Roles for growth factors and mutations in metastatic dissemination

Mechanisms of Melanoma Progression and Treatment Resistance: Role of Cancer Stem-like Cells

Melanoma is the third most common type of skin cancer, characterized by its heterogeneity and propensity to metastasize to distant organs. Melanoma is a heterogeneous tumor, composed of genetically divergent subpopulations, including a small fraction of melanoma-initiating cancer stem-like cells (CSCs) and many non-cancer stem cells (non-CSCs). CSCs are characterized by their unique surface proteins associated with aberrant signaling pathways with a causal or consequential relationship with tumor progression, drug resistance, and recurrence. Melanomas also harbor significant alterations in functional genes (BRAF, CDKN2A, NRAS, TP53, and NF1). Of these, the most common are the BRAF and NRAS oncogenes, with 50% of melanomas demonstrating the BRAF mutation (BRAFV600E). While the successful targeting of BRAFV600E does improve overall survival, the long-term efficacy of available therapeutic options is limited due to adverse side effects and reduced clinical efficacy. Additionally, drug resistance develops rapidly via mechanisms involving fast feedback re-activation of MAPK signaling pathways. This article updates information relevant to the mechanisms of melanoma progression and resistance and particularly the mechanistic role of CSCs in melanoma progression, drug resistance, and recurrence.

Proteomic profiling and network biology of colorectal cancer liver metastasis

INTRODUCTION

Tissue-based proteomic studies of colorectal cancer (CRC) metastasis have delivered fragmented results, with very few therapeutic targets and prognostic biomarkers moving beyond the discovery phase. This situation is likely due to the difficulties in obtaining and analyzing large numbers of patient-derived metastatic samples, the own heterogeneity of CRC, and technical limitations in proteomics discovery. As an alternative, metastatic CRC cell lines provide a flexible framework to investigate the underlying mechanisms and network biology of metastasis for target discovery.

AREAS COVERED

In this perspective, we comment on different in-depth proteomic studies of metastatic versus non-metastatic CRC cell lines. Identified metastasis-related proteins are introduced and discussed according to the spatial location in different cellular fractions, with special emphasis on membrane/adhesion proteins, secreted proteins, and nuclear factors, including miRNAs associated with liver metastasis. Moreover, we analyze the biological significance and potential therapeutic applications of the identified liver metastasis-related proteins.

EXPERT OPINION

The combination of protein discovery and functional analysis is the only way to accelerate the progress to clinical translation of the proteomic-derived findings in a relatively fast pace. Patient-derived organoids represent a promising alternative to patient tissues and cell lines, but further optimizations are still required for achieving solid and reproducible results.

The efficacy and timing of adjuvant chemotherapy in upper tract urothelial carcinoma

BACKGROUND

A recovery period between surgery and initiation of adjuvant chemotherapy (AC) is common in patients with upper tract urothelial carcinoma (UTUC), which can progress after a relatively long time. Therefore, the efficacy of AC initiated within 90 days after radical nephroureterectomy (RNU) was evaluated in UTUC patients at stage ≥pT2 (N0-3M0), in addition to the effect of delayed AC initiation on survival outcomes.

METHODS

Clinical data for 428 UTUC patients diagnosed with transitional cell carcinoma with postoperatively confirmed pathological stages, muscle-invasive or greater-stage (pT2-4) disease, any nodal status, and metastasis-free (M0) disease were retrospectively analyzed. All patients who received AC were treated within 90 days after RNU and underwent at least 4 cycles of the AC procedure. Then, patients receiving AC were divided into the "within 45 days" and "45 to 90 days" groups according to the time interval between RNU and AC initiation. Their clinicopathological characteristics were evaluated and the survival outcomes of the 2 groups were compared. Any adverse events that occurred during the AC process were also recorded.

RESULTS

A total of 428 patients were analyzed in the study, including 132 individuals who underwent the AC procedure with platinum in combination with gemcitabine within 90 days after RNU and 296 patients who failed to initiate AC within 90 days. The median age of all patients was 68 years (mean 67, range 28-90 years), and the median follow-up was 25 months (mean 36, range 1-129 months). There were no significant differences in age, sex, lymph node metastasis, tumor location, hydronephrosis status, hematuria status, cancer grade, or multifocality between the 2 groups. Individuals undergoing AC initiated within 90 days of RNU showed a significantly decreased mortality relative to those patients who did not receive AC. Shorter intervals between RNU and AC initiation within 45 days vs. 45-90 days did not improve patient OS and cancer-specific survival (CSS) and may have increased the incidence of adverse events.

CONCLUSION

The present study data supported the finding that a platinum-based combination with gemcitabine regimen initiated postoperatively significantly improved OS and CSS in patients with UTUC at stages ≥pT2 (N0-3M0). Furthermore, no survival benefit was evident in patients who started AC within 45 days after RNU compared to those who received AC within 45 to 90 days.

Vessel co-option and angiotropic extravascular migratory metastasis: a continuum of tumour growth and spread?

Two fields of cancer research have emerged dealing with the biology of tumour cells localised to the abluminal vascular surface: vessel co-option (VCo), a non-angiogenic mode of tumour growth and angiotropic extravascular migratory metastasis (EVMM), a non-hematogenous mode of tumour migration and metastasis. VCo is a mechanism by which tumour cells gain access to a blood supply by spreading along existing blood vessels in order to grow locally. Angiotropic EVMM involves "pericytic mimicry" (PM), which is characterised by tumour cells continuously migrating in the place of pericytes distantly along abluminal vascular surfaces. When cancer cells are engaged in PM and EVMM, they migrate along blood vessels beyond the advancing front of the tumour to secondary sites with the formation of regional and distant metastases. In the present perspective, the authors review the current scientific literature, emphasising the analogies between embryogenesis and cancer progression, the re-activation of embryonic signals by "cancer stem cells", and the important role of laminins and epithelial-mesenchymal-transition. This perspective maintains that VCo and angiotropic EVMM constitute complementary processes and represent a continuum of cancer progression from the primary tumour to metastases and of tumour growth to EVMM, analogous to the embryonic development program.