Adoptive immunotherapy using ex vivo-expanded tumor-reactive lymphocytes can mediate durable cancer regression in selected melanoma patients. Analyses of these trials have associated the in vivo engraftment ability of the transferred cells with their antitumor efficacy. Thus, there is intensive clinical interest in the prospective isolation of tumor-specific T cells that can reliably persist after transfer. Animal studies have suggested that central memory CD8(+) T cells (T(CM)) have divergent capabilities including effector differentiation to target antigen and stem cell-like self-renewal that enable long-term survival after adoptive transfer. We sought to isolate human melanoma-specific T(CM) to define their in vivo fate and function after autologous therapeutic transfer to metastatic patients. To facilitate the high-throughput identification of these rare cells from patients, we report that T(CM) have a defined stoichiometric production of interleukin-2 (IL-2) and interferon-γ (IFN-γ) mRNA after antigen stimulation. Melanoma-specific T cells screened for high relative IL-2 production had a T(CM) phenotype and superior in vitro proliferative capacity compared to cells with low IL-2 production. To investigate in vivo effector function and self-renewal capability, we allowed melanoma-specific T(CM) to undergo in vitro expansion and differentiation into lytic effector clones and then adoptively transferred them back into their hosts. These clones targeted skin melanocytes in all five patients and persisted long term and reacquired parental T(CM) attributes in four patients after transfer. These findings demonstrate the favorable engraftment fitness for human T(CM)-derived clones, but further efforts to improve their antitumor efficacy are still necessary.

Cofilin-1, a non-muscle isoform of actin regulatory protein that belongs to the actin-depolymerizing factor (ADF)/cofilin family is known to affect cancer development. Previously, we found that over-expression of cofilin-1 suppressed the growth and invasion of human non-small cell lung cancer (NSCLC) cells in vitro. In this study, we further investigated whether over-expression of cofilin-1 can suppress tumor growth in vivo, and performed a microRNA array analysis to better understand whether specific microRNA would be involved in this event. The results showed that over-expression of cofilin-1 suppressed NSCLC tumor growth using the xenograft tumor model with the non-invasive reporter gene imaging modalities. Additionally, cell motility and invasion were significantly suppressed by over-expressed cofilin-1, and down-regulation of matrix metalloproteinase (MMPs) -1 and -3 was concomitantly detected. According to the microRNA array analysis, the let-7 family, particularly let-7b and let-7e, were apparently up-regulated among 248 microRNAs that were affected after over-expression of cofilin-1 up to 7 days. Knockdown of let-7b or let-7e using chemical locked nucleic acid (LNA) could recover the growth rate and the invasion of cofilin-1 over-expressing cells. Next, the expression of c-myc, LIN28 and Twist-1 proteins known to regulate let-7 were analyzed in cofilin-1 over-expressing cells, and Twist-1 was significantly suppressed under this condition. Up-regulation of let-7 microRNA by over-expressed cofilin-1 could be eliminated by co-transfected Twist-1 cDNA. Taken together, current data suggest that let-7 microRNA would be involved in over-expression of cofilin-1 mediated tumor suppression in vitro and in vivo.

Evolution has provided many organisms with sophisticated sensory systems that enable them to respond to signals in their environment. The response frequently involves alteration in the pattern of movement, either by directed movement, a process called taxis, or by altering the speed or frequency of turning, which is called kinesis. Chemokinesis has been most thoroughly studied in the peritrichous bacterium Escherichia coli, which has four helical flagella distributed over the cell surface, and swims by rotating them. When rotated counterclockwise the flagella coalesce into a propulsive bundle, producing a relatively straight "run," and when rotated clockwise they fly apart, resulting in a "tumble" which reorients the cell with little translocation. A stochastic process generates the runs and tumbles, and in a chemoeffector gradient, runs that carry the cell in a favorable direction are extended. The cell senses spatial gradients as temporal changes in receptor occupancy and changes the probability of counterclockwise rotation (the bias) on a fast timescale, but adaptation returns the bias to baseline on a slow timescale, enabling the cell to detect and respond to further concentration changes. The overall structure of the signal transduction pathways is well characterized in E. coli, but important details are still not understood. Only recently has a source of gain in the signal transduction network been identified experimentally, and here we present a mathematical model based on dynamic assembly of receptor teams that can explain this observation.