chlorin-p6 and Carcinoma--Squamous-Cell

The effect of photodynamic therapy (PDT) is dependent on the localization of photosensitizer in the treatment volume at the time of illumination. Investigation of photosensitizer pharmacokinetics in and around the treatment volume aids in determining the optimal drug light interval for PDT.. In this paper we have investigated the distribution of the photosensitizers chlorin e6 and Bremachlorin in the oral squamous cell carcinoma cell-line OSC19-Luc-Gfp in a tongue tumor, tumor boundary, invasive tumor boundary, and normal tongue tissue by the use of confocal microscopy of frozen sections. Tongues were harvested at t = [3, 4.5, 6, 24, 48] hours after injection.. Both photosensitizers showed a decreasing fluorescence with increasing incubation time, and at all time points higher fluorescence was measured in tumor boundary than in tumor itself. For short incubation times, a higher fluorescence intensity was observed in the invasive tumor border and normal tissue compared to tumor tissue. Bremachlorin showed a small increase in tumor to normal ratio at 24 and 48 hours incubation time. Ce6 was undetectable at 48 hours. We did not find a correlation between photosensitizer localization and the presence of vasculature.. The modest tumor/tumor boundary to normal selectivity of between 1.2 and 2.5 exhibited by Bremachlorin 24 and 48 hours after administration may allow selective targeting of tongue tumors. Further studies investigating the relationship between Bremachlorin concentration and therapeutic efficacy PDT with long incubation times are warranted.

Topics: Animals; Carcinoma, Squamous Cell; Chlorophyllides; Drug Combinations; Mice; Mice, Inbred BALB C; Microscopy, Confocal; Photochemotherapy; Photosensitizing Agents; Porphyrins; Random Allocation; Tongue Neoplasms

Over-expression of histamine receptors has been reported in several types of malignancies. Earlier we have successfully demonstrated use of chlorin p6-histamine conjugate (Cp6-his) for improving cellular uptake and photo toxicity of Cp6 in oral cancer cell lines. In the present study, after having confirmed that histamine receptors are over-expressed in tumors of hamster cheek pouch, we investigated the efficacy of Cp6-his for photodynamic treatment (PDT) of tumors in this animal model.. Cp6-his (3mg/kg body weight) was injected intraperitoneally and its accumulation in tumor, surrounding tissue, normal mucosa and abdominal skin was monitored non-invasively by fluorescence spectroscopy. For PDT, tumors at 4h after Cp6-his administration were exposed to red light (660±25nm, 100J/cm(2)). Tumor damage and regression were assessed by histology and tumor volume measurements, respectively. Expression of histamine H2 receptors in tumor and normal mucosa was assessed by immuno-staining.. The accumulation of Cp6-his was higher in tumors as compared to normal mucosa at 4h after its administration. For Cp6 similar preferential accumulation was observed except that in normal mucosa the accumulation of Cp6 was more as compared to Cp6-his. The clearance of Cp6-his from skin was rapid showing ∼80% decrease within 48h from its peak level at 4h after drug injection. PDT led to extensive cellular damage and tumors of size up to ∼1000mm(3) regressed completely one week after PDT.. Higher tumor selectivity of Cp6-his and complete regression of bigger tumors after PDT suggest that conjugating Cp6 to histamine is a promising approach to improve PDT efficacy.

Topics: Animals; Carcinoma, Squamous Cell; Cell Line, Tumor; Cheek; Cricetinae; Disease Models, Animal; Histamine; Humans; Male; Mesocricetus; Mouth Neoplasms; Photosensitizing Agents; Porphyrins; Treatment Outcome

We investigated tumor regression and the mode of tumor cell death induced by photodynamic treatment (PDT) with chlorin p(6) (Cp(6)) in hamster cheek pouch model of oral squamous cell carcinoma. Cp(6) was administered systemically through intraperitoneal injection and after 4h the tumors were subjected to photodynamic treatment using red light (660±25nm, fluence ∼100J/cm(2)). Tumor response to PDT was monitored by measuring the tumor volume before PDT and 1week after. Results show that smaller tumors (⩽80mm(3)) regressed completely after PDT with Cp(6) dose of 2.0mg/kg body weight and for the bigger tumors (∼180mm(3)) higher dose of Cp(6) (4.0mg/kg) was more effective. Tumors treated with lower Cp(6) dose showed infiltration of immune cells, absence of TUNEL labeling, smeared pattern of DNA fragmentation and no significant increase in caspase-3 activity suggestive of necrotic cell death and inflammation. In tumors treated with higher Cp(6) dose, features characteristic of apoptotic cell death such as extensive TUNEL positive labeling, increase in caspase-3 activity and laddered pattern of DNA fragmentation were observed and there was no infiltration of immune cells. PDT with Cp(6) was also found to lead to expression of matrix metalloprotease-9 (MMP-9) which was greater at lower drug dose PDT as compared to higher drug dose PDT. These results suggest that drug dose plays an important role in determining the mechanism of tumor cell death and effectiveness of PDT.

Topics: Animals; Carcinoma, Squamous Cell; Caspase 3; Cell Death; Cheek; Cricetinae; Dose-Response Relationship, Drug; Female; Models, Animal; Mouth Mucosa; Mouth Neoplasms; Photochemotherapy; Photosensitizing Agents; Porphyrins; Remission Induction; Tumor Burden

We studied pharmacokinetics and tumor response to photodynamic therapy (PDT) using chlorin p6 (CP6) in hamster cheek pouch model. CP6 was administered either intraperitoneally (IP) at a dose of 1.5 mg/kg body weight or applied topically at 1.0 mg/kg body weight and its accumulation in tumor, normal mucosa, and abdominal skin was measured by optical fiber-based fluorescence spectroscopy. Photodynamic therapy was performed by superficial illumination of tumor with 660 nm (+/-25 nm) light at a fluence rate of 100J/cm2 and tumor response to PDT was analyzed by histological examination. CP6 accumulation was higher in tumors as compared to adjoining tissue and normal mucosa at 4-6h after its IP administration. For relatively large tumors (size >8mm) topical application was observed to be more effective than IP. The level of CP6 in tumor, surrounding tissue, normal mucosa and skin was seen to decrease rapidly within 24h after its administration and was undetectable at longer time (>72 h) intervals. PDT of small tumors at 4h after IP injection of CP6 resulted in complete tumor necrosis. Whereas, PDT of large tumors receiving CP6 topically caused necrosis in 300-800 microm superficial region of the tumor. In one animal kept for follow up in each treatment group, it was observed that small tumors disappeared completely leaving scar tissue, while large tumor had significant reduction in tumor size. The use of CP6 for PDT of oral cancer is suggested.

Topics: Animals; Carcinoma, Squamous Cell; Cheek; Cricetinae; Drug Screening Assays, Antitumor; Male; Models, Animal; Mouth Mucosa; Mouth Neoplasms; Photochemotherapy; Photosensitizing Agents; Porphyrins