Cationic ceramides and analogues, LCL30 and LCL85, as adjuvants to photodynamic therapy of tumors

Abstract

Photodynamic therapy (PDT) is known to alter the expression of various genes in treated cells. This prompted us to examine the activity of genes encoding two important enzymes in sphingolipid (SL) metabolism, dihydroceramide desaturase (DES) and sphingosine kinase (SPHK), in mouse SCCVII tumor cells treated by PDT using either the porphyrin-based photosensitizer Photofrin or silicon phthalocyanine Pc4. The results revealed that PDT induced an upregulation in the expression of two major isoforms of both genes (DES1 and DES2 as well as SPHK1 and SPHK2). While the changes were generally moderate (2-3 fold gains), the increase in DES2 expression was more pronounced and it was much greater with Photofrin-PDT than with Pc4-PDT (over 23-fold vs. less than 5-fold). Combining either Photofrin-PDT or Pc4-PDT with the cationic C16-ceramide LCL30 (20 mg/kg i.p.) for treatment of subcutaneously growing SCCVII tumors rendered important differences in the therapy outcome. Photofrin-PDT, used at a dose that attained good initial response but no tumor cures, produced 50% cures when combined with a single LCL30 treatment. In contrast, the same LCL30 treatment combined with Pc4-PDT had no significant effect on tumor response. The optimal timing of LCL30 injection was immediately after Photofrin-PDT. The therapeutic benefit was lost when LCL30 was given in two 20 mg/kg injections encompassing intervals before and after PDT. LCL85, the cationic B13 ceramide analogue and SL-modulating agent, also increased cure rates of Photofrin-PDT treated tumors, but the therapeutic benefit was less pronounced than with LCL30. These results with LCL30 and LCL85, and our previous findings for LCL29 (another SL analogue), assert the potential of SLs for use as adjuvants to augment the efficacy of PDT-mediated tumor destruction.

Enhanced apoptotic cancer cell killing after Foscan photodynamic therapy combined with fenretinide via de novo sphingolipid biosynthesis pathway

“…1). Thus HPR shares with several other sphingolipid metabolism-modulating drugs the potential to enhance PDT-mediated tumor cures [22, 23]. …”

Ceramide and sphingosine-1-phosphate act as photodynamic therapy-elicited damage-associated molecular patterns: Cell surface exposure

“…Such drug alone effect was not observed with Temoporfin, ce6 and Pc4 at the concentrations used for PDT. The above differences between Photofrin- and Pc4-PDT in vitro may have relevance for the therapy outcome in vivo , as evidenced by superior control of SCCVII tumors by Photofrin-PDT compared to Pc4-PDT when combined with sphingolipid modulating agents [28]. …”

Interaction of acid ceramidase inhibitor LCL521 with tumor response to photodynamic therapy and photodynamic therapy‐generated vaccine

“…Total RNA, extracted from either spleen, tumor‐draining lymph nodes (inguinal) or thymus of mice using Trizol and cleaned with Qiagen Min Elute (Qiagen Canada, Montreal, QC, Canada) was used for generating complementary strand DNA transcripts, which were then amplified by quantitative RT‐PCR in presence of primers specific for investigated mouse genes that were designed and tested in our laboratory. Further details were described earlier . The Foxp3 primers were listed elsewhere .…”

“…We have demonstrated that several sphingolipid metabolism‐modulating compounds, including short‐chain and long‐chain ceramide analogues (LCL 29 and LCL30, respectively) as well as a B13 analogue (LCL85), were effective in improving therapeutic outcome of tumor photodynamic therapy (PDT) . Destruction of tumors by PDT, which is a clinically established modality for treatment of various malignant and nonmalignant lesions, is initiated by the generation of cytotoxic oxygen species formed upon the interaction of molecular oxygen in cells of targeted lesion with light energy‐excited molecules of photosensitizing drug administered to the patient .…”