Improving Therapeutic Outcomes in Non-small Cell Lung Cancer not Suitable for Curative Intent Therapy — A Review of the Role of Radiation Therapy in an Era of Increasing Systemic Therapy Options

ABT-737, a BH3 Mimetic, Enhances the Therapeutic Effects of Ionizing Radiation in K-ras Mutant Non-Small Cell Lung Cancer Preclinical Model

PURPOSE

Tumor radioresistance and dose-limiting toxicity restrict the curative potential of radiotherapy, requiring novel approaches to overcome the limitations and augment the efficacy. Here, we investigated the effects of signal transducer and activator of transcription 3 (STAT3) activation and autophagy induction by irradiation on antiapoptotic proteins and the effectiveness of the BH3 mimetic ABT-737 as a radiosensitizer using K-ras mutant non-small cell lung cancer (NSCLC) cells and a Kras^G12D:p53^fl/fl mouse (KP mouse) model.

MATERIALS AND METHODS

A549 and H460 cells were irradiated, and the expression of Bcl-2 family proteins, JAK/STAT transcriptional pathway, and autophagic pathway were evaluated by immunoblotting. The radiosensitizing effects of ABT-737 were evaluated using A549 and H460 cell lines with clonogenic assays and also by a KP mouse model with microcomputed tomography and immunohistochemistry.

RESULTS

In A549 and H460 cells and mouse lung tissue, irradiation-induced overexpression of the antiapoptotic molecules Bcl-xL, Bcl-2, Bcl-w, and Mcl-1 through JAK/STAT transcriptional signaling induced dysfunction of the autophagic pathway. After treatment with ABT-737 and exposure to irradiation, the number of surviving clones in the cotreatment group was significantly lower than that in the group treated with radiation or ABT-737 alone. In the KP mouse lung cancer model, cotreatment with ABT-737 and radiation-induced significant tumor regression; however, body weight changes in the combination group were not significantly different, suggesting that combination treatment did not cause systemic toxicity.

CONCLUSION

These findings supported the radiosensitizing activity of ABT-737 in preclinical models, and suggested that clinical trials using this strategy may be beneficial in K-ras mutant NSCLC.

Chimeric antibody targeting SRPK-1 in the treatment of non-small cell lung cancer by inhibiting growth, migration and invasion

Non-small cell lung cancer (NSCLC) is one of the most common types of cancer in humans, and is characterized by rapid growth, migration, invasion and reoccurrence. Evidence has indicated that the protein and mRNA levels of serine‑arginine protein kinase‑1 (SRPK‑1) are upregulated in NSCLC tissues. However, the functions of SRPK1 and targeted therapy for SRPK1 in the progression and treatment of NSCLC remain to be fully elucidated. In the present study, the mRNA and protein expression levels of SRPK‑1 in NSCLC cells and tissues were analyzed using reverse transcription‑quantitative polymerase chain reaction analysis and SDS‑PAGE, and the role of SRPK1 in the progression of NSCLC was investigated. In addition, a chimeric antibody target for SRPK‑1 (ChanSRPK‑1) was constructed, and the therapeutic effects of ChanSRPK‑1 were investigated in H358‑bearing mice. The curative effects of ChanSRPK‑1 on the inhibition of growth, migration and invasion of NSCLC were also examined in vitro and in vivo. The results revealed that the mRNA and protein levels of SRPK‑1 were upregulated in NSCLC cells and tumor tissues. Higher expression of SRPK1 promoted NSCLC cell growth, migration and invasion, whereas lower expression of SRPK‑1 suppressed growth, migration and invasion of the NSCLC cells. Animal experiments demonstrated that ChanSRPK‑1 inhibited the β‑catenin/T‑cell factor complex. ChanSRPK‑1 treatment also downregulated the phosphorylation levels of glycogen synthase kinase 3-β and prolonged the survival of tumor‑bearing mice. Taken together, SRPK‑1 may offer potential as a therapeutic target oncogenic molecular in NSCLC, and ChanSRPK‑1 may be a therapeutic agent with functions as a target and for oncolytic therapy in the treatment of NSCLC.