Inhibition of autophagy and MEK promotes ferroptosis in Lkb1-deficient Kras-driven lung tumors.

LKB1 and KRAS are the third most frequent co-mutations detected in non-small cell lung cancer (NSCLC) and cause aggressive tumor growth. Unfortunately, treatment with RAS-RAF-MEK-ERK pathway inhibitors has minimal therapeutic efficacy in LKB1-mutant KRAS-driven NSCLC. Autophagy, an intracellular nutrient scavenging pathway, compensates for Lkb1 loss to support Kras-driven lung tumor growth. Here we preclinically evaluate the possibility of autophagy inhibition together with MEK inhibition as a treatment for Kras-driven lung tumors. We found that the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and the MEK inhibitor Trametinib displays synergistic anti-proliferative activity in KrasG12D/+;Lkb1-/- (KL) lung cancer cells, but not in KrasG12D/+;p53-/- (KP) lung cancer cells. In vivo studies using tumor allografts, genetically engineered mouse models (GEMMs) and patient-derived xenografts (PDXs) showed anti-tumor activity of the combination of HCQ and Trametinib on KL but not KP tumors. We further found that the combination treatment significantly reduced mitochondrial membrane potential, basal respiration, and ATP production, while also increasing lipid peroxidation, indicative of ferroptosis, in KL tumor-derived cell lines (TDCLs) and KL tumors compared to treatment with single agents. Moreover, the reduced tumor growth by the combination treatment was rescued by ferroptosis inhibitor. Taken together, we demonstrate that autophagy upregulation in KL tumors causes resistance to Trametinib by inhibiting ferroptosis. Therefore, a combination of autophagy and MEK inhibition could be a novel therapeutic strategy to specifically treat NSCLC bearing co-mutations of LKB1 and KRAS.

Comparison of perioperative complications for extended vs standard pelvic lymph node dissection in patients undergoing radical prostatectomy for prostate cancer: a meta-analysis.

INTRODUCTION: Pelvic lymph node dissection (PLND) is widely performed for staging in men undergoing radical prostatectomy (RP) for prostate cancer. Our goal was to synthesize all available evidence and data to evaluate perioperative complications for two templates of PLND, standard (sPLND) vs extended (ePLND), at the time of RP in patients with prostate cancer. METHODS: A meta-analysis was performed on relevant literature about complications during PLND. Pubmed, Scopus, WebofScience, and Cochrane Library were systematically searched through July 2021. Meta-analysis was conducted with both fixed-effects and random-effects models to estimate risk ratios (RRs) between treatments. A subgroup analysis was also conducted based on surgery type - open vs robotic. RESULTS: 13 (1 randomized clinical trial and 12 observational studies) studies published between 1997 and 2019 with a total of 7,036 patients were analyzed. Pooled data showed complications in a random-effects model was lower in the sPLND group than the ePLND group (RR, 0.62; 95% CI 0.40-0.97). In a subgroup analysis, neither the open surgery subgroup nor the robotic surgery subgroup showed significant differences in complication rate between sPLND and ePLND. CONCLUSION: ePLND is associated with a significantly greater risk of perioperative complication compared to sPLND, but not when comparing these templates performed via a robotic approach. Additional studies comparing the complication rates of sPLND and ePLND when utilizing a robotic approach should be conducted.

Autophagy and tumorigenesis.

Autophagy is a catabolic process that captures cellular waste and degrades them in the lysosome. The main functions of autophagy are quality control of cytosolic proteins and organelles, and intracellular recycling of nutrients in order to maintain cellular homeostasis. Autophagy is upregulated in many cancers to promote cell survival, proliferation, and metastasis. Both cell-autonomous autophagy (also known as tumor autophagy) and non-cell-autonomous autophagy (also known as host autophagy) support tumorigenesis through different mechanisms, including inhibition of p53 activation, sustaining redox homeostasis, maintenance of essential amino acids levels in order to support energy production and biosynthesis, and inhibition of antitumor immune responses. Therefore, autophagy may serve as a tumor-specific vulnerability and targeting autophagy could be a novel strategy in cancer treatment.