MicroRNAs (miRNAs) are small, 20–22-nucleotide-long members of the non-protein-coding RNA family. In fact, rituximab and imexon could efficiently enhance the radiosensitivity of NHL cells. Therefore, it is important to develop new drugs to decrease radio-resistance or increase radiosensitivity in these lymphomas. Eliminating these radiation-resistant cells may be a key to improving lymphoma radiotherapy. These data suggest a subset of resistant disease in the range of 20%. However, for diffuse histiocytic lymphoma, local failure rates were in the range of 20–30% regardless of the radiation dose delivered.

NHLs are known to be radiosensitive tumors. In aggressive NHL, radiotherapy is used in stage I disease with curative intent after a short course of chemotherapy, and may also be used to consolidate chemotherapy response in bulk or extra-nodal disease. In indolent NHL, radiotherapy may cure early stage disease and palliate more advanced diseases. Radiotherapy is a well-established approach in the management of NHL across different histological and clinical sub-types. The increased incidence of NHL has been partly attributed to recent advances in molecular diagnostic techniques, the aging of the population, the acquired immune deficiency syndrome (AIDS) epidemic, other infectious agents and occupational exposures. The incidence of NHL has increased strikingly during the last four decades, nearly doubling from 1970 to 1990. Non-Hodgkin's lymphoma (NHL) is a heterogeneous group of lymphoid malignancies characterized by an abnormal clonal proliferation of B cells, T cells or both. Taken together, these results demonstrate that miR-148b increased the radiosensitivity of NHL cells probably by promoting radiation-induced apoptosis, which suggests that miR-148b plays an important role in the response of NHL to ionizing radiation. An apoptosis assay showed that miR-148b enhanced apoptosis of Raji cells after irradiation. MiR-148b did not affect the cell cycle profile of post-radiation Raji cells compared with controls. A clonogenic assay demonstrated that miR-148b sensitized Raji cells to radiotherapy. A proliferation assay showed that miR-148b could inhibit the proliferation of Raji cells before and after radiation. Transient transfection experiments showed that miR-148b was up-regulated by miR-148b mimic and down-regulated by miR-148b inhibitor in the Raji cells. A quantitative real-time polymerase chain reaction (PCR) assay confirmed the up-regulation of miR-148b after radiation.

Among the differentially expressed miRNAs, miR-148b was up-regulated 1.53-fold in response to radiation treatment. A total of 20 differentially expressed miRNAs were identified including 10 up-regulated and 10 down-regulated (defined as P < 0.05). Microarray was employed to compare the miRNA expression profiles in B cell lymphoma cell line Raji before and after a 2-Gy dose of radiation. This study aimed to explore the role of miRNAs in non-Hodgkin's lymphoma (NHL) radiosensitivity. Growing evidence has demonstrated that microRNAs (miRNAs) play an important role in regulating cellular radiosensitivity.

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