Search

BACKGROUND: Pancreatic cancer (PC) can be considered a representative cancer type of the human body. As demonstrated by some studies, microRNA (miR)-499 is dysregulated in various cancer types including PC, for which chemotherapy involving 5-fluorouracil (5-FU) has long been considered the first-line therapy. However, there are complex and comprehensive mechanisms related to 5-FU, which have not been fully elucidated. This study thus aimed to examine the molecular mechanisms of 5-FU resistance through miR-499a-5p in PC. METHODS: The expression of miR-499a-5p in PC was measured using quantitative polymerase chain reaction (PCR). MiR-499a-5p was examined in-vivo for its effects on the malignant phenotypes of PC cells. RESULTS: The results of the present study demonstrated miR-499a-5p to be upregulated in PC and 5-FU resistant PC tissues. According to in vitro assays in PC cells (PANC1/FR), miR-499a-5p was found to affect adenosine triphosphate (ATP) binding cassette subfamily B member 1 (P-gp), ATP binding cassette subfamily C member 1 (MRP1), and ATP binding cassette subfamily G member 2 (BCRP), thereby facilitating 5-FU resistance in PC cells. Functions assays indicated that suppressed miR-499a-5p expression inhibited the proliferation and migration of cells but facilitated apoptosis in the PC cell line; by contrast, miR-499a-5p overexpression triggered the inverse phenotypic changes of cells. Concerning the mechanisms involved, miR-499a-5p increased PI3K/Akt signaling by targeting phosphatase and tensin homolog (PTEN). CONCLUSIONS: Taken together, these findings demonstrate that miR-499a-5p can be potentially applied to PC therapy.

Based on Maxwell’s stress tensor and the generalized Lorenz–Mie theory, a theoretical approach is introduced to study the radiation force exerted on a uniaxial anisotropic sphere illuminated by dual counter-propagating (CP) Gaussian beams. The beams propagate with arbitrary direction and are expanded in terms of the spherical vector wave functions (SVWFs) in a particle coordinate system using the coordinate rotation theorem of the SVWFs. The total expansion coefficients of the incident fields are derived by superposition of the vector fields. Using Maxwell stress tensor analysis, the analytical expressions of the radiation force on a homogeneous absorbing uniaxial anisotropic sphere are obtained. The accuracy of the theory is verified by comparing the radiation forces of the anisotropic sphere reduced to the special cases of an isotropic sphere. In order to study the equilibrium state, the effects of beam parameters, particle size parameters, and anisotropy parameters on the radiation force are discussed in detail. Compared with the isotropic particle, the equilibrium status is sensitive to the anisotropic parameters. Moreover, the properties of optical force on a uniaxial anisotropic sphere in a single Gaussian beam trap and Gaussian standing wave trap are compared. It indicates that the CP Gaussian beam trap may more easily capture or confine the anisotropic particle. However, the radiation force exerted on an anisotropic sphere exhibits very different properties when the beams do not propagate along the primary optical axis. The influence of the anisotropic parameter on the radiation force by CP Gaussian beams is different from that of a single Gaussian beam. In summary, even for anisotropic particles, the Gaussian standing wave trap also exhibits significant advantages when compared with the single Gaussian beam trap. The theoretical predictions of radiation forces exerted on a uniaxial anisotropic sphere by dual Gaussian beams provide effective ways to achieve the improvement of optical tweezers as well as the capture, suspension, and high-precision delivery of anisotropic particles.

Oral cancer, which occurs in the mouth, lips, and tongue, is a multifactorial disease whose etiology involves environment, genetic, and epigenetic factors. Tobacco use and alcohol consumption are regarded as the primary risk factors for oral squamous cell carcinoma (OSCC), and betel use, other chemicals, radiation, environmental, and genetics are reported as relevant risk factors for oral carcinogenesis. The human papillomavirus infection is an independent risk factor. Traditional epidemiology studies have revealed that environmental carcinogens are risk factors for OSCC. Molecular epidemiology studies have revealed that the susceptibility to OSCC is influenced by both environmental and genetic risk factors. However, the details and mechanisms of risk factors involved in OSCC are unclear. Advanced methods and techniques used in human genome studies provide great opportunities for researchers to explore and identify (a) the details of such risk factors and (b) genetic susceptibility involved in OSCC. Human genome epidemiology is a new branch of epidemiology, which leads the epidemiology study from the molecular epidemiology era into the era of genome-wide association study. In the era of precision medicine, molecular epidemiology studies should focus on biomarkers for cancer genomics and their potential utility in clinical practice. Here, we briefly reviewed several molecular epidemiology studies of OSCC, focusing on biomarkers as valuable utility in risk assessment, clinical screening, diagnosis, and prognosis prediction of OSCC in the era of precision medicine.