How cholesterol influences intercellular interaction: Its possible role in metastasis

Tensiometric Profiles and Their Modulation by Cholesterol: Implications in Cervical Cancer

Langmuir monolayers offer a convenient model for understanding the behavior of many natural systems like biological membranes. This technique was used to characterize the role of cholesterol, lipophilic, and lipophobic components of tissues in cervical cancer by evaluating their tensiometric profiles. Monolayers were formed on the surface of deionized water by spreading tissue components corresponding to 1 mg of the tissue for studying their surface pressure-area isotherms at body temperature. The cholesterol content of cancerous human cervical tissues was higher than that of the normal human cervical tissues. The addition of 3 mug cholesterol/mg tissue to the normal organic phase changed its tensiometric profile to that of the cancerous profile. Statistically significant tensiometric parameters showed that cholesterol acts as a rigidifier in the cervical tissues and has a remarkable role in shifting the normal cervical lipophilic surface activity towards that of the cancerous lipophilic monolayer. Several mixtures of the lipophilic-lipophobic components of both cancerous as well as normal cervical tissues also were characterized to reveal the relative contribution of these phases in the cervical cancer tensiometric profiles. Though the actual ratio of aqueous and organic phases in the normal tissue was 97:3 by weight, the tissue homogenate behavior was similar to that of a 50:50 mixture by weight, indicating the nonadditivity of the lipophilic-lipophobic components. The addition of cholesterol to a 97: 3 by weight aqueous: organic mixture of normal cervical tissue also revealed the rigidifying role of cholesterol. Unlike in normal tissue homogenates, the cancerous tissue homogenate tensiometric profile had more contribution from its aqueous phase components and an additive interaction between the lipophilic and lipophobic components was observed in the tissue homogenate. Thus, distinct differences in the interactions between lipophilic and lipophobic components were observed in cancerous and normal states. The Langmuir monolayer technique was sensitive to detect such changes in the form of altered tensiometric profiles. Therapeutic strategies may be designed to modulate these tensiometric profiles to our benefit.

Interfacial properties as biophysical markers of cervical cancer

Monolayers at air-liquid interfaces offer a convenient model for understanding the behavior of many natural systems like biological membranes. Langmuir monolayers were used to characterize the interfacial properties of tissue homogenates, organic phases and aqueous phases of tissue biopsy samples from 30 patients of cervical cancer and 15 normals. Our results reveal that the tensiometric parameters can differentiate between cancer and normal tissues obtained from human cervix and were statistically significant using t-test (P<0.05). The minimum surface tension of the cancer tissue monolayer was 52.9+/-4.4 mN/m, 1.4-folds greater than the normal cervical tissue homogenate value of 38.5+/-2.6 mN/m. The normal tissue homogenate isotherm had a hysteresis area of 90.3 microJ, which was approximately 6.2 times greater than that of the cervical cancer tissue monolayer. The total lipid and phospholipid contents of the cancerous cervical tissue were roughly double that of the normal cervical tissue and the surface activity was also in line with this observation. The difference in hysteresis of the cancerous and normal tissues indicates a decreased stability of the cancerous tissue film as compared to normal. The difference in surface activity denotes alterations in the molecular packing of the tissues in the cancerous state, which may have implications in terms of drug permeability and responsiveness. Further, differences in surface activity may play a role in altered cell adhesion and metastasis. This study is the first to evaluate surface properties of cancerous tissues and can lead to the development of a biophysical marker of cervical cancer based on interfacial properties.