Type V collagen in experimental granulation tissue

To evaluate the spatial and temporal expression of type V collagen in a wound healing model, subcutaneously implanted viscose cellulose sponges in rats were used to induce granulation tissue formation. Analyses on granulation tissue were carried out on days 3, 5, 8, 14, 21, 30, 59 and 84. Acid soluble collagens were extracted and the relative amount of type V collagen was quantified by SDS-PAGE. Specific antibodies to type I, III and V collagens were used in immunohistochemistry and specific RNA probes to proalpha1(I), proalpha1(III) and proalpha1(V) collagen in in situ hybridization. Type V collagen content increased relative to type I and III collagens up to day 8 and remained at the same level for up to the three months. Type V collagen was expressed strongly in blood vessel walls as seen in immunohistochemistry. In situ hybridization showed that all of the three types of collagen were expressed mostly in fibroblast-like cells and also in rounded cells, especially type V collagen. In conclusion, type V collagen was seen in the wound healing model in increasing amounts from day 3 onwards, its localization being highly associated with blood vessels in granulation tissue and it was synthesized by fibroblast-like and rounded cells.

Predictive value of p53, mdm-2, p21, and mib-1 for chemotherapy response in advanced breast cancer

p53 is a transcription factor that participates in cell cycle checkpoint processes and apoptosis. The protein product of the murine double minute gene 2 (mdm-2) plays a central role in the regulation of p53. In response to DNA-damaging agents, the wild-type p53-activated fragment 1 (WAF1 also known as p21) is an important downstream effector in the p53-specific growth arrest pathway. In breast cancer patients, it is unclear whether measuring p53, mdm-2, or p21 expression provides information on how patients will respond to chemotherapy. Mib-1 monoclonal antibody recognizes the proliferation-related antigen Ki-67. High tumor proliferation has previously been associated with response to chemotherapy. p53, mdm-2, p21, and mib-1 expression were assessed by immunohistochemical methods in primary tumors derived from 134 patients who took part in a randomized multicenter trial comparing docetaxel to sequential methotrexate and 5-fluorouracil (MF) in advanced breast cancer. Low mib-1 staining correlated with negative p53 staining (P = 0.001), and mdm-2 and p21 stainings correlated positively with each other (P < 0.001). p53, mdm-2, p21, and mib-1 expression were not significantly associated with response to chemotherapy, time to progression, or overall survival in the whole patient population or in the docetaxel group. However, in the MF group, a low mib expression (<25%) and a high mdm-2 expression (> or =10%) predicted a better response (P = 0.014 and P = 0.046, respectively) to treatment and a longer time to progression in both univariate and multivariate analyses. p53 staining status was not associated with response to treatment in either group. Interestingly, tumors with both negative mdm-2 and p21 expression, irrespective of p53 status, had a high response rate to docetaxel but no response to MF. Although highly preliminary, the findings suggest that different tumor biological factors may predict response to different chemotherapy regimens with distinct mechanisms of action. The results of our phenotype analysis also indicate that it is more likely that a panel of tumor biological factors instead of only one single factor may be needed for better prediction of chemotherapy response.

MRI enhancement and microvascular density in gliomas. Correlation with tumor cell proliferation

RATIONALE AND OBJECTIVES

Angiogenesis and proliferation activity are important indicators of tumor behavior in human gliomas. The authors studied how tumor enhancement in MR imaging and intratumoral vascular density were correlated with cell proliferation in cerebral gliomas.

METHODS

The authors studied retrospectively 62 cerebral gliomas. Patients were examined before surgery with contrast-enhanced MR imaging. Microvessel density and the cell proliferation rate of tumor specimens were measured immunohistochemically using factor VIII and MIB-1 antibodies. Contrast enhancement of the tumors was evaluated by two radiologists.

RESULTS

Contrast enhancement was observed in 45 tumors and was correlated with histologic cell proliferation (P = 0.0007) and microvessel density (P = 0.01). There was also a correlation between tumor vascular density and the cell proliferation rate (r = 0.51, P < 0.0001). Histologic tumor grade was associated with vascular density (P = 0.001).

CONCLUSIONS

Lesion enhancement on preoperative contrast-enhanced MR imaging correlates with vascularity and proliferation activity of gliomas. The additional correlation between tumor vascularity and proliferation suggests that intratumoral microvessel density could be useful in estimating tumor proliferation.