINP) and its Col1 domain. Intact PINP was isolated from the pleural fluids of cancer patients by a combination of ion-exchange, gel-filtration, and reversed-phase chromatographies. The amino-terminal Col1 domain of PINP was isolated after bacterial collagenase treatment of the heat-denatured trimeric propeptide. For the intact PINP assay we used a polyclonal antibody with only 1.2% cross-reaction with the monomeric Col1 domain. In human serum, this assay detects only one peak of PINP antigenicity that has the size of known intact PINP. Under similar conditions, an assay for the Coll domain of PINP recognized two circulating antigens. The biological relevance was further verified in wound fluid. Interassay and intraassay CVs were 3.1-9.3% for values within the reference intervals (mean +/- 2SD) for intact PINP in serum, which were 19-84 microg/L for women and 20-76 microg/L for men.

Procollagen synthesis and extracellular matrix deposition in MG-63 osteosarcoma cells

We compared the procollagen synthetic properties of MG-63 osteosarcoma cells with those of cultured human skin fibroblasts. In both cells, the expressions of type I and III procollagens are largely dependent on the constant presence of ascorbate and coordinately decreased by the neutral polymer dextran T-40. The amino-terminal propeptides of pro-alpha 1 and pro-alpha 2 chains of type I procollagen are phosphorylated and those of the pro-alpha 1 and pN-alpha 1 chains of type III procollagen both phosphorylated and sulfated, there being no difference in net charge in the propeptides between these cell types. The major differences between MG-63 and normal fibroblasts are the exceptionally high relative synthesis of type III procollagen by MG-63 cells, up to about 40% of the total of types I and III (6% in cultured skin fibroblasts), and the inability of ascorbate-supplemented MG-63 cells to deposit collagens into an insoluble pericellular matrix. A longer dextran treatment shifts up to one-fourth of the proline-labeled extracellular macromolecules into the matrix fraction within 4 days (in control 4%). Despite processing of the procollagens to the respective collagens in the matrix, neither control matrices nor those induced by dextran induced increased production of alkaline phosphatase. In cultures up to 4 days postconfluence the proportion of type III collagen produced tended to increase over that in early confluent cultures. With respect to collagen production, the MG-63 cell line is not a representative of the osteoblast lineage but rather resembles a proliferative wound fibroblast.

Effect of dextran on synthesis, secretion and deposition of type III procollagen in cultured human fibroblasts

When subconfluent cultures of primary human skin fibroblasts are incubated for 20 h in the presence of 5% neutral dextran, the newly synthesized procollagens are shifted from the medium into the pericellular matrix fraction. This is accompanied by an overall decrease by 30-50% in the secretion rates of these proteins, as indicated by the incorporation of tritiated proline into collagenase-sensitive macromolecules and by radioimmunoassays for the propeptide regions of type I and III procollagens. Inhibition of tyrosine sulphation in newly formed type III procollagen by NaClO3 does not change the distribution of this protein between the medium and matrix fractions either in the presence or in the absence of the polymer. Processing of type III procollagen at its N-terminus is incomplete in this situation, irrespective of whether the protein is present mainly in the medium or in the pericellular matrix. The concentrations of the mRNAs for the pro alpha 1(I)- and pro alpha 1(III)-chains of procollagens and for actin were monitored for up to 20 h; in the dextran-treated cultures these are not different from the corresponding concentrations in control cultures, indicating that the rapid down-regulation of the synthesis of type I and III procollagens in response to the enhanced pericellular matrix deposition induced by dextran is not due to transcriptional mechanisms.

Chlorate inhibits tyrosine sulfation of human type III procollagen without affecting its secretion or processing

Sodium chlorate, a potent inhibitor of sulfation reactions, completely inhibits the formation of tyrosine-o-sulfate in type III procollagen in human fibroblasts, when used in concentrations that do not affect the incorporation of radioactive amino acids into protein. The unsulfated type III procollagen is secreted into the medium at a rate comparable, to those of sulfated type III procollagen and type I procollagen, which normally does not undergo sulfation. The enzymatic cleavage of the aminoterminal propeptide of type III procollagen is incomplete in fibroblast cultures, irrespective of the sulfation status of the protein.

