Abstract. Merkel cell carcinoma (MCC) is an aggressive skin cancer with an increasing incidence. Aberrant activation of the phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is common in human cancers and has been revealed to play an important function in cell proliferation, metabolism and tumorigenesis. In the present study, NVP-BEZ235, a dual PI3K/mTOR inhibitor, was revealed to be effective in inhibiting proliferation and inducing cell cycle arrest in MKL-1 cells. Additional investigations revealed that NVP-BEZ235 attenuated PI3K/Akt/mTOR signaling and upregulated the levels of the cell cycle inhibitors p21 and p27. Overall, the present results possess considerable implications for future development of dual PI3K/mTOR inhibitor as potential agents in the management of MCC.

Ribosomal S6 kinase 1 (S6K1) that acts downstream of the mammalian target of rapamycin (mTOR) plays an important role in cell proliferation, protein translation, and cell survival. The gene RPS6KB1 encoding for S6K1 had been found to be alternatively spliced to form different isoforms. In this study, we identified that short isoforms of S6K1 splice variant were overproduced in non-small cell lung cancer (NSCLC). Moreover, suppression of S6K1 short isoforms inhibited NSCLC cell growth and induced apoptosis via upregulation of the BH3-only protein Bim in vitro and in vivo. Additionally, short isoforms of S6K1 activated mTORC1, leading to increased 4E-BP1 phosphorylation. Taken together, our findings suggested that S6K1 short isoforms were deregulated in NSCLC and promoted cell survival. Altogether, our study opens possibilities of new therapeutic approaches for NSCLC that selectively downregulate S6K1 shorter isoforms.

Peripheral T-cell lymphomas (PTCLs) account for 12% of non-Hodgkin’s lymphomas (NHLs). Immunoglobulin (Ig) A pemphigus is an autoimmune blistering disease characterized by tissue-bound and circulating IgA antibodies that target epidermal cell surface components. Malignant lymphomas are often linked with autoimmune disease and the autoimmune blistering disease, paraneoplastic pemphigus, has been associated with NHL. However, cases of PTCLs that are complicated by IgA pemphigus are particularly rare. The current study presents the first known case of PTCL complicated by IgA pemphigus. A 43-year-old male was admitted to the Union Hospital (Wuhan, China) in March 2012 with multiple swollen lymph nodes. Pathology examinations revealed PTCL. Immunohistochemical staining was positive for cluster of differentiation (CD)2, CD3, CD5, CD7 and CD47, and negative for CD20. Ki-67 was ~40% positive. The patient was treated with four cycles of cyclophosphamide, Adriamycin, vincristine and prednisone, and two cycles of gemcitabine, cisplatin and dexamethasone; in addition, the patient received radiation of the retroperitoneal region (total dose, 36 Gy). The patient underwent thalidomide maintenance therapy for 20 days before flaccid blisters appeared on the trunk and limbs. Histopathology and immunofluorescence indicated IgA pemphigus, and intravenous methylprednisolone was administered, followed by treatment with prednisone. Subsequently, no evidence of recurrent lymphoma or pemphigus has been observed.