Clinical outcome and bromodeoxyuridine-derived proliferation indices in 75 invasive breast carcinomas

Flavopiridol Blocks Integrin-Mediated Survival in Dormant Breast Cancer Cells

PURPOSE

Breast cancer micrometastases in the bone marrow are resistant to chemotherapy. They can remain dormant for years before some begin to proliferate. We seek to understand survival mechanisms and develop targeted approaches to eliminating these cells.

EXPERIMENTAL DESIGN

In an in vitro model of dormancy, basic fibroblast growth factor 2 (FGF-2), abundant in the bone marrow, inhibits the growth of well-differentiated cells in the 2- to 10-cell stage and up-regulates integrin alpha(5)beta(1). Through this integrin, cells bind fibronectin, spread out, and acquire a survival advantage, partly through activation of the phosphatidylinositol 3-kinase/Akt pathway. We investigated the effects of Taxotere, flavopiridol, and mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase and p38 inhibitors on survival of dormant clones and that of flavopiridol on expression of integrins, adhesion strength, and phosphorylation of Akt, ERK 1/2, and p38.

RESULTS

Dormant MCF-7 and T-47D cell clones were resistant to Taxotere concentrations 10-fold higher than needed to eliminate growing clones but were almost completely eradicated by 200 nmol/L flavopiridol. Flavopiridol caused a decrease in FGF-2-induced expression of integrins, including alpha(5) and beta(1), and decreased FGF-2-induced specific adhesion to fibronectin. It diminished Akt phosphorylation, but reexpression of active Akt was not sufficient to reverse dormant clone inhibition. Flavopiridol did not affect phosphorylation of ERK 1/2 and p38 but diminished total protein levels. Chemical inhibition of these pathways partially abrogated dormant clone survival.

CONCLUSIONS

Flavopiridol has pleiotropic effects on key targets involved with survival of dormant breast cancer cells and may represent a useful approach to eliminating cells dependent on multiple signal pathways for survival.

Colocalization of Carbonic Anhydrase 9 Expression and Cell Proliferation in Human Head and Neck Squamous Cell Carcinoma

Purpose: Tumor cells undergo a variety of biological changes under sustained hypoxic conditions, allowing cells to survive and retain their clonogenic potential. The purpose of this study is to relate the expression of the hypoxia marker carbonic anhydrase 9 (CA9) to the uptake of iododeoxyuridine (IdUrd), a marker of proliferation, in head and neck squamous cell carcinomas. Colocalization of IdUrd and CA9 may identify an important subpopulation of tumor cells that might be responsible for repopulation and disease progression.

Experimental Design: Expression of CA9, IdUrd labeling, and colocalization between IdUrd and CA9 was examined by immunohistochemistry in biopsies of head and neck squamous cell carcinomas. Biopsies were taken from 51 patients recruited between 1998 and 2001 after administration of the proliferation marker IdUrd.

Results: A large variation was observed between the tumors in CA9 expression (range 0-39%), IdUrd labeling (range 0-81%), and colocalization between IdUrd and CA9 [FId(CA9); range 0-53%]. FId(CA9), the fraction of IdUrd-labeled cells positive for CA9, was highest at an intermediate distance from the blood vessels (100-150 μm). IdUrd labeling was higher in T4 carcinomas relative to lower stage tumors (P = 0.04). High FId(CA9) correlated with the worst disease-free survival rates (P = 0.04).

Conclusions: Colocalization between IdUrd labeling and CA9 expression was observed in head and neck squamous cell carcinomas, suggesting the presence of a population of tumor cells under intermediate hypoxic conditions which still has proliferative capacity. The size of this subpopulation may be indicative of tumor aggressiveness and is associated with the worst disease-free survival rates.

Outcome and human epidermal growth factor receptor (HER) 1-4 status in invasive breast carcinomas with proliferation indices evaluated by bromodeoxyuridine labelling

Background

We have shown previously that whereas overexpression of human epidermal growth factor receptor (HER)1, HER2 and HER3 is associated with poor prognosis in breast cancer, HER4 is associated with a good prognosis. Cell proliferation is a key component of aggressive cancers and is driven by growth factors. In this study, bromodeoxyuridine (BrdU)-derived proliferation indices are correlated with clinical outcome and HER1–4 status for further clarification of the differing roles for the HER family at a biological level.

Methods

Seventy-eight invasive breast cancers had BrdU labelling in vivo to determine the BrdU labelling index (BLI) and the potential tumour doubling time (T_pot). Long-term clinical follow-up was available for these patients. We used immunohistochemistry to establish the HER1–4 status in 55 patients from the BrdU cohort.

Results

We demonstrate a significant correlation between high BLI values and breast cancer-specific death (P = 0.0174). Low T_pot times were also significantly correlated with breast cancer-specific death (P = 0.0258). However, BLI did not independently predict survival in Cox's multiple regression analysis when combined with other prognostic factors such as size, grade and nodal status. Tumours found to be positive for HER1, HER2 or HER3 had significantly (P = 0.041) higher labelling indices, with HER1 also showing significantly higher indices when considered independently (P = 0.024). Conversely, HER4 positivity was significantly correlated (P = 0.013) with low BLI values, in line with previous data associating this receptor with good prognosis tumours.

Conclusions

These results support the hypothesis that HER1–3 are associated with driving tumour proliferation, whereas HER4 is involved in a non-proliferative or even protective role.

Clinical outcome and bromodeoxyuridine derived proliferation indices in 100 colonic and rectal carcinomas

AIM

In vivo labelling of human colonic and rectal tumours with bromodeoxyuridine (BrdUrd) and analysis by flow cytometry (FCM) allows the labelling index (LI), S phase duration (Ts) and the potential doubling time (Tpot) of the tumour to be estimated in vivo.

METHODS

The data for a series of 100 tumour specimens from 97 patients with colonic and rectal carcinoma was reported in 1991, and correlated with Dukes' classification and histological differentiation.

RESULTS

This study reports the eventual outcome of the 97 patients after 12 years. There were no significant associations between proliferation data of the index tumours and patient outcome. No adverse events were identified which could be attributed to the use of the halogenated pyrimidine label in vivo.

CONCLUSION

Dynamic cell proliferation indices provide detailed information on the cell kinetics of colorectal tumours but these do not correlate with clinical prognostic markers or outcome.