The role of fibronectin in tumor implantation at surgical sites

Tumour angiogenesis: the relevance to surgeons

INTRODUCTION

Angiogenesis is the process of new blood vessel formation from pre-existing vessels, and is a key feature of malignant tumours. Surgeons involved in the management of patients with malignant disease need to be aware of angiogenic mechanisms and their surgical implications.

PATIENTS AND METHODS

A literature search was used to review recent developments in our understanding of the factors and processes involved in tumour angiogenesis, and how these will impact on the care of patients with malignant disease encountered by surgeons.

RESULTS

Angiogenesis is fundamental to all stages of the malignant process, and involves a complex interaction between mediators secreted by tumour cells and host cells. Intense investigation continues into therapies targeting components of the angiogenic cascade. Imaging modalities capable of measuring the angiogenic activity of a tumour are also being studied in order to predict prognosis and select suitable patients for anti-angiogenic therapy.

CONCLUSIONS

As the use of these anti-angiogenic therapies becomes more wide-spread, they may have implications on the healing rates of cutaneous wounds and intracorporeal anastomoses.

Significance of angiogenesis in cancer therapy

BACKGROUND

For most solid tumours, surgery remains the most effective primary treatment. Despite apparently curative resection, significant numbers of patients develop secondary disease due to growth of undetected micrometastases. The ability of a tumour to metastasize is related to the degree of angiogenesis it induces. In addition, micrometastases rely on new vessel formation to provide the nutrients necessary for growth. A better understanding of how tumours acquire their blood supply may lead to more effective adjuvant therapies and improve survival following surgery.

METHODS

A systematic review of the literature on angiogenesis between 1971 and 1997 was performed using the Medline database to ascertain current thinking on angiogenesis and its relevance in oncological surgery.

RESULTS

Angiogenesis is a physiological process subject to autocrine and paracrine regulation which has the potential to become abnormal and play a part in a number of pathological states, including cancer. Increased angiogenic stimuli in the perioperative period, associated with concomitant reduction in tumour-derived antiangiogenic factors following resection of a primary tumour, result in a permissive environment which allows micrometastases to grow.

CONCLUSION

Recognition of the role of angiogenesis in metastatic tumour growth represents a significant development in our understanding of tumour biology. The development of antiangiogenic agents offers new promise in the treatment of malignancy. Such agents may prevent or control the development and growth of primary and metastatic tumours.

The potential role of integrin receptor subunits in the formation of local recurrence and distant metastasis by mouse breast cancer cells

BACKGROUND

The mechanisms by which surgical injury fosters tumor growth are examined.

METHODS

TA3Ha mouse breast tumor line and its subline (TA3AD) differing in their metastatic abilities as tested by two models were used. In model a, TA3Ha/TA3AD tumors were grown in the mammary fat pads of mice and then surgically removed with a curative intent. In model b, TA3Ha/TA3AD cells were injected intravenously into mice subjected to liver or spleen wedge resection. Frequency of tumor formation at various sites was assessed. Expression of integrin, immunoglobulin, and proteoglycan cell adhesion receptors on TA3Ha and TA3AD cells was examined by flow cytometry. The roles of these receptors in metastasis were examined by blocking them by selected ligands and/or antibodies.

RESULTS

Frequencies of local recurrence and axillary metastasis after surgical resection, were 43% (32/74), and 37% (27/74) with TA3Ha tumors and 4% (1/29) at both sites with TA3AD tumors. Tumors at surgically injured spleen and the liver were seen in 75% (141/189) and 45% (107/240) of the mice with TA3Ha cells and in 8% (3/38) and 10% (4/42) of the mice with TA3AD cells. alpha 5 and CD44 receptors were expressed by TA3Ha cells but not by TA3AD cells. Other receptors examined were similarly expressed by both cell lines. Blocking of alpha 5 receptor by fibronectin reduced tumor implantation in a dose-dependent manner.

CONCLUSIONS

The data suggest a correlation among the ability to implant at surgically injured sites, to form local recurrence, and to express the fibronectin receptor subunit.

