PI(4,5)P2 diffuses freely in the plasma membrane even within high-density effector protein complexes.

The lipid phosphatidyl-D-myo-inositol-4,5-bisphosphate [PI(4,5)P2] is a master regulator of plasma membrane (PM) function. Its effector proteins regulate transport, signaling, and cytoskeletal processes that define PM structure and function. How a single type of lipid regulates so many parallel processes is unclear. We tested the hypothesis that spatially separate PI(4,5)P2 pools associate with different PM complexes. The mobility of PI(4,5)P2 was measured using biosensors by single-particle tracking. We found that PM lipids including PI(4,5)P2 diffuse rapidly (∼0.3 µm2/s) with Brownian motion, although they spend one third of their time diffusing more slowly. Surprisingly, areas of the PM occupied by PI(4,5)P2-dependent complexes did not slow PI(4,5)P2 lateral mobility. Only the spectrin and septin cytoskeletons showed reduced PI(4,5)P2 diffusion. We conclude that even structures with high densities of PI(4,5)P2 effector proteins, such as clathrin-coated pits and focal adhesions, do not corral unbound PI(4,5)P2, questioning a role for spatially segregated PI(4,5)P2 pools in organizing and regulating PM functions.

Families Addressing Cancer Together (FACT): feasibility and acceptability of a web-based psychosocial intervention for parents with cancer.

PURPOSE: Although parents with cancer report that talking with their children about cancer and dying is distressing, accessible support is rare. We assessed the feasibility, acceptability, and preliminary effects of Families Addressing Cancer Together (FACT), a web-based, tailored psychosocial intervention to help parents talk about their cancer with their children. METHODS: This pilot study used a pre-posttest design. Eligible participants were parents with new or metastatic solid tumors who had minor (ages 3-18) children. Participants who completed baseline assessments received online access to FACT. We assessed feasibility through enrollment and retention rates and reasons for study refusal. Acceptability was evaluated by satisfaction ratings. We examined participants' selection of intervention content and preliminary effects on communication self-efficacy and other psychosocial outcomes (depression and anxiety symptoms, health-related quality of life, family functioning) at 2- and 12-week post-intervention. RESULTS: Of 68 parents we approached, 53 (78%) agreed to participate. Forty-six parents completed baseline assessments and received the FACT intervention. Of the 46 participants, 35 (76%) completed 2-week assessments, and 25 (54%) completed 12-week assessments. Parents reported that FACT was helpful (90%), relevant (95%), and easy to understand (100%). Parents' psychosocial outcomes did not significantly improve post-intervention, but parents endorsed less worry about talking with their child (46% vs. 37%) and reductions in the number of communication concerns (3.4 to 1.8). CONCLUSION: The FACT intervention was feasible, acceptable, and has potential to address communication concerns of parents with cancer. A randomized trial is needed to test its efficacy in improving psychological and parenting outcomes. TRIAL REGISTRATION: This study was IRB-approved and registered with clinicaltrials.gov (NCT04342871).

Genetic susceptibility and dietary patterns in lung cancer.

Cigarette smoking is the dominant risk factor for lung cancer, but only a minority of smokers ever develops tumors. Though genetic susceptibility is likely to explain some of the variability in risk, results from previous studies of genetic polymorphisms have been inconclusive. As diet may also affect the risk of lung cancer, it is possible that the degree of risk produced by smoking and genetic susceptibility varies, depending on diet. To assess this hypothesis, we conducted a case-control study to examine the effect of cigarette smoking, dietary patterns and variation in genes involved in phase II metabolism. A total of 254 individuals with lung cancer and 184 healthy controls were recruited for the study. To identify persons with similar dietary patterns, cluster analysis was performed using nutrient densities of four major dietary constituents: protein, carbohydrate, animal fat, and dietary fiber. Two groups of individuals were identified with distinct dietary patterns: (1) a group (n=241) with a high intake of animal fat and protein and a low intake of carbohydrates and dietary fiber (the 'unhealthy' pattern) and (2) a group (n=197) with a high intake of fiber and carbohydrate and a low intake of protein and animal fat (the 'healthy' pattern) [corrected]. On stratified analysis, several genotype/dietary pattern combinations were found to affect risk of lung cancer. Smokers who were not homozygous for the most common GSTP1 allele and had a healthy dietary pattern were at significantly lower risk than smokers who were homozygous for the GSTP1 common allele and who had an unhealthy dietary pattern (OR=0.16, 95%CI: 0.04-0.57). Among smokers who were GSTM1 null, persons with a healthy dietary pattern were at lower risk than persons with an unhealthy dietary pattern (OR: 0.46, 95%CI: 0.21-1.01). Among smokers with an unhealthy dietary patterns, persons with a His/His genotype in the exon 3 polymorphism of EPHX1 were at significantly lower risk that persons who were not homozygous. These data suggest that dietary factors may affect the risk imposed by genetic susceptibility at detoxification loci. Adjustments using dietary pattern may be useful in elucidating the effects of polymorphisms in genes responsible for carcinogen metabolism.