Acquiring the temperature of a single living cell is not a trivial task. In this paper, we devise a novel nanothermometer, capable of accurately determining the temperature of solutions as well as biological systems such as HeLa cancer cells. The nanothermometer is based on the temperature-sensitive fluorescence of NaYF(4):Er(3+),Yb(3+) nanoparticles, where the intensity ratio of the green fluorescence bands of the Er(3+) dopant ions ((2)H(11/2) --> (4)I(15/2) and (4)S(3/2) --> (4)I(15/2)) changes with temperature. The nanothermometers were first used to obtain thermal profiles created when heating a colloidal solution of NaYF(4):Er(3+),Yb(3+) nanoparticles in water using a pump-probe experiment. Following incubation of the nanoparticles with HeLa cervical cancer cells and their subsequent uptake, the fluorescent nanothermometers measured the internal temperature of the living cell from 25 degrees C to its thermally induced death at 45 degrees C.

Non-melanoma skin cancer (NMSC) is the most common form of cancer in the Caucasian population. Among NMSC types, basal cell carcinoma (BCC) has the highest incidence and squamous cell carcinoma (SCC) is less common although it can metastasize, accounting for the majority of NMSC-related deaths. Treatment options for NMSC include both surgical and non-surgical modalities. Even though surgical approaches are most commonly used to treat these lesions, Photodynamic Therapy (PDT) has the advantage of being a non-invasive option, and capable of field treatment, providing optimum cosmetic outcomes. Numerous clinical research studies have shown the efficacy of PDT for treating pre-malignant and malignant NMSC. However, resistant or recurrent tumors appear and sometimes become more aggressive. In this sense, the enhancement of PDT effectiveness by combining it with other therapeutic modalities has become an interesting field in NMSC research. Depending on the characteristics and the type of tumor, PDT can be applied in combination with immunomodulatory (Imiquimod) and chemotherapeutic (5-fluorouracil, methotrexate, diclofenac, or ingenol mebutate) agents, inhibitors of some molecules implicated in the carcinogenic process (COX2 or MAPK), surgical techniques, or even radiotherapy. These new strategies open the way to a wider improvement of the prevention and eradication of skin cancer.

The role of reactive oxygen species (ROS) in the regulation of hair follicle cycle and skin homeostasis is poorly characterized. ROS have been traditionally linked to human disease and ageing, but recent findings suggest that can also have beneficial physiological functions in vivo in mammals. To test this hypothesis, we transiently switched on in situ ROS production in mouse skin. This process activated cell proliferation in the tissue and, interestingly, in the bulge region of the hair follicle, a major reservoir of epidermal stem cells, promoting hair growth as well as stimulating tissue repair after severe burn injury. We further show that these effects were associated with a transient Src kinase phosphorylation at Tyr416 and with a strong transcriptional activation of the prolactin family 2 subfamily c of growth factors. Our results point to potentially relevant modes of skin homeostasis regulation and demonstrate that a local and transient ROS production can regulate stem cell and tissue function in the whole organism.

Photodynamic therapy (PDT) employing methyl δ-aminolevulinic acid (Me-ALA), as a precursor of the photosensitizer protoporphyrin IX (PpIX), is used for the treatment of non melanoma cutaneous cancer (NMCC). However, one of the problems of PDT is the apparition of resistant cell populations. The aim of this study was to isolate and characterize squamous carcinoma cells SCC-13 resistant to PDT with Me-ALA. The SCC-13 parental population was submitted to successive cycles of Me-ALA-PDT and 10 resistant populations were finally obtained. In parental and resistant cells there were analyzed the cell morphology (toluidine blue), the intracellular PpIX content (flow cytometry) and its localization (fluorescence microscopy), the capacity of closing wounds (scratch wound assay), the expression of cell-cell adhesion proteins (E-cadherin and β-catenin), cell-substrate adhesion proteins (β1-integrin, vinculin and phospho-FAK), cytoskeleton proteins (α-tubulin and F-actin) and the inhibitor of apoptosis protein survivin, in the activated form as phospho-survivin (indirect immunofluorescence and Western blot). The results obtained indicate that resistant cells showed a more fibroblastic morphology, few differences in intracellular content of the photosensitizer, higher capacity of closing wounds, higher number of stress fibers, more expression of cell-substrate adhesion proteins and higher expression of phospho-survivin than parental cells. These distinctive features of the resistant cells can provide decisive information to enhance the efficacy of Me-ALA applications in clinic dermatology.

Photodynamic therapy (PDT) is a treatment modality for different forms of cancer based on the combination of light, molecular oxygen, and a photosensitizer (PS) compound. When activated by light, the PS generates reactive oxygen species leading to tumor destruction. Phthalocyanines are compounds that have already shown to be efficient PSs for PDT. Several examples of carbohydrate substituted phthalocyanines have been reported, assuming that the presence of carbohydrate moieties could improve their tumor selectivity. This work describes the photoeffects of symmetric and asymmetric phthalocyanines with D-galactose (so-called GPh1, GPh2, and GPh3) on HeLa carcinoma cells and their involvement in cell death. Photophysical properties and in vitro photodynamic activities for the compounds considered revealed that the asymmetric glycophthalocyanine GPh3 is very efficient and selective, producing higher photocytotoxicity on cancer cells than in nonmalignat HaCaT. The cell toxiticy after PDT treatment was dependent upon light exposure level and GPh3 concentration. GPh3 causes cell cycle arrest at the metaphase stage leading to multiple spindle poles, mitotic catastrophe, followed by apoptosis in cancer cells. These effects were partially negated by the pancaspase inhibitor Z-VAD-FMK. Together, these results indicate that GPh3 is an excellent candidate drug for PDT, able to induce selective tumor cell death.