Effect Of Rapamycin On The Potential Metastasis Of Squamous Cell Carcinoma

Background&Objective: Sirolimus is a new kind of macrolides immunosuppressorextracted from the fermentation broth of water absorbent streptomyces. It can bespecifically bound to phosphatidylinositol3kinase/protein kinase B/downstreamprotein mTOR of mammal RAPA target protein (PI3K/AKT/mTOR) signaling pathway,so as to block the stimulating response and transmission of this signaling pathway toimpact factors around. RAPA has been the focus of attention at home and abroad inrecent years. Many studies have found that RAPA has good antitumor effect, includingbreast cancer, lung cancer, renal carcinoma, prostate cancer, etc. It has a stronginhibitory effect on the growth and proliferation of tumor cell. Recently, it has beendiscovered that RAPA can also be used to treat Alzheimer’s disease at abroad, but thereare few reports about its effect on skin epithelial squamous cancer cells. Skin epithelialsquamous cell carcinoma (squamous carcinoma) is a malignant tumor of skin epidermiscells, also called dermoid cancer. It occurs in high rate among old people over the age of50, mostly happened in scalp, face, mouth, tongue, etc, especially the junction of skinand mucosa. Squamous carcinoma of epithelium has the characteristics of rapiddevelopment, high damage on tissue, and strong invasiveness and mobility. Clinicaltreatment mainly applies the radical resection, combined with postoperativeradiotherapy or chemotherapy. Due to the high invasiveness and mobility of squamouscarcinoma cells and its high rate of relapse and metastasis, squamous carcinoma haspoor clinical prognosis. Although the pathogenesis of dermoid cancer is not fully understood, some studies show that the activation of Ras signaling pathway and furtheractivated PI3K/AKT/mTOR signaling pathway probably promote the overgrowth,migration and dedifferentiation/transdifferentiation of epithelial cells, meanwhileleading to the thickened epidermal barrier and its dysfunction, even the failure ofepidermization. In this study, we focus on observing the function of RAPA to epithelialsquamous carcinoma cells and the change in biological behavior. Also, we conduct theprimary discussion on RAPA’s mechanism of action. This may provide the theoreticalbasis for subsequent clinical partial treatment of skin squamous carcinoma andprevention of local infiltration and migration.Methods:1. Experiment was divided into the Control (normal Control group) andRAPA treatment group (5,10,20nmol L-1).2. MTT assay was used to investigateproliferation of A431cells treated by rapamycin at different concentrations of (5，10，20nmol·L-1).3. Apoptosis was evaluated by Annexin V-FITC apoptosis detection Kit.4.Wound healing and Transwell assays were performed to detect migration and invasionability of A431cells treated by rapamycin.5. To detect osteopontin (OPN) expression atmRNA level or protein level in the A431cells treated by rapamycin, reversetranscription PCR (RT-PCR) and Western Blotting was performed, respectively.Results:1. Comparing with the controls, the growth inhibition ratio of A431treatedby rapamycin at differentiation concentrations was significantly decreased, but theresult of Facs assay is negative.2. The migration ability and the invasion ability werealso significantly suppressed, but the result of Facs show no effect on promoting apoptosis.3. After treated by rapamycin, expression level of osteopontin in A431cells wasdecreased.Conclusions: Rapamycin could inhibit the proliferation, migration and invasion ofsquamous cell carcinoma (SCC) A431, which may be related to down-regulate the expression of osteopontin.