Hitting cancer where it hurts

Evaluation of the ability of digital infrared imaging to detect vascular changes in experimental animal tumours

Infrared imaging has frequently been used in the past to detect changes in skin surface temperature associated with breast cancer. Usually a 1-2 degrees C elevation in skin surface temperature is observed at the tumour periphery, and it has been proposed that this change is due to hypervascularity resulting from tumour-associated angiogenesis. In our study, we used the rat mammary adenocarcinoma 13762 MAT, a tumour that has been used to identify antiangiogenic drugs, to investigate whether infrared imaging can detect angiogenesis in malignant tumours. If successful, it was hoped that this technique would represent a simple, noninvasive, procedure for monitoring the activity of antiangiogenic drugs. It was found that, unlike breast cancer patients, no tumour-associated increase in skin surface temperature was observed, but a constant and highly significant reduction in temperature was noted that was independent of tumour size and was produced by relatively small tumours (>/= 0.5 cm in diameter). The explanation for this effect is unclear but it may be due to the poorly vascularised nature of rapidly growing tumours. Nevertheless, our study indicates that the peripheral temperature elevation reported in breast cancer patients is unlikely to be due to hypervascularity resulting from tumour-induced angiogenesis. An alternative explanation is that the temperature increase is due to a chronic inflammatory response around developing breast tumours. With increasing evidence that inflammation can enhance tumour growth and is associated with a poor prognosis, this suggestion implies that infrared imaging may have considerable prognostic value.

Cells as vehicles for cancer gene therapy: the missing link between targeted vectors and systemic delivery?

Systemic administration of currently manufactured viral stocks has not so far achieved sufficient circulating titers to allow therapeutic targeting of metastatic disease. This is due to low initial viral titers, immune inactivation, nonspecific adhesion, and loss of particles. One way to exploit the elegant molecular manipulations that have been made to increase vector targeting is to protect these vectors until they reach the local sites of tumor growth. Various cell types home preferentially to tumors and can be loaded with the constructs required to produce targeted vectors. Here we discuss the potential of using such cell carriers to chaperone precious vectors directly to the tumors. The vectors can incorporate mechanisms to achieve tumor site-inducible expression, along with tumor cell-specific expression of the therapeutic gene and/or replicating viral genomes that would be released at the tumor. In this way, the great advances that have so far been made with the engineering of vector tropisms might be genuinely exploited and converted into clinical benefit.

A fibrous-bed bioreactor for continuous production of developmental endothelial locus-1 by osteosarcoma cells

Genetically engineered human osteosarcoma cells containing developmental endothelial locus-1 (del-1) gene were studied for production of Del-1, a protein that has the properties of an extracellular matrix protein and can regulate vascular morphogenesis and remodeling. Del-1 has been studied as a potential anti-angiogenesis drug targeting solid tumors. In this study, osteosarcoma cells were cultured in a fibrous-bed bioreactor (FBB) to continuously produce Del-1. The FBB was constructed by packing a polyester fibrous matrix into a 1.5-l spinner flask. The effects of media composition, including the serum content in the medium, and dilution rate on cell growth, metabolism, and Del-1 production were studied. A gradual reduction of serum content from 10% (v/v) to 0.5% (v/v) caused no loss in Del-1 production. However, the production of Del-1 decreased significantly in a serum-free medium, suggesting some nutrients present in the serum were important to culture viability and Del-1 production. The continuous FBB culture was stable for long-term production of Del-1, with a higher Del-1 titer than that normally obtained in T-flask cultures and overall productivity similar to the total production from 300 25-cm(2) T-flasks. Reducing geneticin in the medium from 250 microg ml(-1) to zero at later culturing stages had no significant effect on Del-1 production. The FBB was operated for a period of more than 4 months without any notable degeneration, and reached a final cell density of 3 x 10(8) cells ml(-1) of packing volume with >90% cell viability. The good reactor performance can be attributed to the three-dimensional environment provided by the fibrous matrix that allows for efficient mass transfer and cell immobilization and growth. Scanning electron microscopic and confocal scanning laser microscopic studies of the cell-matrix showed that cells formed large aggregates in the fibrous matrix and cell density was relatively uniform in the matrix.

Increased expression of preprotachykinin-I and neurokinin receptors in human breast cancer cells: implications for bone marrow metastasis

Neuropeptides are implicated in many tumors, breast cancer (BC) included. Preprotachykinin-I (PPT-I) encodes multiple neuropeptides with pleiotropic functions such as neurotransmission, immune/hematopoietic modulation, angiogenesis, and mitogenesis. PPT-I is constitutively expressed in some tumors. In this study, we investigated a role for PPT-I and its receptors, neurokinin-1 (NK-1) and NK-2, in BC by using quantitative reverse transcription-PCR, ELISA, and in situ hybridization. Compared with normal mammary epithelial cells (n = 2) and benign breast biopsies (n = 21), BC cell lines (n = 7) and malignant breast biopsies (n = 25) showed increased expression of PPT-I and NK-1. NK-2 levels were high in normal and malignant cells. Specific NK-1 and NK-2 antagonists inhibited BC cell proliferation, suggesting autocrine and/or intercrine stimulation of BC cells by PPT-I peptides. NK-2 showed no effect on the proliferation of normal cells but mediated the proliferation of BC cells. Cytosolic extracts from malignant BC cells enhanced PPT-I translation whereas extracts from normal mammary epithelial cells caused no change. These enhancing effects may be protein-specific because a similar increase was observed for IL-6 translation and no effect was observed for IL-1alpha and stem cell factor. The data suggest that PPT-I peptides and their receptors may be important in BC development. Considering that PPT-I peptides are hematopoietic modulators, these results could be extended to understand early integration of BC cells in the bone marrow, a preferred site of metastasis. Molecular signaling transduced by PPT-I peptides and the mechanism that enhances translation of PPT-I mRNA could lead to innovative strategies for BC treatments and metastasis.