Prognostic significance and therapeutic implications of Caveolin-1 in gastrointestinal tract malignancies

Caveolin-1 (CAV1) is expressed in several solid tumors both in cancerous cells as well as in tumor stroma and is reported to be related to cancer progression, metastasis, therapy resistance and clinical outcomes. Many studies report contrasting functions of this protein depending on the tumor cell model, the tumor type, or the stage of cancer studied. This protein is reported to function both as tumor suppressor and as tumor promoter. In this review, we aim to summarize translational and clinical studies that provide evidence of the role of CAV1 in tumor progression and survival outcome focusing on tumors of the gastrointestinal (GI) tract. Towards this aim, a detailed search has been performed for studies on the expression and the role of CAV1 in oesophageal, gastric, colorectal, pancreatic cancer and cholangiocarcinoma prognosis. We also review and discuss the implication of CAV1 in the outcome of pharmacological interventions. We conclude that CAV1 has the potential to become an important prognostic, and possibly predictive, biomarker in GI malignancies. It may also become a novel target towards the development of improved cancer therapies. However, it is obvious that there remains a lack of consensus on important issues such as the methodologies and cut-off levels in caveolin assessment. This ultimately result in many studies being contradictory not only in terms of the role of CAV1 as a tumor-promoting or suppressing gene but also in terms of the tumor compartment in which the levels of this protein may be of clinical significance. Addressing these important technical issues, in conjunction with a further elucidation of the role of CAV1 in tumor formation and progression, will delineate the importance of CAV1 in prognostic and therapeutic perspectives.