Cellular Invasion Assay for the Real-Time Tracking of Individual Cells in Spheroid or Tumor-like Mimics.

Cellular invasion is the gateway to metastasis, with cells moving from a primary tumor into neighboring regions of healthy tissue. Invasion assays provide a tractable experimental platform to quantitatively assess cellular movement in the presence of potential chemokines or inhibitors. Many such assays involve cellular movement from high cell densities to cell-free regions. To improve the physiological relevance of such assays, we developed an assay format to track cellular movement throughout a uniform density of cells. This assay format imparts diffusion-dominated environments along the channel, resulting in oxygen and nutrient gradients found in spheroids or poorly vascularized tumors. By incorporating oxygen- and pH-sensing films, we quantified spatial and temporal changes in the extracellular environment while simultaneously tracking the movement of a subset of cells engineered to express fluorescent proteins constitutively. Our results show the successful invasion into neighboring tissues likely arises from a small population with a highly invasive phenotype. These highly invasive cells continued to move throughout the 48 h experiment, suggesting they have stem-like or persister properties. Surprisingly, the distance these persister cells invaded was unaffected by the density of cells in the channel or the presence or absence of an oxygen gradient. While these datasets cannot determine if the invasive cells are inherent to the population or if diffusion-dominated environments promote them, they highlight the need for further study.

Association between Delay to Radical Prostatectomy and Clinically Meaningful Outcomes among Patients with Intermediate and High-Risk Localized Prostate Cancer.

PURPOSE: There are limited data regarding the effect of treatment delays on important long-term outcomes among men with intermediate/high-risk prostate cancer (PC). MATERIALS AND METHODS: We identified 3,962 men with intermediate/high-risk disease from the SEARCH cohort treated with radical prostatectomy (RP) from 1988 to 2018. Cox proportional hazard models assessed the association between time from biopsy to RP (up to 1 year) and time to castration-resistant PC (CRPC), metastasis and all-cause mortality. Interaction terms were used to test for effect modification by risk group. RESULTS: Of the 3,962 men, 167 developed CRPC, 248 developed metastases and 884 died after a median followup of 85 months. Longer delays between biopsy and RP were associated with a decreased risk of CRPC (adjusted HR=0.88, 95% CI: 0.80-0.98, p=0.02), independent of D'Amico risk group (interaction p >0.05). In men with intermediate and high-risk disease, we found no statistically significant association between length of time to RP and risk of developing metastases (p=0.5 and 0.9, respectively) or all-cause mortality (p=0.1 and 0.1, respectively). CONCLUSIONS: Among men with intermediate and high-risk PC, we found no statistically significant increased risk of adverse long-term outcomes, including CRPC, metastasis and death, for men who had treatment delays up to 1 year following PC diagnosis.