Effect of intraperitoneal chemotherapy and fibrinolytic therapy on tumor implantation in wound sites

Failure of surgical treatment for gastrointestinal cancers is often caused by recurrence of the tumor in traumatized peritoneal surfaces. This study examined the effect of intraperitoneal administration of doxorubicin and recombinant tissue plasminogen activator (rt-PA), a fibrinolytic agent, on incidence and volume of postoperative tumor implants in peritoneal wounds. Prior to randomization, a surgical wound was created on the right parietal peritoneum of 110 BDIX rats and 6 x 10(5) DHD/K12 colon cancer cells were inoculated intraperitoneally (ip). The control group was given an intraperitoneal injection of saline. Five groups received 1 mg/kg of ip doxorubicin at different times postoperatively: at the end of surgery (D0), 3 hr after surgery (D + 3), postoperative day 1 (D1), postoperative day 3 (D3), and postoperative day 7 (D7). In a second set of experiments, five groups of rats received, in addition to postoperative doxorubicin, 5 mg/kg of intraoperative ip rt-PA. Incidence and volume of tumor implants in peritoneal wounds were assessed for each group 20 days after the tumor inoculation. All rats of the control group (incidence = 100%) developed tumor implants in peritoneal wounds. Mean (SD) volume was 16.2 (4.7) mm3. When administered at D0, D + 3, and D1 intraperitoneal doxorubicin reduced significantly the incidence and volume of tumor implants in wounds. Postoperative administration of doxorubicin at D3 and D7 did not affect significantly the incidence and the volume of tumor implants in peritoneal wounds. When rt-PA was administered intraoperatively, ip injection of doxorubicin at any postoperative timing decreased significantly the incidence and volume of tumor implants. In conclusion, ip doxorubicin administered before postoperative D3 may act on tumor cell implanted in peritoneal wounds. Delayed (D3, D7) ip administration of doxorubicin does not prevent the development of tumor implants in peritoneal wounds. Intraoperative administration of rt-PA may significantly increase the efficacy of delayed ip chemotherapy.

Role of cytokines and growth factors in promoting the local recurrence of breast cancer

The pathogenesis of local recurrence in breast cancer is not well understood. Breast-conserving surgery is particularly prone to local recurrence as it leaves behind breast tissue that may harbour occult cancer, and lends itself to enhanced intraoperative shedding of cancer cells due to narrower resection margins and transection of lymphatic channels. A review of clinical breast cancer studies as well as experimental research strongly suggests that these persisting cancerous cells are unlikely to develop into clinically evident disease if their environment remains unstimulated. However, an inordinately high local recurrence rate occurs at the surgical scar, and such recurrence must be triggered by the release of growth factors and cytokines into the healing wound. These factors can stimulate any available cancer cells which express the proper growth factor receptors. Perioperative strategies to neutralize this tumour cell-growth factor interaction should maximize local control.

The prognostic importance of fibronectin and sialic acid levels in human pituitary adenomas

In this study, fibronectin and sialic acid levels were determined in human pituitary adenomas. The mean fibronectin and sialic acid levels for human pituitary adenomas were found to be 31.64 +/- 15.82 microgram/mg protein and 21.90 +/- 9.82 microgram/mg protein, respectively, versus 6.30 +/- 2.96 microgram/mg protein and 9.88 +/- 2.81 microgram/mg protein for the normal brain tissues. Fibronectin and sialic acid levels were significantly higher (P < 0.001) in human pituitary adenomas than the normal brain tissues. In human infiltrative and non-infiltrative pituitary adenomas, the mean fibronectin and sialic acid levels were found to be 40.87 +/- 15.90 microgram/mg protein, 27.59 +/- 11.10 microgram/mg protein and 22.40 +/- 9.51 microgram/mg protein, 16.21 +/- 3.20 microgram/mg protein, respectively. Fibronectin and sialic acid levels were slightly elevated (P < 0.05) in human infiltrative pituitary adenomas compared with non-infiltrative adenomas.

