Patient's attitudes and perceptions around attending oncology consultations following surgery for colorectal cancer: A qualitative study

Background: The oncology consultation following surgery for colorectal cancer (CRC) is usually the first step in the receipt of chemotherapy. Non-compliance with this consultation results in non-receipt of recommended chemotherapy, when appropriate, and worse clinical outcomes. This study sought to explore South African patients' attitudes and perceptions around attending scheduled oncology consultations following their CRC surgery. Methods: Semi-structured qualitative interviews were conducted with patients who had surgery for CRC at a quaternary South African hospital and who had to decide whether they would return for an oncology consultation. The "Model of health services use" informed the design of the interview guide, which included questions on factors that impact health seeking behavior. Demographics of participants, CRC disease stage, and compliance with scheduled oncology consultations were also collected. Descriptive statistics were used to analyse the quantitative data, while deductive thematic analysis was used to analyse the qualitative data. Results: Seven participants were interviewed. The median age was 60.0 years and four participants (57.1%) were female. Black African, White, and Asian participants accounted for 85.7% of the study sample. Most participants had stage III CRC (71.4%). The oncology consultation no-show rate was 14.3%. Participant's knowledge and beliefs around CRC proved to be an important predisposing factor that influenced follow-up decisions. Family support and religion were cited as important enabling factors. Travel costs to the hospital and frustrations related to the clinic appointment booking/scheduling process were cited as important disabling factors. Lastly, the participant's self-perceived need for additional oncology care also appeared to influence their decision to return for ongoing oncology consultation after the initial surgery. Conclusion: Several contextual factors can potentially influence a patient's compliance with a scheduled oncology consultation following CRC surgery. A multipronged approach which addresses these factors is required to improve compliance with oncology consultations.

Combination of long-acting TRAIL and tumor cell-targeted photodynamic therapy as a novel strategy to overcome chemotherapeutic multidrug resistance and TRAIL resistance of colorectal cancer

Chemotherapeutic multidrug resistance (MDR) is the major hindrance for clinical therapy of colorectal cancer (CRC). Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) with selective cytotoxicity might overcome MDR of CRC cells. Unfortunately, cross-resistance to TRAIL has been detected in many CRC cells, suggesting the need to combine TRAIL with sensitizers to combat refractory CRC. Our purpose is to explore the potential of combination therapy of TRAIL and tumor-cell targeted photodynamic therapy (PDT) in combating CRC with both chemotherapeutic MDR and TRAIL resistance.

Methods: Tumor cell-targeted PDT was performed using a Ze-IR700 photosensitizer with high affinity for epidermal growth factor receptor (EGFR). The impact of PDT on the gene expression of CRC cells was revealed by RNA sequencing. The synergistic antitumor effect of long-acting TRAIL and PDT was evaluated in mice bearing tumor grafts of CRC cells with both chemotherapeutic MDR and TRAIL resistance.

Results: Chemotherapeutic MDR and TRAIL resistance are common in CRC cells. Pretreatment of CRC cells with tumor cell-targeted PDT significantly (10-60 times) increased the sensitivity of these CRC cells to TRAIL by upregulating death receptors. Combination therapy, but not monotherapy, of long-acting TRAIL and PDT greatly induced apoptosis of CRC cells, thus efficiently eradicated large (~150 mm³) CRC tumor xenografts in mice.

Conclusions: Tumor cell-targeted PDT extensively sensitizes CRC cells to TRAIL. Combination therapy of long-acting TRAIL and PDT is promising to combat CRC with both chemotherapeutic MDR and TRAIL resistance, which might be developed as a novel strategy for precision therapy of refractory CRC.

Connexin 43 enhances oxaliplatin cytotoxicity in colorectal cancer cell lines

Oxaliplatin, a platinum-based chemotherapeutic agent, is an important first-line drug in the treatment of colorectal cancers, but drug resistance causes treatment failure. It has been reported that gap junctional communication can enhance the cytotoxicity of platinum drugs.  The gap junction formed of connexin proteins provides a direct pathway for electrical and metabolic cell-cell interaction. The voltage-dependent gating of gap junction allows small hydrophilic molecules and ions to permeate to adjacent cells. Connexin 43 is a diagnostic marker for cancer therapy and the predominant connexin isoform in many cell types. The purpose of this study was to investigate the role of connexin 43 in oxaliplatin activity by using colorectal cancer cell lines. LoVo and HCT116 cell lines were used for analysis. Connexin 43 expression was confirmed by western blot and immunocytochemistry. MTT, western blot, "Parachute" dye-coupling assays and reactive oxygen species measurement were used to detect cytotoxicity and the inhibition of connexin 43 expression induced by oxaliplatin. Results showed that connexin 43 enhanced oxaliplatin cytotoxicity through gap junctional communication function and high concentration of oxaliplatin inhibited connexin 43 expression to counteract its cytotoxicity. This study suggested that connexin 43 could be considered a molecular target of oxaliplatin activity in colorectal cancer.