Covalent binding of acetaldehyde to type III collagen

Incubation of neutral salt soluble type III pN-collagen with [14C]acetaldehyde in vitro resulted in the formation of spontaneously stable acetaldehyde-protein adducts. This reaction occurred primarily at lysine residues and it was not affected by 0.2-2 mM concentrations of ascorbate but addition of sodiumcyanoborohydride increased the stable adducts by 3-5-fold. When confluent cultures of human skin fibroblasts were incubated with physiologically relevant concentrations of acetaldehyde, it became covalently bound to type III procollagen secreted into the medium. We propose that acetaldehyde binding to collagen fibrils occurs in vivo following chronic alcohol consumption.

Incorporation of sulphate into type III procollagen by cultured human fibroblasts. Identification of tyrosine O-sulphate

Confluent cultures of normal human skin fibroblasts were labelled overnight with [35S]sulphate, and the incorporation of the isotope into type III procollagen, secreted into the medium, was verified by radioimmunoassay and immunoprecipitation after removing the heavily sulphated proteoglycans by anion-exchange chromatography. Type III procollagen and its pro and pN alpha chains were visualized in fluorographs of the immunoprecipitates. The labelled procollagen could be isolated by a combination of ion-exchange chromatography and gel filtration and was found to contain tyrosine O-sulphate, which was identified by thin-layer electrophoresis after Ba(OH)2 hydrolysis. The regions sulphated in the type III procollagen molecule were susceptible to pepsin digestion. Digestion with purified bacterial collagenase at +37 degrees C produced a labelled fragment that was recognized by antibodies against the aminoterminal propeptide of type III procollagen, indicating that the sulphated tyrosine residues are located either in this propeptide or in the non-helical telopeptide region of the type III collagen molecule proper. Sulphation of tyrosine residues is a new post-translational modification in procollagen, which could be involved in the regulation of the processing of type III procollagen into collagen and thus affect the formation of collagen fibres.

Effects of experimental nephrosis on basement-membrane components and enzymes of collagen biosynthesis in rat kidney

The aim of the present study was to find out whether the basement-membrane proteins laminin and type IV collagen are involved in the development of aminonucleoside-induced nephrosis. These proteins were measured by specific radioimmunoassays in serum, urine and kidney-cortex samples, and they were localized in the glomeruli by indirect immunofluorescence. Nephrosis was induced in rats with a single intraperitoneal injection of puromycin aminonucleoside. Serum laminin concentrations, detected by a radioimmunoassay for the P2 domain of the protein, increased to reach a maximum at days 5-7, and they remained elevated until at least day 14. The increase preceded the development of proteinuria, suggesting a role for laminin in glomerular function. Concomitant with proteinuria, increasing amounts of laminin antigenicity were also found in the urine. The size of the laminin antigen in serum was estimated by gel filtration, and the serum forms were found to contain both the P1 and the P2 regions of the intact laminin molecule. On the other hand, there were no changes in the serum or urinary concentrations of type-IV-collagen-derived antigens, as detected by a radioimmunoassay for the 7S collagen domain of this protein. The total content of laminin in kidney cortex, measured after digestion of the tissue with trypsin and collagenase, was, at day 9, still comparable with normal values, and the distribution of both basement-membrane proteins in the glomeruli, studied by indirect immunofluorescence, was similar to that in the controls. The tissue damage induced by aminonucleoside, however, seems to stimulate collagen biosynthesis, as the activities of prolyl 4-hydroxylase, lysyl hydroxylase and galactosylhydroxylysyl glucosyltransferase in kidney tissue increased significantly, with maxima at days 8-10.