High-fat diet (HFD) could induce prostate cancer progression. The aim of this study is to identify mechanisms of HFD-induced prostate cancer progression, focusing on inflammation. We administered HFD and celecoxib to autochthonous immunocompetent Pb-Cre;(fl/fl) model mice for prostate cancer. Tumor growth was evaluated by tumor weight and Ki67 stain, and local immune cells were assessed by flow cytometry at 22 weeks of age. Cytokines which correlated with tumor growth were identified, and the changes of tumor growth and local immune cells after inhibition of the cytokine signals were evaluated in the mice. IHC analyses using prostatectomy specimens of obese patients were performed. HFD accelerated tumor growth and increased the myeloid-derived suppressor cells (MDSCs) fraction and M2/M1 macrophage ratio in the model mice. Celecoxib-suppressed tumor growth, and decreased both local MDSCs and M2/M1 macrophage ratio in HFD-fed mice. HFD-induced tumor growth was associated with IL6 secreted by prostatic macrophages, as were phosphorylated STAT3 (pSTAT3)-positive tumor cells. Anti-IL6 receptor antibody administration suppressed tumor growth, and decreased local MDSCs and pSTAT3-positive cell fractions in HFD-fed mice. The tumor-infiltrating CD11b-positive cell count was significantly higher in prostatectomy specimens of obese than those of nonobese patients with prostate cancer. HFD increased MDSCs and accelerated prostate cancer tumor growth via IL6/pSTAT3 signaling in the mice. This mechanism could exist in obese patients with prostate cancer. IL6-mediated inflammation could be a therapeutic target for prostate cancer. .

Excessive intake of animal fat and resultant obesity are major risk factors for prostate cancer. Because the composition of the gut microbiota is known to change with dietary composition and body type, we used prostate-specific Pten knockout mice as a prostate cancer model to investigate whether there is a gut microbiota–mediated connection between animal fat intake and prostate cancer. Oral administration of an antibiotic mixture (Abx) in prostate cancer–bearing mice fed a high-fat diet containing a large proportion of lard drastically altered the composition of the gut microbiota including Rikenellaceae and Clostridiales, inhibited prostate cancer cell proliferation, and reduced prostate Igf1 expression and circulating insulin-like growth factor-1 (IGF1) levels. In prostate cancer tissue, MAPK and PI3K activities, both downstream of the IGF1 receptor, were suppressed by Abx administration. IGF1 directly promoted the proliferation of prostate cancer cell lines DU145 and 22Rv1 in vitro. Abx administration also reduced fecal levels of short-chain fatty acids (SCFA) produced by intestinal bacteria. Supplementation with SCFAs promoted tumor growth by increasing IGF1 levels. In humans, IGF1 was found to be highly expressed in prostate cancer tissue from obese patients. In conclusion, IGF1 production stimulated by SCFAs from gut microbes influences the growth of prostate cancer via activating local prostate MAPK and PI3K signaling, indicating the existence of a gut microbiota-IGF1-prostate axis. Disrupting this axis by modulating the gut microbiota may aid in prostate cancer prevention and treatment. Significance: These results suggest that intestinal bacteria, acting through short-chain fatty acids, regulate systemic and local prostate IGF1 in the host, which can promote proliferation of prostate cancer cells.

Reliable biomarkers for renal cell carcinoma (RCC) have yet to be determined. Circulating tumor DNA (ctDNA) is an emerging resource to detect and monitor molecular characteristics of various tumors. The present study aims to clarify the clinical utility of ctDNA for RCC. Fifty‐three patients histologically diagnosed with clear cell RCC were enrolled. Targeted sequencing was carried out using plasma cell‐free DNA (cfDNA) and tumor DNA. We applied droplet digital PCR (ddPCR) to validate detected mutations. cfDNA fragment size was also evaluated using a microfluidics‐based platform and sequencing. Proportion of cfDNA fragments was defined as the ratio of small (50‐166 bp) to large (167‐250 bp) cfDNA fragments. Association of mutant allele frequency of ctDNA with clinical course was analyzed. Prognostic potential was evaluated using log‐rank test. A total of 38 mutations across 16 (30%) patients were identified from cfDNA, including mutations in TP53 (n = 6) and VHL (n = 5), and median mutant allele frequency of ctDNA was 10%. We designed specific ddPCR probes for 11 mutations and detected the same mutations in both cfDNA and tumor DNA. Positive ctDNA was significantly associated with a higher proportion of cfDNA fragments (P = .033), indicating RCC patients with ctDNA had shorter fragment sizes of cfDNA. Interestingly, the changes of mutant allele frequency in ctDNA concurrently correlated with clinical course. Positive ctDNA and fragmentation of cfDNA were significantly associated with poor cancer‐specific survival (P < .001, P = .011). In conclusion, our study shows the clinical utility of ctDNA status and cfDNA fragment size as biomarkers for prognosis and disease monitoring in RCC.

Background: Ground-glass opacity (GGO) lesions are difficult to diagnose by transbronchial biopsy (TBB). Objectives: We attempted to diagnose solitary peripheral GGO predominant-type lesions by TBB using endobronchial ultrasonography with a guide sheath (EBUS-GS) under X-ray fluoroscopic guidance, and to evaluate several factors associated with diagnostic yield. Methods: The medical records of 67 patients with GGO predominant-type lesions who underwent TBB using EBUS-GS under X-ray fluoroscopic guidance were retrospectively reviewed. Results: Of the 67 lesions, 38 (57%) were successfully diagnosed by EBUS-GS (5/11 pure GGO lesions and 33/56 mixed GGO lesions). The diagnosable lesions were significantly larger than the nondiagnosable lesions (24 vs. 17 mm, respectively; p < 0.01). Regarding the diagnostic yield by signs on computed tomography, the lesions with a bronchus leading directly to a lesion had a significantly higher diagnostic yield than the others (p < 0.05). When GGO lesions were confirmed under X-ray fluoroscopic guidance, the diagnostic yield was 79% (vs. 40% in lesions not visible on X-ray fluoroscopy; p < 0.05). Conclusions: EBUS-GS is a useful and valuable diagnostic modality, even for GGO predominant-type lesions located at the lung periphery.