Establishment of culture conditions for patient-derived tumor explants of Basal Cell Carcinoma

Basal Cell Carcinoma (BCC) is the most common type of skin cancer present nowadays: in fact, in the USA it is estimated that there are 4.3 million new cases each year, most of which are among Caucasians. This is probably due to the increased exposure to UV light with the climate change and the tendency of some people to stress the skin using artificial light to have a better tan. Although the number of people diagnosed with this disease has increased dramatically in the last 30 years, BCC has a low mortality rate because it rarely metastasizes. Nevertheless, there is still the urge of finding a new pharmacological treatment that can replace surgery, because not all patients are eligible to it; furthermore, it would allow countries to save money for the Global and National Health Care Systems. Even if it is one of the most frequent types of skin cancer worldwide, it seems that BCC is not entirely understood after all: it is recognized by little papules on the face and the neck, which are the body parts that are most exposed to UV rays, or by superficial lesions that are flat, erythematous, and scaly with well-demarcated edges; for more advanced tumors we have difficult-to-treat lesions, which have been left without treatment for many years. The primary cause of BCC is the excessive activation of Hedgehog pathway, that can derive from a mutation due to long exposure to the sun or artificial light, or from genetic factors: normally, Hedgehog pathway plays an essential role during vertebrate embryonic development, after which, it remains silent, but during tumorigenesis it can be reactivated. Hedgehog pathway is activated mainly by Sonic Hedgehog ligand (SH), a protein that binds Patched 1 (PTCH1), which normally is bound to Smoothened factor (SMO), keeping it inhibited; SH disadvantages this binding, and PTCH1 releases SMO, which activates the cascade signal that increases levels of GLI1 tumorigenic gene, leading to the decrease of PTCH1and to tumorigenesis. In this Master thesis work the aim was to find a new medium for the culturing of tumor explants. To do so, a comparison between M154CF and the control Co-culture medium + EGF has been done, to preserve the intrinsic characteristics of the tumor after 24 hours of incubation. The two media were compared based on the histological structure of the tumor explants, their level of proliferation and apoptosis and on the level of reactivation of the Hedgehog pathway. Another test was performed later to observe the transition between localized and metastasized tumor in some tumor explants, to determine if these conditions are influenced by the two media. Thanks to this work, we will be able to understand the characteristics of the tumor and it will be possible to do further test with a drug, ensuing that any changes in the BCC explant will be due to the drug itself and not any other factor.