Fibronectin and sialic acid levels in human meningiomas and gliomas

In this study, fibronectin and sialic acid levels have been assayed in human meningiomas and gliomas. The mean fibronectin and sialic acid levels for human meningiomas were 22.01 +/- 9.70 micrograms/mg protein and 19.58 +/- 4.89 micrograms/mg protein, respectively, and for human gliomas were 27.30 +/- 13.70 micrograms/mg protein and 25.67 +/- 11.60 micrograms/mg protein, respectively, versus 9.23 +/- 5.40 micrograms/mg protein and 13.50 +/- 4.30 micrograms/mg protein for normal brain tissues. Fibronectin and sialic acid levels were significantly higher in human meningiomas (P < 0.01 and P < 0.05) and gliomas (P < 0.001 and P < 0.01) than control group. Also the mean fibronectin and sialic acid levels were found to be 18.27 +/- 7.08 micrograms/mg protein and 17.04 +/- 6.25 micrograms/mg protein in Grade I-II and 32.60 +/- 15.00 micrograms/mg protein and 29.50 +/- 11.60 micrograms/mg protein in Grade III-IV gliomas, respectively. Fibronectin and sialic acid levels were significantly higher in Grade III-IV gliomas than Grade I-II gliomas (P < 0.05).

Growth and metastasis of human breast cancers in athymic nude mice

To evaluate critically the merit of utilizing a wound model for growing human tumors, a series of increasingly difficult human tumor types were tested for growth at sites of trauma in athymic nude mice. In vitro tumor lines as well as fresh tumors from the breast, colon, rectum, lung, and a metastasis from an unknown primary were intraperitoneally injected into mice subjected to intra-abdominal organ injury. Successful xenografts were obtained from nine of 10 cell lines and 14 of 24 fresh tumors. The latter included five of six (83%) colon cancers, one lung tumor, metastatic tumor of unknown primary, three of four (75%) metastatic breast cancers and four of six (67%) estrogen receptor (ER)-negative breast primary tumors. Six ER-positive breast tumors tested failed to grow in mice without estrogen supplementation. Xenografts from two breast, two colon and the lung cancers formed spontaneous metastases and all xenografts tested were able to yield serial transplants in the surgical wound model. Histologically, all xenografts and their metastases were identical to their respective donor tumors. Transplantability in mice without exogenous estrogen supplementation was linked to the absence of estrogen and progesterone receptors in breast tumors. Transplantability of the cell lines was associated with the expression of cell surface receptors for fibronectin and hyaluronic acid. Receptors for other extracellular matrix components, namely, laminin, vitronectin, collagen, fibrinogen or von Willebrand factor were not associated with transplantability. These results demonstrate that a large proportion of human tumors, including the breast tumors, can be successfully xenografted into athymic mice by providing them with a healing wound environment, and that such xenografts grown at ectopic sites exhibit metastatic ability.

Molecular and cellular basis of cancer invasion and metastasis: implications for treatment

In the past decade significant advances in establishing the underlying biological mechanisms of tumour invasion and metastasis have been made. Some of the triggering factors and genes relevant to metastatic spread have been identified. Advances have also been made in understanding the signal transduction pathways involved in invasion and metastasis. This increased comprehension of the malignant metastatic process has enabled new antimetastatic strategies to be devised. This review summarizes progress in these areas and discusses the implications for the treatment of metastasis.

Effect of trauma on implantation of metastatic tumor in bone in mice

We studied the influence of surgical trauma to the iliac bone on the implantation of I.V. injected tumor cells, which formed tumor in the surgical wounds of 27/84 mice (32%). None of these mice or nonsurgical mice developed tumor in the opposite or uninjured pelvic bone (P < 0.0001). When different numbers (10(5), 5 x 10(5), and 10 x 10(5)) of TA3Ha cells were injected I.V. immediately after surgery, the frequency of tumor formation showed an increase (respectively, 32%, 63%, 71%). As the interval between induction of trauma and tumor cell injection was increased from 0 to 15 days, the frequency of tumor formation declined from 32% to 0%. These results suggest that the healing wound is a privileged site for experimental metastasis, particularly in the early stages. It is likely that the proteins in the blood clotting cascade are involved in local tumor implantation.